EP4650687A1 - Refrigerant circulation pipe and refrigeration apparatus - Google Patents

Refrigerant circulation pipe and refrigeration apparatus

Info

Publication number
EP4650687A1
EP4650687A1 EP25172612.1A EP25172612A EP4650687A1 EP 4650687 A1 EP4650687 A1 EP 4650687A1 EP 25172612 A EP25172612 A EP 25172612A EP 4650687 A1 EP4650687 A1 EP 4650687A1
Authority
EP
European Patent Office
Prior art keywords
refrigerant
heat exchanger
plate
type water
refrigerant circulation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP25172612.1A
Other languages
German (de)
French (fr)
Inventor
Ryoto Tasaka
Hiroshi Arashima
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Intellectual Property Management Co Ltd
Original Assignee
Panasonic Intellectual Property Management Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Panasonic Intellectual Property Management Co Ltd filed Critical Panasonic Intellectual Property Management Co Ltd
Publication of EP4650687A1 publication Critical patent/EP4650687A1/en
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B13/00—Compression machines, plants or systems, with reversible cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2339/00—Details of evaporators; Details of condensers
    • F25B2339/04—Details of condensers
    • F25B2339/043—Condensers made by assembling plate-like or laminated elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2339/00—Details of evaporators; Details of condensers
    • F25B2339/04—Details of condensers
    • F25B2339/047—Water-cooled condensers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/01—Geometry problems, e.g. for reducing size
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B39/00—Evaporators; Condensers
    • F25B39/02—Evaporators
    • F25B39/022—Evaporators with plate-like or laminated elements

Definitions

  • the present disclosure relates to a refrigerant circulation pipe and a refrigeration apparatus.
  • Japanese Patent Laid-Open No. 61-62756 discloses a refrigerant supply apparatus that evenly supplies a gas-liquid two-phase refrigerant to individual evaporation tubes of a dry evaporator.
  • the refrigerant supply apparatus includes a refrigerant distribution apparatus connected to an expansion valve, and a pressure reducing apparatus connecting the refrigerant distribution apparatus and the dry evaporator.
  • the present disclosure provides a refrigerant circulation pipe and a heat exchanger capable of easily making a refrigerant flowing into a plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • a refrigerant circulation pipe is a refrigerant circulation pipe that is connected to a plate-type water-refrigerant heat exchanger and is provided between the plate-type water-refrigerant heat exchanger and an expansion valve, the refrigerant circulation pipe including: a plurality of straight sections extending linearly; and a plurality of curved sections that connect ends of the straight sections and are curved, wherein a bend angle at each of the curved sections is an obtuse angle or a right angle.
  • a refrigeration apparatus includes: an expansion valve; a plate-type water-refrigerant heat exchanger; and a refrigerant circulation pipe connected to the plate-type water-refrigerant heat exchanger and provided between the expansion valve and the plate-type water-refrigerant heat exchanger, wherein the refrigerant circulation pipe includes a plurality of straight sections that extend linearly, and a plurality of curved sections that connect ends of the straight sections and are curved, a bend angle at each of the curved sections being an obtuse angle or a right angle.
  • the refrigerant circulation pipe and the refrigeration apparatus allows the refrigerant to flow into the plate-type water-refrigerant heat exchanger while reducing effect of centrifugal force, the refrigerant having flowed into the refrigerant circulation pipe from the expansion valve in a gas-liquid two-phase state. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • apparatuses using refrigeration cycles each commonly made a refrigerant having passed through an expansion valve into a gas-liquid two-phase state, and then allowed the refrigerant to flow into an evaporator. For this reason, a problem in the industry was to improve the efficiency of heat exchange in the evaporator. To solve this problem, a technique had been proposed to cause the refrigerant distributed by the refrigerant distribution apparatus to reduce in pressure and to flow into the evaporator in parallel in order to distribute the gas phase and the liquid phase evenly to individual portions of the evaporator.
  • a plate-type water-refrigerant heat exchanger has only one inlet and one outlet for the refrigerant in many cases even when having a plurality of channels; and needs to receive the refrigerant in a mixed state of the gas phase and the liquid phase in order to evenly distribute the gas phase and the liquid phase.
  • the inventors have come to compose the subject of the present disclosure.
  • the present disclosure provides a refrigerant circulation pipe and a heat exchanger capable of easily making a refrigerant flowing into a plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • Embodiment 1 will be described below with reference to the drawings.
  • FIG 1 is a diagram showing a refrigeration circuit of a refrigeration apparatus 1 according to Embodiment 1.
  • the refrigeration apparatus 1 is an outdoor unit of a heat-pump-type hot water supply heater.
  • the hot water supply heater is an apparatus that heats a room by allowing water heated by a refrigeration cycle of the refrigeration apparatus 1 to flow to a heat exchanger of an indoor unit.
  • the hot water supply heater of this embodiment can also perform cooling operation by allowing water cooled by the refrigeration cycle of the refrigeration apparatus 1 to flow to the indoor unit.
  • the flow of a refrigerant and water in the cooling operation of the hot water heater is indicated by arrows.
  • the refrigeration apparatus 1 is provided with a compressor 2.
  • the compressor 2 is an apparatus that sucks in, compresses, and discharges the refrigerant.
  • a flow path switching mechanism 3 is connected to the discharge side and suction side of the compressor 2.
  • the flow path switching mechanism 3 switches the destination of the refrigerant discharged by the compressor 2 between an air heat exchanger 4 and a plate-type water-refrigerant heat exchanger 10, and causes either of the heat exchangers 4, 10 at the destination to function as a condenser.
  • the flow path switching mechanism 3 also causes the compressor 2 to suck in the refrigerant that has passed through the evaporator that is either of the heat exchangers 4 and 10.
  • the flow path switching mechanism 3 is, for example, a four-way valve.
  • the air heat exchanger 4 is a heat exchanger that exchanges heat between the internal refrigerant and the outside air.
  • the air heat exchanger 4 is, for example, a fin-tube type heat exchanger.
  • the refrigeration apparatus 1 is provided with blowers 5 that allow outside air to flow to the air heat exchanger 4.
  • the blowers 5 are axial fans.
  • the plate-type water-refrigerant heat exchanger 10 is a plate type heat exchanger that exchanges heat between the refrigerant flowing inside and water.
  • the water heated or cooled by the plate-type water-refrigerant heat exchanger 10 circulates between the refrigeration apparatus 1 and the indoor unit to air-condition the room.
  • the air heat exchanger 4 and the plate-type water-refrigerant heat exchanger 10 are connected via an expansion valve 6. Between the plate-type water-refrigerant heat exchanger 10 and the expansion valve 6, there is a receiver tank 46 that stores low-temperature, high-pressure liquid-phase refrigerant cooled by the condenser (see Figure 2 ).
  • the expansion valve 6 is a valve that reduces the pressure of the refrigerant flowing in it from the condenser, which is either of the heat exchangers 4, 10, through the receiver tank 46 to make the refrigerant into the refrigerant in a gas-liquid two-phase state, and allows the refrigerant to flow into the evaporator, which is the other of the heat exchangers 4, 10.
  • the opening degree of the expansion valve 6 can be adjusted by electronic control, and changing the opening degree adjusts the flow rate of the refrigerant.
  • Figure 2 is a perspective view showing an inside of the refrigeration apparatus 1.
  • symbol X indicates the left side of the refrigeration apparatus 1
  • symbol Y indicates the front side of the refrigeration apparatus 1
  • symbol Z indicates the upper side.
  • the inside of the refrigeration apparatus 1 includes: a blower room 7 that is a space defined on the left side of the partition plate 9; and a machine room 8 that is a space defined on the right side of the partition plate 9.
  • the partition plate 9 is made of sheet metal and is provided in a position that is approximately perpendicular to the left-right direction.
  • the blower room 7 is provided with the air heat exchanger 4 and the blowers 5.
  • the air heat exchanger 4 is provided on the left side surface and rear surface of the blower room 7.
  • the blowers 5 blow the air inside the refrigeration apparatus 1 forward to suck in outside air through the air heat exchanger 4, and exchange heat between the outside air and the refrigerant inside the air heat exchanger 4.
  • the refrigeration apparatus 1 is described as an example in which two blowers 5 are provided so as to be lined up one above the other in the blower room 7, but there is no particular limit to the number of blowers 5 in the refrigeration apparatus 1.
  • the machine room 8 is provided with the compressor 2, the flow path switching mechanism 3, the expansion valve 6, the receiver tank 46, and the plate-type water-refrigerant heat exchanger 10.
  • the compressor 2 is placed on the bottom plate 1a of the refrigeration apparatus 1 via rubber legs.
  • the flow path switching mechanism 3 is placed above the compressor 2.
  • the plate-type water-refrigerant heat exchanger 10 is provided at a position spaced above the bottom plate 1a via a support member 8a made of sheet metal.
  • Figure 3 is an enlarged view of Figure 2 .
  • Figure 4 is a side view showing the internal configuration of the refrigeration apparatus 1, and shows the inside of the refrigeration apparatus 1 as viewed from the right side.
  • the plate-type water-refrigerant heat exchanger 10 is provided with a first refrigerant-side connection port 11 and a second refrigerant-side connection port 12.
  • Each refrigerant-side connection port 11, 12 is an opening that communicates with the flow path through which the refrigerant flows in the plate-type water-refrigerant heat exchanger 10.
  • the first refrigerant-side connection port 11 is formed at the front lower end of the right side surface of the plate-type water-refrigerant heat exchanger 10.
  • the second refrigerant-side connection port 12 is formed above the first refrigerant-side connection port 11 on the right side surface of the plate-type water-refrigerant heat exchanger 10.
  • a refrigerant circulation pipe 30 is connected to the first refrigerant-side connection port 11.
  • the refrigerant circulation pipe 30 is a refrigerant pipe provided between the first refrigerant-side connection port 11 and the expansion valve 6.
  • the refrigerant circulation pipe 30 is connected to the first refrigerant-side connection port 11 and the pipe 47 in detail.
  • the pipe 47 is connected to the receiver tank 46.
  • the gas side pipe 13 is connected to the second refrigerant-side connection port 12.
  • the gas side pipe 13 is a refrigerant pipe extending from the second refrigerant-side connection port 12 and connected to the flow path switching mechanism 3.
  • the gas side pipe 13 allows mainly gas refrigerant with a large specific volume to flow, and it has a larger diameter than the refrigerant circulation pipe 30 through which liquid refrigerant or refrigerant in a gas-liquid two-phase state flows.
  • the plate-type water-refrigerant heat exchanger 10 is provided with a first water-side connection port 14 and a second water-side connection port 15.
  • Each water-side connection port 14, 15 is an opening that communicates with the flow path through which water flows in the plate-type water-refrigerant heat exchanger 10.
  • the first water-side connection port 14 is provided at the rear lower end of the right side surface of the plate-type water-refrigerant heat exchanger 10.
  • the second water-side connection port 15 is provided above the first water-side connection port 14 on the right side surface of the plate-type water-refrigerant heat exchanger 10.
  • the first water-side connection port 14 is connected to the discharge side of a circulation pump 16 that circulates water.
  • a valve 16a is provided that protrudes rearward to the outside of the refrigeration apparatus 1 and can be connected to a water pipe outside the refrigeration apparatus 1.
  • the second water-side connection port 15 is provided with a gas-liquid separator 17 to remove gas from the water flowing out of the plate-type water-refrigerant heat exchanger 10.
  • a valve 18a is provided that can be connected to a water pipe outside the refrigeration apparatus 1 via an outlet-side water pipe 18.
  • a flow rate sensor 19 that measures the flow rate of water is provided in the outlet-side water pipe 18.
  • FIG. 5 is a perspective view of a refrigerant circulation pipe 30.
  • the refrigerant circulation pipe 30 includes five straight sections 31 to 35 that extend linearly, and four curved sections 36 to 39 that connect adjacent straight sections 31 to 35.
  • Figure 6 is a front view of the refrigerant circulation pipe 30, showing the refrigerant circulation pipe 30 as viewed from the front.
  • Figure 7 is a side view of the refrigerant circulation pipe 30, showing the refrigerant circulation pipe 30 as viewed from the right.
  • Figure 8 is a top view of the refrigerant circulation pipe 30, showing the refrigerant circulation pipe 30 as viewed from above.
  • the first straight section 31 that is parallel to the left-right direction is formed at the lower end of the refrigerant circulation pipe 30. In other words, the first straight section 31 extends horizontally. The left end of the first straight section 31 is connected to the first refrigerant-side connection port 11.
  • the right end of the first straight section 31 is connected to the first curved section 36.
  • the first curved section 36 is a part of the refrigerant circulation pipe 30, the part curving upward from the right end of the first straight section 31.
  • the upper end of the first curved section 36 is connected to the lower end of the second straight section 32.
  • the second straight section 32 is a part of the refrigerant circulation pipe 30, the part extending linearly in the up-down direction. More specifically, in this embodiment, the second straight section 32 extends linearly parallel to the vertical up-down direction. As shown in Figure 6 , the length L2 of the second straight section 32 is longer than the length L1 of the first straight section 31.
  • the bend angle A1 at the first curved section 36 is a right angle.
  • the bend angle A1 is, in other words, the angle between the first straight section 31 and the second straight section 32.
  • the bend angles A1 to A4 of the respective curved sections 36 to 39 each mean an angle between two of the straight sections 31 to 35 connected to opposite ends of the corresponding curved section among the curved sections 36 to 39.
  • each of the curved sections 36 to 39 is closer to a straight line, compared to a case in which the curved sections 36 to 39 include a small bend angle.
  • the upper end of the second straight section 32 is connected to the lower end of the second curved section 37.
  • the second curved section 37 is a part of the refrigerant circulation pipe 30, the part curving leftward and frontward from the upper end of the second straight section 32.
  • the bend angle A2 of the second curved section 37 is a right angle.
  • the left front end of the second curved section 37 is connected to the third straight section 33.
  • the third straight section 33 is a part of the refrigerant circulation pipe 30, the part linearly extending leftward and frontward from the left front end of the second curved section 37. More specifically, the third straight section 33 horizontally extends leftward and frontward.
  • the left front end of the third straight section 33 is connected to the right rear end of the third curved section 38.
  • the third curved section 38 is a part of the refrigerant circulation pipe 30, the part diagonally curving upward, leftward, and frontward from the left front end of the third straight section 33.
  • the bend angle A3 of the third curved section 38 is an obtuse angle.
  • the upper end of the third curved section 38 is connected to the lower end of the fourth straight section 34.
  • the fourth straight section 34 is a part of the refrigerant circulation pipe 30, the part linearly extending from the upper end of the third curved section 38 in a direction in which the left front side is located upward.
  • the upper end of the fourth straight section 34 is connected to the lower end of the fourth curved section 39.
  • the fourth curved section 39 is a part of the refrigerant circulation pipe 30, the part curving leftward from the upper end of the fourth straight section 34.
  • the bend angle A4 of the fourth curved section 39 is an obtuse angle.
  • the left end of the fourth curved section 39 is connected to the right end of the fifth straight section 35.
  • the fifth straight section 35 is a part of the refrigerant circulation pipe 30, the part linearly extending leftward from the left end of the fourth curved section 39. More specifically, the fifth straight section 35 horizontally extends leftward.
  • the left end of the fifth straight section 35 is connected to the right end of the pipe 47.
  • the pipe 47 is connected to the receiver tank 46, so that the fifth straight section 35 is connected to the expansion valve 6 via the pipe 47 and the receiver tank 46.
  • the fifth straight section 35 is formed with a protrusion 35a that protrudes radially outward for positioning with respect to the pipe 47.
  • the refrigerant circulation pipe 30 is configured by fixing the first pipe member 41, the second pipe member 43, and the connection pipe 45 by brazing.
  • the first pipe member 41 is a hollow member with a circular cross section in the refrigerant circulation pipe 30, the hollow member including almost the entire first straight section 31, the entire first curved section 36, and almost the entire second straight section 32 except for the upper end.
  • the second pipe member 43 is a hollow member with a circular cross section in the refrigerant circulation pipe 30, the hollow member including the upper end of the second straight section 32, the second curved section 37, the third straight section 33, the third curved section 38, the fourth straight section 34, the fourth curved section 39, and the fifth straight section 35.
  • the connection pipe 45 is a hollow member with a circular cross section that is provided in the first straight section 31 and extends in the left-right direction.
  • Figure 9 is a cross-sectional view showing IX-IX cross section of Figure 7 , and shows the brazed part between the first pipe member 41 and the second pipe member 43 cut at a cross section perpendicular to the front-rear direction.
  • the upper end of the first pipe member 41 which is inserted into the lower end of the second pipe member 43, is brazed to the second pipe member 43. Therefore, the outer diameter D2 of the first pipe member 41 is equal to or smaller than the inner diameter D3 of the second pipe member 43, and the inner diameter D1 of the first pipe member 41 is smaller than the inner diameter D3 of the second pipe member 43.
  • the inner diameter D1 of the first pipe member 41 on the side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than the inner diameter D3 of the second pipe member 43 on the side closer to the expansion valve 6 (the side closer to the receiver tank 46).
  • the first pipe member 41 has a protrusion 42a protruding radially outward. The protrusion 42a comes in contact with the end surface of the second pipe member 43 to position the first pipe member 41 and the second pipe member 43.
  • Figure 10 is a cross-sectional view showing X-X cross section of Figure 8 , and shows the brazed part between the first pipe member 41 and the connection pipe 45 cut at a cross section perpendicular to the front-rear direction.
  • the connection pipe 45 which is placed over the outside of the first pipe member 41, is brazed to the first pipe member 41. Therefore, the outer diameter D2 of the first pipe member 41 is equal to or smaller than the inner diameter D5 of the connection pipe 45, and the inner diameter D1 of the first pipe member 41 is smaller than the inner diameter D5 of the connection pipe 45.
  • the first pipe member 41 has a protrusion 42b protruding radially outward.
  • the protrusion 42b comes into contact with the end surface of the connection pipe 45 to position the first pipe member 41 and the connection pipe 45.
  • the inner diameter D5 and the outer diameter D6 of the connection pipe 45 are made into a size that allows the connection pipe 45 to connect to the first refrigerant-side connection port 11 of the plate-type water-refrigerant heat exchanger 10.
  • the inner diameter D5 and outer diameter D6 of the connection pipe 45 are substantially equal to the inner diameter D3 and outer diameter D4 of the second pipe member 43.
  • the left end of the first pipe member 41 extends leftward to a position that is approximately aligned with the left end of the connection pipe 45. Therefore, the inner diameter of the substantially entire range of the first straight section 31 is the same as the inner diameter D1 of the first pipe member 41.
  • the inventors have conducted an experiment to verify the suitable sizes of the inner diameter D1 and the outer diameter D2 for a refrigerant circulation rate in the refrigeration circuit of the refrigeration apparatus 1, that is, a refrigerant circulation rate passing through the inside of the refrigerant circulation pipe 30.
  • the outer diameter D2 is preferably 7.94 mm or less.
  • the suitable range of the outer diameter D2 is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate passing through the inside of the refrigerant circulation pipe 30.
  • the relationship between the refrigerant circulation rate and the inner diameter D1 and the outer diameter D2 will be explained in the examples described later.
  • the refrigeration apparatus 1 is capable of operating in an energy saving mode.
  • the energy saving mode is an operation mode in which the compressor 2 is driven at a lower capacity than the full capacity in order to save energy in the refrigeration apparatus 1.
  • the refrigerant circulation rate passing through the refrigerant circulation pipe 30 is less than the refrigerant circulation rate in the operation mode in which the full capacity of the compressor 2 is used.
  • the refrigerant circulation rate in cooling operation in the energy saving mode of the refrigeration apparatus 1, the refrigerant circulation rate is 2.27 kg/min, the outer diameter D2 is 7.94 mm, and the outer diameter D2 per refrigerant circulation rate of 1.0 kg/min is 3.50 mm.
  • the flow path switching mechanism 3 allows the refrigerant discharged from the compressor 2 to flow to the air heat exchanger 4 to dissipate heat.
  • the refrigerant having dissipated heat in the air heat exchanger 4 is liquefied, passes through the expansion valve 6, becomes a refrigerant in a gas-liquid two-phase state, and flows into the refrigerant circulation pipe 30 via the receiver tank 46 and pipe 47.
  • the refrigerant in a gas-liquid two-phase state having flowing into the refrigerant circulation pipe 30 passes through the fifth straight section 35, the fourth curved section 39, the fourth straight section 34, the third curved section 38, the third straight section 33, the second curved section 37, the second straight section 32, the first curved section 36, and the first straight section 31, in this order.
  • the refrigerant having passed through the first straight section 31 flows into the plate-type water-refrigerant heat exchanger 10 through the first refrigerant-side connection port 11.
  • the bend angles A1 to A4 at the respective curved sections 36 to 39 are each configured to be an obtuse angle or a right angle. For this reason, in comparison with the case in which the bend angles A1 to A4 of the curved sections 36 to 39 include acute angles unlike this embodiment, this embodiment makes it possible to reduce the centrifugal force acting on the refrigerant flowing through each of the curved sections 36 to 39, making the gas phase and the liquid phase less likely to separate.
  • the second straight section 32 which is the straight section immediately before the first straight section 31 connected to the plate-type water-refrigerant heat exchanger 10, extends upward from the first curved section 36 connecting the first straight section 31 and the second straight section 32. Therefore, in the second straight section 32, the direction of the refrigerant flow coincides with the direction of gravity acting on the refrigerant, both of which are a downward direction, making it easier to maintain or promote mixing of the gas phase and the liquid phase of the refrigerant.
  • the second straight section 32 is parallel to the vertical up-down direction, making it easier to maintain or promote mixing of the gas phase and the liquid phase.
  • the gas phase and the liquid phase are less likely to separate when the refrigerant passes through the first straight section 31, in a state in which the mixing of the gas phase and the liquid phase has been maintained or promoted in the second straight section 32.
  • the inner diameter D1 of the first pipe member 41 on the side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than the inner diameter D3 of the second pipe member 43 on the side closer to the expansion valve 6.
  • the connection pipe 45 which is connected to the first refrigerant-side connection port 11 of the plate-type water-refrigerant heat exchanger 10, is placed over the outside of the first pipe member 41, so that the inner diameter in almost the entire first straight section 31 is the inner diameter D1.
  • the outer diameter D2 is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate.
  • the refrigerant in a gas-liquid two-phase state which has flowed into the plate-type water-refrigerant heat exchanger 10, absorbs heat from the water flowing through the plate-type water-refrigerant heat exchanger 10, evaporates, and returns to the compressor 2 as a gas refrigerant.
  • This embodiment makes it easier to maintain mixing of the gas phase and the liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, so that the gas phase and the liquid phase is likely to flow evenly in the plate-type water-refrigerant heat exchanger 10, and water is easily cooled efficiently.
  • the refrigeration apparatus 1 cools the room by circulating water between the indoor unit and the plate-type water-refrigerant heat exchanger 10 while cooling the water by driving the circulation pump 16.
  • the refrigerant circulation pipe 30 is connected to a plate-type water-refrigerant heat exchanger 10 and is provided between the plate-type water-refrigerant heat exchanger 10 and an expansion valve 6.
  • the refrigerant circulation pipe 30 includes: a plurality of straight sections 31 to 35 extending linearly; and a plurality of curved sections 36 to 39 that connect ends of the straight sections 31 to 35 and are curved, wherein bend angles A1 to A4 at the respective curved sections 36 to 39 are each an obtuse angle or a right angle.
  • the refrigerant circulation pipe 30 may be configured to further include: a first straight section 31 that is the straight section connected to the plate-type water-refrigerant heat exchanger 10; a first curved section 36 that is the curved section connected to the first straight section 31; and a second straight section 32 that is the straight section connected to the first curved section 36, wherein the second straight section 32 extends upward from the first curved section 36.
  • the direction of gravity coincides with the direction of the refrigerant flow, making it easier to maintain or promote mixing of the gas phase and the liquid phase.
  • the refrigerant circulation pipe 30 may be configured such that the second straight section 32 is longer than the first straight section 31.
  • the refrigerant circulation pipe 30 may be configured such that an inner diameter D1 on a side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than an inner diameter D3 on a side closer to the expansion valve 6 (on a side closer to a receiver tank 46).
  • the refrigerant circulation pipe 30 is composed of the second pipe member 43 connected to the expansion valve 6 via the pipe 47 and the receiver tank 46, and the first pipe member 41 that has an inner diameter D1 smaller than the inner diameter D3 and is fixed to the second pipe member 43. This can actualize the refrigerant circulation pipe 30 having different inner diameters D1, D3 with a simple configuration.
  • the refrigerant circulation pipe 30 may be configured such that a connection pipe 45 connectable to the plate-type water-refrigerant heat exchanger 10 is placed over an outside of a first straight section 31 that is the straight section to be connected to the plate-type water-refrigerant heat exchanger 10.
  • the refrigerant circulation pipe 30 to be used can be a pipe including the first pipe member 41 with a diameter smaller than a diameter corresponding to the plate-type water-refrigerant heat exchanger 10, making it easier to increase the flow velocity of the refrigerant.
  • placing the connection pipe 45 from the outside makes it possible to reduce the range in which the inner diameter is large immediately before the plate-type water-refrigerant heat exchanger 10, making the flow velocity less likely to decrease. Therefore, with a simple configuration, the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be easily made into a state in which a liquid phase and a gas phase are mixed.
  • the left end of the first pipe member 41 extends leftward to the position that is almost aligned with the left end of the connection pipe 45, making it easier to maintain the flow velocity until immediately before the refrigerant flows into the plate-type water-refrigerant heat exchanger 10.
  • the refrigerant circulation pipe 30 may be configured such that at least part of an outer diameter D2 is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate passing through an inside.
  • the outer diameter D2 is 3.50 mm or less per refrigerant circulation rate of 1.0 kg/min in the energy saving mode, in which the refrigerant circulation rate is likely to decrease and the refrigerant flow velocity is difficult to be secured.
  • the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be easily brought into a state in which a liquid phase and a gas phase are mixed.
  • a refrigeration apparatus 1 includes: an expansion valve 6; a plate-type water-refrigerant heat exchanger 10; and a refrigerant circulation pipe 30 connected to the plate-type water-refrigerant heat exchanger 10 and provided between the expansion valve 6 and the plate-type water-refrigerant heat exchanger 10, wherein the refrigerant circulation pipe 30 includes a plurality of straight sections 31 to 35 that extend linearly and a plurality of curved sections 36 to 39 that connect ends of the straight sections 31 to 35 and are curved, bend angles A1 to A4 at the respective curved sections 36 to 39 each being an obtuse angle or a right angle.
  • the inventors have conducted an experiment to verify the optimal sizes of the outer diameter D2 and inner diameter D1 for the refrigerant circulation rate. The following describes the experiment conducted by the inventors.
  • the inventors conducted a first preliminary verification and a second preliminary verification before conducting the experiment described below.
  • the first preliminary verification the inventors had the refrigeration apparatus 1 execute cooling operation using a pipe having a curved section with an acute bend angle immediately before the connection part with the first refrigerant-side connection port 11 instead of using the refrigerant circulation pipe 30.
  • the inventors obtained a result that the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, are not sufficiently mixed in the first preliminary verification. From this result, the inventors have obtained suggestion that the bend angle of the curved section needs to be a non-acute angle to reduce the centrifugal force acting on the gas-liquid two-phase refrigerant.
  • the inventors had the refrigeration apparatus 1 execute cooling operation using a pipe with a non-acute bend angle instead of using the refrigerant circulation pipe 30.
  • the pipe in the second preliminary verification was configured such that three straight sections and two curved sections were located immediately before the connection part with the first refrigerant-side connection port 11 and extended substantially horizontally.
  • part of the pipe was configured to have a smaller pipe diameter than the pipe used in the first preliminary verification. The inventors obtained a result that the mixing degree of the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, in the second preliminary verification was better than that in the first preliminary verification, but the degree was still insufficient.
  • the inventors From the result of the second preliminary verification, the inventors have obtained suggestion that increasing the flow velocity of the refrigerant by narrowing the pipe diameter is effective in improving the mixed state of the gas phase and the liquid phase of the refrigerant.
  • the inventors have obtained suggestion that if the part where the pipe extends horizontally is long immediately before the connection part with the first refrigerant-side connection port 11, the gas phase and the liquid phase of the refrigerant is likely to separate due to the action of gravity.
  • the inventors Based on suggestion obtained from the first and second preliminary verifications, the inventors have come up with the idea of the shape of the refrigerant circulation pipe 30 described in the Embodiment 1 above. The inventors then have conducted the experiment described below to verify specific pipe diameters of the refrigerant circulation pipe 30.
  • the inventors had the refrigeration apparatus 1 execute cooling operation with different refrigerant circulation pipes 30 each connected between the expansion valve 6 and the plate-type water-refrigerant heat exchanger 10, the refrigerant circulation pipes 30 including three patterns of refrigerant pipes with different outer diameters and inner diameters.
  • the outer diameters D2 of the refrigerant circulation pipes 30 used by the inventors were 12.7 mm (1/2 inch), 9.52 mm (3/8 inch), and 7.94 mm (2.5/8 inch).
  • the thickness of the first pipe member 41 was 0.8 mm in each pattern of refrigerant circulation pipe 30. Therefore, the inner diameters D1 of the refrigerant circulation pipes 30 in the individual patterns used by the inventors were 11.1 mm, 7.92 mm, and 6.34 mm.
  • the inventors had the refrigeration apparatus 1 execute cooling operation using the three patterns of refrigerant circulation pipes 30 as described above. Then, the inventors determined, from the suction pressure of the compressor 2, whether the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, were sufficiently mixed. In other words, the inventors determined that when the suction pressure of the compressor 2 was high, the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, were sufficiently mixed, and determined when the suction pressure of the compressor 2 was low, the gas phase and the liquid phase of the refrigerant were not sufficiently mixed.
  • the suction pressure of the compressor 2 increased by 0.007 MPa (approximately 1.6%) and the refrigeration capacity improved by approximately 2.4%.
  • the power consumptions of both were almost the same (2.599 kW and 2.600 kW).
  • the inventors determined that making the bend angle of the upper curved section into a non-acute angle improved the mixing degree of the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10.
  • the inventors determined that the gas and liquid phases of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, were sufficiently mixed only in the pattern in which the outer diameter D2 was 7.94 mm and the inner diameter D1 was 6.34 mm.
  • Figure 11 is a table showing various parameters of the refrigeration apparatus 1 during the experiment, and shows the operating conditions in the experiment.
  • “experimental values” indicates various parameters in determining whether the gas phase and the liquid phase of the refrigerant are sufficiently mixed in the pattern in which the outer diameter D2 of the refrigerant circulation pipe 30 is 7.94 mm.
  • “reference values” indicates various parameters when the frequency of the compressor 2 is 1 Hz lower than the “experimental values”.
  • the dry-bulb temperature of the outside air was 35°C
  • the wet-bulb temperature was 24°C.
  • the temperature of water flowing into the plate-type water-refrigerant heat exchanger 10 was 12°C
  • the temperature of water flowing out of the plate-type water-refrigerant heat exchanger 10 was 7°C.
  • the refrigerant circulation rate flowing through the refrigerant circulation pipe 30 was 2.16 kg/min during cooling operation in the example.
  • the refrigerant circulation rate is a calculated value calculated as the product of the volume of the compressor 2, the frequency of the compressor 2, and the suction density of the compressor 2.
  • the inventors Taking into account the differences between the "experimental values” and the “reference values”, and the measurement errors of various parameters, the inventors have also found that the calculated value of the refrigerant circulation rate of 2.16 kg/min can include an error of ⁇ 3.6%.
  • the inventors also have taken into consideration that the gas phase and the liquid phase of the refrigerant are more likely to separate as the refrigerant circulation rate decreases, to take a margin, and they have estimated that the maximum refrigerant circulation rate during the experiment is 2.27 kg/min, which is 1.05 times the calculated value.
  • the inventors have concluded that in order to maintain mixing of the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, the outer diameter D2 is desirably set to 7.94 mm or less when the refrigerant circulation rate is 2.27 kg/min or less.
  • the inner diameter D1 is desirably set to 6.34 mm or less when the refrigerant circulation rate is 2.27 kg/min or less.
  • the inventors have divided the outer diameter D2 and the inner diameter D1 by the refrigerant circulation rate, to calculate the outer diameter D2 and the inner diameter D1 per refrigerant circulation rate of 1.0 kg/min.
  • the inventors have concluded that in order to maintain mixing of the gas phase and the liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, the outer diameter D2 is desirably set to 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate.
  • the inner diameter D1 is desirably set to 2.93 mm or less per 1.0 kg/min of refrigerant circulation rate.
  • Embodiment 1 has been described as an example of the technique disclosed in this application.
  • the technique disclosed in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, and the like are made.
  • Embodiment 1 has been described with one example of the refrigerant circulation pipe 30 including five straight sections 31 to 35 and four curved sections 36 to 39, but this is just one example.
  • the number of straight sections 31 to 35 and curved sections 36 to 39 formed in the refrigerant circulation pipe 30 is not particularly limited.
  • Embodiment 1 has been described with the second straight section 32 parallel to the vertical up-down direction.
  • the second straight section 32 may extend upward from the first straight section 31 side.
  • the second straight section 32 is not limited to being parallel to the vertical up-down direction, and may be inclined.
  • the direction in which gravity acts coincides with the flow direction of the refrigerant in the second straight section 32, and the effect can be obtained that further promotes or maintains mixing of the gas phase and the liquid phase.
  • Embodiment 1 has been described with the refrigerant circulation pipe 30 formed by integrally fixing the first pipe member 41, the second pipe member 43, and the connection pipe 45 by brazing, but this is just one example.
  • the refrigerant circulation pipe 30 may be composed of two or less members, or four or more members.
  • the first pipe member 41, the second pipe member 43, and the connection pipe 45 of the refrigerant circulation pipe 30 may be fixed by a fixing method other than brazing such as welding.
  • Embodiment 1 has been described with the refrigeration apparatus 1 that is the outdoor unit of a hot water supply heater, but this is just one example.
  • the refrigeration apparatus 1 may be any apparatus that allows the refrigerant in a gas-liquid two-phase state in the expansion valve 6 to flow through the plate-type water-refrigerant heat exchanger 10, and is not limited to an outdoor unit of a hot water supply heater.
  • a refrigerant circulation pipe that is connected to a plate-type water-refrigerant heat exchanger and is provided between the plate-type water-refrigerant heat exchanger and an expansion valve, the refrigerant circulation pipe including: a plurality of straight sections extending linearly; and a plurality of curved sections that connect ends of the straight sections and are curved, wherein a bend angle at each of the curved sections is an obtuse angle or a right angle.
  • the refrigerant circulation pipe according to Technique 1 further including: a first straight section that is the straight section connected to the plate-type water-refrigerant heat exchanger; a first curved section that is the curved section connected to the first straight section; and a second straight section that is the straight section connected to the first curved section, wherein the second straight section extends upward from the first curved section.
  • the refrigerant flowing into the plate-type water-refrigerant heat exchanger can be easily made into a state in which a liquid phase and a gas phase are mixed while reducing decrease in efficiency when the flow rate of the refrigerant is high.
  • the refrigerant circulation pipe to be used can be a pipe with a diameter smaller than a diameter corresponding to the plate-type water-refrigerant heat exchanger, making it easier to increase the flow velocity of the refrigerant.
  • placing the connection pipe from the outside makes it possible to reduce the range in which the inner diameter is large immediately before the plate-type water-refrigerant heat exchanger, making the flow velocity less likely to decrease. Therefore, with a simple configuration, the refrigerant flowing into the plate-type water-refrigerant heat exchanger can be easily made into a state in which a liquid phase and a gas phase are mixed.
  • a refrigeration apparatus including: an expansion valve; a plate-type water-refrigerant heat exchanger; and a refrigerant circulation pipe connected to the plate-type water-refrigerant heat exchanger and provided between the expansion valve and the plate-type water-refrigerant heat exchanger, wherein the refrigerant circulation pipe includes a plurality of straight sections that extend linearly, and a plurality of curved sections that connect ends of the straight sections and are curved, a bend angle at each of the curved sections being an obtuse angle or a right angle.
  • the present disclosure is applicable to a refrigerant circulation pipe, which is connected to a plate-type water-refrigerant heat exchanger and provided between the plate-type water-refrigerant heat exchanger and an expansion valve, and to a refrigeration apparatus having such a refrigerant circulation pipe.
  • the present disclosure is applicable to an apparatus having a heat exchanger that exchanges heat between water and a refrigerant, such as an outdoor unit of a heat-pump-type hot water supply heater, and to a refrigerant circulation pipe provided in the apparatus.

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  • Physics & Mathematics (AREA)
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  • General Engineering & Computer Science (AREA)
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Abstract

The present disclosure provides a refrigerant circulation pipe and a heat exchanger capable of easily making a refrigerant flowing into a plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed. A refrigerant circulation pipe in the present disclosure is a refrigerant circulation pipe that is connected to a plate-type water-refrigerant heat exchanger and is provided between the plate-type water-refrigerant heat exchanger and an expansion valve, the refrigerant circulation pipe including: a plurality of straight sections extending linearly; and a plurality of curved sections that connect ends of the straight sections and are curved, wherein a bend angle at each of the curved sections is an obtuse angle or a right angle.

Description

    BACKGROUND OF THE INVENTION Field of the Invention
  • The present disclosure relates to a refrigerant circulation pipe and a refrigeration apparatus.
    • Description of the Related Art
  • Japanese Patent Laid-Open No. 61-62756 discloses a refrigerant supply apparatus that evenly supplies a gas-liquid two-phase refrigerant to individual evaporation tubes of a dry evaporator. The refrigerant supply apparatus includes a refrigerant distribution apparatus connected to an expansion valve, and a pressure reducing apparatus connecting the refrigerant distribution apparatus and the dry evaporator.
  • The present disclosure provides a refrigerant circulation pipe and a heat exchanger capable of easily making a refrigerant flowing into a plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
    • SUMMARY OF THE INVENTION
  • A refrigerant circulation pipe according to the present disclosure is a refrigerant circulation pipe that is connected to a plate-type water-refrigerant heat exchanger and is provided between the plate-type water-refrigerant heat exchanger and an expansion valve, the refrigerant circulation pipe including: a plurality of straight sections extending linearly; and a plurality of curved sections that connect ends of the straight sections and are curved, wherein a bend angle at each of the curved sections is an obtuse angle or a right angle.
  • A refrigeration apparatus according to the present disclosure includes: an expansion valve; a plate-type water-refrigerant heat exchanger; and a refrigerant circulation pipe connected to the plate-type water-refrigerant heat exchanger and provided between the expansion valve and the plate-type water-refrigerant heat exchanger, wherein the refrigerant circulation pipe includes a plurality of straight sections that extend linearly, and a plurality of curved sections that connect ends of the straight sections and are curved, a bend angle at each of the curved sections being an obtuse angle or a right angle.
  • The refrigerant circulation pipe and the refrigeration apparatus according to the present disclosure allows the refrigerant to flow into the plate-type water-refrigerant heat exchanger while reducing effect of centrifugal force, the refrigerant having flowed into the refrigerant circulation pipe from the expansion valve in a gas-liquid two-phase state. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
    • BRIEF DESCRIPTION OF THE DRAWINGS
    • Figure 1 is a diagram showing a refrigeration circuit of a refrigeration apparatus according to Embodiment 1;
    • Figure 2 is a perspective view showing an inside of the refrigeration apparatus;
    • Figure 3 is an enlarged view of Figure 2;
    • Figure 4 is a side view showing an inside of the refrigeration apparatus;
    • Figure 5 is a perspective view of a refrigerant circulation pipe;
    • Figure 6 is a front view of the refrigerant circulation pipe;
    • Figure 7 is a side view of the refrigerant circulation pipe;
    • Figure 8 is a top view of the refrigerant circulation pipe;
    • Figure 9 is a cross-sectional view showing IX-IX cross section of Figure 7;
    • Figure 10 is a cross-sectional view showing X-X cross section of Figure 8; and
    • Figure 11 is a table showing various parameters of a refrigeration apparatus 1 during an experiment in an example.
    DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Knowledge and the like on which the present disclosure is based)
  • At the time when the inventors came up with an idea of the present disclosure, apparatuses using refrigeration cycles each commonly made a refrigerant having passed through an expansion valve into a gas-liquid two-phase state, and then allowed the refrigerant to flow into an evaporator. For this reason, a problem in the industry was to improve the efficiency of heat exchange in the evaporator. To solve this problem, a technique had been proposed to cause the refrigerant distributed by the refrigerant distribution apparatus to reduce in pressure and to flow into the evaporator in parallel in order to distribute the gas phase and the liquid phase evenly to individual portions of the evaporator. Under such circumstances, the inventors have found that there is a problem in which a plate-type water-refrigerant heat exchanger: has only one inlet and one outlet for the refrigerant in many cases even when having a plurality of channels; and needs to receive the refrigerant in a mixed state of the gas phase and the liquid phase in order to evenly distribute the gas phase and the liquid phase. To solve this problem, the inventors have come to compose the subject of the present disclosure.
  • The present disclosure provides a refrigerant circulation pipe and a heat exchanger capable of easily making a refrigerant flowing into a plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessarily detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configurations may be omitted. This is to avoid the following description from being more redundant than necessary and to facilitate understanding of those skilled in the art.
  • Note that the accompanying drawings and the following description are provided to allow those skilled in the art to sufficiently understand the present disclosure, and are not intended to limit the subject matter described in the claims.
    • (Embodiment 1)
  • Embodiment 1 will be described below with reference to the drawings.
    • [1-1. Configuration] [1-1-1. Configuration of refrigeration circuit]
  • Figure 1 is a diagram showing a refrigeration circuit of a refrigeration apparatus 1 according to Embodiment 1. In this embodiment, the refrigeration apparatus 1 is an outdoor unit of a heat-pump-type hot water supply heater. The hot water supply heater is an apparatus that heats a room by allowing water heated by a refrigeration cycle of the refrigeration apparatus 1 to flow to a heat exchanger of an indoor unit. The hot water supply heater of this embodiment can also perform cooling operation by allowing water cooled by the refrigeration cycle of the refrigeration apparatus 1 to flow to the indoor unit. In Figure 1, the flow of a refrigerant and water in the cooling operation of the hot water heater is indicated by arrows.
  • The refrigeration apparatus 1 is provided with a compressor 2. The compressor 2 is an apparatus that sucks in, compresses, and discharges the refrigerant. In the refrigeration apparatus 1, a flow path switching mechanism 3 is connected to the discharge side and suction side of the compressor 2. The flow path switching mechanism 3 switches the destination of the refrigerant discharged by the compressor 2 between an air heat exchanger 4 and a plate-type water-refrigerant heat exchanger 10, and causes either of the heat exchangers 4, 10 at the destination to function as a condenser. The flow path switching mechanism 3 also causes the compressor 2 to suck in the refrigerant that has passed through the evaporator that is either of the heat exchangers 4 and 10. The flow path switching mechanism 3 is, for example, a four-way valve.
  • The air heat exchanger 4 is a heat exchanger that exchanges heat between the internal refrigerant and the outside air. The air heat exchanger 4 is, for example, a fin-tube type heat exchanger. The refrigeration apparatus 1 is provided with blowers 5 that allow outside air to flow to the air heat exchanger 4. In this embodiment, the blowers 5 are axial fans.
  • The plate-type water-refrigerant heat exchanger 10 is a plate type heat exchanger that exchanges heat between the refrigerant flowing inside and water. The water heated or cooled by the plate-type water-refrigerant heat exchanger 10 circulates between the refrigeration apparatus 1 and the indoor unit to air-condition the room.
  • The air heat exchanger 4 and the plate-type water-refrigerant heat exchanger 10 are connected via an expansion valve 6. Between the plate-type water-refrigerant heat exchanger 10 and the expansion valve 6, there is a receiver tank 46 that stores low-temperature, high-pressure liquid-phase refrigerant cooled by the condenser (see Figure 2). The expansion valve 6 is a valve that reduces the pressure of the refrigerant flowing in it from the condenser, which is either of the heat exchangers 4, 10, through the receiver tank 46 to make the refrigerant into the refrigerant in a gas-liquid two-phase state, and allows the refrigerant to flow into the evaporator, which is the other of the heat exchangers 4, 10. In this embodiment, the opening degree of the expansion valve 6 can be adjusted by electronic control, and changing the opening degree adjusts the flow rate of the refrigerant.
    • [1-1-2. Placement of each component in refrigeration apparatus]
  • Figure 2 is a perspective view showing an inside of the refrigeration apparatus 1. In the figure, symbol X indicates the left side of the refrigeration apparatus 1, symbol Y indicates the front side of the refrigeration apparatus 1, and symbol Z indicates the upper side. As shown in Figure 2, the inside of the refrigeration apparatus 1 includes: a blower room 7 that is a space defined on the left side of the partition plate 9; and a machine room 8 that is a space defined on the right side of the partition plate 9. The partition plate 9 is made of sheet metal and is provided in a position that is approximately perpendicular to the left-right direction.
  • The blower room 7 is provided with the air heat exchanger 4 and the blowers 5. The air heat exchanger 4 is provided on the left side surface and rear surface of the blower room 7. The blowers 5 blow the air inside the refrigeration apparatus 1 forward to suck in outside air through the air heat exchanger 4, and exchange heat between the outside air and the refrigerant inside the air heat exchanger 4. In this embodiment, the refrigeration apparatus 1 is described as an example in which two blowers 5 are provided so as to be lined up one above the other in the blower room 7, but there is no particular limit to the number of blowers 5 in the refrigeration apparatus 1.
  • The machine room 8 is provided with the compressor 2, the flow path switching mechanism 3, the expansion valve 6, the receiver tank 46, and the plate-type water-refrigerant heat exchanger 10. The compressor 2 is placed on the bottom plate 1a of the refrigeration apparatus 1 via rubber legs. The flow path switching mechanism 3 is placed above the compressor 2. The plate-type water-refrigerant heat exchanger 10 is provided at a position spaced above the bottom plate 1a via a support member 8a made of sheet metal.
  • Figure 3 is an enlarged view of Figure 2. Figure 4 is a side view showing the internal configuration of the refrigeration apparatus 1, and shows the inside of the refrigeration apparatus 1 as viewed from the right side. As shown in Figure 3 and Figure 4, the plate-type water-refrigerant heat exchanger 10 is provided with a first refrigerant-side connection port 11 and a second refrigerant-side connection port 12. Each refrigerant-side connection port 11, 12 is an opening that communicates with the flow path through which the refrigerant flows in the plate-type water-refrigerant heat exchanger 10. The first refrigerant-side connection port 11 is formed at the front lower end of the right side surface of the plate-type water-refrigerant heat exchanger 10. The second refrigerant-side connection port 12 is formed above the first refrigerant-side connection port 11 on the right side surface of the plate-type water-refrigerant heat exchanger 10.
  • A refrigerant circulation pipe 30 is connected to the first refrigerant-side connection port 11. The refrigerant circulation pipe 30 is a refrigerant pipe provided between the first refrigerant-side connection port 11 and the expansion valve 6. The refrigerant circulation pipe 30 is connected to the first refrigerant-side connection port 11 and the pipe 47 in detail. The pipe 47 is connected to the receiver tank 46. The gas side pipe 13 is connected to the second refrigerant-side connection port 12. The gas side pipe 13 is a refrigerant pipe extending from the second refrigerant-side connection port 12 and connected to the flow path switching mechanism 3. The gas side pipe 13 allows mainly gas refrigerant with a large specific volume to flow, and it has a larger diameter than the refrigerant circulation pipe 30 through which liquid refrigerant or refrigerant in a gas-liquid two-phase state flows.
  • The plate-type water-refrigerant heat exchanger 10 is provided with a first water-side connection port 14 and a second water-side connection port 15. Each water-side connection port 14, 15 is an opening that communicates with the flow path through which water flows in the plate-type water-refrigerant heat exchanger 10. The first water-side connection port 14 is provided at the rear lower end of the right side surface of the plate-type water-refrigerant heat exchanger 10. The second water-side connection port 15 is provided above the first water-side connection port 14 on the right side surface of the plate-type water-refrigerant heat exchanger 10.
  • The first water-side connection port 14 is connected to the discharge side of a circulation pump 16 that circulates water. On the suction side of the circulation pump 16, a valve 16a is provided that protrudes rearward to the outside of the refrigeration apparatus 1 and can be connected to a water pipe outside the refrigeration apparatus 1.
  • The second water-side connection port 15 is provided with a gas-liquid separator 17 to remove gas from the water flowing out of the plate-type water-refrigerant heat exchanger 10. On the outlet side of the gas-liquid separator 17, a valve 18a is provided that can be connected to a water pipe outside the refrigeration apparatus 1 via an outlet-side water pipe 18. In addition, a flow rate sensor 19 that measures the flow rate of water is provided in the outlet-side water pipe 18.
    • [1-1-3. Configuration of refrigerant circulation pipe]
  • Figure 5 is a perspective view of a refrigerant circulation pipe 30. As shown in Figure 5, the refrigerant circulation pipe 30 includes five straight sections 31 to 35 that extend linearly, and four curved sections 36 to 39 that connect adjacent straight sections 31 to 35.
  • Figure 6 is a front view of the refrigerant circulation pipe 30, showing the refrigerant circulation pipe 30 as viewed from the front. Figure 7 is a side view of the refrigerant circulation pipe 30, showing the refrigerant circulation pipe 30 as viewed from the right. Figure 8 is a top view of the refrigerant circulation pipe 30, showing the refrigerant circulation pipe 30 as viewed from above.
  • The first straight section 31 that is parallel to the left-right direction is formed at the lower end of the refrigerant circulation pipe 30. In other words, the first straight section 31 extends horizontally. The left end of the first straight section 31 is connected to the first refrigerant-side connection port 11.
  • The right end of the first straight section 31 is connected to the first curved section 36. The first curved section 36 is a part of the refrigerant circulation pipe 30, the part curving upward from the right end of the first straight section 31. The upper end of the first curved section 36 is connected to the lower end of the second straight section 32. The second straight section 32 is a part of the refrigerant circulation pipe 30, the part extending linearly in the up-down direction. More specifically, in this embodiment, the second straight section 32 extends linearly parallel to the vertical up-down direction. As shown in Figure 6, the length L2 of the second straight section 32 is longer than the length L1 of the first straight section 31.
  • As shown in Figures 6 and 7, the bend angle A1 at the first curved section 36 is a right angle. The bend angle A1 is, in other words, the angle between the first straight section 31 and the second straight section 32. In the following description herein, the bend angles A1 to A4 of the respective curved sections 36 to 39 each mean an angle between two of the straight sections 31 to 35 connected to opposite ends of the corresponding curved section among the curved sections 36 to 39. In other words, when the curved sections 36 to 39 respectively have large bend angles A1 to A4, each of the curved sections 36 to 39 is closer to a straight line, compared to a case in which the curved sections 36 to 39 include a small bend angle.
  • The upper end of the second straight section 32 is connected to the lower end of the second curved section 37. The second curved section 37 is a part of the refrigerant circulation pipe 30, the part curving leftward and frontward from the upper end of the second straight section 32. The bend angle A2 of the second curved section 37 is a right angle.
  • The left front end of the second curved section 37 is connected to the third straight section 33. The third straight section 33 is a part of the refrigerant circulation pipe 30, the part linearly extending leftward and frontward from the left front end of the second curved section 37. More specifically, the third straight section 33 horizontally extends leftward and frontward.
  • The left front end of the third straight section 33 is connected to the right rear end of the third curved section 38. The third curved section 38 is a part of the refrigerant circulation pipe 30, the part diagonally curving upward, leftward, and frontward from the left front end of the third straight section 33. As shown in Figure 6 to Figure 8, the bend angle A3 of the third curved section 38 is an obtuse angle.
  • The upper end of the third curved section 38 is connected to the lower end of the fourth straight section 34. The fourth straight section 34 is a part of the refrigerant circulation pipe 30, the part linearly extending from the upper end of the third curved section 38 in a direction in which the left front side is located upward.
  • The upper end of the fourth straight section 34 is connected to the lower end of the fourth curved section 39. The fourth curved section 39 is a part of the refrigerant circulation pipe 30, the part curving leftward from the upper end of the fourth straight section 34. As shown in Figure 6 to Figure 8, the bend angle A4 of the fourth curved section 39 is an obtuse angle.
  • The left end of the fourth curved section 39 is connected to the right end of the fifth straight section 35. The fifth straight section 35 is a part of the refrigerant circulation pipe 30, the part linearly extending leftward from the left end of the fourth curved section 39. More specifically, the fifth straight section 35 horizontally extends leftward. The left end of the fifth straight section 35 is connected to the right end of the pipe 47. As described above, the pipe 47 is connected to the receiver tank 46, so that the fifth straight section 35 is connected to the expansion valve 6 via the pipe 47 and the receiver tank 46. In addition, the fifth straight section 35 is formed with a protrusion 35a that protrudes radially outward for positioning with respect to the pipe 47.
  • Specifically in this embodiment, the refrigerant circulation pipe 30 is configured by fixing the first pipe member 41, the second pipe member 43, and the connection pipe 45 by brazing. The first pipe member 41 is a hollow member with a circular cross section in the refrigerant circulation pipe 30, the hollow member including almost the entire first straight section 31, the entire first curved section 36, and almost the entire second straight section 32 except for the upper end. The second pipe member 43 is a hollow member with a circular cross section in the refrigerant circulation pipe 30, the hollow member including the upper end of the second straight section 32, the second curved section 37, the third straight section 33, the third curved section 38, the fourth straight section 34, the fourth curved section 39, and the fifth straight section 35. The connection pipe 45 is a hollow member with a circular cross section that is provided in the first straight section 31 and extends in the left-right direction.
  • Figure 9 is a cross-sectional view showing IX-IX cross section of Figure 7, and shows the brazed part between the first pipe member 41 and the second pipe member 43 cut at a cross section perpendicular to the front-rear direction. As shown in Figure 9, the upper end of the first pipe member 41, which is inserted into the lower end of the second pipe member 43, is brazed to the second pipe member 43. Therefore, the outer diameter D2 of the first pipe member 41 is equal to or smaller than the inner diameter D3 of the second pipe member 43, and the inner diameter D1 of the first pipe member 41 is smaller than the inner diameter D3 of the second pipe member 43. In other words, in the refrigerant circulation pipe 30, the inner diameter D1 of the first pipe member 41 on the side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than the inner diameter D3 of the second pipe member 43 on the side closer to the expansion valve 6 (the side closer to the receiver tank 46). As shown in Figure 9, the first pipe member 41 has a protrusion 42a protruding radially outward. The protrusion 42a comes in contact with the end surface of the second pipe member 43 to position the first pipe member 41 and the second pipe member 43.
  • Figure 10 is a cross-sectional view showing X-X cross section of Figure 8, and shows the brazed part between the first pipe member 41 and the connection pipe 45 cut at a cross section perpendicular to the front-rear direction. As shown in Figure 10, the connection pipe 45, which is placed over the outside of the first pipe member 41, is brazed to the first pipe member 41. Therefore, the outer diameter D2 of the first pipe member 41 is equal to or smaller than the inner diameter D5 of the connection pipe 45, and the inner diameter D1 of the first pipe member 41 is smaller than the inner diameter D5 of the connection pipe 45. As shown in Figure 10, the first pipe member 41 has a protrusion 42b protruding radially outward. The protrusion 42b comes into contact with the end surface of the connection pipe 45 to position the first pipe member 41 and the connection pipe 45. The inner diameter D5 and the outer diameter D6 of the connection pipe 45 are made into a size that allows the connection pipe 45 to connect to the first refrigerant-side connection port 11 of the plate-type water-refrigerant heat exchanger 10. In this embodiment, the inner diameter D5 and outer diameter D6 of the connection pipe 45 are substantially equal to the inner diameter D3 and outer diameter D4 of the second pipe member 43.
  • The left end of the first pipe member 41 extends leftward to a position that is approximately aligned with the left end of the connection pipe 45. Therefore, the inner diameter of the substantially entire range of the first straight section 31 is the same as the inner diameter D1 of the first pipe member 41.
  • Here, the inventors have conducted an experiment to verify the suitable sizes of the inner diameter D1 and the outer diameter D2 for a refrigerant circulation rate in the refrigeration circuit of the refrigeration apparatus 1, that is, a refrigerant circulation rate passing through the inside of the refrigerant circulation pipe 30. As a result, the inventors have found that when the refrigerant circulation rate passing through the inside is 2.27 kg/min or less, the outer diameter D2 is preferably 7.94 mm or less. The inventors also have found that the suitable range of the outer diameter D2 is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate passing through the inside of the refrigerant circulation pipe 30. The relationship between the refrigerant circulation rate and the inner diameter D1 and the outer diameter D2 will be explained in the examples described later.
  • In this embodiment, the refrigeration apparatus 1 is capable of operating in an energy saving mode. The energy saving mode is an operation mode in which the compressor 2 is driven at a lower capacity than the full capacity in order to save energy in the refrigeration apparatus 1. In the energy saving mode, the refrigerant circulation rate passing through the refrigerant circulation pipe 30 is less than the refrigerant circulation rate in the operation mode in which the full capacity of the compressor 2 is used. In this embodiment, in cooling operation in the energy saving mode of the refrigeration apparatus 1, the refrigerant circulation rate is 2.27 kg/min, the outer diameter D2 is 7.94 mm, and the outer diameter D2 per refrigerant circulation rate of 1.0 kg/min is 3.50 mm.
    • [1-2. Operation]
  • The following describes the operation of the refrigeration apparatus 1 configured as above in cooling operation.
  • In cooling operation, as shown in Figure 1, the flow path switching mechanism 3 allows the refrigerant discharged from the compressor 2 to flow to the air heat exchanger 4 to dissipate heat. The refrigerant having dissipated heat in the air heat exchanger 4 is liquefied, passes through the expansion valve 6, becomes a refrigerant in a gas-liquid two-phase state, and flows into the refrigerant circulation pipe 30 via the receiver tank 46 and pipe 47.
  • The refrigerant in a gas-liquid two-phase state having flowing into the refrigerant circulation pipe 30 passes through the fifth straight section 35, the fourth curved section 39, the fourth straight section 34, the third curved section 38, the third straight section 33, the second curved section 37, the second straight section 32, the first curved section 36, and the first straight section 31, in this order. The refrigerant having passed through the first straight section 31 flows into the plate-type water-refrigerant heat exchanger 10 through the first refrigerant-side connection port 11.
  • When the refrigerant in a gas-liquid two-phase state passes through each of the curved sections 36 to 39, a centrifugal force acts on the refrigerant depending on the bend angles A1 to A4 and curvature radiuses of the individual curved sections 36 to 39. Normally, when centrifugal force acts on a refrigerant in a gas-liquid two-phase state, the liquid phase refrigerant with a high specific gravity is likely to flow more toward the outside of the curve than the gas phase refrigerant with a low specific gravity, and the gas and liquid phases are likely to separate.
  • In contrast, in this embodiment, the bend angles A1 to A4 at the respective curved sections 36 to 39 are each configured to be an obtuse angle or a right angle. For this reason, in comparison with the case in which the bend angles A1 to A4 of the curved sections 36 to 39 include acute angles unlike this embodiment, this embodiment makes it possible to reduce the centrifugal force acting on the refrigerant flowing through each of the curved sections 36 to 39, making the gas phase and the liquid phase less likely to separate.
  • In this embodiment, the second straight section 32, which is the straight section immediately before the first straight section 31 connected to the plate-type water-refrigerant heat exchanger 10, extends upward from the first curved section 36 connecting the first straight section 31 and the second straight section 32. Therefore, in the second straight section 32, the direction of the refrigerant flow coincides with the direction of gravity acting on the refrigerant, both of which are a downward direction, making it easier to maintain or promote mixing of the gas phase and the liquid phase of the refrigerant. In this embodiment, the second straight section 32 is parallel to the vertical up-down direction, making it easier to maintain or promote mixing of the gas phase and the liquid phase. Furthermore, since the length L2 of the second straight section 32 is longer than the length L1 of the first straight section 31, the gas phase and the liquid phase are less likely to separate when the refrigerant passes through the first straight section 31, in a state in which the mixing of the gas phase and the liquid phase has been maintained or promoted in the second straight section 32.
  • In the refrigerant circulation pipe 30, the inner diameter D1 of the first pipe member 41 on the side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than the inner diameter D3 of the second pipe member 43 on the side closer to the expansion valve 6. In addition, in the refrigerant circulation pipe 30, the connection pipe 45, which is connected to the first refrigerant-side connection port 11 of the plate-type water-refrigerant heat exchanger 10, is placed over the outside of the first pipe member 41, so that the inner diameter in almost the entire first straight section 31 is the inner diameter D1. Furthermore, the outer diameter D2 is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate. This makes it easier to increase the flow velocity of the refrigerant passing through the first pipe member 41 immediately before flowing into the plate-type water-refrigerant heat exchanger 10, and makes it easier to prevent separation of the gas phase and the liquid phase due to the action of gravity or the like.
  • The refrigerant in a gas-liquid two-phase state, which has flowed into the plate-type water-refrigerant heat exchanger 10, absorbs heat from the water flowing through the plate-type water-refrigerant heat exchanger 10, evaporates, and returns to the compressor 2 as a gas refrigerant. This embodiment makes it easier to maintain mixing of the gas phase and the liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, so that the gas phase and the liquid phase is likely to flow evenly in the plate-type water-refrigerant heat exchanger 10, and water is easily cooled efficiently. The refrigeration apparatus 1 cools the room by circulating water between the indoor unit and the plate-type water-refrigerant heat exchanger 10 while cooling the water by driving the circulation pump 16.
    • [1-3. Effects and the like]
  • As described above, in this embodiment, the refrigerant circulation pipe 30 is connected to a plate-type water-refrigerant heat exchanger 10 and is provided between the plate-type water-refrigerant heat exchanger 10 and an expansion valve 6. The refrigerant circulation pipe 30 includes: a plurality of straight sections 31 to 35 extending linearly; and a plurality of curved sections 36 to 39 that connect ends of the straight sections 31 to 35 and are curved, wherein bend angles A1 to A4 at the respective curved sections 36 to 39 are each an obtuse angle or a right angle.
  • This allows the refrigerant in a gas-liquid two-phase state, which has flowed into the refrigerant circulation pipe 30 after passing through the expansion valve 6, to flow into the plate-type water-refrigerant heat exchanger 10 while reducing the effect of centrifugal force. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 into a state in which a liquid phase and a gas phase are mixed.
  • As in this embodiment, the refrigerant circulation pipe 30 may be configured to further include: a first straight section 31 that is the straight section connected to the plate-type water-refrigerant heat exchanger 10; a first curved section 36 that is the curved section connected to the first straight section 31; and a second straight section 32 that is the straight section connected to the first curved section 36, wherein the second straight section 32 extends upward from the first curved section 36.
  • This allows the direction of gravity acting on the refrigerant to be closer to the direction of the refrigerant flow in the second straight section 32 through which the refrigerant passes immediately before flowing into the plate-type water-refrigerant heat exchanger 10, making it easier to maintain or promote mixing of the gas phase and the liquid phase. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 into a state in which a liquid phase and a gas phase are mixed.
  • In particular, in this embodiment, since the second straight section 32 extends parallel to the vertical up-down direction, the direction of gravity coincides with the direction of the refrigerant flow, making it easier to maintain or promote mixing of the gas phase and the liquid phase.
  • As in this embodiment, the refrigerant circulation pipe 30 may be configured such that the second straight section 32 is longer than the first straight section 31.
  • This allows the second straight section 32, where it is easier to maintain or promote mixing of the gas phase and the liquid phase of the refrigerant, to be longer, and allows the first straight section 31, which is located between the second straight section 32 and the plate-type water-refrigerant heat exchanger 10, to be shorter. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 into a state in which a liquid phase and a gas phase are mixed.
  • As in this embodiment, the refrigerant circulation pipe 30 may be configured such that an inner diameter D1 on a side closer to the plate-type water-refrigerant heat exchanger 10 is smaller than an inner diameter D3 on a side closer to the expansion valve 6 (on a side closer to a receiver tank 46).
  • This makes it easier to increase the flow velocity of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 while reducing increase in the pipe resistance of the refrigerant circulation pipe 30. Therefore, the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be easily made into a state in which a liquid phase and a gas phase are mixed while reducing decrease in efficiency when the flow rate of the refrigerant is high.
  • In particular, in this embodiment, the refrigerant circulation pipe 30 is composed of the second pipe member 43 connected to the expansion valve 6 via the pipe 47 and the receiver tank 46, and the first pipe member 41 that has an inner diameter D1 smaller than the inner diameter D3 and is fixed to the second pipe member 43. This can actualize the refrigerant circulation pipe 30 having different inner diameters D1, D3 with a simple configuration.
  • As in this embodiment, the refrigerant circulation pipe 30 may be configured such that a connection pipe 45 connectable to the plate-type water-refrigerant heat exchanger 10 is placed over an outside of a first straight section 31 that is the straight section to be connected to the plate-type water-refrigerant heat exchanger 10.
  • Thereby, the refrigerant circulation pipe 30 to be used can be a pipe including the first pipe member 41 with a diameter smaller than a diameter corresponding to the plate-type water-refrigerant heat exchanger 10, making it easier to increase the flow velocity of the refrigerant. In addition, placing the connection pipe 45 from the outside makes it possible to reduce the range in which the inner diameter is large immediately before the plate-type water-refrigerant heat exchanger 10, making the flow velocity less likely to decrease. Therefore, with a simple configuration, the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be easily made into a state in which a liquid phase and a gas phase are mixed.
  • In particular, in this embodiment, the left end of the first pipe member 41 extends leftward to the position that is almost aligned with the left end of the connection pipe 45, making it easier to maintain the flow velocity until immediately before the refrigerant flows into the plate-type water-refrigerant heat exchanger 10.
  • As in this embodiment, the refrigerant circulation pipe 30 may be configured such that at least part of an outer diameter D2 is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate passing through an inside.
  • This makes it easier to secure the flow velocity of the refrigerant. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 into a state in which a liquid phase and a gas phase are mixed.
  • In particular, in this embodiment, the outer diameter D2 is 3.50 mm or less per refrigerant circulation rate of 1.0 kg/min in the energy saving mode, in which the refrigerant circulation rate is likely to decrease and the refrigerant flow velocity is difficult to be secured. For this reason, in many operation modes of the refrigeration apparatus 1, the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 can be easily brought into a state in which a liquid phase and a gas phase are mixed.
  • As in this embodiment, a refrigeration apparatus 1 includes: an expansion valve 6; a plate-type water-refrigerant heat exchanger 10; and a refrigerant circulation pipe 30 connected to the plate-type water-refrigerant heat exchanger 10 and provided between the expansion valve 6 and the plate-type water-refrigerant heat exchanger 10, wherein the refrigerant circulation pipe 30 includes a plurality of straight sections 31 to 35 that extend linearly and a plurality of curved sections 36 to 39 that connect ends of the straight sections 31 to 35 and are curved, bend angles A1 to A4 at the respective curved sections 36 to 39 each being an obtuse angle or a right angle.
  • This allows the refrigerant to flow into the plate-type water-refrigerant heat exchanger 10 while reducing the effect of centrifugal force, the refrigerant having flowed into the refrigerant circulation pipe 30 in a gas-liquid two-phase state after passing through the expansion valve 6. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10 into a state in which a liquid phase and a gas phase are mixed.
    • [1-4. Example]
  • The inventors have conducted an experiment to verify the optimal sizes of the outer diameter D2 and inner diameter D1 for the refrigerant circulation rate. The following describes the experiment conducted by the inventors.
  • Note that the inventors conducted a first preliminary verification and a second preliminary verification before conducting the experiment described below. As the first preliminary verification, the inventors had the refrigeration apparatus 1 execute cooling operation using a pipe having a curved section with an acute bend angle immediately before the connection part with the first refrigerant-side connection port 11 instead of using the refrigerant circulation pipe 30. Then, the inventors obtained a result that the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, are not sufficiently mixed in the first preliminary verification. From this result, the inventors have obtained suggestion that the bend angle of the curved section needs to be a non-acute angle to reduce the centrifugal force acting on the gas-liquid two-phase refrigerant.
  • In addition, as the second preliminary verification, the inventors had the refrigeration apparatus 1 execute cooling operation using a pipe with a non-acute bend angle instead of using the refrigerant circulation pipe 30. The pipe in the second preliminary verification was configured such that three straight sections and two curved sections were located immediately before the connection part with the first refrigerant-side connection port 11 and extended substantially horizontally. In addition, part of the pipe was configured to have a smaller pipe diameter than the pipe used in the first preliminary verification. The inventors obtained a result that the mixing degree of the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, in the second preliminary verification was better than that in the first preliminary verification, but the degree was still insufficient. From the result of the second preliminary verification, the inventors have obtained suggestion that increasing the flow velocity of the refrigerant by narrowing the pipe diameter is effective in improving the mixed state of the gas phase and the liquid phase of the refrigerant. In addition, from the result of the second preliminary verification, the inventors have obtained suggestion that if the part where the pipe extends horizontally is long immediately before the connection part with the first refrigerant-side connection port 11, the gas phase and the liquid phase of the refrigerant is likely to separate due to the action of gravity.
  • Based on suggestion obtained from the first and second preliminary verifications, the inventors have come up with the idea of the shape of the refrigerant circulation pipe 30 described in the Embodiment 1 above. The inventors then have conducted the experiment described below to verify specific pipe diameters of the refrigerant circulation pipe 30.
  • In the experiment, the inventors had the refrigeration apparatus 1 execute cooling operation with different refrigerant circulation pipes 30 each connected between the expansion valve 6 and the plate-type water-refrigerant heat exchanger 10, the refrigerant circulation pipes 30 including three patterns of refrigerant pipes with different outer diameters and inner diameters. Specifically, the outer diameters D2 of the refrigerant circulation pipes 30 used by the inventors were 12.7 mm (1/2 inch), 9.52 mm (3/8 inch), and 7.94 mm (2.5/8 inch). In addition, the thickness of the first pipe member 41 was 0.8 mm in each pattern of refrigerant circulation pipe 30. Therefore, the inner diameters D1 of the refrigerant circulation pipes 30 in the individual patterns used by the inventors were 11.1 mm, 7.92 mm, and 6.34 mm.
  • The inventors had the refrigeration apparatus 1 execute cooling operation using the three patterns of refrigerant circulation pipes 30 as described above. Then, the inventors determined, from the suction pressure of the compressor 2, whether the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, were sufficiently mixed. In other words, the inventors determined that when the suction pressure of the compressor 2 was high, the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, were sufficiently mixed, and determined when the suction pressure of the compressor 2 was low, the gas phase and the liquid phase of the refrigerant were not sufficiently mixed.
  • For example, when a pipe with a curved section that was a non-acute angle was used instead of the pipe with an acute bend angle used in the first preliminary verification, the suction pressure of the compressor 2 increased by 0.007 MPa (approximately 1.6%) and the refrigeration capacity improved by approximately 2.4%. Here, the power consumptions of both were almost the same (2.599 kW and 2.600 kW). The inventors determined that making the bend angle of the upper curved section into a non-acute angle improved the mixing degree of the gas phase and the liquid phase of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10.
  • The reason why the suction pressure of the compressor 2 thus determines the mixing degree of the gas and liquid phases of the refrigerant, which flows into the plate-type water-refrigerant heat exchanger 10, is that the refrigeration capacity of the refrigeration apparatus 1 improves as the suction pressure of the compressor 2 increases. Increase in the suction pressure means that the evaporation performance of the plate-type water-refrigerant heat exchanger 10 is improved. Furthermore, since the evaporation capacity is improved in the plate-type water-refrigerant heat exchanger 10, it can be determined that the heat absorption effect due to the evaporation heat of the refrigerant is improved in the plate-type water-refrigerant heat exchanger 10. This leads to a determination that when the suction pressure of the compressor 2 is high, the gas phase and the liquid phase of the refrigerant in the plate-type water-refrigerant heat exchanger 10 are in a state in which they are likely to flow evenly to individual portions of the plate-type water-refrigerant heat exchanger 10, and the gas phase and the liquid phase of the refrigerant are sufficiently mixed.
  • As a result, the inventors determined that the gas and liquid phases of the refrigerant, which flowed into the plate-type water-refrigerant heat exchanger 10, were sufficiently mixed only in the pattern in which the outer diameter D2 was 7.94 mm and the inner diameter D1 was 6.34 mm.
  • Figure 11 is a table showing various parameters of the refrigeration apparatus 1 during the experiment, and shows the operating conditions in the experiment. Note that in Figure 11, "experimental values" indicates various parameters in determining whether the gas phase and the liquid phase of the refrigerant are sufficiently mixed in the pattern in which the outer diameter D2 of the refrigerant circulation pipe 30 is 7.94 mm. In Figure 11, "reference values" indicates various parameters when the frequency of the compressor 2 is 1 Hz lower than the "experimental values". In addition, in the experiment, the dry-bulb temperature of the outside air was 35°C, and the wet-bulb temperature was 24°C. Furthermore, in the experiment, the temperature of water flowing into the plate-type water-refrigerant heat exchanger 10 was 12°C, and the temperature of water flowing out of the plate-type water-refrigerant heat exchanger 10 was 7°C.
  • As shown in Figure 11, the refrigerant circulation rate flowing through the refrigerant circulation pipe 30 was 2.16 kg/min during cooling operation in the example. In addition, the refrigerant circulation rate is a calculated value calculated as the product of the volume of the compressor 2, the frequency of the compressor 2, and the suction density of the compressor 2.
  • Taking into account the differences between the "experimental values" and the "reference values", and the measurement errors of various parameters, the inventors have also found that the calculated value of the refrigerant circulation rate of 2.16 kg/min can include an error of ±3.6%. The inventors also have taken into consideration that the gas phase and the liquid phase of the refrigerant are more likely to separate as the refrigerant circulation rate decreases, to take a margin, and they have estimated that the maximum refrigerant circulation rate during the experiment is 2.27 kg/min, which is 1.05 times the calculated value.
  • From these results, the inventors have concluded that in order to maintain mixing of the gas and liquid phases of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, the outer diameter D2 is desirably set to 7.94 mm or less when the refrigerant circulation rate is 2.27 kg/min or less. The inventors have also concluded that in order to maintain mixing of the gas phase and the liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, the inner diameter D1 is desirably set to 6.34 mm or less when the refrigerant circulation rate is 2.27 kg/min or less.
  • The inventors have divided the outer diameter D2 and the inner diameter D1 by the refrigerant circulation rate, to calculate the outer diameter D2 and the inner diameter D1 per refrigerant circulation rate of 1.0 kg/min. As a result, the inventors have concluded that in order to maintain mixing of the gas phase and the liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, the outer diameter D2 is desirably set to 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate. The inventors have also concluded that in order to maintain mixing of the gas phase and the liquid phase of the refrigerant flowing into the plate-type water-refrigerant heat exchanger 10, the inner diameter D1 is desirably set to 2.93 mm or less per 1.0 kg/min of refrigerant circulation rate.
    • (Other embodiments)
  • As described above, Embodiment 1 has been described as an example of the technique disclosed in this application. However, the technique disclosed in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, and the like are made. In addition, it is possible to combine the components described in the above Embodiment 1 to create a new embodiment.
  • The following illustrates other embodiments.
  • Embodiment 1 has been described with one example of the refrigerant circulation pipe 30 including five straight sections 31 to 35 and four curved sections 36 to 39, but this is just one example. The number of straight sections 31 to 35 and curved sections 36 to 39 formed in the refrigerant circulation pipe 30 is not particularly limited.
  • Embodiment 1 has been described with the second straight section 32 parallel to the vertical up-down direction. The second straight section 32 may extend upward from the first straight section 31 side. For this reason, the second straight section 32 is not limited to being parallel to the vertical up-down direction, and may be inclined. However, if the second straight section 32 to be used is parallel to the vertical up-down direction, the direction in which gravity acts coincides with the flow direction of the refrigerant in the second straight section 32, and the effect can be obtained that further promotes or maintains mixing of the gas phase and the liquid phase.
  • Embodiment 1 has been described with the refrigerant circulation pipe 30 formed by integrally fixing the first pipe member 41, the second pipe member 43, and the connection pipe 45 by brazing, but this is just one example. The refrigerant circulation pipe 30 may be composed of two or less members, or four or more members. In addition, the first pipe member 41, the second pipe member 43, and the connection pipe 45 of the refrigerant circulation pipe 30 may be fixed by a fixing method other than brazing such as welding.
  • Embodiment 1 has been described with the refrigeration apparatus 1 that is the outdoor unit of a hot water supply heater, but this is just one example. The refrigeration apparatus 1 may be any apparatus that allows the refrigerant in a gas-liquid two-phase state in the expansion valve 6 to flow through the plate-type water-refrigerant heat exchanger 10, and is not limited to an outdoor unit of a hot water supply heater.
  • Note that the above-mentioned embodiments are intended to illustrate the technique in the present disclosure, and various modifications, substitutions, additions, omissions, and the like may be made within the scope of the claims or equivalents thereof.
    • (Supplementary note)
  • The above description of the embodiment discloses the following techniques.
  • (Technique 1) A refrigerant circulation pipe that is connected to a plate-type water-refrigerant heat exchanger and is provided between the plate-type water-refrigerant heat exchanger and an expansion valve, the refrigerant circulation pipe including: a plurality of straight sections extending linearly; and a plurality of curved sections that connect ends of the straight sections and are curved, wherein a bend angle at each of the curved sections is an obtuse angle or a right angle.
  • This allows the refrigerant in a gas-liquid two-phase state to flow into the plate-type water-refrigerant heat exchanger while reducing the effect of centrifugal force, the refrigerant having flowed into the refrigerant circulation pipe after passing through the expansion valve. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • (Technique 2) The refrigerant circulation pipe according to Technique 1, further including: a first straight section that is the straight section connected to the plate-type water-refrigerant heat exchanger; a first curved section that is the curved section connected to the first straight section; and a second straight section that is the straight section connected to the first curved section, wherein the second straight section extends upward from the first curved section.
  • This allows the direction of gravity acting on the refrigerant to be closer to the direction of the refrigerant flow in the second straight section through which the refrigerant passes immediately before flowing into the plate-type water-refrigerant heat exchanger, making it easier to maintain or promote mixing of the gas phase and the liquid phase. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • (Technique 3) The refrigerant circulation pipe according to Technique 2, wherein the second straight section is longer than the first straight section.
  • This allows the second straight section, where it is easier to maintain or promote mixing of the gas phase and the liquid phase of the refrigerant, to be longer, and allows the first straight section, which is located between the second straight section and the plate-type water-refrigerant heat exchanger, to be shorter. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • (Technique 4) The refrigerant circulation pipe according to any of Techniques 1 to 3, wherein an inner diameter on a side closer to the plate-type water-refrigerant heat exchanger is smaller than an inner diameter on a side closer to the expansion valve.
  • This makes it easier to increase the flow velocity of the refrigerant flowing into the plate-type water-refrigerant heat exchanger while reducing increase in the pipe resistance of the refrigerant circulation pipe. Therefore, the refrigerant flowing into the plate-type water-refrigerant heat exchanger can be easily made into a state in which a liquid phase and a gas phase are mixed while reducing decrease in efficiency when the flow rate of the refrigerant is high.
  • (Technique 5) The refrigerant circulation pipe according to any of Techniques 1 to 4, wherein a connection pipe connectable to the plate-type water-refrigerant heat exchanger is placed over an outside of a first straight section that is the straight section to be connected to the plate-type water-refrigerant heat exchanger.
  • Thereby, the refrigerant circulation pipe to be used can be a pipe with a diameter smaller than a diameter corresponding to the plate-type water-refrigerant heat exchanger, making it easier to increase the flow velocity of the refrigerant. In addition, placing the connection pipe from the outside makes it possible to reduce the range in which the inner diameter is large immediately before the plate-type water-refrigerant heat exchanger, making the flow velocity less likely to decrease. Therefore, with a simple configuration, the refrigerant flowing into the plate-type water-refrigerant heat exchanger can be easily made into a state in which a liquid phase and a gas phase are mixed.
  • (Technique 6) The refrigerant circulation pipe according to any of Techniques 1 to 5, wherein at least part of an outer diameter is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate passing through an inside.
  • This makes it easier to secure the flow velocity of the refrigerant. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
  • (Technique 7) A refrigeration apparatus, including: an expansion valve; a plate-type water-refrigerant heat exchanger; and a refrigerant circulation pipe connected to the plate-type water-refrigerant heat exchanger and provided between the expansion valve and the plate-type water-refrigerant heat exchanger, wherein the refrigerant circulation pipe includes a plurality of straight sections that extend linearly, and a plurality of curved sections that connect ends of the straight sections and are curved, a bend angle at each of the curved sections being an obtuse angle or a right angle.
  • This allows the refrigerant in a gas-liquid two-phase state to flow into the plate-type water-refrigerant heat exchanger while reducing the effect of centrifugal force, the refrigerant having flowed into the refrigerant circulation pipe after passing through the expansion valve. This makes it easier to make the refrigerant flowing into the plate-type water-refrigerant heat exchanger into a state in which a liquid phase and a gas phase are mixed.
    • Industrial Applicability
  • The present disclosure is applicable to a refrigerant circulation pipe, which is connected to a plate-type water-refrigerant heat exchanger and provided between the plate-type water-refrigerant heat exchanger and an expansion valve, and to a refrigeration apparatus having such a refrigerant circulation pipe. Specifically, the present disclosure is applicable to an apparatus having a heat exchanger that exchanges heat between water and a refrigerant, such as an outdoor unit of a heat-pump-type hot water supply heater, and to a refrigerant circulation pipe provided in the apparatus.
    • Reference Signs List
    • 1 refrigeration apparatus
    • 1a bottom plate
    • 2 compressor
    • 3 flow path switching mechanism
    • 4 air heat exchanger
    • 5 blower
    • 6 expansion valve
    • 7 blower room
    • 8 machine room
    • 8a support member
    • 9 partition plate
    • 10 plate-type water-refrigerant heat exchanger
    • 11 first refrigerant-side connection port
    • 12 second refrigerant-side connection port
    • 13 gas side pipe
    • 14 first water-side connection port
    • 15 second water-side connection port
    • 16 circulation pump
    • 16a valve
    • 17 gas-liquid separator
    • 18 outlet-side water pipe
    • 18a valve
    • 19 flow rate sensor
    • 30 refrigerant circulation pipe
    • 31 first straight section (straight section)
    • 32 second straight section (straight section)
    • 33 third straight section (straight section)
    • 34 fourth straight section (straight section)
    • 35 fifth straight section (straight section)
    • 35a protrusion
    • 36 first curved section (curved section)
    • 37 second curved section (curved section)
    • 38 third curved section (curved section)
    • 39 fourth curved section (curved section)
    • 41 first pipe member
    • 42a, 42b protrusion
    • 43 second pipe member
    • 45 connection pipe
    • 46 receiver tank
    • 47 pipe

Claims (7)

  1. A refrigerant circulation pipe (30) characterized in that that is connected to a plate-type water-refrigerant heat exchanger (10) and is provided between the plate-type water-refrigerant heat exchanger and an expansion valve (6), the refrigerant circulation pipe comprising:
    a plurality of straight sections (31 to 35) extending linearly; and
    a plurality of curved sections (36 to 39) that connect ends of the straight sections and are curved,
    wherein a bend angle at each of the curved sections is an obtuse angle or a right angle.
  2. The refrigerant circulation pipe according to claim 1, further comprising:
    a first straight section (31) that is the straight section connected to the plate-type water-refrigerant heat exchanger;
    a first curved section (36) that is the curved section connected to the first straight section; and
    a second straight section (32) that is the straight section connected to the first curved section,
    wherein the second straight section extends upward from the first curved section.
  3. The refrigerant circulation pipe according to claim 2, wherein the second straight section is longer than the first straight section.
  4. The refrigerant circulation pipe according to claim 1, wherein an inner diameter on a side closer to the plate-type water-refrigerant heat exchanger is smaller than an inner diameter on a side closer to the expansion valve.
  5. The refrigerant circulation pipe according to claim 4, wherein a connection pipe (45) connectable to the plate-type water-refrigerant heat exchanger is placed over an outside of a first straight section that is the straight section to be connected to the plate-type water-refrigerant heat exchanger.
  6. The refrigerant circulation pipe according to claim 1, wherein at least part of an outer diameter is 3.50 mm or less per 1.0 kg/min of refrigerant circulation rate passing through an inside.
  7. A refrigeration apparatus (1), comprising:
    the refrigerant circulation pipe according to any one of claims 1 to 6;
    the expansion valve; and
    the plate-type water-refrigerant heat exchanger.
EP25172612.1A 2024-05-13 2025-04-25 Refrigerant circulation pipe and refrigeration apparatus Pending EP4650687A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2024078207A JP2025172603A (en) 2024-05-13 2024-05-13 Refrigerant circulation piping and refrigeration device

Publications (1)

Publication Number Publication Date
EP4650687A1 true EP4650687A1 (en) 2025-11-19

Family

ID=95474444

Family Applications (1)

Application Number Title Priority Date Filing Date
EP25172612.1A Pending EP4650687A1 (en) 2024-05-13 2025-04-25 Refrigerant circulation pipe and refrigeration apparatus

Country Status (2)

Country Link
EP (1) EP4650687A1 (en)
JP (1) JP2025172603A (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6162756A (en) 1984-09-03 1986-03-31 株式会社デンソー Method and device for feeding refrigerant to dry type evaporator
WO2016038659A1 (en) * 2014-09-08 2016-03-17 三菱電機株式会社 Refrigeration cycle apparatus
US10054377B2 (en) * 2015-09-08 2018-08-21 Hitachi-Johnson Controls Air Conditioning, Inc. Air conditioner

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6162756A (en) 1984-09-03 1986-03-31 株式会社デンソー Method and device for feeding refrigerant to dry type evaporator
WO2016038659A1 (en) * 2014-09-08 2016-03-17 三菱電機株式会社 Refrigeration cycle apparatus
US10054377B2 (en) * 2015-09-08 2018-08-21 Hitachi-Johnson Controls Air Conditioning, Inc. Air conditioner

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