JP2009236483A - Hot water supply device using co2 refrigerant and its operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot water supply device using a CO<SB>2</SB>refrigerant that does not cause increase in size of a device, inexpensive, and for supplying hot water and drying by displaying stable heating capacity when starting in the case of the outside temperature changing such as in winter and summer, and its operating method. <P>SOLUTION: In the operating method of the hot water supply device forming a refrigerating cycle operated while a CO<SB>2</SB>refrigerant path T1 on a high side is maintained in a supercritical state, for distributing water not raised in temperature and other fluids to a gas cooler 4 and raising the temperature thereof, a hot water supply device, and a fluid heating device, a refrigerant bypass path T4 for connecting the gas cooler 4 and a compressor 2 to an outlet side of an expansion means 6 is provided, a supercritical refrigerant tank 30 is interposed in the refrigerant bypass path T4, a first solenoid valve 32 at the inlet side of the supercritical refrigerant tank 30 and a second solenoid valve 34 at the outlet side of the tank are operated to open and close, and the refrigerant in the refrigerant bypass path T4 is maintained in a supercritical state along with the CO<SB>2</SB>refrigerant in the supercritical refrigerant tank from the discharge side of the compressor 2 to the second solenoid valve 34. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a hot water supply apparatus using a CO ₂ refrigerant of a heat pump system type capable of performing stable hot water supply and fluid heating irrespective of a change in the outside air temperature, and the operation method thereof, in particular, the heat pump system. The present invention relates to an invention using a carbon dioxide (CO ₂ ) refrigerant.

In recent years, the use of carbon dioxide (CO ₂ ) refrigerant as a refrigerant that is friendly to the global environment has been promoted, and a heat pump system type hot water supply device that uses this carbon dioxide (CO ₂ ) refrigerant to circulate the high pressure side with supercritical pressure. Studies have been conducted and various proposals have been made.
For example, in a supercritical vapor compression cycle using a carbon dioxide refrigerant, a cooling capacity is controlled by adjusting the amount of circulating refrigerant flowing on the high pressure side (Patent Document 1).
In addition, in a water heater that uses the high-temperature side gas cooler heat dissipation as water heating, in order to enable efficient and stable hot water supply throughout the year, the pressure fluctuation of the low-pressure refrigerant that occurs in response to changes in the outside air temperature due to seasonal fluctuations It is known that a buffer that absorbs the fluctuation difference in the amount of high-pressure side refrigerant accompanying the branching from the main circuit is provided between the high-pressure side gas cooler outlet and the refrigerant expansion valve (Patent Document 2).
Furthermore, similarly, a buffer that absorbs the fluctuation difference in the high-pressure side refrigerant amount due to the pressure fluctuation of the low-pressure side refrigerant that occurs according to the change in the outside air temperature due to seasonal fluctuations is connected to the upstream side and the downstream side of the refrigerant expansion valve. The high-pressure refrigerant liquid upstream of the refrigerant expansion valve and the low-pressure refrigerant liquid downstream of the refrigerant expansion valve are collected in the buffer, and the discharge pressure of the compressor is applied to the inside of the buffer, or the refrigerant liquid inside the buffer is evaporated by the heater. In addition, there is known one that discharges a refrigerant liquid toward an upstream side and a downstream side of a refrigerant expansion valve (Patent Document 3).

Japanese Patent Publication No. 7-18602 Japanese Patent No. 36002116 (paragraph 0018, paragraph 0019) Japanese Patent No. 3443702 (paragraph 0036 to paragraph 0040)

However, the invention described in Patent Document 1 is an invention that adjusts the refrigerating capacity by changing the remaining amount of liquid in the refrigerant receiver to vary the pressure on the high pressure side of the vapor compression cycle, and the adjustment of the refrigerating capacity is discussed. However, focusing on water heating, air heating, etc. using heat radiation in the high-pressure side cooling device (gas cooler), it does not describe that it exhibits stable heating capability against changes in outside air temperature, etc. .
In particular, in the refrigeration cycle shown in Patent Document 1 as shown in FIG. 5, a heat exchanger 212 is provided on the downstream side of the cooling device (gas cooler) 211 so that the throttle means 213 is bypassed from the downstream side. A configuration in which a refrigerant receiver 225 is provided and connected to the outlet side of the throttle means 213 is shown. However, since the remaining amount of liquid exists in the receiver 225 as described in the claims of Patent Document 1, the refrigerant discharged from the receiver 225 is in a liquid state or a saturated gas-liquid mixed phase state with high wetness. Therefore, it is easy to affect the superheat degree on the inflow side of the compressor 210 after the discharge, and it is difficult to obtain an appropriate superheat degree for a long time because the unstable state of the superheat degree lasts for a long time. . In order to obtain a stable degree of superheat on the inflow side of the compressor 210, it is necessary to apply a quick response control to the throttle means 213, or to provide a heat exchanger 212 to improve by heating. Have the problem of

  Further, according to the technology described in Patent Document 2 as shown in FIG. 6, the branch circuit T15 branches off from the main circuit T11 at the outlet of the heat exchanger 214 provided on the downstream side of the gas cooler on the high pressure side of the refrigeration cycle. And a buffer 209 is provided in the branch circuit T15. For this reason, there is a time delay with respect to the sudden rise in the compressor outlet pressure, and the refrigerant recovered in the buffer 209 has a main circuit T11 when the pressure in the buffer 209 and the main circuit T11 are the same. In addition, the refrigerant inside the buffer 209 is difficult to be released, and the buffer function cannot be sufficiently exhibited.

According to the technique described in Patent Document 3 as shown in FIG. 7, the low-pressure refrigerant liquid is recovered from the junction A to the buffer 310 through the branch C by opening the second buffer solenoid valve 311, From the point B, the high-pressure refrigerant liquid is recovered in the buffer 310 through the branch part C. If the first buffer solenoid valve 309 is opened, the discharge pressure of the compressor 301 is applied to the buffer 310, and the refrigerant liquid inside is discharged toward the junction A and the point B downstream of the refrigerant expansion valve 304. Things are shown.
The refrigerant is recovered in the buffer 310 in a liquid state, and the discharge pressure of the compressor 301 is used for discharge. As another example, the buffer 310 is heated by a heater to increase the internal pressure to be released.

However, since the buffer 310 is configured to recover through the junction A or B from the gas cooler outlet to the evaporator, it cannot cope with a sudden pressure increase at the compressor outlet.
Further, it is shown that the refrigerant recovered into the buffer 310 is in a liquid state, and since the released refrigerant is also in a liquid state or a saturated gas-liquid mixed phase state with high wetness, the compression on the downstream side after the discharge is performed. This affects the degree of superheat at the inlet of the machine 301, and the unstable state of the degree of superheat tends to continue for a long time, and the discharge gas temperature and pressure of the compressor 301 vary greatly. In addition, when discharging in such a liquid state, it is necessary to heat by providing an accumulator 307 and a heat exchanger 303 for separating gas and liquid in the previous stage of the compressor 301, resulting in a problem that the apparatus becomes large and complicated. is there.
Furthermore, although it has been shown that the superheat degree at the compressor inlet can be automatically controlled to an appropriate value by the automatic expansion valve, the expansion control by the automatic expansion valve is responsive to temperature changes, and to sudden state changes. Cause a delay. Furthermore, there is a problem that the cost is higher than that using a fixed throttle means without controllability such as a capillary tube.

Therefore, the present invention has been made in view of such a background, is inexpensive without accompanying large-scale complexity of the apparatus, and responds to changes in the outside air temperature due to seasonal fluctuations and winter defrost, It is an object of the present invention to provide a hot water supply apparatus using a CO ₂ refrigerant that exhibits a stable heating capability against a sudden pressure rise at the compressor outlet at the start-up and an operation method thereof.

In order to solve the above-mentioned problem, a hot water supply apparatus using a CO ₂ refrigerant according to the present invention is as follows.
A compressor, gas cooler, expansion means, and evaporator are connected in series on the CO ₂ refrigerant path, and the pressure in the high-side refrigerant path from the compressor discharge side to the expansion means inlet side is maintained in a supercritical state. A hot water supply apparatus using a CO ₂ refrigerant that forms a refrigeration cycle that is heated to heat the water to be heated through the gas cooler and heat-exchanged with the CO ₂ refrigerant in the supercritical state,
A refrigerant bypass path is provided upstream from the gas cooler and connecting the discharge side of the compressor to the outlet side of the expansion means, and the temperature of the CO ₂ refrigerant is set to 32 ° C. or higher by a heater in the refrigerant bypass path. Interposing a supercritical refrigerant tank maintained at a critical temperature, and providing a first valve means on the inlet side and a second valve means on the outlet side of the supercritical refrigerant tank;
Detects the pressure on the discharge side of the compressor and the pressure and temperature from the outlet side of the evaporator to the compressor suction side, and allows the water to be heated to flow through the gas cooler. Together with the CO ₂ refrigerant, the first and second valve means so as to maintain the CO ₂ refrigerant in the refrigerant bypass path from the discharge side of the compressor to the inlet side of the second valve means in a supercritical state. A control device for opening and closing is provided.

Further, the method of operating the hot water supply apparatus using CO ₂ refrigerant according to the present invention, the compressor on the CO ₂ refrigerant passages, a gas cooler, expansion means, an evaporator connected in series, the expansion means inlet side of the compressor discharge side To form a refrigeration cycle that is operated while maintaining the pressure in the high-side refrigerant path up to a supercritical state, and allows the water to be heated to flow through the gas cooler to heat the CO ₂ refrigerant in the supercritical state. In the operation method of the hot water supply device that raises the temperature by replacement,
A refrigerant bypass path is provided upstream from the gas cooler and connecting the discharge side of the compressor to the outlet side of the expansion means, and the temperature of the CO ₂ refrigerant is set to 32 ° C. or higher by a heater in the refrigerant bypass path. Interposing a supercritical refrigerant tank maintained at a critical temperature, and providing a first valve means on the inlet side and a second valve means on the outlet side of the supercritical refrigerant tank;
Detects the pressure on the discharge side of the compressor and the pressure and temperature from the outlet side of the evaporator to the compressor suction side, and allows the water to be heated to flow through the gas cooler. Together with the CO ₂ refrigerant, the first and second valve means so as to maintain the CO ₂ refrigerant in the refrigerant bypass path from the discharge side of the compressor to the inlet side of the second valve means in a supercritical state. It is characterized by opening and closing operations.

According to this invention, when the first valve means is opened, the supercritical CO ₂ refrigerant pressurized by the compressor is recovered in the supercritical refrigerant tank, and then the second valve means is opened to expand the refrigerant. A supercritical CO ₂ refrigerant is released downstream of the means. As a result, the amount of CO ₂ refrigerant in the refrigeration cycle can be adjusted and held in an optimal state.

In particular, in the present invention, the CO ₂ refrigerant recovered in the supercritical refrigerant tank by the first valve means is maintained in a high-pressure and high-temperature supercritical state by heater heating, and this state is maintained until the second valve means. Therefore, the CO ₂ refrigerant can be reliably released by the pressure difference when discharging from the second valve means to the outlet side of the expansion means.
Furthermore, since the tank refrigerant is in a supercritical state, it has less influence on the degree of superheat on the inlet side of the compressor and does not last longer than that discharged in a liquid state or a saturated gas-liquid mixed phase state with high wetness. Therefore, fluctuations in the temperature and pressure on the compressor discharge side can be quickly and stably maintained at appropriate values, and the heating ability by the gas cooler is stabilized.
Further, since the tank refrigerant is in a supercritical state (at least a hot gas state), it is not necessary to provide an accumulator for gas-liquid separation, a heat exchanger for heating, etc., and the apparatus is not complicated and can be reduced in size and weight. .
Furthermore, since the tank refrigerant is in a supercritical state (at least a hot gas state), the CO ₂ refrigerant released to the outlet side of the expansion means is then transferred to the evaporator, the compressor, and the gas cooler to the high side refrigerant path. Is performed quickly, so that the responsiveness is good and the unstable state of the heat pump system does not last for a long time.
The supercritical state refers to a state where the pressure is higher than the critical pressure and higher than the critical temperature, or at least the temperature is higher than the critical temperature.

  In the present invention, the compressor is an oil lubricated compressor, and the outlet of the supercritical refrigerant tank is set at the lower end of the tank, so that it is stored in the lower part of the tank via the second valve means and the evaporator. The operation method of the hot water supply apparatus according to claim 1, wherein the operation can be performed while returning the oil to the inlet side of the compressor. When the compressor is an oil lubricated compressor, the outlet of the supercritical refrigerant tank is connected to the lower end side of the tank. And the oil stored in the lower part of the tank via the second valve means and the evaporator is operated while being returned to the inlet side of the compressor.

  According to this invention, when the compressor is an oil lubricated compressor, the outlet of the supercritical refrigerant tank is installed on the lower end side of the tank, so that the lubricating oil of the compressor accumulated in the lower portion of the tank is supplied to the second valve. It can be discharged from the means to the refrigeration cycle and returned to the compressor inlet side via an evaporator.

In the present invention, the water cooling operation mode of the gas cooler is such that the first and second valve means are opened and closed so that the pressure difference between the inlet side pressure and the outlet side pressure of the expansion means becomes a constant pressure. It is preferable that the operation mode is such that the CO ₂ refrigerant is recovered to the supercritical refrigerant tank in the refrigerant bypass path or the CO ₂ refrigerant is discharged from the supercritical refrigerant tank.

According to this invention, the refrigerant discharged from the compressor is collected or collected in the supercritical refrigerant tank so that the pressure difference between the inlet side pressure and the outlet side pressure of the expansion means becomes a constant pressure in the gas cooler water flow operation mode. Since the first and second valve means are opened and closed so as to release the supercritical CO ₂ refrigerant to the outlet side of the expansion means, the differential pressure across the expansion means becomes constant. Can be controlled by a fixed throttle means without controllability such as a capillary tube, it becomes possible to control the amount of expansion of the expansion means by controlling the number of them, and no device such as a variable throttle valve mechanism is provided. In addition, the control of the amount of drawing can be achieved at low cost, and the entire hot water supply apparatus can be manufactured at low cost.

Further, the present invention is an outside air intake type evaporator in which the evaporator takes in outside air and evaporates CO ₂ refrigerant, and selects a target discharge pressure range of the compressor based on the outside air temperature or in season units, it is preferable to control so as to perform the release of CO ₂ refrigerant from the recovery or supercritical refrigerant tank CO ₂ refrigerant into a supercritical refrigerant tank of said refrigerant bypass path so as to the target discharge pressure range.

According to this invention, when the outside air temperature in winter is low, the evaporation temperature is lowered, and the pressure in the low-side refrigerant path from the outlet side of the expansion means of the refrigeration cycle to the compressor inlet side is reduced. Therefore, if the amount of CO ₂ refrigerant in the refrigeration cycle is constant, the gas density in the high side refrigerant path increases and the pressure in the high side CO ₂ refrigerant path increases, but at this time, the first valve means is By opening and recovering the supercritical CO ₂ refrigerant pressurized by the compressor to the supercritical refrigerant tank, the pressure in the high side refrigerant path is prevented from rising excessively, and the target discharge pressure in winter Controlled to range.

Further, when the outside air temperature is high in summer, the evaporation temperature rises and the pressure in the low-side refrigerant path of the refrigeration cycle rises. Therefore, if the amount of CO ₂ refrigerant in the refrigeration cycle is constant, the gas density in the high side refrigerant path becomes low and the pressure in the high side refrigerant path becomes low. At this time, the second valve means is opened. By operating, the supercritical state CO ₂ refrigerant recovered in the supercritical refrigerant tank is discharged to the outlet side of the expansion means to prevent the pressure in the high side refrigerant path from decreasing, and the summer target The discharge pressure range is controlled.

In this way, an excessive increase in the pressure in the high-side refrigerant path is prevented during the winter, and a decrease in the pressure in the high-side refrigerant path is prevented during the summer. In order to open and close the first valve means and the second valve means so as to fall within the target discharge pressure range of the compressor set based on the season or on a seasonal basis, the low side refrigerant path and the high side refrigerant path The pressure difference from the inside can be kept within a certain range throughout the four seasons, and the differential pressure across the expansion means can be kept within a certain range.
As a result, for example, when the expansion means is constituted by a fixed throttle means such as a capillary tube, it is possible to control the throttle amount within a certain range throughout the season by controlling the number of the expansion means, such as a variable throttle valve mechanism. Control of the drawing amount can be achieved at low cost without providing a device, and the entire hot water supply device can be manufactured at low cost.

Therefore, in the present invention, when the gas cooler water-flow operation is started, the first valve means is opened, the second valve means is closed, and the CO ₂ refrigerant is recovered to the supercritical refrigerant tank, whereby the high side refrigerant is It is preferable to control the pressure in the path to be equal to or lower than the target pressure value and then shift to the gas cooler water flow operation mode.

The water flow temperature of the gas cooler water flow operation is as follows: (1) When water is supplied at around 15 ° C., (2) the water is gradually heated to increase the temperature of the hot water tank, and hot water at around 60 ° C. is supplied. In this case, there are three cases where (3) high-temperature water at around 60 ° C. is supplied from the start-up for pursuit.
In the case of (1), the compressor starts when the pressure of the gas cooler is below the supercritical pressure. In the case of (2), the gas cooler pressure increases as the water flow temperature rises after the compressor starts. The change in compressor outlet pressure is not abrupt.
In the case of (3), the pressure of the gas cooler is under a high pressure equal to or higher than the supercritical pressure before the compressor is started, and the pressure at the outlet of the compressor rises abruptly when starting from such a high pressure.

  A safety valve and a high-pressure shut-off device are attached to the compressor outlet as a safety device that can return to the allowable pressure or lower. In the case of (3), the high-pressure shut-off device operates depending on the water flow temperature or the outside air temperature.

  According to this invention, even if the pressure at the outlet of the compressor rises too much at the time of start-up, the emergency stop of the hot water supply device is performed by opening the first valve means and allowing the refrigerant at the outlet of the compressor to escape into the supercritical refrigerant tank. It is possible to prevent unnecessary operation of the high-pressure shut-off device, and to smoothly transition to the gas cooler water-flowing operation mode, so that the hot water supply device can be used stably.

Here, the pressure of the supercritical refrigerant tank according to claim 1 is rapidly increased so that the temperature of the CO ₂ refrigerant is maintained at a critical temperature or higher by the heater and is not in a liquid state or a saturated gas-liquid mixed phase state with high wetness. It also plays a major role in letting the compressor outlet refrigerant escape to the supercritical refrigerant tank in a short circuit.

That is, if the volume of the supercritical tank is VT and the volume of the liquid that is not heated is VL, the volume of the supercritical refrigerant tank when the refrigerant at the compressor outlet is short-circuited and allowed to escape to the supercritical refrigerant tank. Is as follows.
(1) When the supercritical refrigerant tank holds the temperature of the CO ₂ refrigerant at a critical temperature or higher by a heater V1 = VT
(2) When the supercritical refrigerant tank is not heated and is in a liquid state or a saturated gas-liquid mixed phase (vapor) state with high wetness V2 = VT−VL
At that time, V1> V2, and it is easy to avoid a sudden pressure increase at the outlet of the compressor.

  In the present invention, a defrost operation mode for defrosting the evaporator is set together with the gas cooler water flow operation mode in the control device, and the defrost operation mode stops a heat sink load of the gas cooler and the evaporator. In this state, the compressor is driven, the first valve means and the second valve means are opened in addition to the path of the expansion means to open the refrigerant bypass path, and the supercritical refrigerant in the supercritical refrigerant tank is opened. In this mode, the gas is discharged to the evaporator side.

According to this invention, in the defrosting operation mode, in addition to the path of the expansion means, the first valve means and the second valve means are opened to open the refrigerant bypass path, so that the supercritical state in the supercritical refrigerant tank is reached. The CO ₂ refrigerant is discharged between the outlet side of the expansion means and the inlet side of the evaporator, and the compressor is driven with the heat sink load of the gas cooler and the evaporator stopped, and the CO ₂ refrigerant is driven. In order to circulate the refrigerant in the path of the refrigeration cycle, the refrigerant state discharged from the supercritical refrigerant tank and the CO ₂ refrigerant state supplied by driving the compressor are supercritical states, and fluctuations in the hot water supply device can be kept small. The released high-temperature and high-pressure supercritical CO ₂ refrigerant immediately goes to the nearest evaporator and is defrosted, so that it can be defrosted in a short time.

  In the present invention, the expansion means is constituted by a plurality of constant pressure throttle means arranged in parallel in the refrigerant path, and the throttle obtained by selectively opening the plurality of constant pressure throttle means in the gas cooler water flow operation mode. When the range is outside the target superheat range on the inlet side of the compressor, the first and second valve means are opened and closed to maintain the superheat level on the inlet side of the compressor in the target superheat range. To be controlled.

According to this invention, since a plurality of constant pressure throttling means are selectively opened, the amount of throttling is in the range when all the constant pressure throttling means are selected and when one constant pressure throttling means is selected, and there is a gap between them. It will change step by step.
For this reason, for example, if the superheat degree on the compressor inlet side does not rise too much beyond the target superheat range even if all constant pressure throttling means are opened, the second valve means is controlled to open. Reduce the superheat on the inlet side of the compressor and maintain it in the target superheat range. On the other hand, even if one constant pressure throttle means is selected, if the degree of superheat on the compressor inlet side does not rise too much beyond the target superheat degree range, the first valve means is controlled to open and compressed. Increase the superheat on the inlet side of the machine and maintain it in the target superheat range.
In this way, the first and second valve means can be controlled to be opened and closed so that the superheat degree on the compressor inlet side can be maintained within the target superheat degree range, so that the pressure and temperature on the compressor outlet side can be maintained without fluctuation. It is possible to stabilize the inflow temperature to the gas cooler.
Further, for example, when a capillary tube is used as the constant pressure throttle means, it is possible to configure the hot water supply apparatus at a lower cost than when using a variable throttle valve mechanism.

In the operation method of the present invention, when the operation is stopped, the operation of the compressor is stopped and the expansion means is closed. At the same time, both the first valve means and the second valve means are opened, and then the gas cooler is connected. By shutting off water and stopping the blowing to the evaporator, the CO ₂ refrigerant on the discharge side of the compressor is caused to flow to the evaporator side via the refrigerant bypass path, and the high side refrigerant path and the low side The pressure is equalized between the two refrigerant paths.

  According to this invention, when the hot water supply device is stopped, the compressor is stopped, the throttle means is closed, the flow to the evaporator of the high side refrigerant path via the gas cooler is interrupted, and the first valve means and By opening the second valve means together, the compressor discharge side refrigerant is caused to flow to the evaporator side via the refrigerant bypass path, and pressure is equalized between the high side refrigerant path and the low side refrigerant path. Therefore, since there is no pressure difference before and after the compressor at the start after the stop, the compressor can be easily started.

  According to the present invention, the apparatus is inexpensive without increasing the size of the apparatus, and can respond to a change in the outside air temperature due to seasonal fluctuations and a defrost in winter, and a sudden pressure rise at the compressor outlet at the start of the apparatus In addition, a hot water supply apparatus that exhibits stable heating capability and an operation method thereof can be provided.

  In addition, according to the present invention, the temperature and pressure on the compressor discharge side can be stably maintained at appropriate values when the outside air temperature changes due to seasonal fluctuations such as winter and summer, and when the apparatus is started up, etc. Further, it is possible to obtain a hot water supply apparatus and an operation method thereof that can achieve a reduction in size and weight of the apparatus.

It is a system outline figure of the hot-water supply apparatus concerning a 1st embodiment of the present invention. It is a flowchart figure which shows control of the solenoid valve with respect to external temperature change. It is explanatory drawing which shows a series of operation | movement patterns of a hot water supply apparatus. It is a system outline | summary figure of the fluid heating apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram which shows a prior art. It is a schematic block diagram which shows a prior art. It is a schematic block diagram which shows a prior art.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. However, as long as there is no specific description, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
In the drawings to be referred to, FIG. 1 is a system schematic diagram of a hot water supply apparatus according to a first embodiment of the present invention. FIG. 2 is a flowchart showing the control of the solenoid valve (valve means) with respect to changes in the outside air temperature. FIG. 3 is an explanatory diagram showing a series of operation patterns. FIG. 4 is a system schematic diagram of a fluid heating apparatus according to the second embodiment of the present invention.

1st Embodiment is described with reference to the system schematic diagram of the hot water supply apparatus 1 shown in FIG.
The compressor 2, the gas cooler 4, the expansion means 6, and the evaporator 8 are arranged in series. The high-side refrigerant path T <b> 1 from the discharge side of the compressor 2 to the inlet side of the expansion means 6, and the outlet side of the expansion means 6 The basic refrigeration cycle is formed by being connected by the low-side refrigerant path T2 to the inlet side of the compressor 2. Carbon dioxide (CO ₂ ) is used as the refrigerant in the refrigeration cycle, and the refrigerant is operated while being maintained in a supercritical state in the high-side refrigerant path T1.

The expansion means 6 is composed of four capillary tubes 7a, 7b, 7c and 7d as constant pressure throttling means arranged in parallel in the refrigerant path, and the inlet side of each capillary tube 7a, 7b, 7c and 7d is electromagnetic. Valves 10a, 10b, 10c, 10d are provided.
A capillary tube is a thin tube that performs expansion by utilizing the flow resistance (pressure drop or differential pressure across the tube) when the refrigerant flows through the tube (tube). The aperture amount is determined by the length and the like.

  The evaporator 8 is an outside air intake type evaporator that takes in outside air by the blower fan 12 and evaporates the refrigerant. The gas cooler 4 is connected to a water supply path T3 for passing water heated by exchanging heat with a supercritical refrigerant in the refrigeration cycle. The water supply path T3 includes a water inlet 14 and water. An outlet 16 and a water supply pump 18 are provided. The water supply pump 18 may be provided outside the hot water supply apparatus 1 instead of in the water supply path T3.

  The water inlet 14 and the water outlet 16 are connected to a hot water tank 20 provided outside the hot water supply device 1. A replenishing water supply pipe 22 that replenishes hot water in the hot water storage tank 20 and a hot water storage water supply pipe 24 that supplies hot water separately from the reheating water supply pipe 22 are connected via a switching valve 26. Connected to the water inlet 14. In addition, a hot water storage pipe 28 that stores water heated by the gas cooler 4 back to the hot water storage tank 20 is connected to the water outlet 16.

  A refrigerant bypass path T4 is provided so as to bypass the gas cooler 4 and the expansion means 6 by connecting the discharge side of the compressor 2 and the outlet side of the expansion means 6 upstream of the gas cooler 4. A supercritical refrigerant tank 30 is interposed in the refrigerant bypass path T4, and a first electromagnetic valve 32 (first valve means) is provided on the outlet side of the supercritical refrigerant tank 30 on the inlet side of the supercritical refrigerant tank 30. Are each provided with a second electromagnetic valve 34 (second valve means).

  When the first electromagnetic valve 32 is opened, high-pressure and high-temperature supercritical refrigerant is recovered from the compressor 2 into the tank 30, and when the second electromagnetic valve 34 is opened, the refrigerant recovered in the tank 30 is supplied to the outlet side of the expansion means 6 and the evaporator. 8 is released.

  The supercritical refrigerant tank 30 has an inlet connected to the upper end and an outlet connected to the lower end. For this reason, even if the compressor 2 is an oil lubrication type compressor and the lubricating oil is mixed in the refrigerant, the lubricating oil is accumulated in the lower part of the supercritical refrigerant tank 30 and is second from the outlet installed on the lower end side of the tank 30. It is discharged between the outlet side of the expansion means 6 and the evaporator 8 through the electromagnetic valve 34 and can be returned from the evaporator 8 to the compressor 2.

  The supercritical refrigerant tank 30 is covered with a heat insulating material 36 so as not to be cooled due to the influence of the outside air temperature, and is constantly heated to a temperature of 32 ° C. or higher by the heater 38, so that the refrigerant in the tank 30 is constantly It is controlled to be maintained in a supercritical state (at least a hot gas state).

For this reason, the refrigerant recovered in the supercritical refrigerant tank 30 by the first electromagnetic 32 is maintained in a high-pressure and high-temperature supercritical state by the heating of the heater 38, and this state is maintained up to the second electromagnetic valve 34. When discharging from the second electromagnetic valve 34 to the outlet side of the expansion means 6, the refrigerant can be reliably discharged by the pressure difference.
Further, since the tank refrigerant is in a supercritical state, it has less influence on the degree of superheat on the inlet side of the compressor 2 compared with that discharged in a liquid state or a saturated gas-liquid mixed phase state with a high wetness, and may last longer. Therefore, the temperature and pressure fluctuations on the compressor discharge side are small and can be stably held at appropriate values, and the heating ability by the gas cooler 4 is stabilized.
Further, since the tank refrigerant is in a supercritical state (at least a hot gas state), it is not necessary to provide an accumulator for gas-liquid separation, a heat exchanger for heating, etc., and the apparatus is not complicated and can be reduced in size and weight. .
Furthermore, since the tank refrigerant is in a supercritical state (at least a hot gas state), the refrigerant released to the outlet side of the expansion means is then sent to the evaporator 8, the compressor 2 and the gas cooler 4 to the high side refrigerant path T1. Since the movement of the heat pump system is performed quickly, the response is good, and the unstable state of the heat pump system does not last for a long time.

  The water heater 1 is configured as described above. Next, the first electromagnetic valve 32, the second electromagnetic valve 34, and the inlet side of the capillary tubes 7a, 7b, 7c, and 7d provided in the refrigerant bypass path T4. A control device 50 for controlling the electromagnetic valves 10a, 10b, 10c, and 10d will be described. The control device 50 includes a bypass control unit 52 that controls opening and closing operations of the first solenoid valve 32 and the second solenoid valve 34, and a throttle control unit 54 that controls the selective opening of the capillary tubes 7a, 7b, 7c, and 7d. Become.

  The bypass control means 52 detects the pressure Pd on the discharge side of the compressor 2, the temperature Tc and the pressure Pc from the outlet side of the evaporator 8 to the suction side of the compressor 2, and the detection signal of the compressor 2 is detected from these detection signals. The refrigerant in the refrigerant bypass path T4 from the discharge side to the inlet side of the second solenoid valve is maintained in a supercritical state, and the refrigerant discharged from the compressor 2 is transferred to the supercritical refrigerant tank 30 according to the operation mode of the hot water supply device 1. Control is performed so that the recovered refrigerant or the recovered refrigerant is discharged to the outlet side of the expansion means 6.

The bypass control means 52 controls the pressure difference between the inlet side pressure and the outlet side pressure of the capillary tubes 7a, 7b, 7c, 7d constituting the expansion means 6 to be a constant pressure even if the outside air temperature changes throughout the seasons. Alternatively, the pressure on the discharge side of the compressor 2 is controlled to an appropriate pressure so that it does not rise abnormally during startup.
Further, the bypass control means 52 controls the superheat degree control on the inlet side of the compressor 2 so as to fall within the target superheat degree range together with the throttle control means 54 described later.

  When the outside air temperature is low in winter, the evaporation temperature is lowered, and the pressure in the low-side refrigerant path T2 from the outlet side of the expansion means 6 of the refrigeration cycle to the inlet side of the compressor 2 is reduced. Therefore, if the refrigerant amount in the refrigeration cycle is constant, the gas density in the high-side refrigerant path T1 increases and the pressure in the high-side refrigerant path T1 increases. At this time, the bypass control means 52 is By opening the solenoid valve 32 and recovering the supercritical refrigerant that has been pressurized by the compressor 2 in the supercritical refrigerant tank 30, an excessive increase in pressure in the high-side refrigerant path T1 is prevented, and the winter season The target discharge pressure at the time is controlled.

  Further, when the outside air temperature is high in summer, the evaporation temperature rises and the pressure in the low-side refrigerant path T2 of the refrigeration cycle rises. Therefore, if the amount of refrigerant in the refrigeration cycle is constant, the gas density in the high-side refrigerant path T1 becomes low and the pressure in the high-side refrigerant path T1 becomes low. By opening the solenoid valve 34, the supercritical refrigerant recovered in the supercritical refrigerant tank 30 is discharged to the outlet side of the expansion means 6 to prevent the pressure in the high side refrigerant path T1 from decreasing. Thus, the target discharge pressure is controlled in summer.

The operation of the bypass control means 52 with respect to changes in the outside air temperature will be described with reference to the flowchart of FIG.
First, the first electromagnetic valve 32 and the second electromagnetic valve 34 are closed (S1). Next, a seasonal mode of winter, summer or intermediate period is set by the outside air temperature sensor 33 or a manual changeover switch (not shown) (S3).

  In the winter mode, it is determined whether or not the pressure Pd on the discharge side of the compressor 2 is equal to or higher than the target discharge pressure L in the winter mode (S5). (S7), a predetermined time (1 second) has elapsed (S9), and then it is determined whether the pressure Pd has dropped below the target discharge pressure L-Δl (S11), and the discharge pressure Pd falls below L-Δl. Until the first electromagnetic valve 32 is opened, the operation is repeated. This Δl indicates a certain allowable value. When the discharge pressure Pd becomes L−Δl or less, the first electromagnetic valve 32 is closed (S13).

Further, it is determined whether or not the pressure Pd on the discharge side of the compressor 2 is equal to or lower than the target discharge pressure L in the winter mode (S15), and if it is equal to or lower than the target pressure L, the second electromagnetic valve 34 is opened (S17), After a predetermined time (1 second) has elapsed (S19), it is then determined whether the pressure Pd has risen above the target discharge pressure L + Δl (S21), and the opening operation of the second electromagnetic valve 34 is repeated until the discharge pressure Pd becomes L + Δl or more. . Then, when the discharge pressure Pd becomes L + Δl or more, the second electromagnetic valve 34 is closed (S23).
As described above, the pressure Pd on the discharge side of the compressor 2 can be maintained within the range of the target discharge pressure L ± Δl in winter by controlling the first solenoid valve 32 and the second solenoid valve 34.

  Similarly, in the intermediate period, the pressure Pd on the discharge side of the compressor 2 can be maintained within the range of the target discharge pressure M ± Δm in the intermediate period, and in the summer period, the pressure Pd on the discharge side of the compressor 2 can be maintained. Can be maintained within the range of the target discharge pressure H ± Δh in summer.

  As a result, although the pressure in the low-side refrigerant path T2 varies depending on the season (outside air temperature), the pressure in the high-side refrigerant path T1 is changed to the target discharge pressure value L ± Δl, M ± Δm, H ± Δh for each season. The differential pressure between the pressure in the low-side refrigerant path T2 and the pressure in the high-side refrigerant path T1 is set to one year depending on the set values of the target discharge pressure values L, M, and H. And can be set within a certain range.

Since the pressure difference between the inlet side pressure and the outlet side pressure of the capillary tubes 7a, 7b, 7c, 7d is maintained at a constant pressure so as not to vary greatly depending on the season as described above, the capillary tubes 7a, 7b, 7c, The suction superheat degree on the inlet side of the compressor 2 can be stably controlled by selecting the number 7d.
As described above, since the largest amount of refrigerant flows in the refrigeration cycle during summer and the smallest amount during winter, the capacity of the supercritical refrigerant tank 30 can recover the maximum refrigerant state during summer during winter. Of course, it is necessary to set the capacity.

Next, the aperture control means 54 will be described.
The throttle control means 54 detects the temperature Tc and the pressure Pc from the outlet side of the evaporator 8 to the suction side of the compressor 2 to obtain the saturation temperature with respect to the pressure Pc, and from the difference between the saturation temperature and the detected temperature Tc. Then, the degree of superheat on the suction side of the compressor 2 is obtained. The capillary tubes 7a, 7b are opened by controlling the solenoid valves 10a, 10b, 10c, 10d on the inlet side of the four capillary tubes 7a, 7b, 7c, 7d so that the degree of superheat falls within the target superheat range. , 7c, 7d are selected.

  Even if the throttle control means 54 controls the degree of superheat by selecting the capillary tubes 7a, 7b, 7c, 7d in this way, the control by the throttle control means 54 controls the four capillary tubes 7a, 7b, 7c, 7d. In order to selectively open, the refrigerant flow rate changes stepwise between the case where four are selected and the case where one is selected.

  Therefore, for example, even if all four are opened, the superheat degree on the inlet side of the compressor 2 may exceed the target superheat degree range and not rise down. In this case, the bypass control means 52 opens the second electromagnetic valve 34 to lower the superheat degree on the inlet side of the compressor 2 and maintain it in the target superheat degree range. On the contrary, although only one is open | released, the superheat degree of the inlet side of the compressor 2 may fall too much exceeding a target superheat degree range, and may not go up. In this case, the first solenoid valve 32 is opened by the bypass control means 52 and a part of the refrigerant discharged from the compressor 2 is collected in the supercritical refrigerant tank 30 so that the overheating on the inlet side of the compressor 2 is performed. Increase the temperature to maintain the target superheat range.

  In this way, the bypass control means 52 can open and close the first solenoid valve 32 and the second solenoid valve 34 to maintain the superheat degree on the inlet side of the compressor 2 within the target superheat degree range. The pressure and temperature on the side can be maintained without fluctuation, and the inflow temperature to the gas cooler 4 can be stabilized.

  As in this embodiment, by selecting the capillary tubes 7a, 7b, 7c, 7d, the refrigerant flow rate is controlled to control the degree of superheat, so that the throttle is not provided without a device such as a variable throttle valve mechanism. The amount can be controlled at low cost, and the entire hot water supply apparatus can be manufactured at low cost.

Next, the operation mode of the hot water supply apparatus 1 will be described.
The operation mode as shown in FIG. 3 is set in the hot water supply apparatus 1, and the operation pattern is changed from the start time 102 by the mode changeover switch 100 to the hot water supply operation mode (gas cooler water operation mode) 104, the defrost operation mode 106, The hot water supply operation mode 104 can be switched to the stop time 108, and in the hot water supply operation mode 104, the hot water storage mode 110 in which the hot water is heated and stored in the hot water tank 20, and the hot water from the hot water tank 20 is reheated and stored in the hot water tank 20 again. The chasing mode 112 can be switched.

(At startup)
At the start-up time 102, the water supply pump 18 is operated to supply water to be heated to the gas cooler 4, the evaporator 8 is operated, the blower fan 12 is rotated, and finally the compressor 2 is driven, and the refrigerant Begins to circulate in the refrigeration cycle, and heat loads act on the gas cooler 4 and the evaporator 8 respectively. At the same time, the selected capillary tubes 7a, 7b, 7c, 7d are opened by operating the solenoid valves 10a, 10b, 10c, 10d of the capillary tubes 7a, 7b, 7c, 7d, and the first solenoid valve 32 and the second solenoid valve 32 Both solenoid valves 34 are closed.

  At the time of start-up 102, the first electromagnetic valve 32 and the second electromagnetic valve 34 are both opened by the bypass control means 52 at the time of stop 108, which will be described later, and flowed to the evaporator side through the refrigerant bypass path T4. Since the pressure is equalized between the high-side refrigerant path T1 and the low-side refrigerant path T2, there is no pressure difference before and after the compressor 2 when starting after the stop, and the compressor 2 is started. Easy to do.

  Further, at the time of startup 102, the pressure in the high-side refrigerant path T1 increases too much due to abrupt refrigerant movement from the low-side refrigerant path T2 to the high-side refrigerant path T1, and an abnormal pressure is detected and hot water is supplied. In order not to unnecessarily activate the high-pressure shut-off device 56 for emergency stop of the device, the bypass control means 52 opens the first electromagnetic valve 32 based on the pressure Pd on the discharge side of the compressor 2 and short-circuits it. Then, the refrigerant is recovered into the supercritical refrigerant tank 30 to control the pressure in the high-side refrigerant path T1 to be equal to or lower than the target pressure (set to be equal to or lower than the operating pressure of the high-pressure shut-off device 56 for emergency stop). The hot water supply operation mode (gas cooler water operation mode) 104 can be smoothly shifted to.

The water temperature of the gas cooler 4 during water flow operation is (1) when clean water is supplied at around 15 ° C, (2) the water is gradually heated and the hot water tank temperature rises, and hot water at around 60 ° C is supplied. (3) There are three cases where high-temperature water at around 60 ° C. is supplied from the start-up for tracking.
In the case of (1), the compressor 2 starts up when the pressure of the gas cooler 4 is below the supercritical pressure. In the case of (2), the gas cooler pressure increases as the water flow temperature rises after the compressor starts. In any case, the change in the compressor outlet pressure is not abrupt.
In the case of (3), the pressure of the gas cooler 4 is under a high pressure that is equal to or higher than the supercritical pressure before the compressor 2 is started, and the pressure at the outlet of the compressor 2 suddenly rises when starting from such a high pressure. To do.

  A safety valve (not shown) and the high-pressure shut-off device 56 are attached to the outlet of the compressor 2 as a safety device that can return to a pressure lower than the allowable pressure. In some cases, the high-pressure shut-off device 56 is activated.

  Even if the pressure at the outlet of the compressor 2 rises too much at the time of startup, the first electromagnetic valve 32 is opened and the refrigerant at the outlet of the compressor 2 escapes to the super supercritical refrigerant tank 30 in a short circuit. The high pressure shut-off device 56 is prevented from being operated unnecessarily, and the transition to the gas cooler water flow operation mode can be performed smoothly, and the hot water supply device 1 can be used stably.

  The supercritical refrigerant tank 30 is maintained at a temperature higher than the critical temperature by the heater 38 and is not in a liquid state or a saturated gas-liquid mixed phase state with high wetness. Is also a major role in letting the short circuit escape to the supercritical refrigerant tank 30.

That is, when the volume of the supercritical refrigerant tank 30 is VT and the volume of the liquid that is not heated is VL, the supercritical refrigerant when the outlet refrigerant of the compressor 2 is short-circuited and escaped to the supercritical refrigerant tank 30. The volume of the tank 30 is as follows.
(1) When the supercritical refrigerant tank 30 is maintained at a temperature equal to or higher than the critical temperature by the heater 38 V1 = VT
(2) When the supercritical refrigerant tank 30 is not heated and is in a liquid state or a saturated gas-liquid mixed phase state with high wetness V2 = VT−VL
At that time, V1> V2, and it is easy to avoid a sudden pressure increase at the compressor outlet.

(Hot water operation mode)
When the hot water storage mode 110 in the hot water supply operation mode (gas cooler water operation mode) 104 is selected, the switching valve 26 is operated so that the hot water storage water supply pipe 24 is connected to the water inlet 14 as shown in FIG. Then, the water from the hot water storage water supply pipe 24 is supplied to the gas cooler 4 by the water supply pump 18 and is heated by exchanging heat with the refrigerant of the refrigeration cycle, and is stored in the hot water storage tank 20 through the pipe 28 from the water outlet 16. Is connected.

Normally, the refrigerant evaporation temperature by the evaporator 8 is 10 ° C. to 15 ° C. lower than the outside air temperature, and the evaporation temperature (pressure in the low-side refrigerant path T2) is substantially determined by the outside air temperature. The density of the refrigerant to be determined is determined, and the refrigerant circulation amount is determined.
Further, when the degree of superheated suction to the compressor 2 is appropriate, that is, when refrigerant in an appropriate superheated gas state flows into the compressor 2, a stable pressure Pd and temperature Td with little fluctuation are determined on the output side. When the pressure Pd and temperature Td on the discharge side are determined, the heating capacity in the gas cooler 4 is substantially determined.

For this reason, in order to obtain the stable heating capability for hot water supply, it is necessary to control the superheat degree of the suction side gas of the compressor 2 within an appropriate range. However, since the outside air temperature fluctuates depending on the season and the pressure in the low-side refrigerant path T2 fluctuates, in order to obtain a stable heating capacity by the gas cooler 4, an appropriate amount of refrigerant is charged in the refrigeration cycle throughout the season. It is necessary to control the superheat degree of the suction side gas of the compressor 2 to an appropriate value.
For this reason, as already described, the bypass control means 52 and the throttle control means 54 control the degree of superheat of the suction side gas of the compressor 2 to an appropriate value by filling the refrigeration cycle with an appropriate amount of refrigerant throughout the season. ing.

For example, the superheat degree of the suction side gas of the compressor 2 is controlled in the range of 7 ° C. to 12 ° C., and the pressure Pd in the high side refrigerant path T1 is set to 11.5 to 12.5 MPa in the summer, and the intermediate period In the winter, the temperature Td on the discharge side of the compressor 2 is set to a refrigerant temperature of 115 ° C. to 125 ° C. by controlling in the range of L = 9.5 to 10.5 MPa in winter. Can be achieved.
And since it becomes possible to always supply about 120 degreeC refrigerant | coolant to the gas cooler 4, water can be heated by heat exchange with the refrigerant | coolant and supply water in the gas cooler 4, and can be made into about 90 degreeC hot water. The hot water temperature after heating can be controlled by adjusting the amount of water supplied to the gas cooler 4 with the water supply pump 18.

When the reheating mode 112 in the hot water supply operation mode (gas cooler water operation mode) 104 is selected, the switching valve 26 is operated so that the reheating water supply pipe 22 is connected to the water inlet 14 as shown in FIG. To do. Then, the water from the replenishing water supply pipe 22 is supplied to the gas cooler 4 by the water supply pump 18 and is heated by exchanging heat with the refrigerant of the refrigeration cycle, and is accumulated in the hot water storage tank 20 through the pipe 28 from the water outlet 16. Connected.
The operation method is the same as that in the hot water storage mode 110 described above. However, since the feed water temperature to the gas cooler 4 is already accumulated in the hot water storage tank 20, it is as high as about 65 ° C., and it is necessary to control the flow rate of the feed water pump 18 to obtain a desired hot water temperature. is there.

(Defrost operation mode)
When the defrost (defrosting) operation mode 106 is selected, the water supply to the gas cooler 4 is shut off, and the blower fan 12 of the evaporator 8 is stopped to stop the heat removal load, and the compressor 2 is driven. At the same time, in addition to the path of the expansion means 6, both the first electromagnetic valve 32 and the second electromagnetic valve 34 are opened to open the refrigerant bypass path T4, and the supercritical gas in the supercritical refrigerant tank 30 is released to the evaporator 8 side. To do.

  For this reason, the first electromagnetic valve 32 and the second electromagnetic valve 34 are opened to open the refrigerant bypass path T4, and the supercritical refrigerant in the supercritical refrigerant tank 30 is supplied to the outlet side of the expansion means 6 and the evaporator 8. In order to circulate the refrigerant in the path of the refrigeration cycle by driving the compressor 2 with the heat sinking load of the gas cooler 4 and the evaporator 8 stopped, the refrigerant is circulated in the path of the refrigeration cycle. The refrigerant state discharged from the refrigerant tank 30 and the refrigerant state supplied by driving the compressor 2 are supercritical states, and fluctuations of the hot water supply device 1 can be suppressed to a small level. The refrigerant immediately goes to the nearest evaporator 8 and defrosting is performed, so that defrosting can be performed in a short time.

(When stopped)
At the time of stop 108, the operation of the compressor 2 is stopped and the expansion means 6 is closed. At the same time, both the first electromagnetic valve 32 and the second electromagnetic valve 34 are opened, and then the water flow to the gas cooler 4 is shut off. At the same time, by stopping the blower fan 12 of the evaporator 8, the refrigerant on the discharge side of the compressor 2 is caused to flow to the evaporator 8 side via the refrigerant bypass path T <b> 4, and the high side refrigerant path T <b> 1 and the low side refrigerant are passed. The pressure is equalized between both paths T2. For this reason, since there is no pressure difference before and after the compressor 2 at the start after the stop, the compressor 2 is easily started.

Next, a second embodiment applied to a fluid heating device 120 that performs fluid heating instead of the hot water supply device 1 will be described with reference to FIG.
As shown in FIG. 4, only the water supply portion of the hot water supply apparatus 1 is changed to supply of fluid. The gas cooler 4 is connected to an air supply path T5 for passing a fluid heated by exchanging heat with the supercritical refrigerant in the refrigeration cycle. In the air supply path T5, a fluid inlet 122, a fluid outlet 124, and a fluid supply pump 126 (in the case of gas, an air supply blower 126 ') are provided. The fluid supply pump 126 may be provided outside the fluid heating device 120 instead of in the air supply path T5.

As for the operation mode of the fluid heating device 120, the operation modes such as the hot water storage mode 104 and the reheating mode 112 set in the hot water supply operation mode (gas cooler water operation mode) 104 of the hot water supply device 1 are distinguished. There is only a heating operation mode.
Other components are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

If brine is passed as the fluid to be heated, it can be used for snow melting or the like, and can be used as a gas dryer by flowing gas.
In addition, the second embodiment also has the same effect as the first embodiment related to the hot water supply device 1 and compresses even when the outside air temperature changes in winter, summer, etc., at the time of startup, etc. The temperature and pressure on the machine discharge side can be stably maintained at appropriate values, a stable heating ability by a gas cooler can be obtained, and a fluid heating apparatus that can achieve a reduction in size and weight without being complicated.

  According to the present invention, the apparatus is inexpensive without increasing the size of the apparatus, and can respond to a change in the outside air temperature due to seasonal fluctuations and a defrost in winter, and a sudden pressure rise at the compressor outlet at the start of the apparatus Therefore, it is possible to exert a stable heating capability, which is advantageous when applied to an operation method of a hot water supply apparatus, a hot water supply apparatus, or a fluid heating apparatus.

DESCRIPTION OF SYMBOLS 1 Hot-water supply apparatus 2 Compressor 4 Gas cooler 6 Refrigerant expansion valve (expansion means)
8 Evaporator 7a, 7b, 7c, 7d Capillary tube 10a, 10b, 10c, 10d Electromagnetic valve 30 Supercritical refrigerant tank 32 First electromagnetic valve 34 Second electromagnetic valve 38 Heating heater 50 Control device 52 Bypass control means 54 Restriction control means 120 Fluid heating device

Claims (10)

A compressor, gas cooler, expansion means, and evaporator are connected in series on the CO ₂ refrigerant path, and the pressure in the high-side refrigerant path from the compressor discharge side to the expansion means inlet side is maintained in a supercritical state. A hot water supply apparatus using a CO ₂ refrigerant that forms a refrigeration cycle that is heated to heat the water to be heated through the gas cooler and heat-exchanged with the CO ₂ refrigerant in the supercritical state,
A refrigerant bypass path is provided upstream from the gas cooler and connecting the discharge side of the compressor to the outlet side of the expansion means, and the temperature of the CO ₂ refrigerant is set to 32 ° C. or higher by a heater in the refrigerant bypass path. Interposing a supercritical refrigerant tank maintained at a critical temperature, and providing a first valve means on the inlet side and a second valve means on the outlet side of the supercritical refrigerant tank;
Detecting the pressure on the discharge side of the compressor and the pressure and temperature from the outlet side of the evaporator to the suction side of the compressor, and passing the water to be heated to the gas cooler in the water-cooled water operation mode, the supercritical refrigerant tank Together with the CO ₂ refrigerant, the first and second valve means so as to maintain the CO ₂ refrigerant in the refrigerant bypass path from the discharge side of the compressor to the inlet side of the second valve means in a supercritical state. A hot water supply apparatus using a CO ₂ refrigerant, comprising a control device for opening and closing. The compressor is an oil lubricated compressor, and by setting the outlet of the supercritical refrigerant tank to the lower end side of the tank, the oil stored in the lower part of the tank via the second valve means and the evaporator is supplied to the compressor. The hot water supply apparatus using the CO ₂ refrigerant according to claim 1, wherein the apparatus is configured to be operable while being returned to the inlet side. A defrost operation mode for defrosting the evaporator is set together with the gas cooler water flow operation mode in the control device, and the defrost operation mode is set in a state in which the heat sink load of the gas cooler and the evaporator is stopped. In addition to driving the compressor, in addition to the path of the expansion means, the first valve means and the second valve means are opened to open the refrigerant bypass path, and the supercritical gas in the supercritical refrigerant tank is removed from the evaporator side. The hot water supply apparatus using the CO ₂ refrigerant according to claim 1, wherein the hot water supply apparatus is a mode in which the CO ₂ refrigerant is discharged. A compressor, gas cooler, expansion means, and evaporator are connected in series on the CO ₂ refrigerant path, and the pressure in the high-side refrigerant path from the compressor discharge side to the expansion means inlet side is maintained in a supercritical state. In the operation method of the hot water supply apparatus, the refrigeration cycle is formed, and the temperature-controlled water is passed through the gas cooler to raise the temperature by heat exchange with the CO ₂ refrigerant in the supercritical state.
A refrigerant bypass path is provided upstream from the gas cooler and connecting the discharge side of the compressor to the outlet side of the expansion means, and the temperature of the CO ₂ refrigerant is set to 32 ° C. or higher by a heater in the refrigerant bypass path. Interposing a supercritical refrigerant tank maintained at a critical temperature, and providing a first valve means on the inlet side and a second valve means on the outlet side of the supercritical refrigerant tank;
Detects the pressure on the discharge side of the compressor and the pressure and temperature from the outlet side of the evaporator to the compressor suction side, and allows the water to be heated to flow through the gas cooler. Together with the CO ₂ refrigerant, the first and second valve means so as to maintain the CO ₂ refrigerant in the refrigerant bypass path from the discharge side of the compressor to the inlet side of the second valve means in a supercritical state. A method for operating a hot water supply apparatus using a CO ₂ refrigerant, characterized by opening and closing. In the gas cooler water flow operation mode, the first and second valve means are opened and closed so that the pressure difference between the inlet side pressure and the outlet side pressure of the expansion means becomes a constant pressure. how the operation of the water heater using a CO ₂ refrigerant according to claim 4, characterized in that the release of CO ₂ refrigerant from the recovery or supercritical refrigerant tank CO ₂ refrigerant into a supercritical refrigerant tank. The evaporator is an outside air intake type evaporator that takes in outside air and evaporates CO ₂ refrigerant, and selects a target discharge pressure range of the compressor based on the outside air temperature or by a season unit, and the target discharge pressure range use of CO ₂ refrigerant according to claim 4 or 5, wherein by performing the release of CO ₂ refrigerant from the recovery or supercritical refrigerant tank CO ₂ refrigerant into a supercritical refrigerant tank of said refrigerant bypass path so as to The operation method of the hot water heater. At the start of the gas cooler water flow operation, the first valve means is opened, the second valve means is closed, and the CO ₂ refrigerant is recovered to the supercritical refrigerant tank, whereby the pressure in the high side refrigerant path is reduced. The method of operating a hot water supply apparatus using CO ₂ refrigerant according to claim 4, wherein the operation is controlled to be equal to or lower than a target pressure value, and then the mode is shifted to the gas cooler water flow operation mode. In the defrost operation mode in which the evaporator is defrosted, the compressor is driven with the heat sink load of the gas cooler and the evaporator stopped, and in addition to the path of the expansion means, the first valve means and the second 5. The hot water supply device using CO ₂ refrigerant according to claim 4, wherein the valve means of 2 is opened to open the refrigerant bypass path to discharge supercritical gas in the supercritical refrigerant tank to the evaporator side. how to drive. The expansion means is composed of a plurality of constant pressure throttle means arranged in parallel with the refrigerant path, and a throttle range obtained by selectively opening the plurality of constant pressure throttle means in the gas cooler water flow operation mode is the compressor. And when the first and second valve means are opened and closed, the superheat degree on the inlet side of the compressor is maintained within the target superheat degree range when the target superheat degree range on the inlet side of the compressor is out of range. how the operation of the water heater using a CO ₂ refrigerant according to claim 4, wherein. At the time of stop, the operation of the compressor is stopped and the expansion means is closed, and at the same time, both the first valve means and the second valve means are opened, and then water flow to the gas cooler is shut off and the evaporator By stopping the air flow to the compressor, the refrigerant on the compressor discharge side is caused to flow to the evaporator side via the refrigerant bypass path, and the pressure is balanced between the high side refrigerant path and the low side refrigerant path. The operation method of the hot water supply apparatus using the CO ₂ refrigerant according to claim 4.

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