JP2004232905A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator capable of accurately controlling flow division to respective use side heat exchangers even when use side units have different use side temperatures. <P>SOLUTION: The use side heat exchanger 6 is provided in a heat source side unit 1 equipped with a compressor and a heat source side heat exchanger, a plurality of the use side units 5, 10 and 20 having the different use side temperature of the use side heat exchanger are connected in parallel through a refrigerant pipe, and a refrigerant of which high pressure side is a supercritical pressure during operation is sealed in the refrigerant pipe. The refrigerator 30 is provided with flow division control means 8, 17 and 27 for varying a refrigerant inflow amount to the respective use side units in accordance with the load of the respective use side units. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for controlling the flow of water to each use-side unit of a refrigeration system including a plurality of use-side units having different use-side temperatures.
[0002]
[Prior art]
Generally, a refrigerating apparatus is known in which a plurality of use-side units provided with use-side heat exchangers are connected in parallel via a refrigerant pipe to a heat-source-side unit provided with a compressor and a heat-source-side heat exchanger. (See Patent Document 1). In this type, it is necessary to appropriately divert the refrigerant to each use-side unit. In the split flow control in this case, in order to effectively use the use side heat exchanger, the saturation temperature or another representative temperature at the intermediate portion of the use side heat exchanger and the temperature at the outlet portion of the use side heat exchanger. When the heat exchanger acts as a condenser, a subcool (SC) control is performed based on the difference ΔT, and when the heat exchanger acts as an evaporator, the difference ΔT is used based on the difference ΔT. The superheat (SH) control is performed, or the valve opening of the electronic control valve connected to the outlet of each use side heat exchanger is adjusted to an appropriate opening so that the outlet temperature of each use side heat exchanger becomes approximately equal. Is generally controlled. In this specification, the refrigeration apparatus includes a heat pump.
[0003]
[Patent Document 1]
Japanese Patent No. 2804527.
[0004]
[Problems to be solved by the invention]
However, when the conventional branch control technology is used in a refrigeration system using a supercritical refrigerant ("a refrigerant in which the high pressure side has a supercritical pressure during operation"), when the use side temperatures of a plurality of use side units are different. However, there is a problem in that the outlet temperature of each use-side heat exchanger varies, and accurate branch control cannot be performed.
[0005]
Therefore, an object of the present invention is to solve the problems of the above-described conventional technology and to perform accurate branch control to each use-side heat exchanger even when the use-side temperatures of the use-side units are different. It is an object of the present invention to provide a refrigeration apparatus capable of performing the above.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 is a heat source side unit including a compressor and a heat source side heat exchanger, including a use side heat exchanger, and a plurality of use side units having different use side temperatures of the use side heat exchangers. Are connected in parallel via a refrigerant pipe, and in a refrigeration system in which a refrigerant having a supercritical pressure on the high pressure side during operation is sealed in the refrigerant pipe, each refrigeration unit is connected to each usage-side unit according to the load of each usage-side unit. It is characterized by comprising a branch control means for changing the refrigerant inflow amount.
[0007]
According to a second aspect of the present invention, the heat source side unit including the compressor and the heat source side heat exchanger includes a use side heat exchanger, and a plurality of use side units having different use side temperatures of the use side heat exchangers. Are connected in parallel via a refrigerant pipe, and in a refrigeration system in which a refrigerant having a supercritical pressure on the high pressure side during operation is sealed in the refrigerant pipe, the outlet temperature of the refrigerant of each utilization side heat exchanger and the load side It is characterized by having a branch control means for changing the amount of refrigerant flowing into each use-side unit in accordance with the temperature difference between the medium and the inlet temperature to each use-side heat exchanger.
[0008]
According to a third aspect of the present invention, in the first or second aspect, at least one of the use side units is a hot water supply unit in which a hot water storage tank is connected to a use side heat exchanger via a water pipe. Features.
[0009]
The invention according to claim 4 is the floor heating unit according to claim 1 or 2, wherein at least one of the usage-side units is a floor heating unit in which a floor heating panel is connected to a usage-side heat exchanger via a water pipe. It is characterized by the following.
[0010]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the branch control means includes an electronic control valve for controlling a refrigerant inflow amount.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
FIG. 1 is a refrigerant circuit diagram showing one embodiment of a refrigeration apparatus according to the present invention. The refrigerating device 30 includes a heat source side unit 1 including a compressor 2, a heat source side heat exchanger 3, and a decompression device 4, and a hot water supply unit 10 including a gas cooler 11, a hot water storage tank 13, a circulation pump 15, and an electronic control valve 17. And a floor heating unit 20 including a gas cooler 21, a floor heating panel 23, a circulation pump 25, and an electronic control valve 27, and an air conditioning unit 5 including a use side heat exchanger 6 and a use side electronic control valve 8. It is composed.
[0013]
In hot water storage unit 10, one end of gas cooler 11 is connected to gas pipe 31, and the other end of gas cooler 11 is connected to liquid pipe 33 via electronic control valve 17. A water pipe 16 is connected to the gas cooler 11, and a hot water storage tank 13 is connected to the water pipe 16 via a circulation pump 15.
[0014]
In the floor heating unit 20, one end of the gas cooler 21 is connected to the gas pipe 31, and the other end of the gas cooler 21 is connected to the liquid pipe 33 via the electronic control valve 27. A water pipe 26 is connected to the gas cooler 21, and a floor heating panel 23 is connected to the water pipe 26 via a circulation pump 25.
[0015]
The heat source side unit 1, the hot water supply unit 10, the floor heating unit 20, and the air conditioning unit 5 are connected by the gas pipe 31 and the liquid pipe 33, and the refrigeration apparatus 30 operates the hot water supply unit 10 and the floor heating unit 20. The heating operation of the air conditioning unit 5 is enabled. 1A is a control device of the heat source side unit 1, 10A is a control device of the hot water supply unit 10, 20A is a control device of the floor heating unit 20, and 5A is a control device of the air conditioning unit 5.
[0016]
In the present embodiment, carbon dioxide refrigerant is sealed in the heat source side unit 1, the hot water supply unit 10, the floor heating unit 20, the air conditioning unit 5, the gas pipe 31, and the liquid pipe 33. In the above configuration, each of the hot water supply unit 10, the floor heating unit 20, and the air conditioning unit 5 constitutes a use side unit.
[0017]
When the carbon dioxide refrigerant is charged, the inside of the high-pressure gas pipe 31 is operated at a supercritical pressure during operation, as shown in the enthalpy-pressure diagram of FIG. The refrigerant in which the inside of the high-pressure gas pipe 31 is operated at a supercritical pressure includes, for example, ethylene, diborane, ethane, nitrogen oxide, etc. in addition to the carbon dioxide refrigerant.
[0018]
In FIG. 2, the outlet of the compressor 2 is shown in state a. The refrigerant circulates through the gas coolers 11 and 21 and the use side heat exchanger 6, is cooled to the state b at the outlet of the gas cooler 21, releases heat to the circulating water, and the state g at the outlet of the use side heat exchanger 6. The gas cooler 11 cools to the state c at the outlet of the gas cooler 11 and releases the heat to the circulating water. The refrigerant then reaches state d due to the pressure drop in the decompressors 17, 27, 8, 4 where a gas / liquid two-phase mixture is formed. The refrigerant absorbs heat in the heat source side heat exchanger 3 by evaporating the liquid phase. In the heat source side heat exchanger 3, after passing through the state e, the gas phase refrigerant is heated to the state f by the heat source side heat exchanger 3, and then flows toward the suction pipe of the compressor 2.
[0019]
In the supercritical cycle, the high-pressure single-phase gas refrigerant discharged from the compressor 2 is not condensed, but the temperature of the gas coolers 11, 21 and the use-side heat exchanger 6 decreases. In FIG. 2, the temperatures (states b, g, and c) at the outlets of the gas coolers 11 and 21 and the use-side heat exchanger 6 are different from each other.
[0020]
Next, the operation of the refrigeration apparatus 30 will be described.
[0021]
In the hot water supply unit 10, the refrigerant discharged from the compressor 2 is guided to the gas cooler 11 through the gas pipe 31, and the water passing through the water pipe 16 is heated by the gas cooler 11, and the hot water is stored in the hot water storage tank 13. Can be
[0022]
Since a carbon dioxide refrigerant is used and a high pressure and high supercritical cycle is performed, it is possible to set the use side temperature (state c in FIG. 2) in the gas cooler 11 to be high. The temperature rises to 80 ° C or higher. The hot water stored in the hot water storage tank 13 is sent to various facilities via piping not shown.
[0023]
In the floor heating unit 20, the refrigerant discharged from the compressor 2 is guided to the gas cooler 21 through the gas pipe 31, and the water passing through the water pipe 26 is heated by the gas cooler 21, and the hot water is supplied to the floor heating panel 23. Supplied to
[0024]
Because of the floor heating, not so high panel temperature is required, and the use side temperature (state b in FIG. 2) in the gas cooler 21 is set low.
[0025]
In the air conditioning unit 5, the refrigerant discharged from the compressor 2 is guided to the use side heat exchanger 6 through the gas pipe 31 and exchanges heat with the use side heat exchanger 6 to heat the conditioned room. In this case, a very high air temperature is not required, and the use side temperature in the use side heat exchanger 6 (state g in FIG. 2) is set higher than the use side temperature in the gas cooler 21 (state b in FIG. 2). Is set lower.
[0026]
The present embodiment is characterized in that the refrigerant discharged from the heat source unit 1 is divided into the hot water supply unit 10, the floor heating unit 20, and the air conditioning unit 5. In this type, it is necessary to appropriately divert the refrigerant to each use-side unit.
[0027]
The flow dividing control is performed by controlling the valve opening of each of the electronic control valves 17, 27, and 8 according to the load of each of the use-side units. The load of each usage-side unit is obtained according to the temperature difference between the set target temperature set in the control device of each usage-side unit and the actual measured temperature. In the hot water supply unit 10, for example, the target hot water temperature in the hot water storage tank 13 set in the control device 10A is the set target temperature, and in the floor heating unit 20 and the air conditioning unit 5, for example, each of the control devices 20A and 5A is set. The target room temperature of the conditioned room is the set target temperature.
[0028]
As described above, the use-side temperatures of the gas cooler 11 of the hot water supply unit 10, the gas cooler 21 of the floor heating unit 20, and the use-side heat exchanger 6 of the air conditioning unit 5 are different. In the refrigerating apparatus 30, a carbon dioxide refrigerant is used to form a supercritical cycle with a high pressure and a high pressure. In particular, in the gas cooler 11 of the hot water supply unit 10, the stored hot water is heated to about 80 ° C. or higher. Therefore, the use side temperature is set to be considerably high. In contrast, in the gas cooler 21 of the floor heating unit 20 and the use side heat exchanger 6 of the air conditioning unit 5, the use side temperature is not set so high, and the use side temperature is set lower than that of the hot water supply unit 10. You. In this case, the outlet temperatures of the refrigerants of the gas coolers 11 and 21 and the use-side heat exchanger 6 are not equal and vary. Therefore, in the case of the conventional flow dividing control in which the opening degree of the electronic control valve is controlled to an appropriate opening degree so that the outlet temperature of the use side heat exchanger becomes substantially equal, accurate flow dividing control cannot be performed.
[0029]
In the present embodiment, the load of each usage-side unit (determined according to the temperature difference between the set target temperature and the actual measured temperature) is detected, and each of the electronic control valves 17, 27, 8 is determined according to this load. Of the valve is controlled. Therefore, only the required amount, that is, the appropriate amount of refrigerant can be almost accurately diverted to the corresponding gas coolers 11 and 21 or the use-side heat exchanger 6.
[0030]
Next, another embodiment will be described.
[0031]
FIG. 3 shows a change in temperature of the refrigerant from the inlet to the outlet of the gas coolers 11 and 21 and the use-side heat exchanger 6.
[0032]
For example, when a refrigerant that changes phase (Freon-based refrigerant) is used in the refrigeration cycle, the temperature change is represented by a curve L4 or a curve L5. A large change appears in the temperature difference Δ between the intermediate temperature and the outlet temperature of the heat exchanger between a case where the branch flow is normal and a case where the branch flow failure occurs. When the branch flow is normal, a temperature difference Δ3 appears between the intermediate temperature t1 and the outlet temperature t2 of the heat exchanger as shown by a curve L4. A temperature difference Δ4 appears between the intermediate temperature t1 of the exchanger and the outlet temperature t3. According to this, it is possible to accurately determine whether the flow is normal or defective based on the value of the temperature difference Δ3 and the value of the temperature difference Δ4. Therefore, by controlling the valve opening of each of the electronic control valves 17, 27, and 8 according to the determination, it is possible to control the flow division of each of the use-side units.
[0033]
In contrast, a refrigerant such as a carbon dioxide refrigerant has a temperature gradient. In FIG. 3, a curve L1 shows a temperature change when the refrigerant having the temperature gradient is used and the branch flow is normal, and a curve L2 shows the temperature when the refrigerant having the same temperature gradient is used and the branch flow is poor. The curve L3 indicates the temperature change on the load side. The temperature difference Δ1 between the intermediate temperature t1 ′ of the heat exchanger and the outlet temperature t2 when the branch flow is normal, and the temperature difference Δ2 between the intermediate temperature t1 ″ and the outlet temperature t3 of the heat exchanger when the branch flow failure occurs. Therefore, even if the temperature difference between the intermediate temperature of the heat exchanger and the outlet temperature is measured, the values are all small, and based on this value, the normal or defective flow can be accurately determined. Cannot be determined.
[0034]
Therefore, in the above configuration, when a refrigerant having a temperature gradient is used, the outlet temperature (t2, t3) of the refrigerant of each use-side heat exchanger and the inlet temperature of the load-side medium to each use-side heat exchanger. The temperature difference Δ from (t0) is detected, and by controlling the valve opening of each of the electronic control valves 17, 27, 8 based on this detected value, the flow to each of the usage-side units is performed. Referring to FIG. 1, the outlet temperature (t2, t3) of the refrigerant of the use side heat exchanger is detected by temperature sensors 41, 43, 45, and the inlet temperature (t0) of the load side medium to the use side heat exchanger. ) Are detected by the temperature sensors 42, 44, 46. The temperature sensors 42 and 44 detect the temperature of the water in the water pipe, and the temperature sensor 46 detects the air temperature of the conditioned room.
[0035]
As described above, the present invention has been described based on one embodiment, but the present invention is not limited to this.
[0036]
【The invention's effect】
According to the present invention, even when the use-side temperatures of the use-side units are different, accurate branch control to each use-side heat exchanger can be performed.
[Brief description of the drawings]
FIG. 1 is a refrigerant circuit diagram showing an embodiment of a refrigeration apparatus according to the present invention.
FIG. 2 is an enthalpy-pressure diagram of a supercritical cycle.
FIG. 3 is a diagram showing a temperature change of the heat exchanger.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heat source side unit 2 Compressor 3 Heat source side heat exchanger 5 Air conditioning unit 6 User side heat exchanger 8, 17, 27 Electronic control valve 10 Hot water supply unit 11 Gas cooler 20 Floor heating unit 21 Gas cooler 30 Refrigeration device

Claims (5)

A heat source side unit provided with a compressor and a heat source side heat exchanger, a use side heat exchanger is provided, and a plurality of use side units having different use side temperatures of the use side heat exchanger are arranged in parallel via refrigerant piping. In a refrigeration system in which a refrigerant whose high pressure side is at a supercritical pressure during operation is sealed in the refrigerant pipe,
A refrigeration apparatus comprising: a diversion control unit that changes a refrigerant inflow amount into each usage-side unit according to a load of each usage-side unit. A heat source side unit provided with a compressor and a heat source side heat exchanger, a use side heat exchanger is provided, and a plurality of use side units having different use side temperatures of the use side heat exchanger are arranged in parallel via refrigerant piping. In a refrigeration system in which a refrigerant whose high pressure side is at a supercritical pressure during operation is sealed in the refrigerant pipe,
Dividing control means for changing the amount of refrigerant flowing into each use-side unit according to the temperature difference between the outlet temperature of the refrigerant of each use-side heat exchanger and the inlet temperature of the load-side medium to each use-side heat exchanger. A refrigeration apparatus comprising: 3. The refrigeration system according to claim 1, wherein at least one of the use side units is a hot water supply unit in which a hot water storage tank is connected to the use side heat exchanger via a water pipe. The refrigeration apparatus according to claim 1, wherein at least one of the use-side units is a floor heating unit in which a floor heating panel is connected to the use-side heat exchanger via a water pipe. The refrigeration apparatus according to any one of claims 1 to 4, wherein the branch control means includes an electronic control valve for controlling a refrigerant inflow amount.

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