JP3741793B2 - Hot water generator for dishwashers - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for generating hot water using a heat pump in a dishwasher .
[0002]
[Prior art]
For example, when hot water for rinsing to be used in a dishwasher is obtained, a hot pump that generates and supplies hot water with a heat pump constituting a refrigeration cycle is being developed for practical use. This is because the evaporator in the heat pump is placed in a state where heat can be exchanged in the recovery tank that stores the hot water from the dishwasher, while the condenser can exchange heat with the raw water fed to the water supply pipe. In such a state, warm water is generated by heating the raw water with a condenser while recovering exhaust heat with an evaporator. In this case, the hot water as a heat source overflows from the washing tank of the dishwasher every time the rinsing process is performed, and is taken into the collection tank.
[0003]
[Problems to be solved by the invention]
By the way, because the dishwasher handles dirt, the entire washing tank is drained every day at the end of work. Therefore, when starting work every morning, new hot water is supplied to the washing tank. It is necessary to supply hot water. At the time of this initial hot water supply, there is no waste hot water that overflows from the washing tank, that is, there is no heat source. Therefore, when the heat pump is operated as it is, there is a problem that the low pressure side of the compressor becomes abnormally low. Such a problem occurs in the same way even when the hot water is collected during cleaning, or when the hot water is cooled down. This is a problem specific to the generation device.
The present invention has been completed based on the above-described circumstances, and its purpose is to be able to generate hot water even when there is no or insufficient heat source when using a heat pump. There is to do.
[0004]
[Means for Solving the Problems]
As a means for achieving the above object, a hot water generating apparatus for a dishwasher according to the invention of claim 1 is refrigerated by pipe-connecting a compressor, a condenser, an expansion valve and an evaporator to enclose a refrigerant. A heat pump configured in a cycle, and the evaporator of the heat pump is disposed in a hot water recovery tank for storing hot water from a dishwasher serving as a heat source so that heat can be exchanged . while recovering heat, in which generate hot water by heating the raw water fed to the water supply pipe by the condenser, the bypass pipe is provided between the high pressure side and low pressure side of the compressor in the heat pump Further, when the pressure on the low pressure side falls below a set value, the pressure control means is provided to increase the pressure by bypassing the refrigerant gas on the high pressure side to the low pressure side by the bypass pipe .
The invention of claim 2 is characterized in that, in the invention of claim 1, the pressure set value on the low pressure side of the compressor is set in the vicinity of the saturation pressure of 0 ° C. of the refrigerant used.
[0005]
[Action and effect of the invention]
<Invention of Claim 1>
When the heat source to be recovered by the condenser is absent or insufficient, the pressure on the low pressure side of the compressor is reduced, but the high pressure side refrigerant gas is bypassed to the low pressure side and increased in pressure by the pressure control means. In addition, when there is a shortage of heat source, there is a possibility that a liquid return phenomenon may occur from the expansion valve to the compressor side, but the returned liquid refrigerant is vaporized by mixing with the bypassed hot gas, which is compressed. This can contribute to boosting the low pressure side of the machine.
Thus, even when there is no heat source or when there is a shortage of heat, normal operation of the compressor, that is, the heat pump can be achieved and hot water can be generated.
<Invention of Claim 2>
Since the evaporation temperature of the refrigerant used in the evaporator is in the vicinity of 0 ° C., even if there is residual water around the evaporator, it can be prevented from freezing.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
In FIG. 1, the code | symbol 1 is a tableware washing machine, Comprising: The hot water production | generation apparatus 20 equipped with the heat pump 21 is installed in the side. First, the structure of the dishwasher 1 will be described. A cleaning chamber 2 in which tableware can be put in and out through a rack (not shown) is formed on the upper side of the interior thereof. A pair of cleaning nozzles 3 and rinse nozzles 4 are disposed on the lower surface side. A cleaning tank 6 for storing cleaning water mixed with an alkaline detergent is formed on one side of the bottom surface of the cleaning chamber 2, and the cleaning water stored therein is pumped up by a cleaning pump 7 and described above. Is sprayed toward the tableware and is then circulated and supplied so as to be collected in the washing tank 6.
[0007]
A hot water storage tank 8 for storing hot water for rinsing is provided below the cleaning tank 6. In the hot water storage tank 8, as will be described in detail later, hot water generated by the hot water generator 20 is supplied and stored by a water supply pipe 10 provided with a hot water supply valve 9. The stored hot water is pumped up by the rinse pump 11, sprayed from the rinse nozzle 4 toward the tableware, and collected in the washing tank 6. The wash tank 6 is equipped with an overflow pipe 13, which takes in the hot water that has overflowed from the wash tank 6, and passes through the hot water pipe 14 to provide a hot water recovery tank 30 provided in the hot water generator 20. It is designed to be discharged inside. The washing tank 6 and the hot water storage tank 8 are equipped with heaters 15 and 16 and a thermostat (not shown), respectively, so that the washing water is kept at about 60 ° C. and the rinsing hot water is kept at about 80 ° C. ing.
[0008]
That is, when the tableware is stored in the washing chamber 2, washing water is jetted from the washing nozzle 3 to wash the tableware, and then hot water is jetted from the rinse nozzle 4 to perform rinsing. Then, the hot water that has overflowed without being collected in the washing tank 6 is discharged to the hot water generator 20 to recover the exhaust heat, and the recovered heat is used as raw water such as tap water supplied to the water supply pipe 10. The hot water is generated by heat exchange with the hot water storage tank 8 and is supplied to the hot water storage tank 8 described above.
[0009]
Next, the hot water generator 20 will be described in detail. The hot water generator 20 includes a heat pump 21 and is accommodated in a box-shaped main body 22. As shown in FIG. 6, in the heat pump 21, a compressor 24, a condenser 25, an expansion valve 26, and an evaporator 27 are connected in a circulating manner, and chlorofluorocarbon (R-22), which is a refrigerant, is enclosed therein so that it can circulate. This constitutes the refrigeration cycle.
[0010]
The compressor 24 is comparatively large, and is installed on the bottom surface in the main body 22 as shown in FIGS. On the side of the compressor 24, a hot water recovery tank 30 with a cover plate 31 is installed. As shown in FIGS. 4 and 5, a pipe-shaped evaporator 27, which is a component part of the refrigeration cycle, is spirally wound around the exhaust hot water recovery tank 30 along the inner peripheral surface thereof. The inlet 27a and the outlet 27b protrude from the upper surface of the cover plate 31 and are connected to the refrigerant pipe 21a. A hot water inlet 32 is provided on one side of the upper part of the hot water recovery tank 30 and is connected to a hot water pipe 14 drawn from the overflow pipe 13 of the cleaning tank 6 in the dishwasher 1. The hot water overflowed from 6 can be introduced. On the other side, a discharge port 33 for discharging the overflow water of the hot water recovery tank 30 itself is provided, and a drain pipe 34 is connected.
[0011]
A propeller-like stirrer 36 is provided in the waste water recovery tank 30 and is driven to rotate via a shaft 38 by a drive motor 37 provided on the lid plate 31. Further, a drain valve 40 is provided on the bottom surface of the hot water recovery tank 30. This drain valve 40 is a normally open type, and opens and closes at the tip of a rod 41 that passes through the cover plate 31 and freely moves up and down, and contacts and separates from the upper surface side of the valve port 42 opened at the bottom surface. The valve body 43 is provided, and the rod 41 is always urged upward by the spring member 44, and the valve body 42 is pulled up as shown by the chain line in FIG. The valve opening 42 is closed by pushing down the rod 41 and the valve body 43 against the urging force by the exciting force of the solenoid 46 mounted on the bracket 31 via the bracket 45 as shown by the solid line in FIG. It has become. The drain valve 40 joins and is connected to the drain pipe 34 described above. Further, the cover plate 31 of the hot water recovery tank 30 is provided with two watering nozzles 48 for cleaning the water by spraying hot water toward the evaporator 27.
[0012]
The condenser 25 is formed in the shape of a large-diameter pipe, and a middle portion of the water supply pipe 10 that feeds the raw water of the rinse water is inserted into the condenser 25 to form a double pipe portion 28 that enables heat exchange. Has been. As shown in FIGS. 2 and 3, the double pipe portion 28 is stretched around the inside of the two side surfaces of the main body 22 while turning. The outlet side of the water supply pipe 10 is connected to the hot water storage tank 8 of the dishwasher 1 as described above. The expansion valve 26 is a temperature type provided with a temperature sensitive cylinder 26a (see FIG. 6). In the main body 22, a control box 49 containing a device for controlling the refrigeration cycle, water supply / drainage, and the like of the heat pump 21 is provided.
[0013]
Further reference is made to the refrigeration cycle with reference to FIG. A bypass pipe 51 is provided between the high pressure side and the low pressure side of the compressor 24, and a capacity adjustment valve 52 is provided there. The capacity adjustment valve 52 bypasses the gas on the high pressure side of the compressor 24 to the low pressure side when the heat load (heat source) is insufficient or at the time of initial hot water supply, so that the pressure on the low pressure side is reduced. This is to prevent excessive reduction.
The structure of the capacity adjustment valve 52 will be briefly described with reference to FIG. The capacity adjustment valve 52 includes a body portion 62 having a T-shaped tube shape. A first port 63 protruding rightward in the drawing is on the high pressure side of the bypass pipe 51, and a second port 64 at the lower end is the bypass pipe 51. Are connected to the low-pressure side. A valve port 65 is provided on the second port 64 side of the main body 62, and a valve body 67 provided at the lower end of a rod 66 penetrating through the valve port 65 vertically contacts and separates from the lower surface side of the valve port 65. A compression coil spring 69 is mounted between an adjustment screw 68 screwed to the upper end side of the main body 62 so as to adjust the screwing amount and a rod 66. The circumference of the compression coil spring 69 is covered with a bellows 70.
[0014]
That is, the upward force associated with the low pressure side pressure and the downward spring force are balanced on the valve body 67. When the low pressure side pressure becomes smaller than the set value, the valve body 67 is pushed down to open the valve port 65. While being opened, the high pressure side hot gas flows into the low pressure side to increase the pressure. The desired pressure setting value on the low pressure side is changed by adjusting the screwing amount of the adjusting screw 68 to change the spring force. In this embodiment, the pressure setting value on the low-pressure side is set to about 4 kgf / cm 2, which is determined in consideration of the saturation pressure at 0 ° C. of the refrigerant used (F-22 gas) (R-22). ing.
[0015]
An automatic water supply valve 53 is provided at the place where the double water pipe portion 28 in the water supply pipe 10 exits. The automatic water supply valve 53 functions to detect the pressure on the high-pressure side, adjust the amount of water supply accordingly, and keep the pressure on the high-pressure side constant. Along with this, hot water having a substantially constant temperature can be taken out.
On the upstream side of the automatic water supply valve 53 in the water supply pipe 10, a watering hose 55 provided with a diversion valve 54 is branched and connected. This watering hose 55 is provided on the lid plate 31 of the above-described hot water recovery tank 30. Connected to the watering nozzle 48. The diversion valve 54 is opened when the operation is stopped, thereby discharging the hot water remaining in the double pipe portion 28 and using it for cleaning the evaporator 27, as well as a transient condensing capacity at the start of the operation. It works to prevent shortages.
[0016]
The refrigerant pipe 21a on the outlet side of the condenser 25 and the portion on the near side that enters the double pipe portion 28 in the feed pipe 10 of the raw water are closely connected in parallel, whereby the first auxiliary heat exchanging portion 57 is It is configured. The first auxiliary heat exchanger 57 functions to preheat the raw water by exchanging heat between the liquid refrigerant discharged from the condenser 25 and the raw water of the rinse water.
Further, the refrigerant pipe 21a on the downstream side of the portion constituting the first auxiliary heat exchanging portion 57 and the refrigerant pipe 21a on the outlet side of the evaporator 27 are similarly piped in parallel to form the second An auxiliary heat exchanging unit 58 is configured. The second auxiliary heat exchanging unit 58 heats the low-temperature refrigerant that has passed through the evaporator 27 with the high-temperature liquid refrigerant that has come out of the condenser 25, so that the liquid return phenomenon to the compressor 24 side occurs particularly in the latter half of the operation. It functions to suppress and increase heat utilization efficiency.
[0017]
A receiver 59 is interposed in the refrigerant pipe 21 a between the portion constituting the second auxiliary heat exchange unit 58 and the expansion valve 26. The receiver 59 functions to prevent liquid refrigerant from staying in the condenser 25, for example, when the refrigerant is overfilled or when the internal balance is lost and the liquid refrigerant becomes excessive. .
A refrigerant solenoid valve 60 is interposed between the receiver 59 and the expansion valve 26. The refrigerant solenoid valve 60 functions to maintain a high pressure by preventing high pressure gas from leaking from the expansion valve 26 to the low pressure side when operation is stopped.
[0018]
In this embodiment, a control circuit as shown in FIGS. In the figure, SW is a push button switch for starting hot water supply, FM is a drive motor of a fan installed in the main body 22 of the hot water generator 20, and CM is a compressor 24 of the heat pump 21. SV is a refrigerant electromagnetic valve 60, M is a drive motor 37 for the stirrer 36, and S is a solenoid 46 for the drain valve 40. Th1 is a protective thermostat provided at the high-pressure side outlet of the compressor 24, and Th2 is a protective thermostat provided in the compressor 24 as well. OCR is an overload relay that is opened when the operating current of the compressor 24 becomes an overcurrent, and PdSW is a pressure switch that is opened when the pressure on the high-pressure side of the compressor 24 abnormally increases.
[0019]
The present embodiment has the structure as described above, and the operation thereof will be described subsequently. First, for convenience of explanation, the operation from the case where the washing tank 6 and the hot water storage tank 8 of the dishwasher 1 are full and can be washed will be described with reference to the timing chart of FIG.
The tableware to be cleaned first is stored in the rack and accommodated in the cleaning chamber 2 (rack operation). When the rack operation is completed, a cleaning cycle is started, and a cleaning operation in which cleaning water in the cleaning tank 6 is pumped up by the cleaning pump 7 and ejected from the cleaning nozzle 3 is performed for several tens of seconds. After a stop time (water draining time) of about 5 seconds, a rinsing cycle is subsequently started, and a rinsing operation in which hot water in the hot water storage tank 8 is pumped up by the rinsing pump 11 and ejected from the rinsing nozzle 4 is 7 seconds. Done about. After that, a stop time of about 5 seconds (similarly draining time) is set, whereby one cleaning process is completed.
[0020]
In the above, when the rinsing cycle is started, the float switch provided in the hot water storage tank 8 is turned off, so that the hot water supply valve 9 is opened, the compressor 24 is turned on, and the heat pump 21 starts operating. . At the same time, the refrigerant solenoid valve 60 is also opened. Further, the solenoid 46 provided in the hot water recovery tank 30 is excited to close the normally open drain valve 40, and the stirrer 36 is driven to rotate. The hot water overflowing from the washing tank 6 after the start of the rinsing cycle flows into the hot water recovery tank 30 with a slight delay, and the evaporator 27 actually starts to absorb heat after a few seconds.
[0021]
Now, in the hot water recovery tank 30, the hot water overflowed from the cleaning tank 6 of the dishwasher 1 is taken in little by little (over several tens of seconds). The heat pump 21 is fully operated from the middle of taking in the hot water and supplies the liquid refrigerant to the evaporator 27. The hot water is stirred by the stirrer 36 to start heat absorption while heat exchange is promoted. Since the time during which heat can actually be absorbed is several tens of seconds, the expansion valve 26 having a relatively large flow rate (refrigeration capacity) is used, and a large amount of refrigerant is supplied immediately after the rise.
During the endothermic process, the overflow from the cleaning tank 6 ends first, and the hot water recovery tank 30 becomes full. Although the heat absorption continues further, when the refrigerant reaches the evaporator 27 sufficiently, the temperature detected by the temperature sensing cylinder 26a decreases, and the expansion valve 26 begins to close. However, since the timing of the flow rate control of the expansion valve 26 is inevitably delayed, the liquid returns slightly. Therefore, the liquid return is suppressed by being heated by the second auxiliary heat exchanging unit 58, and the heat utilization efficiency is improved at the same time.
[0022]
During this time, the raw water of the rinsing water fed to the water supply pipe 10 is preheated by the first auxiliary heat exchanging section 57, and then heat-exchanged with the refrigerant in the double pipe section 28 so as to be heated to become hot water. It is gradually supplied to the hot water storage tank 8 of the dishwasher 1 through the valve 9. When a predetermined amount of hot water is accumulated in the hot water storage tank 8 and the float switch is turned on, the compressor 24 is turned off, the refrigerant solenoid valve 60 is closed, and the operation of the heat pump 21 is stopped. Further, the drain valve 40 of the hot water recovery tank 30 is opened, and the stirring tool 36 is stopped. As a result, the hot water in the hot water recovery tank 30 is discharged. However, since the hot water is discharged as an eddy current due to the inertial force, for example, it is assumed that foreign substances such as small pieces of food are mixed in the hot water. In addition, all of the water is discharged together with the vortex and there is no possibility that the tank 30 is dirty. As the float switch is turned on, the diversion valve 54 is opened for 10 to 15 seconds, and the hot water remaining in the double pipe portion 28 is diverted to the watering hose 55 side. The hot water is sprinkled from the water spray nozzle 48 of the hot water recovery tank 30 toward the evaporator 27, and the surface of the evaporator 27 is washed. After that, the hot water in the hot water recovery tank 30 is completely discharged, and the dishwasher 1 can be rinsed.
As described above, the cleaning operation and the generation of hot water are repeated.
[0023]
On the other hand, since the dishwasher 1 handles dirt, the washing tank 6 is entirely drained at the end of work every day. Therefore, when starting business every morning, it is necessary to supply hot water to the washing tank 6 anew. This hot water supply is called initial hot water supply, and this will be described below with reference to the timing chart of FIG.
In this initial hot water supply, hot water must be stored in the washing tank 6 having a large capacity, and since it is difficult to supply a large volume of hot water at a time, the hot water supply is basically performed in the following procedure. The hot water generated by the hot water generator 20 is once taken into the hot water storage tank 8 and when the float switch in the hot water storage tank 8 is turned on, the hot water supply valve 9 is closed and a rinsing cycle is performed. The hot water is pumped up and ejected from the rinse nozzle 4 and stored in the washing tank 6. This hot water supply cycle is continued until a water level sensor (not shown) provided in the cleaning tank 6 detects it. Thereafter, the hot water supply cycle is executed a predetermined number of times, and the initial hot water supply is completed.
[0024]
The hot water at the time of initial hot water supply is also generated by operating the heat pump 21 in the same manner. However, at the time of initial hot water supply, there is no waste hot water overflowing from the washing tank 6, that is, no heat source. Or abnormal operation (vacuum operation or liquid back operation). If the pressure on the low-pressure side is small, the amount of work of the compressor 24 itself is small and the amount of heat generation is also small. Therefore, it is difficult to satisfactorily generate hot water, and the pressure on the low-pressure side needs to maintain a certain value. Therefore, at the time of initial hot water supply, the pressure of the high-pressure side refrigerant gas is bypassed to the low-pressure side by the action of the capacity adjustment valve 52 attached to the compressor 24 to increase the pressure. On the other hand, since there is a refrigerant leaking from the expansion valve 26 and there is no heat source, it returns to the compressor 24 side. However, just before the suction of the compressor 24, the returned liquid refrigerant is mixed with the high-temperature bypass gas. This helps to increase the pressure on the lower pressure side. The pressure setting value on the low pressure side is about 4 kgf / cm 2 as described above. Thereby, the work amount of the compressor 24 can be increased, and as a result, a good hot water generation capability can be obtained.
Here, if the pressure setting value on the low pressure side is too high, the hot gas is bypassed even when the normal heat pump 21 is operated (the pressure on the low pressure side is 4.5 to 6 kgf / cm @ 2). 24 workloads will be lost. On the other hand, if the pressure set value is too low, a desired work amount cannot be secured, and the problem of freezing of the evaporator 25 occurs. Therefore, the appropriate pressure setting is about 4 kgf / cm2.
[0025]
Returning to the generation of hot water, hot water is generated by the heat pump 21 each time a rinse cycle is performed. Usually, for this purpose, the compressor 24 is intermittently operated in response to the operation and stop of the heat pump 21, but frequent intermittent operation is performed on the compressor 24 that dislikes operation and stop in a short cycle. Despite being predicted, it is problematic in terms of quality and reliability to leave it as it is.
Therefore, in this embodiment, the compressor 24 is continuously operated during the initial hot water supply. However, when the hot water supply valve 9 of the dishwasher 1 is intermittently closed, the water flow to the condenser 25 is cut off on the refrigeration cycle side of the heat pump 21, so that the compressor 24 is continuously operated. Even a short time will cause an abnormal increase in pressure on the high pressure side.
[0026]
Therefore, as shown in the timing chart of FIG. 11, the refrigerant electromagnetic valve 60 is controlled to close in synchronization with the closing operation of the hot water supply valve 9, and during that time, only the bypass refrigerant by the capacity adjustment valve 52 is operated. When the refrigerant solenoid valve 60 is closed, the amount of refrigerant supplied to the low-pressure side of the compressor 24 decreases, so that the pressure on the high-pressure side decreases conversely, thus preventing an abnormal increase in pressure on the high-pressure side. Of course, if the refrigerant solenoid valve 60 continues to close, the pressure on the high pressure side increases, but the valve closing time is at most several seconds to several tens of seconds, so that the pressure on the high pressure side is effectively reduced as described above. To work. In this way, the initial hot water supply is performed, and it is set in a washable state.
[0027]
As described above, according to the present embodiment, even when there is no heat source (hot water) and the pressure on the low pressure side of the compressor 24 decreases as in the initial hot water supply, the high pressure side is provided via the capacity adjustment valve 52. The refrigerant gas is bypassed to the low pressure side and the pressure is increased. Further, when there is no heat source, a liquid return phenomenon may occur from the expansion valve 26 to the compressor 24 side, but the returned liquid refrigerant is vaporized by being mixed with the bypassed hot gas, which is compressed by the compressor. 24 can contribute to boosting of the low pressure side. Therefore, even when there is no heat source, the work amount of the compressor 24 is increased, and hot water can be generated satisfactorily.
[0028]
Further, during the cleaning operation, if the drain valve 40 fails and remains closed, the hot water after heat recovery remains in the hot water recovery tank 30. Then, most of the hot hot water supplied next overflows from the hot water recovery tank 30 as it is, so that the heat source becomes insufficient. Further, the hot water remaining in the hot water recovery tank 30 may be cooled and may not become a heat source. Even in such a case, the pressure on the low pressure side of the compressor 24 is increased by the action of the capacity adjustment valve 52, and similarly, hot water can be generated.
Furthermore, since the set value on the low pressure side is determined in accordance with the evaporation pressure at 0 ° C. of the chlorofluorocarbon (R-22), even if water having a low temperature remains in the hot water recovery tank 30, There is no risk of freezing.
[0029]
<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) In the above embodiment, the case where the capacity adjustment valve is used as the means for reducing the pressure difference between the high pressure side and the low pressure side of the compressor is illustrated, but instead of this, a constant pressure expansion valve is used. Also good.
(2) In the above embodiment, the refrigerant using chlorofluorocarbon as a refrigerant is exemplified, but it is also possible to use a heat pump having a refrigeration cycle using another refrigerant.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall structure of an embodiment of the present invention.
FIG. 2 is a cross-sectional view seen from the upper surface of the hot water generator.
FIG. 3 is a cross-sectional view seen from the front.
FIG. 4 is a cross-sectional view seen from the upper surface of the hot water recovery tank.
FIG. 5 is a cross-sectional view seen from the front.
FIG. 6 is a refrigeration cycle diagram of a heat pump.
FIG. 7 is a cross-sectional view of a capacity adjustment valve.
FIG. 8 is a control circuit diagram of the hot water generator.
FIG. 9 is a control circuit diagram of the dishwasher.
FIG. 10 is a timing chart during a cleaning operation.
FIG. 11 is a timing chart during initial hot water supply.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Dishwasher 10 ... Supply pipe 20 ... Warm water production | generation apparatus 21 ... Heat pump 21a ... Refrigerant piping 24 ... Compressor 25 ... Condenser 26 ... Expansion valve 27 ... Evaporator 30 ... Waste water recovery tank 51 ... Bypass pipe 52 ... Capacity tuning valve

Claims (2)

A compressor, condenser, expansion valve, and evaporator are connected by piping and a refrigerant is sealed in to provide a heat pump that configures a refrigeration cycle, and the evaporator of this heat pump stores hot water from a dishwasher that serves as a heat source. The hot water recovery tank is disposed so that heat can be exchanged, and heat from the heat source is recovered by an evaporator, while the raw water fed to the water supply pipe is heated by the condenser to generate hot water. In things ,
Bypass pipe is provided between the high pressure side and low pressure side of the compressor in the heat pump, if the pressure in the low-pressure falls below the set value, bypassing the low-pressure side refrigerant gas on the high pressure side by the bypass pipe hot water generating device of the dishwasher, characterized in that a pressure control means for boosting. The hot water generating apparatus for a dishwasher according to claim 1, wherein the pressure set value on the low pressure side of the compressor is set in the vicinity of a saturation pressure of 0 ° C of the refrigerant used.

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