JPS644048Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pump system, and particularly to a heat pump system having a plurality of air heat exchangers.

In general, when using exhaust heat to perform heating and cooling in existing subways, etc., it is expected that there will be cases where there is no place to install a heat pump in the machine room or where there is no space to install piping in the tunnel, but normally station buildings A heat pump system is used in which a heat pump is installed in a machine room nearby, and multiple air heat exchangers are installed in the station building to recover heat.

Figure 1 is a configuration diagram showing a conventional example of this type of heat pump system. In the figure, 1 and 2 are air heat exchangers installed in the station building, 3 is the connecting water pipe, and 4 is the air heat exchanger installed in the machine room near the station building. The heat pump is composed of an evaporator 5, a compressor 6, and a condenser 7. Note that 8 is a motor that drives the compressor 6, and 9 is a hot water circulation pump that supplies hot water to the condenser 7.

In the case of this heat pump system, the recovered cold water that has been heat exchanged by the two air heat exchangers 1 and 2 enters the evaporator 5 through the connecting water pipe 3.
Heat is exchanged with the refrigerant circulating through → compressor 6 → condenser 7 → evaporator 5. The recovered cold water that has undergone heat exchange with the refrigerant in the evaporator 5 passes through the connecting water pipe 3 by the pump 10 and is again supplied to the air heat exchangers 1 and 2. On the other hand, the refrigerant that has exchanged heat with the recovered cold water in the evaporator 5 passes through the compressor 6 and enters the condenser 7, where it exchanges heat with the hot water on the user side.

However, in such a conventional heat pump system, the temperature of the air handled by the air heat exchangers 1 and 2 is around 10℃ in winter, so the difference in temperature of recovered cold water is about 3℃, so antifreeze etc. The need to use it arises. Further, since the evaporation temperature in the evaporator 5 is around 0°C to -2°C, the efficiency of the heat pump cycle is reduced and the difference in recovery temperature is small, so the diameter of the connecting water pipe 3 must be made large. The disadvantage was that the cost of equipment increased.

In contrast, a so-called direct expansion type heat pump system has been proposed to compensate for the above-mentioned drawbacks. FIG. 2 is a block diagram of a direct expansion heat pump system, in which the same parts as in FIG. 1 are given the same reference numerals. In the case of this direct expansion type heat pump system, the refrigerant gas that has undergone heat exchange with the air heat exchangers 1 and 2 is supplied to the accumulator 12 through the refrigerant gas outlet pipe 11, and then is sent to the condenser by the compressor 6. 7 and exchanges heat with hot water on the user side. The refrigerant that has undergone heat exchange with hot water on the user side in the condenser 7 becomes a refrigerant liquid and is stored in a liquid receiver 13, and is again supplied to the air heat exchangers 1 and 2 through the refrigerant liquid supply pipe 13. Therefore, in the case of this heat pump system, the evaporation temperature is around 3° C., so the coefficient of performance is improved, and the piping size is small, so equipment costs can be reduced.

However, in the case of this direct expansion type heat pump system, when there is a deviation in air temperature at the location where the air heat exchangers 1 and 2 are installed, the air heat exchangers 1 and 2
The amount of refrigerant liquid supplied to the refrigerant became unstable, causing liquid carryover into the refrigerant gas, which could result in unstable flow due to the two-phase flow effect and difficulty in operating the heat pump. Furthermore, when heat recovery is performed over a long distance, such as between stations, the high-pressure reagent must be transported over a long distance, which is not desirable from a safety standpoint. Further, when the compressor 6 is a centrifugal compressor, when the hot gas bypass valve opens at partial load of the heat pump, the differential pressure decreases, which may impede the refrigerant liquid supply.

The present invention was developed in view of the above circumstances, and aims to provide a heat pump system that can stably supply refrigerant liquid even if there is a deviation in air temperature at the installation locations of multiple air heat exchangers. This is the purpose.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Figure 3 shows a heat pump system that is an embodiment of the present invention, showing the configuration of two air heat exchangers. has been done. In the same figure, numeral 21
2 is a receiver tank that stores the refrigerant gas from the air heat exchangers 1 and 2 and the refrigerant liquid from the heat pump 4; 22 is a level controller that controls the refrigerant liquid level in the receiver tank 21;
Control valves 24 and 25 control the amount of refrigerant liquid supplied to the receiver tank 21 based on a signal from the receiver tank 21, and control valves 24 and 25 forcibly supply the refrigerant liquid in the receiver tank 21 to the air heat exchangers 1 and 2, respectively. It's a pump.

The refrigerant liquid in the receiver tank 21 is supplied to the supply pump 2
4 and 25, and is supplied to the air heat exchangers 1 and 2 via the refrigerant liquid supply pipe 14 and the refrigerant liquid supply amount control valve 15, respectively. The refrigerant liquid supplied to the air heat exchangers 1 and 2 is evaporated by air heat at a pressure corresponding to the receiver tank pressure, becomes refrigerant gas, and is supplied to the receiver tank 21 through the refrigerant gas outlet pipe 11. . In the receiver tank 21, the mist is separated from the refrigerant gas generated in the air heat exchangers 1 and 2 by an appropriate mist separator (not shown) provided inside the tank, and only the refrigerant gas is compressed by the compressor 6. Air is sent to the condenser 7.
The refrigerant gas thus sent from the receiver tank 21 exchanges heat with the hot water on the user side in the condenser 7, and is condensed to become a refrigerant liquid. The refrigerant liquid condensed in the condenser 7 is stored in the liquid receiver 13 at a pressure equal to the condensation pressure, and is sent to the receiver tank 21 via the refrigerant liquid supply pipe 14 while the supply amount is controlled by the level controller 22 and the control valve 23. is supplied to The refrigerant liquid supplied to the receiver tank 21 is
The air is again supplied to the air heat exchangers 1 and 2 by the supply pumps 24 and 25, and circulated through the above-mentioned channels.

In this embodiment, the refrigerant liquid from the heat pump 4 is depressurized and stored in the receiver tank 21, and the refrigerant liquid in the receiver tank 21 is supplied to the air heat exchangers 1 and 2 by the supply pumps 24 and 25. Since each is forcibly supplied, compared to the case of direct supply, even if there is a partial load of the heat pump or a deviation in air temperature at the location where the heat exchanger is installed, the refrigerant liquid can be supplied by the differential pressure difference between the refrigerant liquid and refrigerant gas. instability can be suppressed. In addition, since the refrigerant is forcedly supplied, low-pressure refrigerant can be used, improving safety during long-distance transportation. Furthermore, since this heat pump system uses latent heat from a refrigerant, the piping size and heat exchanger are smaller than in the case of using cold water or antifreeze, which reduces equipment costs.

Next, another embodiment of the present invention will be described. FIG. 4 is a configuration diagram showing a case where a defrosting function is added to the heat pump system of the present invention, in which the same parts as in FIG. 3 are given the same reference numerals. In the figure, 31 is a frost detector installed in the air heat exchanger 1, 32 is an inlet-side shutoff valve installed on the refrigerant gas inlet side of the receiver tank 21, and 33 is installed on the refrigerant liquid outlet side of the receiver tank 21. 34 is a refrigerant gas storage tank, 35 is a refrigerant liquid flow switch, 36 and 37 are relief valves, and 38 is a gas-liquid separator. Although not shown, the air heat exchanger 2 side has a similar configuration.

Next, the operation under defrosting operation will be explained. When a frosting state is detected by the frosting sensor 31 installed in the air heat exchanger 1, the inlet side shutoff valve 32 is fully closed by the frosting signal from the sensor 31, and the refrigerant liquid is completely closed. The supply amount control valve 15 is fully opened. Note that at this time, the supply pump 24 is maintained in an operating state. The refrigerant gas thus trapped between the air heat exchanger 1 and the inlet-side shutoff valve 32 is pressurized by the discharge pressure of the supply pump 24 and liquefied. 32 is filled with refrigerant liquid. When the pressure inside the pipe reaches the set pressure of the relief valve 36, the relief valve 3
6 is opened, and the refrigerant liquid is returned to the refrigerant liquid supply pipe 14 for recycling. At this time, the refrigerant flow switch 35 senses the flow of refrigerant from the relief valve 36 and completely closes the outlet-side shutoff valve 33 to cut off the refrigerant supply from the receiver tank 21.

The refrigerant returned to the refrigerant liquid supply pipe 14 is again supplied to the air heat exchanger 1 by the supply pump 24, and the air heat exchanger 1 → refrigerant gas outlet pipe 11 → gas-liquid separator 38 → relief valve 36 → refrigerant The liquid supply pipe 14 forms a short-circuit loop with the air heat exchanger 1 and circulates. As the refrigerant circulates through the flow path described above, the temperature of the refrigerant increases due to the power of the supply pump 24.
Frost attached to the air heat exchanger 1 is melted.

On the other hand, in the gas-liquid separator 38, bubbles of non-condensable gas contained in the circulating refrigerant from the air heat exchanger 1 and refrigerant liquid bubbles generated near the end of defrosting are stored in the refrigerant gas storage tank 34 and supplied. Cavitation caused by suction of air bubbles by the pump 24 is prevented.

When defrosting is completed, the supply pump 24 is stopped by the defrosting signal from the frost sensor 31, the outlet side shutoff valve 33 is gradually opened, and after the short circuit loop becomes equalized, the inlet and outlet side shutoff valves 32, 33 are opened. is fully opened and normal heat recovery operation begins. Note that the relief valve 36 is automatically closed when the supply pump 24 is stopped. Further, the relief valve 37 releases the pressure increase due to the high temperature inside the pipe to the receiver tank 21 through the bypass pipe when the inlet/outlet side cutoff valves 32, 33 do not operate normally at the end of defrosting.

In this way, in this embodiment, when frost forms, the receiver tank 21 and the heat recovery system are separated, and even if one air heat exchanger becomes frosted, defrosting operation can be performed individually, so the entire system is stopped and the heat recovery system is removed. There is no need to interrupt recovery, and a stable heat supply can be sent to the user.

As described above, according to the present invention, refrigerant gas from a plurality of air heat exchangers and refrigerant liquid from a heat pump are stored in a receiver tank, and the refrigerant liquid in the receiver tank is controlled by a control signal from a level controller. As a result, air temperature was forcibly supplied to each of the multiple air heat exchangers using a supply pump while controlling the temperature to a predetermined level using a control valve. However, it is possible to provide a heat pump system that can stably supply refrigerant liquid.

[Brief explanation of the drawing]

Figures 1 and 2 are both diagrams showing the configuration of a conventional heat pump system. Figure 1 is a configuration diagram of a heat pump system that recovers heat through water piping, and Figure 2 is a configuration diagram of a direct expansion type heat pump system. 3 and 3 are block diagrams of a heat pump system according to an embodiment of the present invention, and FIG. 4 is a block diagram showing a case where a defrosting function is added to the heat pump system of the same embodiment. 1, 2... Air heat exchanger, 6... Compressor, 7...
... Condenser, 12 ... Accumulator, 21 ...
Receiver tank, 22...Level controller, 23...
...control valve, 24, 25...supply pump.

Claims (1)

[Scope of utility model registration request] a receiver tank that stores refrigerant gas from the plurality of air heat exchangers and refrigerant liquid from the heat pump; a level controller that controls the level of the refrigerant liquid in the receiver tank; and a level controller that controls the level of the refrigerant liquid in the receiver tank. The present invention is characterized by comprising a control valve that controls the amount of refrigerant liquid supplied to the receiver tank, and a supply pump that supplies the refrigerant liquid supplied to the receiver tank by the control valve to the plurality of air heat exchangers. heat pump system.