JP5832190B2 - Water refrigerant refrigeration system - Google Patents

Description

  The present invention relates to a water refrigerant refrigeration system using water as a refrigerant, and more particularly, to a water refrigerant refrigeration system that recovers energy using a pressure difference between a refrigerator, a chilled water circuit, and a cooling water circuit. .

  Conventionally, as a water-refrigerant refrigeration system using water as a refrigerant, as shown in FIG. 3, a refrigerator 54 including a circuit in which a refrigerant circulates in the order of an evaporator 51, a compressor 52, and a condenser 53, The refrigerant of the evaporator 51 is supplied to the indoor load through the feed pipe and is returned to the evaporator 51 through the return pipe, and the cooling tower 56 is supplied with the refrigerant of the condenser 53 through the feed pipe. There is known a water-refrigerant refrigeration system 50 connected to a cooling water system circuit 57 that is cooled by a cooling pipe and returned to a condenser 53 through a return pipe (for example, see Patent Document 1 below).

  In such a system 50, water is used as a refrigerant common to all the circuits of the refrigerator 54, the cold water system circuit 55, and the cooling water system circuit 57, and heat is directly exchanged in the evaporator 51 and the condenser 53. There is no need for heat exchange between circuits, and there is no heat loss due to heat exchange, resulting in a system with excellent thermal efficiency.

  In the refrigerator 54, the inside of the evaporator 51 is maintained in a vacuum state by a vacuum pump (not shown) so as to match the evaporation temperature of the refrigerant in the evaporator 51, and the other condenser 53 and the piping system are evacuated. It is in a state. For this reason, a part of the chilled water system circuit and the cooling water system circuit also has a vacuum pressure, and cavitation is likely to occur in the pumps and valves installed in the chilled water system circuit and the cooling water system circuit.

Japanese Patent Application Laid-Open No. 2006-97989

  In order to prevent such cavitation, heat exchange is performed between the cold water circulating in the chilled water circuit and the cooling water circuit and the cold water circulating in the refrigerator with positive pressure in the chilled water circuit and the cooling water circuit. It was necessary to install a vessel.

  However, if such a heat exchanger is installed in the water refrigerant refrigeration system, the effect of improving the thermal efficiency by using the water refrigerant in common with each circuit, which is the feature of this system, will not be exhibited. As a result, there was a problem that the system could not save energy.

  Therefore, a main problem of the present invention is to provide a water refrigerant refrigeration system that saves energy in the system and prevents cavitation.

In order to solve the above-mentioned problem, the present invention according to claim 1 is directed to a refrigerator having a circuit in which water is used as a refrigerant and the refrigerant circulates in the order of an evaporator, a compressor, and a condenser. A chilled water pump is supplied to the indoor load through the feed pipe and the heat exchange is performed , and then a chilled water circuit that is returned to the evaporator through the return pipe, and the refrigerant of the condenser is fed to the feed pipe by the cooling water pump A water refrigerant refrigeration system connected to a cooling water system circuit that is supplied to the cooling tower through and cooled by the cooling tower and then returned to the condenser through a return pipe ,
While the refrigerator is set to a vacuum pressure corresponding to the evaporation temperature of the refrigerant in the evaporator, the chilled water system circuit and the cooling water system circuit are set to a positive pressure,
In the chilled water circuit, a power recovery pump that uses a pressure difference when the refrigerant flows between the refrigerator and the chilled water circuit is disposed in the middle of a return pipe that is returned from the indoor load to the evaporator. And an auxiliary chilled water pump having a power source recovered by the power recovery pump as a part or all of the drive source in the middle of the feed pipe sent from the evaporator to the indoor load and before the cold water pump. The auxiliary chilled water pump is configured to feed water at the same pressure as the pressure recovered by the power recovery pump installed in the chilled water system circuit;
In the cooling water system circuit, a power recovery pump using a pressure difference when refrigerant flows between the refrigerator and the cooling water system circuit is disposed in the middle of a return pipe returned from the cooling tower to the condenser. Auxiliary cooling water pump having a power source recovered by the power recovery pump as a part or all of the drive source in the middle of the feed pipe sent from the condenser to the cooling tower and before the cooling water pump Is provided, and the auxiliary cooling water pump supplies water at the same pressure as the pressure recovered by the power recovery pump installed in the cooling water system circuit .

  In the invention described in claim 1, in the water refrigerant refrigeration system, in the refrigerator, it is necessary to maintain the vacuum pressure to match the evaporation temperature in the evaporator, while in the chilled water system circuit and the cooling water system circuit, the pressure of the pump Since it becomes a positive pressure, a power recovery pump is provided that recovers power by using a pressure difference when refrigerant flows between these refrigerators and the chilled water system circuit / cooling water system circuit. For this reason, the power recovered by each power recovery pump can be used as a power source of the water supply pump, enabling energy-saving operation of the system and effective use of energy.

  Also, when an auxiliary pump is provided in front of each of the cold water pump and the cooling water pump for circulating the refrigerant in the cold water system circuit and the cooling water system circuit, and the power recovered by the power recovery pump is used as a drive source of these auxiliary pumps In addition, the suction side of the cold water pump and the cooling water pump can be set to a positive pressure, and cavitation in these pumps can be prevented.

  As described above, according to the present invention, it is possible to provide a water refrigerant refrigeration system that saves energy in the system and prevents cavitation.

1 is a system configuration diagram of a water refrigerant refrigeration system 1 according to the present invention. It is a system configuration diagram at the time of free cooling operation. FIG. 3 is a system configuration diagram of a conventional water refrigerant refrigeration system 50.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the water refrigerant refrigeration system 1 according to the present invention uses water as a refrigerant, and the refrigerant circulates in the order of the evaporator 2, the compressor 3, and the condenser 4. The refrigerant of the evaporator 2 is supplied to the indoor load (not shown) through the feed pipe by the cold water pump 6 to the refrigerator 5 and is subjected to heat exchange, and then the evaporator 2 through the return pipe. The cooling water system circuit 7 and the refrigerant in the condenser 4 are supplied to the cooling tower 9 through the feed pipe by the cooling water pump 8 and cooled by the cooling tower 9, and then the condenser through the return pipe. The circuit configuration is such that the cooling water system circuit 10 returned to 4 is connected.

  More specifically, in the chilled water circuit 7, a power recovery pump 11 is disposed in the middle of a flow path (return pipe) returning from the indoor load to the evaporator 2, and a flow sent from the evaporator 2 to the indoor load. An auxiliary chilled water pump 13 that uses the power recovered by the power recovery pump 11 as a part or all of the drive source is disposed in the middle of the path (feed piping) and before the chilled water pump 6. In the cooling water system circuit 10, a power recovery pump 12 is disposed in the middle of a flow path (return pipe) returned from the cooling tower 9 to the condenser 4, and a flow path sent from the condenser 4 to the cooling tower 9. An auxiliary cooling water pump 14 that uses the power recovered by the power recovery pump 12 as a part or all of the drive source is disposed in the middle of the (feed pipe) and before the cooling water pump 8.

  In the main water refrigerant refrigeration system 1, it is necessary to maintain the vacuum pressure so that the refrigerator 5 matches the evaporation temperature of the refrigerant in the evaporator 2, while the chilled water system circuit 7 and the cooling water system circuit 10 have a positive pressure. Therefore, since the power recovery pumps 11 and 12 using the pressure difference when the refrigerant flows between the refrigerator 5 and the cold water system circuit 7 and the cooling water system circuit 10 are provided, each power recovery pump 11 is provided. , 12 can be used as a power source of the auxiliary chilled water pump 13 or the auxiliary cooling water pump 14, etc., enabling energy saving operation of the system and effective use of energy.

Specifically describing each component,
The evaporator 2 cools surrounding water refrigerant by evaporating the refrigerant in the evaporator 2 in a reduced pressure state (vacuum state) lower than atmospheric pressure, for example, and absorbing latent heat of evaporation at that time from the surroundings. is there. In order to maintain the vacuum pressure corresponding to the evaporation temperature in the evaporator 2, the vacuum state is maintained by a vacuum pump (not shown). The evaporator 2 is connected to a feed pipe that sends the cooled refrigerant accumulated at the bottom to the indoor load. The evaporator 2 returns from the indoor load to the evaporator 2 and sprinkles the refrigerant into the evaporator 2 to evaporate the refrigerant. The return pipe to be connected is connected.

  The condenser 4 cools and reliquefies the refrigerant vapor by spraying the refrigerant returned through the return pipe of the cooling water circuit 10 to the high-temperature and high-pressure refrigerant vapor compressed by the compressor 3. It is something to be made. The condenser 4 is connected to a feed pipe for sending the reliquefied refrigerant accumulated at the bottom to the cooling tower 9 and a return pipe for returning the refrigerant cooled in the cooling tower 9.

  The compressor 3 may be a known steam compressor such as a turbo type, a roots type, a screw type, or an axial flow type. As the compressor 3, it is desirable to use a compressor whose rotation speed can be controlled by inverter control. As a result, in the chilled water circuit 7, the number of revolutions is controlled in accordance with the temperature difference between the refrigerant temperature in the feed pipe of the evaporator 2 and the refrigerant temperature in the return pipe to control the refrigerating capacity of the refrigerator. It becomes possible.

  The cooling tower 9 is preferably a hermetic cooling tower. A cooling water pipe through which a refrigerant passes is piped in the cooling tower, and the cooling air is sprayed on the outside of the pipe to cool the refrigerant. . The cooling tower 9 can be an open type.

  Next, the power recovery pumps 11 and 12 will be described. The refrigerant sent at a high pressure by the cold water pump 6 or the cooling water pump 8 is kept at a relatively high pressure as compared with the vacuum state of the evaporator 2 or the condenser 4 although the pressure is lowered by the indoor load or the cooling tower 9 or the like. Therefore, there is a large energy loss for discharging to the evaporator 2 and the condenser 4 as they are. For this reason, power recovery pumps 11 and 12 are provided in the return pipes before discharging to the evaporator 2 and the condenser 4, respectively, and the power recovery pumps 11 and 12 are driven by a relatively high pressure refrigerant to recover the energy. Like to do. The recovered energy is obtained by, for example, connecting or directly connecting the rotary shafts of the power recovery pumps 11 and 12 to the motors for driving the auxiliary pumps 13 and 14 provided in the feed pipes of the evaporator 2 and the condenser 4. It is used for driving the auxiliary pumps 13 and 14 so that energy can be effectively used. Moreover, since the pressure on the suction side of the cold water pump 6 is increased by providing the auxiliary cold water pump 13, cavitation can be prevented. The cooling water pump 8 has the same effect.

  Referring to FIG. 1, the chilled water circuit 7 supplies the water with the suction side pressure of 100 kPa increased to 500 kPa, for example, as shown in FIG. If the pressure loss at the indoor load or the like is 400 kPa, the pressure of the return chilled water is 100 kPa. On the other hand, if the evaporation temperature is 20 ° C. in the evaporator 2, the pressure is −99 kPa (101.3−2.3 kPa), so the pressure difference ΔP is 199 kPa. Further, in order to supply cold water cooled by the evaporator 2, it is necessary to supply water from the −99 kPa evaporator 2 to the 100 kPa feed pipe, and the pressure difference is 199 kPa. Accordingly, the power of the pressure difference of 199 kPa may be recovered by the power recovery pump 11 and the auxiliary chilled water pump 13 may supply 199 kPa of water, so that the motor power of the auxiliary chilled water pump 13 is theoretically unnecessary. In practice, however, mechanical loss or the like occurs, so that external power is required. However, the power recovery pump 11 covers most of the power of the auxiliary chilled water pump 13.

  On the other hand, in the cooling water system circuit 10 as well, if the cooling water pump 8 pressurizes the suction side pressure of 100 kPa to 300 kPa and supplies water, and the pressure loss of the cooling water system circuit (mainly the cooling tower 9) is 200 kPa, return cooling The water pressure is 100 kPa. On the other hand, when the condensation temperature is 33 ° C. in the condenser 4, the pressure is −96.3 kPa (101.3−5 kPa), so the pressure difference ΔP is 196.3 kPa. By using the power recovery pump 12 for water supply of this pressure difference, the power consumption is minimized.

  By the way, in this water refrigerant | coolant refrigeration system 1, when the temperature of the refrigerant | coolant which distribute | circulates the return piping of the evaporator 2 vicinity is below or equal to the temperature of the refrigerant | coolant which distribute | circulates a feed piping, as shown in FIG. Without stopping and operating the refrigerator 5, control can be performed to switch to a free cooling operation in which the cooling tower 9 cools the refrigerant.

  As such a water refrigerant refrigeration system 1, as shown in FIGS. 1 and 2, a bypass 15 that branches from a return pipe of the chilled water circuit 7 and reaches a supply pipe to the cooling tower 9 of the cooling water circuit 10. And a bypass path 16 that branches from the middle of the pipe line from the cooling tower 9 of the cooling water system circuit 10 to the condenser 4 and reaches the feed pipe of the cooling water system circuit 7, and is provided in each of the bypass paths 15 and 16. Valves 17 and 18 are provided, and valves 19 and 20 are provided on the way from the branch point of the cold water system circuit 7 to the evaporator 2 and on the way from the branch point of the cooling water system circuit 10 to the condenser 4, respectively. In order to save energy in the system, when the outside air wet bulb temperature is low, the compressor 3 is stopped and the refrigerator 5 is not operated and the valves 17 and 18 are opened and the valves 19 and 2 are opened as shown in FIG. Is closed, the refrigerant in the return pipe is sent to the cooling tower 9 through the bypass passage 15, cooled to a predetermined cold water temperature only by the operation of the cooling tower 9, and then sent to the feed pipe through the bypass passage 16. Free cooling operation is possible.

  DESCRIPTION OF SYMBOLS 1 ... Water refrigerant refrigeration system, 2 ... Evaporator, 3 ... Compressor, 4 ... Condenser, 5 ... Refrigerator, 6 ... Cold water pump, 7 ... Cold water system circuit, 8 ... Cooling water pump, 9 ... Cooling tower, 10 ... Cooling water system circuit, 11.12 ... Power recovery pump, 13 ... Auxiliary cooling water pump, 14 ... Auxiliary cooling water pump

Claims (1)

Using water as a refrigerant, the refrigerant evaporator, compressor, to refrigerator comprising a circuit for circulating in the order of the condenser, the refrigerant of the evaporator is supplied to the indoor load through the feed pipe by chilled water pump, heat exchanger after has been performed, and cold water system circuit through the return pipe is returned to the evaporator, the condenser of the refrigerant is supplied to the cooling tower through a feed pipe by the cooling water pump, after being cooled in the cooling tower A water refrigerant refrigeration system connected to a cooling water system circuit returned to the condenser through a return pipe ,
While the refrigerator is set to a vacuum pressure corresponding to the evaporation temperature of the refrigerant in the evaporator, the chilled water system circuit and the cooling water system circuit are set to a positive pressure,
In the chilled water circuit, a power recovery pump that uses a pressure difference when the refrigerant flows between the refrigerator and the chilled water circuit is disposed in the middle of a return pipe that is returned from the indoor load to the evaporator. And an auxiliary chilled water pump having a power source recovered by the power recovery pump as a part or all of the drive source in the middle of the feed pipe sent from the evaporator to the indoor load and before the cold water pump. The auxiliary chilled water pump is configured to feed water at the same pressure as the pressure recovered by the power recovery pump installed in the chilled water system circuit;
In the cooling water system circuit, a power recovery pump using a pressure difference when refrigerant flows between the refrigerator and the cooling water system circuit is disposed in the middle of a return pipe returned from the cooling tower to the condenser. Auxiliary cooling water pump having a power source recovered by the power recovery pump as a part or all of the drive source in the middle of the feed pipe sent from the condenser to the cooling tower and before the cooling water pump Is provided, and the auxiliary cooling water pump feeds water at the same pressure as the pressure recovered by the power recovery pump installed in the cooling water system circuit .

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