JP2005180822A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device capable of producing cold water, without providing a water storage tank, by cooling water whose flow rate and temperature can vary widely. <P>SOLUTION: The cooling device has a refrigerant cycle 20 to which a compressor 12, a condenser 15, expansion valves 16 and an evaporator 18 are connected to allow circulation of refrigerant therein. Heat exchange occurs between the evaporator 18 of the refrigerant cycle 20 and water to cool the water. The expansion valves 16 include a plurality of expansion valves 16-1, 16-2, 16-3 provided in parallel. Further, the device is provided with a temperature sensor 32 for sensing the temperature of water at the entrance side, a flow rate sensor 34 for detecting the flow rate of water, and a controller 50 that effects selective control over the expansion valves used among the plurality of expansion valves as detection signals from the temperature sensor 32 and the flow rate sensor 34 are inputted thereto. Depending on the temperature and flow rate of water at the entrance side, the expansion valves to be used are switched from one to another. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling device that cools a load medium such as a liquid such as water or a gas such as air.

  Conventionally, as this type of cooling device, for example, Patent Document 1 (Japanese Utility Model Publication No. 62-171744 (Japanese Utility Model Publication No. 1-75769) microfilm) and Patent Document 2 (Japanese Patent Application Laid-Open No. 7-4816) are disclosed. What has been described is known.

  The configuration described in Patent Document 1 includes a refrigerant cycle in which a compressor, a condenser, and an expansion valve are connected to circulate the refrigerant. In the evaporator, the refrigerant and the load medium exchange heat, The compressor motor is controlled by an inverter, and an evaporation pressure adjusting valve for detecting the cooling temperature of the cooling load and controlling the evaporation pressure of the evaporator is provided on the outlet side of the evaporator. . Normally, the pressure of the refrigerant sent to the compressor after heat exchange is detected, and the operation of the compressor is controlled by the inverter based on the pressure, and the amount of refrigerant sent to the evaporator is adjusted. When the temperature of the water is low or the flow rate is reduced and the load is below the lower limit of the load control of the compressor motor, the refrigerant flow into the compressor is reduced by the evaporation pressure adjustment valve, and the evaporation pressure of the evaporator is reduced. It is designed to suppress heat exchange by the evaporator.

  However, when the compressor is controlled by an inverter as in Patent Document 1, depending on the type of the compressor, the compression efficiency may decrease or cause a failure, and the cost may increase. There's a problem. In Patent Document 2, there is a similar problem.

No. 62-171744 (Japanese Utility Model Application No. 1-75769) microfilm) Japanese Patent Laid-Open No. 7-4816

  The present invention has been made in view of such problems, and an object of the present invention is to provide a cooling device that can stably use a compressor at a low cost and can cool a load medium whose flow rate and temperature can fluctuate greatly. Is to provide. Another object of the present invention is to provide a cooling device capable of accurately cooling a load medium to a desired temperature.

In order to achieve the above object, the invention according to claim 1 of the present invention includes a refrigerant cycle in which a compressor, a condenser, an expansion valve, and an evaporator are connected to circulate refrigerant, In the cooling device for performing heat exchange between the refrigerant and the load medium in the evaporator of the refrigerant cycle and cooling the load medium,
A plurality of expansion valves are provided as the expansion valve, and
A temperature sensor for detecting the temperature of the load medium on the inlet side;
A flow sensor for detecting the flow rate of the load medium;
A controller that receives detection signals from the temperature sensor and the flow rate sensor and performs selection control of an expansion valve to be used among the plurality of expansion valves; and
The expansion valve to be used is switched in accordance with the temperature of the load medium on the inlet side detected by the temperature sensor and the flow rate of the load medium detected by the flow sensor.

  Switching between multiple expansion valves may be done by switching the number of use by providing multiple expansion valves with the same throttling capacity, or by switching the capacity of using expansion valves with different throttling capacities. Good.

  The invention according to claim 2 is characterized in that the expansion valve according to claim 1 is a constant pressure expansion valve, and the refrigerant cycle is provided with an evaporation pressure adjusting valve for adjusting an evaporation pressure in an evaporator. To do.

  The invention described in claim 3 is characterized in that the adjustment pressure of the evaporation pressure adjusting valve described in claim 2 is controlled in accordance with the temperature of the load medium on the outlet side.

  According to a fourth aspect of the present invention, in the controller according to any one of the first to third aspects, the controller selects the two parameters of the load medium temperature and the load medium flow rate on the inlet side. A sequencer for determining an expansion valve to be operated is provided.

According to the present invention, the load medium is controlled by switching the expansion valve to be used from among the plurality of expansion valves according to the temperature on the inlet side of the load medium and the flow rate of the load medium, and adjusting the flow rate of the refrigerant flowing through the refrigerant cycle. The load medium can be cooled to a desired temperature in response to large fluctuations in the temperature or flow rate.
According to the second aspect of the present invention, the refrigerant pressure in the evaporator is kept constant by using the evaporation pressure adjusting valve, and a constant amount of refrigerant is caused to flow to the evaporator using the constant pressure expansion valve. Thus, the temperature of the refrigerant in the evaporator can be kept constant, and thus the cooling temperature of the load medium can be made constant.

  According to the third aspect of the invention, the load medium can be cooled to a desired temperature by changing the adjustment pressure of the evaporation pressure adjustment valve.

  According to the fourth aspect of the present invention, the expansion valve to be quickly selected can be determined by the sequencer with respect to fluctuations in two parameters, the temperature of the load medium on the inlet side and the flow rate of the load medium.

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

  FIG. 1 is a circuit diagram of a cooling device according to an embodiment of the present invention. In the figure, the cooling device 10 has a refrigerant cycle 20 in which a compressor 12, a condenser 14, an expansion valve 16, and an evaporator 18 are connected to circulate refrigerant.

  A water pipe 22 through which the load medium flows is provided, the inlet side of the water pipe 22 is connected to a water supply source, the outlet side is connected to a faucet, a valve, and the like, and the water flowing through the water pipe 22 is supplied to the refrigerant cycle 20. In the evaporator 18, heat is exchanged with the refrigerant.

  The water pipe 22 is not provided with a water storage tank or the like, and is provided with a temperature sensor 32 and a flow rate sensor 34 on the inlet side with respect to the evaporator 18. A sensor 36 is provided. The temperature sensor 32 sequentially detects the temperature of water before the heat exchange in the evaporator 18 (referred to as the inlet temperature), and the flow rate sensor 34 sequentially detects the flow rate of the water flowing through the water pipe 22. The temperature sensor 36 sequentially detects the temperature of water after the heat exchange in the evaporator 18 (referred to as outlet temperature). Detection signals from the temperature sensor 32 and the flow sensor 34 are input to the controller 50, and detection signals from the temperature sensor 36 are input to the controller 52.

  The refrigerant cycle 20 is provided with an evaporation pressure adjusting valve 40 on the outlet side of the evaporator 18. The adjustment pressure of the evaporation pressure adjusting valve 40 is controlled by a setting control signal from the controller 52.

  The expansion valve 16 includes a plurality of expansion valves 16-1, 16-2, and 16-3. The plurality of expansion valves 16-1, 16-2, 16-3 are connected in parallel, and each expansion valve 16-1, 16-2, 16-3 has an electromagnetic valve 42-1, 42. -2 and 42-3 are connected in series. The electromagnetic valves 42-1, 42-2, and 42-3 are on-off valves that are controlled to open and close by a command signal from the controller 50. The expansion valves 16-1, 16-2, and 16-3 have different processing capacities, that is, the flow rates of the refrigerant to be passed, respectively. In order to prevent the degree of superheat from being lowered, it is used by switching, and the capacity is expansion valve 16-1 <expansion valve 16-2 <expansion valve 16-3.

  Here, the expansion valves 16-1, 16-2, 16-3 are preferably constant pressure expansion valves, and the pressure of the pressure equalizing pipe 17 connected to the outlet of the evaporation pressure adjusting valve 40, which is the outlet of the evaporator 18, is set to the set pressure. It works to be. This set pressure may be set to about the adjustment pressure set by the evaporation pressure adjustment valve 40, but it is not necessary to exactly match the set pressure. Although it is possible to use temperature expansion valves as the expansion valves 16-1, 16-2, 16-3, in that case, in order to operate to keep the superheat degree of the outlet of the evaporator 18 constant. Since the refrigerant temperature fluctuation at the inlet of the evaporator 18 becomes large and it is difficult to cool the water for heat exchange to a predetermined temperature, it is desirable to use a constant pressure expansion valve.

  Reference numeral 44 denotes an accumulator.

  The controller 50 receives sequential detection signals from the temperature sensor 32 and the flow rate sensor 34 provided in the water pipe 22, and outputs switching signals for opening and closing the electromagnetic valves 42-1, 42-2, and 42-3. Is.

  The controller 52 receives sequential detection signals from the temperature sensor 36 provided in the water pipe 22 and outputs a setting control signal to the evaporation pressure adjusting valve 40. A set temperature that is a desired water outlet temperature is set by the controller 52.

  The operation of the cooling device 10 configured as described above will be described. Water from the water supply source flows through the water pipe 22, and the water exchanges heat with the refrigerant in the evaporator 18. The temperature sensor 32 sequentially detects the temperature before the evaporator 18, and the flow rate sensor 34 sequentially detects the flow rate of the water flowing through the water pipe 22.

  The detection signals from the temperature sensor 32 and the flow rate sensor 34 are input to the controller 50, converted into analog and digital, and then converted into a digital mapping set by the sequencer corresponding to the digital values of the temperature and flow rate. Based on this, an open / close switching signal for the solenoid valves 42-1, 42-2, 42-3 is output. An example of this digital mapping is shown in FIG. In general, as the flow rate Q increases and the temperature T increases, the expansion valve 16 that has a high capacity and can flow a large amount of refrigerant is selected. By using such digital mapping, the expansion valve 16 is sequentially switched according to two parameters of the water flow rate and the inlet temperature, for example, when the water flow rate is low or the water temperature is low. The degree of superheat at the outlet of the evaporator 18 is insufficient, and liquid compression in the compressor 12 is prevented from occurring.

  The evaporation pressure adjustment valve 40 adjusts the evaporation pressure in the evaporator 18 to a predetermined pressure and adjusts the temperature in the evaporator 18 to a constant temperature. The detection signal of the water outlet temperature detected by the temperature sensor 36 is input to the controller 52, and the controller 52 compares the outlet temperature detected by the temperature sensor 36 with the set temperature, and performs control such as PID control. Based on this, a setting control signal is output, and the pressure adjusted by the evaporation pressure adjusting valve 40 is changed. In this way, the outlet temperature is controlled to be the set temperature.

  Since the constant pressure expansion valve is used as the expansion valve 16 and the pressure in the vicinity of the pressure equalizing pipe 17 is adjusted to a predetermined pressure by the evaporation pressure adjusting valve 40, the expansion valve 16 selected by the controller 50 flows a constant flow rate. The refrigerant is allowed to flow regardless of the degree of superheat at the outlet of the evaporation pressure adjusting valve 40. For this reason, in the evaporator 18, the heat-exchanged water can be cooled to a temperature close to 0 ° C. without being frozen. On the other hand, when a temperature expansion valve is used as the expansion valve, the refrigerant flowing through the evaporator 18 is reduced in order to perform a throttling operation so that the degree of superheat at the outlet of the evaporator 18 becomes constant, resulting in water and heat. Since the amount of heat source to be exchanged is reduced, it becomes difficult to take out water at a desired temperature. This difference in effect is represented by the graph of FIG. In the graph, when the temperature expansion valve is used for the portion (a), the water inlet temperature (25 ° C.) when the set temperature is 2 ° C. using the constant pressure expansion valve under the same conditions for the portion (b) Near) and the outlet temperature. As can be seen from this graph, when the temperature expansion valve is used, the temperature fluctuation is large and it is difficult to bring the temperature of the water closer to the set temperature, whereas when the constant pressure expansion valve is used, The temperature fluctuation is small, and the temperature of water can be controlled in the vicinity of the set temperature 2 ° C. close to 0 ° C.

  With the configuration as described above, it is possible to cope with large fluctuations in the flow rate of water by switching between the plurality of expansion valves 16-1, 16-2, 16-3, and further, the evaporation pressure adjusting valve 40 evaporates. By adjusting the pressure and using a constant pressure expansion valve as the expansion valve 16, the load medium can be cooled to a desired temperature in order to flow a constant temperature refrigerant regardless of the degree of superheat.

  In the above embodiment, one expansion valve is always selected and used from among the plurality of expansion valves 16-1, 16-2, 16-3. However, the present invention is not limited to this, and one or more arbitrary combinations of expansion valves can be used at the same time.

It is a circuit diagram of the cooling device concerning the embodiment of the present invention. It is an example of the digital mapping set by the sequencer. It is a graph showing transition of the inlet temperature and outlet temperature of water.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cooling device 12 Compressor 14 Condenser 16 Expansion valve 16-1, 16-2, 16-3 Expansion valve 18 Evaporator 20 Refrigerant cycle 22 Water piping 32 Temperature sensor 34 Flow rate sensor 40 Evaporation pressure adjustment valve 50 Controller

Claims (4)

A compressor, a condenser, an expansion valve, and an evaporator are connected to each other to have a refrigerant cycle in which the refrigerant circulates. The refrigerant and the load medium exchange heat in the evaporator of the refrigerant cycle, In the cooling device for cooling
A plurality of expansion valves are provided as the expansion valve, and
A temperature sensor for detecting the temperature of the load medium on the inlet side;
A flow sensor for detecting the flow rate of the load medium;
A controller that receives detection signals from the temperature sensor and the flow rate sensor and performs selection control of an expansion valve to be used among the plurality of expansion valves; and
The cooling apparatus according to claim 1, wherein the expansion valve to be used is switched according to the temperature of the load medium on the inlet side detected by the temperature sensor and the flow rate of the load medium detected by the flow sensor.   The cooling device according to claim 1, wherein the expansion valve is a constant pressure expansion valve, and the refrigerant cycle is provided with an evaporation pressure adjusting valve for adjusting an evaporation pressure in an evaporator.   The cooling device according to claim 2, wherein the adjustment pressure of the evaporation pressure adjustment valve is controlled according to the temperature of the load medium on the outlet side.   4. The controller according to claim 1, further comprising a sequencer for determining an expansion valve to be selected for two parameters, the temperature of the load medium on the inlet side and the flow rate of the load medium. The cooling device according to item.

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