Low-temperature cold water supply device

Abstract

To provide a low-temperature cold water supply device capable of stably supplying low-temperature cold water by suppressing a decrease in the temperature of the low-temperature cold water below the freezing point, and preventing freezing-induced rupture within a plate-type heat exchanger.SOLUTION: A low-temperature cold water supply device includes a coolant line 16 which circulates refrigerant between a plate type heat exchanger 12 and a refrigerator 11, a cool water line 19 which circulates cool water between the plate type heat exchanger 12 and a load 13A, an evaporating pressure regulating valve 18 which is provided on the coolant line 16 and is capable of regulating an evaporation pressure of coolant, a temperature sensor TE which measures a low-temperature cold water outlet temperature PV of low-temperature cold water cooled by the low-temperature cold water, and a control part 15 which controls respective kinds of equipment of a low-temperature cold water supply device 11. Therein, the control part 15, when the low-temperature cold water outlet temperature PV of the low-temperature cold water which is preset is lower than a reference temperature SV, controls an opening of the evaporating pressure regulating valve 18 and increases the evaporation pressure so that the cold water does not freeze in accordance with a temperature difference between the low-temperature cold water outlet temperature PV and the reference temperature SV.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a low-temperature chilled water supply device, and more particularly to a low-temperature chilled water supply device that can continuously supply low-temperature chilled water at around 0°C without freezing. [Background technology]

[0002] For example, in the food industry or the field of physics and chemistry, low-temperature cold water around 0° C. is used to cool products, keep them at low temperatures, adjust their quality, etc. Low-temperature water chillers that continuously supply low-temperature cold water around 0° C. have also been known for some time (see, for example, Patent Document 1).

[0003] The low-temperature water chiller known from Patent Document 1 uses a plate-type heat exchanger to produce low-temperature chilled water, and is capable of continuously supplying the low-temperature chilled water produced therein.

[0004] However, although plate heat exchangers have good thermal conductivity, are small and inexpensive, their sealed structure increases the risk of freeze punctures when producing low-temperature chilled water.

[0005] Therefore, in the low-temperature water chiller known from Patent Document 1, focusing on the fact that partial freezing or the like occurs in the chilled water line, which makes it difficult for water to flow, a flow sensor is provided in the chilled water line to detect the flow of water passing through the plate heat exchanger.When the flow sensor detects a decrease in the water flow rate, the chilled water line is heated, the flow rate of the flowing water is adjusted, or the evaporation temperature is increased, or other measures are taken to eliminate the partial freezing. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-111062 Summary of the Invention [Problem to be solved by the invention]

[0007] However, with the freeze prevention method for the low-temperature chiller described in Patent Document 1, there is a problem in that the risk of freeze puncture of the plate-type heat exchanger increases when the load fluctuates greatly and the capacity control of the heat source chiller cannot keep up with the decrease in the low-temperature chilled water outlet temperature. In addition, with the direct expansion type, the evaporation temperature of the evaporator is constant, which increases the risk of freeze puncture.

[0008] Therefore, a technical problem that must be solved is to provide a low-temperature chilled water supply device that can prevent freeze bursts in the plate heat exchanger by preventing the temperature of the low-temperature chilled water from dropping below the freezing point, and that can stably supply low-temperature chilled water.The present invention aims to solve this problem. [Means for solving the problem]

[0009] The present invention has been proposed to achieve the above-mentioned object, and the invention described in claim 1 provides a low-temperature chilled water supply device that supplies chilled water to a load, comprising: a plate heat exchanger that exchanges heat between the chilled water and a refrigerant; a refrigerant line that circulates the refrigerant between the plate heat exchanger and a chiller; a chilled water line that circulates the chilled water between the plate heat exchanger and the load; an evaporation pressure regulating valve that is provided in the refrigerant line and can adjust the evaporation pressure of the refrigerant; a temperature sensor that measures the low-temperature chilled water outlet temperature of the low-temperature chilled water that has been cooled by the plate heat exchanger; and a control unit that controls various devices of the low-temperature chilled water supply device, wherein when the low-temperature chilled water outlet temperature is lower than a predetermined reference temperature of the low-temperature chilled water, the control unit controls the opening of the evaporation pressure regulating valve to increase the evaporation pressure so that the chilled water does not freeze, depending on the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature.

[0010] With this configuration, when the outlet temperature of low-temperature chilled water cooled by the plate heat exchanger is lower than a preset reference temperature for low-temperature chilled water, the opening of the evaporation pressure control valve is controlled according to the temperature difference between the outlet temperature and the reference temperature to prevent the chilled water from freezing, and the evaporation pressure of the refrigerant is increased to raise the set value for the evaporation temperature of the refrigerant, thereby raising the temperature of the refrigerant circulating through the refrigerant line. This raises the temperature of the chilled water in the plate heat exchanger in the chilled water line, preventing freeze bursts in the plate heat exchanger, and ensuring a stable supply of low-temperature chilled water.

[0011] The invention described in claim 2 provides a low-temperature chilled water supply device in the configuration described in claim 1, wherein the control unit includes an evaporation temperature determination unit that determines the evaporation temperature of the refrigerant based on the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature, an evaporation pressure determination unit that determines a target value of the evaporation pressure to be adjusted by the evaporation pressure control valve based on the evaporation temperature so that the chilled water does not freeze, and a valve control unit that controls the opening degree of the evaporation pressure control valve according to the target value of the evaporation pressure.

[0012] With this configuration, when the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature deviates from the reference value, the control unit determines the target value of the evaporation pressure based on the temperature difference to prevent the chilled water from freezing, and adjusts the opening of the evaporation pressure control valve via the evaporation pressure determination unit and the valve control unit to adjust the temperature of the refrigerant circulating in the refrigerant line, thereby automatically controlling the chilled water to prevent it from freezing in the plate heat exchanger. This prevents freeze-up in the plate heat exchanger and ensures a stable supply of low-temperature chilled water.

[0013] The invention of claim 3 provides a low-temperature chilled water supply device having the configuration of claim 1, wherein the chilled water line comprises a chilled water tank including a low-temperature tank tank for receiving the low-temperature chilled water discharged from the plate heat exchanger and a high-temperature tank tank for receiving high-temperature chilled water having a water temperature higher than that of the low-temperature tank tank, and a circulation pump for supplying the high-temperature chilled water in the high-temperature tank tank to the plate heat exchanger, and wherein the control unit increases the flow rate of the high-temperature chilled water by the circulation pump in accordance with the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature when the low-temperature chilled water outlet temperature is lower than a preset reference temperature, so as to prevent the chilled water from freezing.

[0014] With this configuration, when the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature deviates from the reference value, the control unit increases the flow rate of high-temperature chilled water from the circulation pump based on the temperature difference to prevent the chilled water from freezing. This prevents freeze-up inside the plate heat exchanger and ensures a stable supply of low-temperature chilled water.

[0015] The invention described in claim 4 provides a low-temperature chilled water supply device in the configuration described in claim 1, wherein the control unit stops the refrigerator depending on the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature when the low-temperature chilled water outlet temperature is lower than the preset reference temperature.

[0016] According to this configuration, when the low-temperature chilled water outlet temperature is lower than a preset reference temperature, the control unit controls the refrigerator to stop according to the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature, thereby preventing further decrease in the low-temperature chilled water outlet temperature. This prevents freeze-up failures in the plate heat exchanger and ensures a stable supply of low-temperature chilled water. [Effects of the Invention]

[0017] According to the present invention, even if the load fluctuation is large, the temperature of the low-temperature chilled water passing through the plate heat exchanger is prevented from dropping to the freezing point, freezing bursts in the plate heat exchanger are suppressed, and low-temperature chilled water can be supplied stably. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic configuration diagram of a low-temperature chilled water supply device shown as an example according to an embodiment of the present invention. [Figure 2] 10 is a diagram showing an example of setting appropriate control according to the low-temperature chilled water outlet temperature in the low-temperature chilled water supply device of the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] In order to achieve the object of the present invention to provide a low-temperature chilled water supply device that can prevent the temperature of low-temperature chilled water from dropping below the freezing point, thereby preventing freeze bursts in a plate heat exchanger and enabling a stable supply of low-temperature chilled water, the device is configured to supply chilled water to a load, and includes: a plate heat exchanger that exchanges heat between the chilled water and a refrigerant; a refrigerant line that circulates the refrigerant between the plate heat exchanger and a chiller; a chilled water line that circulates the chilled water between the plate heat exchanger and the load; an evaporation pressure control valve that is provided in the refrigerant line and can adjust the evaporation pressure of the refrigerant; a temperature sensor that measures the low-temperature chilled water outlet temperature of the low-temperature chilled water that has been cooled by the plate heat exchanger; and a control unit that controls various components of the low-temperature chilled water supply device, and when the low-temperature chilled water outlet temperature is lower than a predetermined reference temperature of the low-temperature chilled water, the control unit controls the opening of the evaporation pressure control valve to increase the evaporation pressure so as to prevent the chilled water from freezing, depending on the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature. [Example]

[0020] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. In the following embodiment, when the number, value, amount, range, etc. of components is mentioned, the number is not limited to the specific number, and may be more or less than the specific number, unless otherwise specified or when it is clearly limited to a specific number in principle.

[0021] Furthermore, when referring to the shape or positional relationship of components, etc., it includes things that are substantially similar or approximate to those shapes, etc., unless otherwise specified or when it is clearly considered otherwise in principle.

[0022] 1 is a schematic diagram showing one embodiment of a low-temperature chilled water supply apparatus 10 according to the present invention. The low-temperature chilled water supply apparatus 10 of this embodiment is a vapor compression type low-temperature chilled water supply apparatus. The low-temperature chilled water supply apparatus 10 includes a refrigerator 11, a plate heat exchanger 12, a chilled water tank 13, a load 14, and a control unit 15. The load 14 here is a location where chilled water stored in a low-temperature tank 13B of the chilled water tank 13 (described later) is supplied to products for cooling, maintaining low temperatures, adjusting quality, etc. The chilled water used in the load 14 absorbs heat from the products, etc., and becomes hot before being returned to the high-temperature tank 13A of the chilled water tank 13.

[0023] The refrigerator 11 has a compressor and a condenser (not shown). The refrigerator 11 and the plate heat exchanger 12 are connected by a refrigerant line 16, which is a refrigerant flow path. The refrigerant line 16 is connected in a circular manner so that the refrigerant from the refrigerator 11 passes through the plate heat exchanger 12 and returns to the refrigerator 11 again. By circulating the refrigerant, a refrigeration cycle of refrigerant compression, condensation, expansion, and evaporation is performed. In addition, an electronic expansion valve 17 is provided in the refrigerant line 16 between the compressor of the refrigerator 11 and the plate heat exchanger 12, and an evaporation pressure regulator (EPR) 18 is provided between the condenser of the refrigerator 11 and the plate heat exchanger 12.

[0024] The electronic expansion valve 17 is an electronic valve whose opening degree can be controlled, and is electrically connected to the control unit 15 via a signal line. By adjusting the opening degree of the electronic expansion valve 17 with the control unit 15, the pressure of the high-pressure, low-temperature liquid refrigerant liquefied in the condenser can be reduced to a state where it is easy to evaporate, thereby ensuring an optimal flow rate inside the plate heat exchanger 12. In addition, it has the function of maintaining the degree of superheat of the refrigerant gas within a certain range in accordance with the capacity of the compressor, which changes depending on the increase or decrease in the cooling load, thereby preventing abnormal heating and liquid backflow.

[0025] The evaporation pressure regulating valve 18 is an electronic regulating valve that can control the evaporation pressure discharged from the plate heat exchanger 12 to a constant value, and is electrically connected to the control unit 15 via a signal line. By adjusting the opening of the evaporation pressure regulating valve 18 with the control unit 15, the evaporation pressure discharged from the plate heat exchanger 12 can be controlled so that it does not fall below a certain value, preventing freezing, and the temperature of the object to be cooled can be adjusted to be approximately constant.

[0026] The cold water tank 13 is equipped with a high-temperature tank 13A and a low-temperature tank 13B arranged in parallel, and is configured so that when a predetermined amount of cold water accumulates in the low-temperature tank 13B, any cold water exceeding the predetermined amount flows to the high-temperature tank 13A side. The cold water tank 13 and the plate heat exchanger 12 are connected by a cold water line 19, which is a cold water flow path, and the cold water tank 13 and the load 14 are connected by a cold water supply line 21, which is a cold water supply flow path.

[0027] The chilled water line 19 is connected so that high-temperature chilled water in the high-temperature tank 13A flows through the plate heat exchanger 12 to the low-temperature tank 13B, and the chilled water cooled by the plate heat exchanger 12 is stored in the low-temperature tank 13B. A temperature sensor TE is provided near the outlet of the plate heat exchanger 12 on the chilled water line 19 to measure the temperature of the chilled water discharged from the outlet of the plate heat exchanger 12, i.e., the low-temperature chilled water outlet temperature PV. A circulation pump 20, which is an inverter pump, and a pressure sensor PE, which are electrically connected to the control unit 15, are provided between the high-temperature tank 13A and the inlet of the plate heat exchanger 12. The control unit 15 detects the pressure at the pressure sensor PE and appropriately controls the flow rate of the circulation pump 20 to send high-temperature chilled water from the high-temperature tank 13A to the plate heat exchanger 12 while maintaining a predetermined pressure.

[0028] The cold water supply line 21 is connected so that the low-temperature cold water in the low-temperature tank 13B flows to the high-temperature tank 13A via the load 14. An inverter pump 22 electrically connected to the control unit 15 is provided between the low-temperature tank 13B and the load 14. The control unit 15 appropriately controls the flow rate of the inverter pump 22, adjusting the flow rate so that the low-temperature cold water is sent from the low-temperature tank 13B to the load 14 while maintaining a predetermined pressure.

[0029] The control unit 15 includes a cold water temperature difference detection unit 23, an evaporation temperature determination unit 24, an evaporation pressure determination unit 25, and a valve control unit .

[0030] The chilled water temperature difference detection unit 23 measures the chilled water outlet temperature of the plate heat exchanger 12, i.e., the low-temperature chilled water outlet temperature PV, using the temperature sensor TE and sends it to the regulator 27. The user sets and inputs the reference temperature SV of the low-temperature chilled water outlet temperature into the regulator 27. The PV measured by the temperature sensor TE and the reference temperature SV set by the user in the regulator 27 are both converted into electrical signals and sent to the evaporation temperature determination unit 24.

[0031] The evaporation temperature determination unit 24 determines the evaporation temperature of the refrigerant based on the temperature difference between the low-temperature chilled water outlet temperature PV and the reference temperature SV. A conversion table is prepared in advance to determine the evaporation temperature here.

[0032] Based on the evaporation temperature ET determined by the evaporation temperature determination unit 24, the evaporation pressure determination unit 25 determines a target value of the evaporation pressure to be adjusted by the evaporation pressure regulating valve 18 so that the cold water does not freeze.

[0033] The valve control unit 26 adjusts the opening of the evaporation pressure regulating valve 18 based on the evaporation pressure determined by the evaporation pressure determination unit 25, thereby adjusting the evaporation pressure of the refrigerant flowing from the plate heat exchanger 12 to the compressor of the refrigerator 11. The control unit 15 also controls the electronic expansion valve 17, the circulation pump 20, and the inverter pump 22.

[0034] FIG. 2 is a diagram showing a specific example in which the control unit 15 controls the evaporation pressure regulating valve 18, the circulation pump 20, and the refrigerator 11 in the low-temperature chilled water supply apparatus 10 when the reference temperature SV is set to 0.5°C and the low-temperature chilled water outlet temperature PV in the plate heat exchanger 12 drops to 0.5°C or below. Hereinafter, an example of the operation of the low-temperature chilled water supply apparatus 10 shown in FIG. 1 will be described with reference to the specific example shown in FIG. 2. The reference temperature SV is set arbitrarily by the user and is not necessarily limited to 0.5°C. The evaporation temperature ET in FIG. 2 is also set by the user using a pre-conversion table.

[0035] When operation starts, the chiller 11 and the circulation pump 20 are operated in the refrigerant line 16 under the control of the control unit 15. When the chiller 11 is operated, a refrigeration cycle is executed in which the refrigerant from the chiller 11 passes through the plate heat exchanger 12 and returns to the chiller 11. Meanwhile, when the circulation pump 20 is operated, a low-temperature chilled water generation cycle is executed in the chilled water line 19, in which chilled water in the high-temperature tank 13A of the chilled water tank 13 is sent to the low-temperature tank 13B of the chilled water tank 13 via the plate heat exchanger 12. Also, the inverter pump 22 is operated in the chilled water supply line 21. When the inverter pump 22 is operated, chilled water at approximately 0.5°C in the low-temperature tank 13B of the chilled water tank 13 is sent to the load 14, and high-temperature chilled water used by the load 14 is sent to the high-temperature tank 13A, executing a low-temperature chilled water supply cycle.

[0036] In the low-temperature chilled water generation cycle, the temperature sensor TE monitors the low-temperature chilled water outlet temperature PV, which is the chilled water outlet temperature of the plate heat exchanger 12, and the low-temperature chilled water outlet temperature PV measured by the temperature sensor TE is converted into an electrical signal via the regulator 27 and sent to the chilled water temperature difference detection unit 23 together with the reference temperature SV.

[0037] The chilled water temperature difference detection unit 23 detects the temperature difference (SV−PV) between the low-temperature chilled water outlet temperature PV and a reference temperature SV prepared in advance, and sends it to the evaporation temperature determination unit 24.

[0038] The evaporation temperature determination unit 24 determines the evaporation temperature ET of the refrigerant based on the temperature difference between the low-temperature chilled water outlet temperature PV and the reference temperature SV, and sends it to the evaporation pressure determination unit 25.

[0039] The evaporation pressure determination unit 25 determines a target value of the evaporation pressure to be adjusted by the evaporation pressure control valve 18 using a pre-conversion table based on the evaporation temperature ET of the refrigerant determined by the evaporation pressure determination unit 25 so that the chilled water passing through the plate heat exchanger 12 does not freeze inside the plate heat exchanger 12, and sends the determined value to the valve control unit 26. Here, for example, if the refrigerant is CO2 and the evaporation temperature ET is -1.8°C, the evaporation pressure becomes 3.22 MPaG at the saturation temperature of -1.8°C, and is adjusted by the evaporation pressure control valve 18.

[0040] The valve control unit 26 adjusts the opening of the evaporation pressure regulating valve 18 based on the evaporation pressure determined by the evaporation pressure determination unit 25, thereby adjusting the evaporation pressure of the refrigerant flowing from the plate heat exchanger 12 to the compressor of the chiller 11. By adjusting the evaporation pressure in this way, a refrigerant with a temperature suitable for producing chilled water of 0.5°C in the plate heat exchanger 12 is generated from the chiller 11 and sent out toward the plate heat exchanger 12.

[0041] Furthermore, for example, if the low-temperature chilled water outlet temperature PV is 0.1°C, which is 0.4°C lower than the reference temperature SV of 0.5°C, and the temperature difference between the low-temperature chilled water outlet temperature PV and the reference temperature SV (SV-PV) becomes large at 0.4 or less, and the temperature of the chilled water in the plate-type heat exchanger 12 drops below 0.1°C, there is a risk of partial freezing occurring along the chilled water line 19. Therefore, the control unit 15 temporarily increases the flow rate of the circulation pump 20 (flow rate UP) to mitigate the sudden drop in the low-temperature chilled water outlet temperature PV of the plate-type heat exchanger 12.

[0042] Furthermore, if the temperature difference (SV-PV) between the low-temperature chilled water outlet temperature PV and the reference temperature SV increases further and becomes large, ie, 0.5°C or less, for example, if the low-temperature chilled water outlet temperature PV is -0.1°C, which is lower than the reference temperature SV of 0.5°C, and the chilled water temperature falls to -0.1°C or less, there is an increased risk of partial freezing occurring along the chilled water line 19. Therefore, the control unit 15 finally stops the operation of the chiller 11 (turns it OFF).

[0043] Therefore, according to the low-temperature chilled water supply device 10 of this embodiment, when the low-temperature chilled water outlet temperature continues to decrease, the following controls (1) to (3) are initiated in order. (1) When the low-temperature chilled water outlet temperature PV falls below the reference temperature SV, control is performed to raise the evaporating temperature ET according to the deviation. Here, the evaporating temperature ET is a value that does not significantly change the low-temperature chilled water outlet temperature PV. For example, if the user's operating conditions are set to operate the low-temperature chilled water outlet temperature PV between 0.5°C and 1.7°C, and the temperature of the load 14 drops, control to raise the evaporating temperature ET may be performed. In this case, if the evaporating temperature ET is suddenly raised and the low-temperature chilled water outlet temperature rises to 1.0°C, the risk of freezing is reduced, but it may become impossible to use the 0.5°C. Therefore, it is preferable to use a pre-conversion table to perform control suited to the operating conditions. (2) When it becomes difficult to control the evaporation temperature ET, the flow rate of the high-temperature side circulation pump 20 is temporarily increased to mitigate a sudden drop in the low-temperature chilled water outlet temperature PV of the plate heat exchanger 12. (3) Furthermore, when control of the evaporation temperature ET becomes impossible, the operation of the refrigerator 11 is finally stopped (turned off). Therefore, even if the load fluctuates greatly, the temperature of the low-temperature chilled water passing through the inside of the plate heat exchanger 12 does not drop to the freezing point. This prevents freeze-up failures in the plate heat exchanger 12 and enables a stable supply of low-temperature chilled water to the load 14.

[0044] The present invention can be modified in various ways without departing from the spirit of the present invention, and it goes without saying that the present invention also covers such modifications. [Explanation of symbols]

[0045] 10: Low temperature chilled water supply device 11: Refrigerator 12: Plate heat exchanger 13: Cold water tank 13A: High temperature tank 13B: Low temperature tank 14: Load 15: Control section 16: Refrigerant line 17: Electronic expansion valve 18: Evaporation pressure regulating valve 19: Cold water line 20: Circulation pump 21: Chilled water supply line 22: Inverter pump 23: Cold water temperature difference detection unit 24: Evaporation temperature determination section 25: Evaporation pressure determination section 26: Valve control section 27: Controller ET: Evaporation temperature PE: Pressure sensor TE: Temperature sensor

Claims

1. A low-temperature chilled water supply device that supplies chilled water to a load, a plate heat exchanger that exchanges heat between the cold water and the refrigerant; a refrigerant line for circulating the refrigerant between the plate heat exchanger and a refrigerator; a chilled water line for circulating the chilled water between the plate heat exchanger and the load; an evaporation pressure regulating valve provided in the refrigerant line and capable of adjusting the evaporation pressure of the refrigerant; a temperature sensor that measures a low-temperature chilled water outlet temperature of the low-temperature chilled water that is the chilled water cooled by the plate-type heat exchanger; A control unit that controls various devices of the low-temperature chilled water supply device; Equipped with The control unit controls the opening degree of the evaporation pressure control valve to increase the evaporation pressure so that the chilled water does not freeze, in accordance with the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature, when the low-temperature chilled water outlet temperature is lower than a predetermined reference temperature of the low-temperature chilled water.

2. The control unit an evaporation temperature determination unit that determines an evaporation temperature of the refrigerant based on a temperature difference between the low-temperature chilled water outlet temperature and the reference temperature; an evaporation pressure determination unit that determines a target value of the evaporation pressure to be adjusted by the evaporation pressure regulating valve based on the evaporation temperature so that the chilled water does not freeze; a valve control unit that controls an opening degree of the evaporation pressure regulating valve in accordance with the target value of the evaporation pressure; 2. The low-temperature chilled water supply device according to claim 1, further comprising:

3. The cold water line includes a cold water tank including a low-temperature tank for receiving the low-temperature cold water discharged from the plate-type heat exchanger and a high-temperature tank for receiving high-temperature cold water having a water temperature higher than that of the low-temperature tank; a circulation pump that supplies the high-temperature cold water in the high-temperature tank to the plate-type heat exchanger; Equipped with The low-temperature chilled water supply device of claim 1, characterized in that when the low-temperature chilled water outlet temperature is lower than the predetermined reference temperature, the control unit increases the flow rate of the high-temperature chilled water by the circulation pump in accordance with the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature so that the chilled water does not freeze.

4. The low-temperature chilled water supply device according to claim 1, characterized in that, when the low-temperature chilled water outlet temperature is lower than the preset reference temperature, the control unit stops the refrigerator depending on the temperature difference between the low-temperature chilled water outlet temperature and the reference temperature.

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