JP2014105930A - Heat source system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically change a cooling water temperature set value in the case that a cooling water inlet temperature set value of a water-cooling refrigerator can be lowered depending on a surrounding atmospheric condition or an air conditioning load or in the case that the cooling water inlet temperature must be increased.SOLUTION: This system comprises: a water-cooling refrigerator using a capacity compression type rotary compressor; a cooling water circulation passage having a cooling water going-side passage having a cooling water pump and a cooling water inlet thermometer, a cooling water returning-side passage and a bypass passage having a cooling water bypass valve arranged between the passages; a cooling tower communicated with the cooling water circulation passage; a cold water circulation passage provided with a cold water going-side passage for a load side and a cold water returning-side passage from a load side and having a cold water pump and a cold water inlet thermometer arranged on a cold water returning-side passage; and an instruction adjustor for outputting an instruction for changing a degree of opening of a cooling water bypass valve in such a way that a cooling water inlet temperature may become a cold water inlet temperature+Tα°C on the basis of a cooling water inlet temperature measured by the cooling water inlet thermometer and a cold water inlet temperature measured by the cold water inlet thermometer.

Description

  The present invention relates to a heat source system for freezing water using a water-cooled refrigerator having a volumetric compression rotary compressor and having a water-cooled condenser.

Production equipment in various facilities that have heat loads such as internal heat generation, building loads, and outside air loads in factories and office buildings, etc. that are required to be cooled during the production process or as health air conditioning As a heat source system that circulates and supplies a heat medium (cold water) with cold heat to water-water heat exchangers and air-water heat exchangers installed in air conditioning equipment, etc., heat is condensed with the air in a cooling tower etc. In general, a heat source system using a water-cooled refrigerator in which heat is thrown away by a condenser and a condenser is a water-cooling system is widely used.
An example is shown in FIG.
The water-cooled refrigerator 1 serves to circulate the refrigerant gas such as low-temperature / low-pressure chlorofluorocarbon gas, ammonia gas, water, etc. in the refrigeration cycle using a high-temperature / high-pressure refrigerant gas. The apparatus (expansion valve, capillary, etc.) 4 and the evaporator 5 are provided, and a refrigerating cycle is comprised.

A cooling water circulation passage 7 for circulating the cooling water from the cooling tower 6 is disposed in the condenser 3. The cooling water circulation passage 7 includes an outward passage 7a from the cooling tower 6 and a return passage 7b to the cooling tower 6. A cooling water pump 8 and a cooling water inlet thermometer 9 are disposed in the outward passage 7a. Has been. The forward side passage 7a and the return side passage 7b are connected by a passage 11 in which a flow rate adjusting valve 12 is arranged in the vicinity of the water-cooled refrigerator 1.
The cooling water inlet thermometer 9 inputs a measured value of the measured cooling water inlet temperature to the indication controller (TIC) 10, and introduces the measured value of the cooling water inlet temperature into the condenser 3 of the water-cooled refrigerator 1. Even if the cooling water temperature that does not have any problem is set, the measured value of the electric actuator 12a of the flow rate adjusting valve 12 is determined from the cooling water temperature setting value according to the deviation between the measured value of the cooling water inlet temperature and the cooling water temperature setting value that has no problem. If the deviation is large and the deviation is large, the flow rate adjustment valve 12 is closed, and if the deviation of the cooling water temperature set value larger than the measured value becomes small, the flow rate adjustment valve 12 is controlled to open. Thereby, it controls so that a cooling water inlet temperature may not fall below the cooling water temperature setting value which does not have the said problem.

The evaporator 5 is connected with a cold water circulation passage 13 for circulating cold water to the load side. The cooling water circulation passage 13 includes an outward passage 13a to the load side and a return passage 13b from the load side.
In the heat source system shown in FIG. 10, the water-cooled refrigerator 1 converts a low-temperature / low-pressure refrigerant gas into a high-temperature / high-pressure gas by the compressor 2 and releases heat from the cooling water from the cooling tower 6 by the condenser 3. After the refrigerant liquid is decompressed by the expansion device (expansion valve or the like) 4 to form a low-pressure refrigerant liquid, the evaporator 5 takes the heat of the return cold water from the load side and returns it to the compressor 2 as the low-pressure refrigerant gas. Circulate.
Here, three types of compressors are known: a volume compression type, an ejector type, and a centrifugal type (turbo). The volume compression type and the centrifugal type (turbo) are currently widely used, and the ejector type is used only for a small portion of industrial use.

The volume compression type is a type in which refrigerant gas is compressed from the suction side to the discharge side by a change in a sealed space generated between the casing and a movable member inscribed in the casing, and there are a reciprocating type and a rotary type.
The reciprocating type compresses the gas in the cylinder by the reciprocating motion of the piston, and includes a fully sealed type, a semi-sealed type, and an open type.
The rotary type includes a rotary type, a scroll type, and a screw type.
The centrifugal type (turbo) imparts energy to the refrigerant gas and compresses it by the rotational movement of the impeller.

By the way, the volume compression type rotary compressor employs a structure in which the gap between the movable parts is sealed with lubricating oil in order to prevent the leakage of compressed gas, and the lubricating oil is used for an important rotor by utilizing the differential pressure of the refrigerant. Oil is circulated through the bearings. Therefore, if the refrigerant differential pressure is too small, that is, in a situation where the compressor does not work and there is no front-rear pressure, it becomes difficult to lubricate and circulate the lubricating oil to important locations, causing seizure of the shaft, etc. There are problems that arise.
In contrast, volumetric compression type reciprocating and centrifugal (turbo) compressors have built-in oil pumps, and some parts of the compressor driving force are used to drive the oil pumps, which require lubricating oil. Since the oil supply circulation is secured, there is an advantage that the lubricating oil is circulated even when the refrigerant pressure difference is small. This is because various controls cannot be performed without using a hot gas bypass mechanism for controlling the capacity of the turbo compressor or forced lubricating oil circulation due to the absence of a pressure difference in the connecting rod portion of the reciprocating compressor.

For the above reasons, the volume compression type rotary compressor 2 has a lower limit temperature in the cooling water inlet temperature of the condenser 3 (for example, cold water inlet temperature + 1.0 ° C.). In view of the fact that the air temperature greatly fluctuates not only in the season but also in the time of the day when introducing the cooling water heat-exchanged with the atmosphere in the cooling tower 6 to the water cooling tower 3, the water-cooled refrigeration of the indication controller (TIC) 10 The cooling water temperature set value that can be safely introduced into the condenser 3 of the machine 1 is such that the cooling water side fluctuates so that the cooling water inlet temperature, which is the return temperature of the cooling water temperature, may be 20 ° C. or more in the equipment situation. In order to improve the operation, a fixed value with a margin (for example, 27 ° C.) is used.
Accordingly, the set temperature of the instruction controller (TIC) 10 is a fixed value with a margin, and the cooling water is often operated at a temperature actually higher than the cooling water lower limit temperature defined on the water-cooled refrigerator 1 side. .

However, due to the recent urgent demand for energy conservation, the maximum use of the reduction in the condensation pressure of the water-cooled refrigerator 1 due to the decrease in the cooling water temperature of the cooling tower 6 due to the decrease in the temperature of the outside air wet bulb during the intermediate period to winter Therefore, chiller manufacturers are increasingly lowering the lower limit temperature of cooling water that can be introduced into the condenser of the chiller (for example, up to 20 ° C and 18 ° C), and fixing with a margin close to this temperature. It is widely known that the coefficient of performance (operating efficiency) COP of a refrigerator can be improved without setting equipment costs by setting the value throughout the year (for example, see Non-Patent Document 1).
Also, in order to effectively utilize the capacity of the cooling tower while satisfying the conditions on the water-cooled refrigerator side, a circulation pipe for introducing the cooling water derived from the water-cooled refrigerator again into the water-cooled refrigerator, and a cooling water flowing through the circulation pipe are provided. When the temperature of the cooling water led out from the cooling tower is lower than the lower limit temperature that can be introduced into the water-cooled refrigerator, the circulating pipe and the water-cooled refrigerator A heat source system has been proposed in which cooling water lower than the lower limit temperature is squeezed to a required flow rate while being circulated through the machine and allowed to flow into a circulation pipe to reduce both the moving zones of the cooling water pump and save energy (for example, patents) Reference 1).

JP 2010-85072 A

"Air-conditioning automatic control and energy saving" (Issue date: April 10, 2011, Issuer Ohm Co., Ltd.) pp. 60-62

About the water-cooled refrigerator 1 provided with the volume compression type rotary compressor 2, the cooling water inlet temperature is automatically changed according to the wet bulb temperature of the outside air as in the water-cooled refrigerator provided with the centrifugal compressor. Conventionally, it has been assumed that the idea can contribute to energy saving.
However, the volume compression type rotary compressor 2 employs a structure in which the gap between the movable parts is sealed with lubricating oil to prevent leakage of compressed gas, and the lubricating oil is used as an important rotor by utilizing the differential pressure of the refrigerant. Oil is circulated through the bearings of the machine. Therefore, if the refrigerant differential pressure is too small, that is, in a situation where the compressor does not work and there is no front-rear pressure, it becomes difficult to lubricate and circulate the lubricating oil to important locations, causing seizure of the shaft, etc. This will cause serious problems in maintaining the state of the refrigeration cycle. For this reason, when the actual temperature of the cooling water inlet sent from the cooling tower side approaches the cooling water lower limit temperature that can be introduced into the condenser of the water-cooled refrigerator, the high-pressure side abnormal low pressure provided as the control of the water-cooled refrigerator 1 The safety circuit operates and the water-cooled refrigerator 1 is stopped due to an error. Although the water-cooled refrigerator 1 can be prevented from being destroyed, it cannot function as a heat source system, and a serious problem occurs on the load side.

For the above reasons, the volume compression type rotary compressor 2 has a lower limit temperature in the cooling water inlet temperature of the condenser 3 (for example, cold water inlet temperature + 1.0 ° C.). In consideration of the fact that the atmospheric temperature fluctuates greatly in the season when the cooling water exchanged with the atmosphere in the cooling tower 6 is introduced into the condenser 3, the condenser 3 of the water-cooled refrigerator 1 of the indication controller (TIC) 10 described above. The cooling water temperature setting value that is not a problem even if it is introduced into the system is operated at a fixed value (for example, 27 ° C.) with a margin so that the cooling water side may fluctuate.
Moreover, in order to make the best use of the ability to reduce the condensation pressure of the water-cooled refrigerator 1, the refrigerator manufacturer has been lowering the lower limit temperature of the cooling water that can be introduced into the condenser of the refrigerator (for example, Even 20 ° C and 18 ° C), the margin of the fixed value with a margin cannot be changed, and the value of the fixed value is slightly lowered.
Thus, the cooling water inlet temperature of the water-cooled refrigerator 1 equipped with the volume compression type rotary compressor 2 is set to a fixed value throughout the year, and the cooling water temperature such as in winter is sufficiently low. Even at the time when the temperature drops to below, the cooling water temperature was set to a fixed value with a margin and introduced.

For this reason, the water-cooled refrigerator 1 having the volumetric compression rotary compressor 2 has a cooling water inlet temperature set value in the winter season when the outdoor air condition and the air conditioning load are low, and the heat load and the cooling water temperature are low. Engineers etc. manually changed the cooling water inlet temperature setting value while looking at the outside air conditions and the return temperature of the cold water, etc., in order to reduce the margin of the fixed value with a margin. The water-cooled refrigerator 1 must be kept from error-stopping, and operation with a high risk of being troublesome is required.
In particular, when the cooling water temperature is lowered even at 1 ° C. from the middle period to the winter period, the coefficient of performance (operating efficiency) COP of the refrigerator can be greatly improved, but the water-cooled refrigerator equipped with the volume compression type rotary compressor 2 In No. 1, it was normally operated at a fixed value with a margin, and it was a halfway high-efficiency operation.

The coefficient of performance (operation efficiency: ratio of output (refrigeration effect) to input (compression work)) COP of the refrigerator is apparent from the performance diagram of the refrigerator shown in FIG. 11 and also from the Mollier diagram. Thus, the lower the cooling water inlet temperature, the lower the condensing pressure, so the compression work can be reduced, the coefficient of performance COP of the refrigerator becomes high efficiency, and the higher the cooling water inlet temperature, the higher the condensing pressure. It is well known that the coefficient of performance COP of the refrigerator is low in efficiency because it requires a lot of compression work.
In addition, since the volume compression type reciprocating type and centrifugal type (turbo) compressors have an oil pump, the lubricating oil is circulated even when the pressure difference of the refrigerant is small. Therefore, the problem that it becomes difficult to circulate the lubricating oil does not occur unlike the volumetric compression type rotary compressor.

  The present invention has been made to solve such a conventional problem, and the cooling water inlet temperature setting value of the water-cooled refrigerator can be lowered depending on the outside air condition or the air conditioning load, or the cooling water inlet temperature is increased. An object of the present invention is to provide a heat source system capable of automatically changing the set value of the cooling water temperature when it has to be.

  The invention according to claim 1 is a cooling system that exchanges heat between a water-cooled refrigerator that includes a volume compression rotary compressor, a water-cooled condenser, a throttling device, and an evaporator, and that constitutes a refrigeration cycle, and the atmosphere and cooling water. A tower, one end connected to the cooling tower, a cooling water pump and a cooling water inlet thermometer are arranged in this order, and the other end is connected to the condenser, and one end is connected to the condenser. A cooling water return side passage connecting an end to the cooling tower, and a bypass passage connecting the cooling water pump suction side of the cooling water going side passage and the cooling water return side passage via a cooling water bypass valve A cooling water circulation passage having a cooling water return side passage to the load side and a cooling water return side passage from the load side, a cooling water pump and a cold water inlet thermometer being disposed in the cooling water return side passage, and the evaporation Cold water circulation passage communicating with the vessel, and the cooling water An instruction adjustment having a cooling water bypass control circuit that calculates a deviation from the set cooling water inlet temperature based on a measured value of the cooling water inlet temperature of the mouth thermometer and outputs an opening degree of the cooling water bypass valve according to the deviation The indicator regulator is configured such that the set cooling water inlet temperature is set to a value that becomes the cold water inlet temperature measurement value + Tα ° C. based on the measurement value of the cold water inlet thermometer. A cascade circuit for outputting as a set value is provided.

The invention according to claim 2 is the heat source system according to claim 1, wherein the cold water circulation passage includes a return header on the cold water pump suction side of the cold water return side passage, a forward header on the cold water return side passage, An inter-header bypass pipe is provided between the return header and the forward header, and cold water flows through the inter-header bypass pipe when a thermal load on the load side becomes small.
The invention according to claim 3 is the heat source system according to claim 1 or 2, wherein the volume compression type rotary compressor is a rotary type compressor, a scroll type compressor or a screw type compressor. To do.
The invention according to claim 4 is the heat source system according to any one of claims 1 to 3, wherein the load is an air conditioning facility that requires high-temperature cold water or a heat source facility for cooling production equipment, and the return temperature of the cold water is It may exceed the cooling water inlet lower limit temperature of the water-cooled refrigerator.
The invention according to claim 5 is the heat source system according to claim 4, wherein the air conditioning equipment is an air conditioning equipment of a data center.

According to the present invention, for a water-cooled refrigerator having a water-cooled condenser, the maximum condensing pressure is lowered so that the temperature of the cooling water that can be lowered according to the atmospheric temperature, which becomes lower depending on the season, can be used as much as possible. Because it can be operated, high-efficiency operation can be maintained.
In addition, since it is not necessary to manually change the cooling water inlet temperature while monitoring even when the cold water return temperature of the water-cooled refrigerator increases, the operation management becomes easy.

It is the schematic which shows the heat source system which concerns on one Embodiment of this invention. Figure 1 of the heat source system to the cooling water inlet thermometer used (T _CDS), is an explanatory diagram showing a relationship between the cold water inlet temperature thermometer (T _CR) and instruction controller (TIC). It is a figure which shows the relationship between the cooling water inlet temperature setting value in case of T (alpha) = 1.0 degreeC, and cold water return temperature. It is a figure which shows the concept of the relationship between the opening degree of a cooling water bypass valve (MV), and cooling water inlet temperature. It is a figure which shows the state at the time of rated operation in case the control of a secondary side chilled water pump is variable flow control in the heat source system which concerns on this embodiment. FIG. 6 is a diagram showing a state when the load of FIG. 5 is reduced and the load factor is 50%. FIG. 6 is a diagram showing a state when the load of FIG. 5 decreases and the load factor is 37.5%. It is a figure which shows the state at the time of rated operation in case the control of a secondary side chilled water pump is constant flow control in the heat source system which concerns on this embodiment. It is a figure which shows the state when the load of FIG. 8 reduces and the load factor is 50%. It is the schematic which shows the conventional heat source system. It is a figure which shows an example which shows the change according to the load factor of the coefficient of performance of a refrigerator by the difference in cooling water inlet temperature.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 shows a heat source system according to this embodiment.
The heat source system according to the present embodiment will be described with respect to a case in which a water-cooled screw chiller 50 is used as a water-cooled refrigerator having a volumetric compression type rotary compressor.
In this embodiment, the cooling water inlet temperature lower limit value of the water cooling screw chiller is 16 ° C., the cooling water return temperature setting is 13 ° C.-20 ° C. (Δt = 7 ° C.), and the cooling water return temperature is higher than that of general office buildings. The purpose is to establish the facilities.

The water-cooled screw chiller 50 functions to circulate the refrigeration cycle by converting the low-temperature / low-pressure refrigerant gas into a high-temperature / high-pressure gas. The screw-type compressor 51, the condenser 52, the expansion device (expansion valve, etc.) 53 The evaporator 54 is provided to constitute a refrigeration cycle.
A cooling water circulation passage 61 that circulates the cooling water from the cooling tower 60 is disposed in the condenser 52. The cooling water circulation passage 61 includes a cooling water forward side passage 61a from the cooling tower 60 and a cooling water return side passage 61b to the cooling tower, and the cooling water forward side passage 61a is connected to the cooling tower 60 at one end for cooling. A water pump 62 and a cooling water inlet thermometer (TCDS) 63 for measuring the water cooling screw chiller cooling water inlet temperature are sequentially arranged, and the condenser 52 is connected to the other end. The cooling water return side passage 61a and the cooling water return side passage 61b are, in the vicinity of the water cooling screw chiller 50, a bypass passage 64 between the cooling water pump 62 suction side and the cooling water return side passage 61b of the cooling water return side passage 61a. Connected by.

A cooling water bypass valve (MV) 65 comprising a two-way valve is disposed in the bypass passage 64. The cooling water bypass valve (MV) 65 can proportionally control the opening and closing of the valve body in accordance with an input signal from the outside. The opening and closing of the valve body is, for example, an old modular roll motor or recently a stepping motor or the like. The electric actuator 65a is operated in accordance with a control signal from the outside.
The cooling tower 60 has an opening 60b in the upper part, a casing 60a in which a tower bottom water tank 60c is provided in the lower part, a blower 60d provided in the opening 60b of the casing 60a, and a cooling water return provided in the casing 60a below the blower 60d. A sprinkler 60e connected to the side passage 61b, a filling 60f disposed in a casing 60a below the sprinkler 60e, and a louver 60g for taking in outside air provided in the casing 60a below the filling 60f. ing.

The evaporator 54 is connected to a cold water circulation passage 70 for circulating cold water to the load side. The chilled water circulation passage 70 includes a chilled water outgoing side passage 70a to the load side and a chilled water return side passage 70b from the load side. A chilled water pump (CP) 71 and a chilled water inlet thermometer (TCR) 72 for measuring the chilled water inlet temperature are disposed in the chilled water return side passage 70b.
The cooling water inlet thermometer (TCDS) 63 uses the measured water cooling screw chiller cooling water inlet temperature as a measured value of the cooling water inlet temperature, and the cooling water inlet thermometer (TCR) 72 uses the measured water cooling screw chiller cooling water inlet temperature as the chilled water inlet. Each output signal is sent to an indicating controller (TIC) 80 as a temperature measurement value.

The instruction controller (TIC) 80 includes a cooling water inlet temperature setting value that is set by inputting the cooling water inlet temperature of the water cooling screw chiller 50 to the cooling water bypass control circuit (control unit 82), and a cooling water inlet thermometer. 63 is calculated as a command to the electric actuator 65a of the cooling water bypass valve (MV) 65, and an opening degree output of the cooling water bypass valve (MV) 65 corresponding to the deviation is calculated. Then, the opening degree of the cooling water bypass valve (MV) 65 is adjusted and controlled so as to always approach the cooling water inlet temperature set value.
In the indication controller (TIC) 80, the measured value of the chilled water inlet temperature of the chilled water inlet thermometer (TCR) 72 is input to the cascade circuit (calculation unit) 81 as the chilled water inlet temperature of the water cooled screw chiller 50, and the cascade circuit (calculated value) is calculated. Part) 81 calculates a value that becomes the measured value of the chilled water inlet temperature + Tα ° C. based on the measured value of the chilled water inlet temperature, and uses this value as the cooling water inlet temperature setting value to set the input of the cooling water bypass control circuit (regulator) 82 Continue to output to the section.

That is, as shown in FIG. 2, the instruction controller (TIC) 80 inputs the water-cooled screw chiller cold water inlet temperature measured by the cold water inlet thermometer (TCR) 72 to the cascade circuit (calculation unit) 81, and the cascade circuit (Calculation unit) Calculate based on the expression TCDS] SP = TCR] PV + Tα stored in 81.
Formula TCDS] SP = TCR] PV + Tα) is output as a cooling water inlet temperature setting value to the cooling water bypass control circuit (regulation unit) 82 as a calculated value, and the cooling water bypass control circuit (regulation unit) 82 has a cascade circuit (Calculation unit) A deviation between the coolant inlet temperature set value input from 81 and the coolant inlet temperature measured value of the coolant inlet thermometer 63 is calculated, and a coolant bypass valve (MV) 65 corresponding to the deviation is calculated. Is output as a command to the electric actuator 65a of the cooling water bypass valve (MV) 65, and the opening degree of the cooling water bypass valve (MV) 65 is adjusted and controlled.
TCDS] SP: Cooling water inlet temperature set value, SP means setting, TCR] PV: Cooling water inlet temperature measured value PV means current value, Tα: Setting difference (determined by control system resolution and time constant Value).

FIG. 3 shows the cooling water inlet temperature set value when Tα = 1.0 ° C.
Here, the formula TCDS] SP = TCR] PV + Tα stored in the cascade circuit (arithmetic unit) 81 is inputted at a time when the water-cooled screw chiller cold water inlet temperature measured by the cold water inlet thermometer (TCR) 72 is 20 ° C. In this case, the setting value of the water cooling screw chiller cooling water inlet temperature is set to 20 ° C. + 1.0 ° C. = 21 ° C., and the setting is changed from the cascade circuit to the cooling water bypass valve control circuit, and the cooling water inlet temperature cascade control is performed. Is shown.
In FIG. 3, although there is a horizontal line segment on the left side, it shows that the cooling water lower limit temperature of the water-cooled screw chiller is given as the setting lower limit value, and when the cold water return temperature is 15 ° C. or less, the setting lower limit value 16 ° C. Here is an example of how to keep it. Also, there is a horizontal line on the right side, but the summer peak outdoor air wet bulb temperature condition is 27 ° C in the Kanto region. At this time, the outside air cooling of the cooling tower at the inlet cooling water temperature of 34 ° C to the outlet water temperature of 29 ° C is performed. In view of this, an example is shown in which the upper limit value of the cooling water inlet temperature is set to 35 ° C.

FIG. 4 shows the opening degree of the cooling water bypass valve (MV) 65 as a concept.
In this figure, the horizontal axis is taken as the cooling water inlet temperature, and the relationship with the actual cooling water inlet temperature is as shown in FIG. 4, but the cooling water bypass valve (MV) opening degree is the cooling water inlet temperature setting value. And an opening of 0 to 100% depending on the amount of deviation between the measured value of the cooling water inlet temperature. If the deviation of cooling water inlet temperature set value-cooling water inlet temperature measurement value is zero, the deviation is zero, which is the intersection of the slope of Fig. 4 and the vertical axis of 0%. Output. As the deviation increases to a plus, the slope moves to the left. With such a correlation, an opening degree signal of the coolant bypass valve (MV) 65 is output from the coolant bypass valve control circuit to the electric actuator 65a.

As is clear from the performance chart of the water-cooled screw chiller shown in FIG. 11, the lower the water-cooled screw chiller cold water inlet temperature, the higher the coefficient of performance (operating efficiency) COP of the refrigerator, and the higher the water-cooled screw chiller cold water inlet temperature. The performance coefficient (operating efficiency) COP of the refrigerator is low.
That is, in order to improve the performance of the water-cooled screw chiller 50, it is indicated that it is desirable to operate with the water-cooled screw chiller cold water inlet temperature lowered.

As described above, according to the present embodiment, the cooling water inlet valve (MV) so that the cooling water inlet temperature of the water cooling screw chiller 50 becomes the cooling water inlet temperature of the water cooling screw chiller 50 + Tα ° C. (for example, 1.0 ° C.). The opening degree of 65 is automatically changed and always operated at the cooling water lower limit temperature of the water-cooled screw chiller 50, so that energy saving can be achieved.
In particular, when the temperature of the chilled water in a data center or equipment cooling water system is higher than that for general air conditioning (for example, 5 ° C to 12 ° C), the energy saving is large. An effect is obtained.

Further, since the cooling water inlet temperature set value is automatically changed even when the cold water return temperature of the water cooling screw chiller 50 rises, it is not necessary to set the cooling water inlet temperature higher (safe side).
In addition, since the component devices are a cooling water inlet thermometer (TCDS) 63, a cooling water inlet thermometer (TCR) 72, an instruction regulator (TIC) 80, and a cooling water bypass valve (MV) 65 including a two-way valve, An inexpensive and complicated control program is not required.

Next, the case where the control of the secondary chilled water pump is the variable flow rate control in the heat source system according to the present embodiment will be described based on FIGS.
In this example, the heat flow side configuration of the cooling water circulation passage 70 of the heat source system shown in FIG. 1 is controlled to change the flow rate to the cold water / cold water going-side passage 70a with respect to the heat load 91 of a chiller rated 800RT production equipment or air conditioning equipment. The secondary side cold water pump 90 is arranged.
FIG. 5 is a diagram illustrating a state during rated operation.
For example, during rated operation, the heat load 91 such as production equipment and air conditioning equipment is operated as 800 RT, and the water-cooled screw chiller 50 is operated as 800 RT. Then, 13 ° C. chilled water is sent out from the water cooling screw chiller 50 to the chilled water chilled water going-side passage 70a, and the 13 ° C. chilled water is supplied from the secondary side chilled water pump 90 of variable flow rate control to the heat load 91 such as production equipment or air conditioning equipment. Then, an operation is performed in which 5,760 L / min of chilled water at 20 ° C. is returned to the water-cooled screw chiller 50 by a chilled water pump (CP) 71 from a heat load 91 such as production equipment or air conditioning equipment.

  In this operation, from the chilled water inlet thermometer (TCR) 72, the measured value of the water cooled screw chiller chilled water inlet temperature is 20 ° C., for example, assigned to a current value of 4 to 20 mA and input to the indicating controller (TIC) 80, and cascaded. The circuit (arithmetic unit) 81 replaces the input signal with a temperature value, and the water cooling measured by the cold water inlet thermometer (TCR) 72 in the formula TCDS] SP = TCR] PV + Tα stored in the cascade circuit (arithmetic unit) 81 Substitute the screw chiller cold water inlet temperature 20 ° C, and output the calculated value of the water cooled screw chiller cooling water inlet temperature 20 ° C + 1.0 ° C = 21 ° C to the cooling water bypass control circuit (control unit) 82 In the cooling water bypass control circuit (control unit) 82, the cooling water inlet temperature set value 21 ° C. and the cooling water inlet temperature from the cooling water inlet thermometer (TCDS) 63 It calculates a deviation between the temperature measured value, and controls the electric actuator 65a of the cooling water bypass valve (MV) 65 for adjusting the opening of the valve body in accordance with the deviation amount. Since the cooling water temperature difference in the condenser 52 is operated at 5 ° C., the cooling water outlet temperature from the water-cooled screw chiller 50 is 26 ° C.

FIG. 6 is a diagram illustrating a state in which the load decreases and the load factor is 50%.
Here, when the load decreases and the load factor reaches 50%, the heat load 91 such as the production equipment and the air conditioning equipment is operated as 400 RT, and the water-cooled screw chiller 50 is operated as 400 RT. Then, 13 ° C. chilled water is sent out from the water cooling screw chiller 50 to the chilled water chilled water going-side passage 70a, and the 13 ° C. chilled water is supplied from the secondary side chilled water pump 90 of variable flow rate control to the heat load 91 such as production equipment or air conditioning equipment. Then, an operation is performed in which 2,880 L / min of chilled water at 20 ° C. is returned to the water-cooled screw chiller 50 by a chilled water pump (CP) 71 from a heat load 91 such as production equipment or air conditioning equipment.

In this operation, since the water-cooled screw chiller cold water inlet temperature measured by the cold water inlet thermometer (TCR) 72 is 20 ° C., the set value of the water-cooled screw chiller cooling water inlet temperature is 21 ° C. as in the rated operation.
FIG. 7 is a diagram illustrating a state in which the load decreases and the load factor is 37.5%.
Further, when the load decreases and the load factor becomes 37.5%, the heat load 91 such as the production equipment and the air conditioning equipment is operated as 300 RT, and the water-cooled screw chiller 50 is operated as 300 RT. Then, 13 ° C. cold water is sent from the water-cooled screw chiller 50 to the cold water going-side passage 70a, and 13 ° C. cold water is supplied from the secondary-side cold water pump 90 with variable flow rate control to a heat load 91 such as production equipment or air conditioning equipment. Then, 2,160 L / min of chilled water at 20 ° C. is returned to the header by the conveying force of the secondary chilled water pump 90 from the heat load 91 of the production equipment or air conditioning equipment.

Generally, the cold water flowing through the evaporator of the refrigerator is a variable flow rate compatible refrigerator, so the lower limit flow rate is often 50% of the rated flow rate, so the heat load of 37.5% corresponding to the load of 37.5% The flow rate of flowing through the refrigerator is greater than the amount of return water from 91, and the flow rate of flowing through the bypass between headers is 50% -37.5% = 12.5%. As a result, 720 L / min chilled water at 13 ° C. is merged with 2,160 L / min chilled water at 20 ° C. from the heat load 91 such as production equipment and air conditioning equipment through the return header 92 through the header bypass pipe 92. The mixing temperature at the header is 18.3 ° C., that is, the water-cooled screw chiller cold water inlet temperature is lowered to 18.3 ° C., and 2,880 L / min of cold water is supplied to the water-cooled screw chiller 50 by the cold water pump (CP) 71. It will be returned.
Therefore, when the measured value of the temperature of the water-cooled screw chiller chilled water inlet from the chilled water inlet thermometer (TCR) 72 is 18.3 ° C., it is input to the indicating controller (TIC) 80, and the cascade circuit (arithmetic unit) 81 Substituting the water-cooled screw chiller cold water inlet temperature 18.3 ° C. measured by the cold water inlet thermometer (TCR) 72 into the formula TCDS] SP = TCR] PV + Tα stored in the computing unit 81), the water-cooled screw chiller cooling water inlet The result of calculating the temperature set value as 18.3 ° C. + 1.0 ° C. = 19.3 ° C. is output to the cooling water bypass control circuit (adjusting unit) 82, and in the cooling water bypass control circuit (adjusting unit) 82, The deviation between the cooling water inlet temperature setting value 19.3 ° C. and the cooling water inlet temperature measurement value from the cooling water inlet thermometer (TCDS) 63 is calculated, and the cooling water bypass valve is calculated according to the deviation amount. By controlling the electric actuator 65a of MV) 65 for adjusting the opening of the valve body. Since the cooling water temperature difference in the condenser 52 is operated at 5 ° C., the cooling water outlet temperature from the water-cooled screw chiller 50 is 24.3 ° C.

Thus, when the cold water inlet temperature of the water cooling screw chiller 50 falls, the cooling water inlet temperature of the water cooling screw chiller 50 can be lowered.
Next, the case where the control of the secondary side chilled water pump is the constant flow control in the heat source system according to the present embodiment will be described based on FIGS.
In this example, the configuration of the load side of the cooling water circulation passage 70 of the heat source system shown in FIG. 1 is controlled by the constant flow rate control in the cold water chilled water going-side passage 70a with respect to the heat load 94 of production equipment or air conditioning equipment having a chiller rating of 800RT. A secondary side cold water pump 93 is disposed.

FIG. 8 is a diagram illustrating a state during rated operation.
For example, during rated operation, the heat load 94 of the production equipment or air conditioning equipment is operated at 800 RT, and the water-cooled screw chiller 50 is operated at 800 RT. Then, 13 ° C. chilled water is sent out from the water cooling screw chiller 50 to the chilled water chilled water going-side passage 70a, and 13 ° C. chilled water is supplied to the heat load 94 such as production equipment or air conditioning equipment from the secondary-side chilled water pump 93 of constant flow control. Then, an operation is performed in which 5,760 L / min of chilled water at 20 ° C. is returned to the water-cooled screw chiller 50 by a chilled water pump (CP) 71 from a heat load 94 such as production equipment or air conditioning equipment.

  In this operation, the chilled water inlet thermometer (TCR) 72 inputs the measured value of the water-cooled screw chiller chilled water inlet temperature to 20 ° C. to the indicating controller (TIC) 80, and the cascade circuit (arithmetic unit) 81 Substituting the water-cooled screw chiller cold water inlet temperature 20 ° C. measured by the cold water inlet thermometer (TCR) 72 into the formula TCDS] SP = TCR] PV + Tα stored in the calculation unit 81), the water cooling screw chiller cooling water inlet temperature The result of calculating the set value as 20 ° C. + 1.0 ° C. = 21 ° C. is output to the cooling water bypass control circuit (control unit) 82, and the cooling water bypass control circuit (control unit) 82 sets the cooling water inlet temperature. The deviation between the value 21 ° C. and the measured value of the cooling water inlet temperature from the cooling water inlet thermometer (TCDS) 63 is calculated, and the cooling water bypass valve (MV) 65 of the cooling water bypass valve (MV) 65 is calculated according to the deviation amount. By controlling the dynamic actuator 65a adjusts the opening degree of the valve body. Since the cooling water temperature difference in the condenser 52 is operated at 5 ° C., the cooling water outlet temperature from the water-cooled screw chiller 50 is 26 ° C.

FIG. 9 is a diagram illustrating a state in which the load decreases and the load factor is 50%.
Here, when the load decreases and the load factor reaches 50%, the heat load 94 such as the production equipment and the air conditioning equipment is operated as 400 RT, and the water-cooled screw chiller 50 is operated as 400 RT. Then, 13 ° C. chilled water is sent out from the water-cooled screw chiller 50 to the chilled water chilled water going-side passage 70a, and 13 ° C. chilled water is supplied from a constant-flow secondary-side chilled water pump 93 to a heat load such as production equipment or air conditioning equipment, An operation is performed in which 5,760 L / min of chilled water at 16.5 ° C. is returned to the header by the conveying force of the secondary chilled water pump 90 from the heat load of the production equipment or air conditioning equipment.

  Therefore, when the measured value of the water-cooled screw chiller chilled water inlet temperature is 16.5 ° C. from the chilled water inlet thermometer (TCR) 72, it is input to the indicating controller (TIC) 80, and the cascade circuit (arithmetic unit) 81 Substituting the water-cooled screw chiller cold water inlet temperature 16.5 ° C. measured by the cold water inlet thermometer (TCR) 72 into the formula TCDS] SP = TCR] PV + Tα stored in the computing unit 81), the water-cooled screw chiller cooling water inlet The result of calculating the temperature set value as 16.5 ° C. + 1.0 ° C. = 17.5 ° C. is output to the cooling water bypass control circuit (adjusting unit) 82, and in the cooling water bypass control circuit (adjusting unit) 82, The deviation between the cooling water inlet temperature setting value 19.3 ° C. and the cooling water inlet temperature measurement value from the cooling water inlet thermometer (TCDS) 63 is calculated, and the cooling water bypass valve is calculated according to the deviation amount. By controlling the electric actuator 65a of MV) 65 for adjusting the opening of the valve body. Since the cooling water temperature difference in the condenser 52 is operated at 5 ° C., the cooling water outlet temperature from the water-cooled screw chiller 50 is 22.5 ° C.

  From the return header to the water-cooled screw chiller 50, it is conveyed by the head of the chilled water pump (CP) 71. Actually, the rated flow rate is reduced even if the heat load is reduced, and the secondary chilled water pump 93 and the chilled water pump (CP) 71 are used. It is not a good idea to continue the flow at all times. In many cases, the number of secondary side cold water pumps 93 and cold water pumps (CP) 71 divided into a plurality of flow rates is controlled. In that case, there is a time when a part of the flow rate flows from the forward header to the return header through the inter-header bypass pipe 95. In this case, the return header raises the cold water at the chilled water temperature and returns from the load side by raising the temperature. The drop in the temperature of the return cold water due to the mixing of the return cold water still occurs.

Thus, since the cold water inlet temperature of the water-cooled screw chiller 50 is lowered due to the load reduction, the cooling water inlet temperature of the water-cooled screw chiller 50 can be lowered.
This water-cooled screw chiller 50 is commercially available as a general-purpose device with a smaller rated capacity than a compressor-inverter-controlled turbo chiller. Due to the characteristics of the compressor, the partial load operation of the refrigeration capacity is greatly reduced to, for example, about 25%. I can put it in. In addition, it has an excellent feature that the start-up is fast, for example, the start-up time after the operation is stopped is less than 10 minutes, and cold water can be frozen to the rated temperature. For this reason, in a heat source system having a heat load that has a cooling load in the intermediate period and winter season other than the summer season, the cold air of the wet air temperature that is lower than the cold water return temperature is effectively used from the intermediate season to the winter season. Recently, a heat source system that uses a free cooling heat source by outside air that does not use a refrigeration cycle has been widely used, but the most suitable heat source system is a complementary heat source that uses a chilled water temperature compensated refrigeration cycle. It is a water-cooled screw chiller 50. As described above, the water-cooled screw chiller 50 has much time to cover most of the temperature difference of the heat medium (cold water) circulated to the heat load from the intermediate period to the winter by heat exchange with the outside air by the cooling tower. This means that a slight refrigeration up to the set temperature of the slightly cold water going back is a refrigerator that has a small device capacity, is flexible in throttle operation, and has good follow-up performance in stopping and starting.

In the above embodiment, the water-cooled screw chiller 50 has been described. However, the present invention is not limited to this, and a volume compression type rotary compressor, that is, a refrigerator having a rotary type, scroll type, screw type compressor. If it is good.
Moreover, although the said embodiment demonstrated the case where the open type cooling tower 60 was used, this invention is not limited to this, For example, a closed type cooling tower may be sufficient.

50 Water-cooled screw chiller 51 Screw type compressor 52 Condenser 53 Throttle device (expansion valve, etc.)
54 Evaporator 60 Cooling Tower 61 Cooling Water Circulation Passage 61a Cooling Water Outward Passage 61b Cooling Water Return Side Passage 62 Cooling Water Pump 63 Cooling Water Inlet Thermometer (T _CDS )
64 Bypass passage 65 Cooling water bypass valve (MV)
65a Electric actuator 70 Chilled water circulation passage 70a Chilled water outgoing side passage 70b Chilled water return side passage 71 Chilled water pump (CP)
72 Cold water inlet thermometer (T _CR )
80 Indicator controller (TIC)
81 Cascade circuit (calculation unit)
82 Cooling water bypass control circuit (regulator)

Claims (5)

A water-cooled refrigerator comprising a volumetric compression type rotary compressor, a water-cooled condenser, a throttling device and an evaporator, and constituting a refrigeration cycle;
A cooling tower for exchanging heat between the atmosphere and cooling water;
One end is connected to the cooling tower and arranged in the order of a cooling water pump and a cooling water inlet thermometer, the other end is connected to the condenser, and the other end is connected to the condenser and the other end is connected to the condenser. A cooling water return side passage connected to the cooling tower, and a bypass passage connecting the cooling water pump suction side of the cooling water outgoing side passage and the cooling water return side passage via a cooling water bypass valve. A cooling water circulation passage,
A cold water return passage from the load side and a cold water return passage from the load side, a cold water pump and a cold water inlet thermometer are arranged in the cold water return passage, and a cold water circulation passage communicating with the evaporator ,
A cooling water bypass control circuit that calculates a deviation from a set cooling water inlet temperature based on a measured value of the cooling water inlet temperature of the cooling water inlet thermometer and outputs an opening degree of the cooling water bypass valve according to the deviation. With an indicating regulator having
Based on the measured value of the cold water inlet thermometer, the set regulator water temperature is output as a set value of the cooling water bypass control circuit to the instruction controller as a value that becomes the measured value of the cold water inlet temperature + Tα ° C. A heat source system comprising a cascade circuit. The heat source system according to claim 1,
The cold water circulation passage includes a return header on the cold water pump suction side of the cold water return side passage, a forward header on the cold water forward side passage, and an inter-header bypass pipe between the return header and the forward header. A heat source system, wherein cold water flows through the inter-header bypass pipe when the load-side heat load is reduced. The heat source system according to claim 1 or 2,
The volumetric compression type rotary compressor is a rotary type compressor, a scroll type compressor, or a screw type compressor. The heat source system according to any one of claims 1 to 3,
The load is a heat source facility for cooling air-conditioning equipment or production equipment that requires high-temperature cold water, and the return temperature of the cold water may exceed the cooling water inlet lower limit temperature of the water-cooled refrigerator. . The heat source system according to claim 4, wherein
The heat source system, wherein the air conditioning equipment is a data center air conditioning equipment.

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