JPH1089742A - Refrigerating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating system, preventing the deterioration of control response or hunting by controlling the number of operating sets employing a control gain in accordance with the flow rate of secondary refrigerant from utilizing side. SOLUTION: A total control unit (TCU) 61 searches an imaginary temperature difference Tdv from a map based on the operating number of sets as well as the operating condition of a refrigerating machine 1, an outdoor air temperature Ta and the like, then, operates a (differential temperature difference) ΔTd between the imaginary temperature difference Tdv and an actual temperature difference Tdr (inlet port side temperature Tfi-outlet port side temperature Tfo) to search a control gain or a flow rate coefficient KF from the map based on the differential temperature difference ΔTd. Thereafter, the TCU 61 obtains a basic operating number of sets increasing and decreasing amount ΔNB based on an inlet port temperature gradient ΔTs (or the changing amount per unit time of the inlet port side temperature Tfi) and a difference (outlet port temperature difference) ΔTo between a set outlet port temperature Tfos and the outlet port side temperature Tfo. Finally, the TCU 61 operates a number of operating set increasing and decreasing amount ΔN by multiplying the basic number of operating set increasing and decreasing amount ΔNB by the flow rate coefficient KF to control the number of operating sets of the refrigerating machine 1 based on the number of operating set increasing and decreasing amount ΔN.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system used for a cold / hot water type air conditioning system, a computer cooling system, and the like. Related to the technology to perform.

[0002]

2. Description of the Related Art In a relatively large-scale building or factory, a refrigeration system having a plurality of chillers is used to cool or heat a secondary refrigerant such as water and use it for air conditioning, computer cooling, and the like. There are many.

[0003] In this type of chilled / hot water type air conditioning system and computer cooling system, various refrigerators such as an absorption type and a heat pump type are used as heat sources in addition to the compression type.
The number of refrigerators is set according to the total load on the user side (such as the total number of air conditioners). Then, the number of operating refrigeration units is controlled to correspond to the outside air temperature and the operating state of the use-side device (such as an air conditioner or a computer cooler). Generally, the temperature (outlet side temperature) of the secondary refrigerant is kept constant.

[0004]

When the number of operating units is controlled based on the outlet-side temperature, hunting may occur on the refrigeration system side depending on the operating condition of the user-side device.

Usually, since a large number of use-side devices are connected to this type of refrigeration system, the control gain at the time of controlling the number of operating units is set to be relatively large. For example, when a large number of utilization-side devices are operating, if a deviation (exit temperature difference) occurs between the outlet-side temperature and the set temperature, the controller increases or decreases the number of operating refrigerators with a relatively large control gain. Thus, the outlet temperature difference can be quickly reduced to zero. However, when only a part of the usage-side device is operating, the secondary refrigerant flow rate from the usage-side device decreases, so when the number of operating units is controlled with the same control gain, the number of operating units increases or decreases. Overshoot of the secondary refrigerant temperature becomes large and hunting occurs.

If the control gain is set to a small value in order to solve this problem, it takes a long time for the outlet differential temperature to disappear when a large number of use-side devices are operating, and the control response is significantly deteriorated. Therefore, it has been considered that a flow rate measuring device for measuring the flow rate of the secondary refrigerant from the use side device is provided, and the control gain is increased or decreased based on the measurement result. However, the flow rate measuring device is generally expensive, so that the cost of the device increases. In addition, there are many mechanical failures, so that there is a problem that the reliability of the control is reduced.

The present invention has been made in view of the above situation,
An object of the present invention is to provide a refrigeration system in which the number of operating units is controlled by using a control gain according to a secondary refrigerant flow rate from a user side, thereby preventing control response deterioration and hunting.

[0008]

In order to solve the above-mentioned problems, according to the present invention, the secondary refrigerant from the utilization side device is passed through the heat exchangers of a plurality of refrigerators, An inlet temperature detecting means for detecting an inlet-side temperature of the secondary refrigerant in the heat exchanger, and detecting an outlet-side temperature of the secondary refrigerant in the heat exchanger. Outlet temperature detecting means, basic increasing / decreasing amount setting means for setting a basic increasing / decreasing amount of the number of operating refrigerators based on a deviation between a detection result of the outlet temperature detecting means and a target outlet side temperature, and detection of the outlet temperature detecting means Correction coefficient setting means for setting a correction coefficient based on a difference between the result and the detection result of the inlet temperature detection means, and an increase / decrease amount for determining the increase / decrease amount of the number of refrigerators operated by multiplying the basic increase / decrease amount by the correction coefficient Determining means; Based on the determination result of the decrease amount determining means, proposes that a number of operating control means for controlling the number of operating the refrigerator.

According to the present invention, for example, the basic increase / decrease amount setting means sets the basic increase / decrease amount of the number of refrigerators operated from a table or the like based on the deviation between the outlet side temperature and the set temperature, and the correction coefficient setting means A correction coefficient is set from a map or the like based on the difference between the temperature and the outlet-side temperature. Thereafter, the increase / decrease amount determining means multiplies the basic increase / decrease amount by the correction coefficient to determine the increase / decrease amount of the number of operating refrigerators, and the operating number control means controls the number of operating refrigerators based on the determination result.

[0010] In the second aspect of the present invention, the secondary refrigerant from the use-side device is circulated through the heat exchangers of the plurality of refrigerators,
An refrigeration system that performs cooling or heating of the secondary refrigerant, an inlet temperature detection unit that detects an inlet-side temperature of the secondary refrigerant in the heat exchanger, and an outlet side of the secondary refrigerant in the heat exchanger. Outlet temperature detecting means for detecting a temperature, inlet temperature gradient detecting means for detecting a change amount of the secondary refrigerant in the heat exchanger on the inlet side per unit time, detection results of the outlet temperature detecting means and a target Basic increase / decrease amount setting means for setting a basic increase / decrease amount of the number of operating chillers based on a deviation from the outlet side temperature and a detection result of the inlet temperature gradient detection means, a detection result of the outlet temperature detection means, and the inlet temperature detection Correction coefficient setting means for setting a correction coefficient based on a deviation from the detection result of the means; and an increase / decrease amount determining means for determining the increase / decrease amount of the number of refrigerators operated by multiplying the basic increase / decrease amount by the correction coefficient. If, based on the determined result of the increase and decrease amount determination means is proposed that a number of operating control means for controlling the number of operating the refrigerator.

According to the present invention, for example, the basic increase / decrease amount setting means sets the basic increase / decrease amount of the number of operating refrigerators from a table or the like based on the deviation between the outlet side temperature and the set temperature and the inlet temperature gradient, and sets the correction coefficient. Means sets a correction coefficient from a map or the like based on the temperature difference between the inlet side temperature and the outlet side temperature.
Thereafter, the increase / decrease amount determining means multiplies the basic increase / decrease amount by the correction coefficient to determine the increase / decrease amount of the number of operating refrigerators, and the operating number control means controls the number of operating refrigerators based on the determination result.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an air conditioning system using a gas heat pump refrigeration system. In FIG. 1, a solid line indicates a refrigerant circuit, and a dashed line indicates a secondary refrigerant circuit. The air conditioning system of the present embodiment includes a plurality of (for example, three) refrigerators 1 and a plurality of (for example, 10
) Indoor unit 3.

Each refrigerator 1 includes a compressor 5, an electromagnetic four-way valve 7, a heat source side heat exchanger (air heat exchanger) 9, an electric fan 11, a receiver tank 13, an electric expansion valve 15, and a use side heat source. An exchanger (water heat exchanger) 17, an accumulator 19 and the like are housed therein. The equipment constituting the refrigerant circuit is a refrigerant (HF
Refrigerant piping 3 for distribution of C-type CFC mixed refrigerant)
They are connected by 1 to 38. In the figure, reference numeral 21 denotes a gas engine, which drives the compressor 5 via a flexible coupling 23.

The use-side heat exchanger 17 of each refrigerator 1 is connected to an indoor heat exchanger 45 in each indoor unit 3 via secondary refrigerant pipes 41 and 43. 45
The inside of the secondary refrigerant (in the present embodiment, the secondary refrigerant discharged to an inverter-controlled water pump 47 provided on the indoor unit 3 side)
(Antifreeze) circulates.

In each refrigerator 1, a control unit (hereinafter referred to as EC) for driving the compressor 5 (gas engine 21), the four-way valve 7, the electric fan 11, the electric expansion valve 15, and the like.
U) 51 are provided. The ECU 51 includes an input / output interface and an RO in addition to the CPU that is the control center.
M, RAM, a timer counter, and the like. The input interface includes an outside air temperature sensor 53 for detecting an outside air temperature Ta, and a secondary refrigerant temperature Tfi on the inlet side and the outlet side of the heat source side heat exchanger 9. , Tfo detecting the first,
Various sensors such as the second temperature sensors 55 and 57 are connected.

Further, in this embodiment, a TCU (total control unit) 61 for integrally controlling each refrigerator 1
The TCU 61 controls the number of operating refrigerators 1 and the capacity of each refrigerator 1. TCU
61 is a CPU, an input / output interface, a ROM,
It is composed of a RAM, a timer counter and the like, and exchanges control signals with each refrigerator 1.

Next, the flow of the refrigerant during the cooling operation will be described.

The gas refrigerant sucked into the compressor 5 from the refrigerant pipe 38 is heated to a high temperature and a high pressure by the adiabatic compression and discharged from the compressor 5, and the refrigerant pipe 31, the four-way valve 7, the cooling water pipe 32
And flows into the heat source side heat exchanger 9 via. The high-temperature and high-pressure gas refrigerant is cooled and condensed by outside air while passing through the heat source side heat exchanger 9 to become a liquid refrigerant.
It flows into the electric expansion valve 15 via the receiver tank 13 and the refrigerant pipe 34.

After the flow rate of the liquid refrigerant is adjusted by the electric expansion valve 15, the liquid refrigerant flows into the use side heat exchanger 17 via the refrigerant pipe 35. The liquid refrigerant is vaporized while passing through the use-side heat exchanger 17 and becomes a gas refrigerant. At that time, the liquid refrigerant absorbs the latent heat of vaporization and cools the secondary refrigerant from the indoor unit 3. The gas refrigerant vaporized in the use side heat exchanger 17 is supplied to a refrigerant pipe 36,
Accumulator 19 via four-way valve 7 and refrigerant pipe 37
To the compressor 5 from the refrigerant pipe 38 again.

Hereinafter, the operation number control according to the present embodiment will be described with reference to the flowcharts of FIGS.

When the air conditioning system is started, the TCU
Reference numeral 61 repeatedly executes the number-of-operated-operation control according to the procedure shown in FIG. 2 based on a predetermined control interval. When the control of the number of operating units is started, the TCU 61 first executes step S in FIG.
At 1, detection information from the sensors 53, 55, 57 and the like of each refrigerator 1 (outside air temperature Ta, inlet side temperature Tfi, outlet side temperature Tfo
Etc.), in step S3, an estimated difference temperature Tdv is retrieved from a map (not shown) based on the present number of operating refrigerators 1 and operating conditions, and variable factors such as the outside air temperature Ta (° C.). The assumed difference temperature Tdv is a temperature difference between the inlet-side temperature and the outlet-side temperature, which is assumed to be generated in the current operating condition when a predetermined amount of the secondary refrigerant flows in the use-side heat exchanger 17. .

Next, the TCU 61 calculates the actual temperature difference Tdr (inlet temperature Tfi) detected by the refrigerator 1 operating in step S5.
-The outlet side temperature Tfo) is calculated, and in step S7, the deviation (difference in temperature) ΔTd between the assumed differential temperature Tdv and the actual differential temperature Tdr is calculated. The temperature difference ΔTd has a negative value when the flow rate of the secondary refrigerant is higher than a predetermined flow rate, and has a positive value when the flow rate of the secondary refrigerant is lower than the predetermined flow rate. The flow rate of the secondary refrigerant varies depending on the number of operating indoor units 3 and also varies depending on the number of revolutions (ie, the discharge amount) of the water pump 47 in each indoor unit 3.

Next, in step S9, the TCU 61 retrieves a flow coefficient KF as a control gain from a map (not shown) based on the temperature difference ΔTd. In the case of the present embodiment, the value of the flow coefficient KF is set, for example, in the range of 0.8 to 1.2, and 1.0 when the value of the temperature difference ΔTd is 0,
When the value of the temperature difference ΔTd is negative, the maximum value is 1.2, and when the value of the temperature difference ΔTd is positive, the value is 0.8 at the minimum.

Next, in step S11, the TCU 61 calculates an inlet temperature gradient ΔTs (that is, a change amount of the inlet side temperature Tfi per unit time). Inlet temperature gradient ΔTs
Indicates an increase or decrease state of the load. If the value is 0, there is no negative increase or decrease. If the value is positive or negative, the load has increased or decreased. After completing the calculation of the inlet temperature gradient ΔTs, the TCU 61 sets the set outlet temperature Tfo in step S13.
The deviation (outlet temperature difference) ΔTo between s and the outlet side temperature Tfo is calculated.

After calculating the inlet temperature gradient ΔTs and the outlet differential temperature ΔTo, the TCU 61 determines in step S15 the basic operating number of the refrigerator 1 from the operating number increase / decrease table (not shown) based on the inlet temperature gradient ΔTs and the outlet differential temperature ΔTo. Quantity ΔPB
(For example, -1.0 to +1.0). In the operating number increase / decrease table, the absolute value of the basic operating number increase / decrease amount ΔNB increases as the absolute value of the inlet temperature gradient ΔTs increases, and the absolute value of the basic operating number increase / decrease amount ΔNB increases as the absolute value of the outlet differential temperature ΔTo increases. The value also increases.

Thereafter, the TCU 61 proceeds to step S17.
Is calculated by multiplying the flow rate coefficient KF by the basic operation number increase / decrease amount ΔNB, and the operation number control based on the operation number increase / decrease amount ΔN is performed in step S19. For example, TC
U61 reads the value of the increase / decrease amount ΔN of the number of operating units. If the value is −0.5 or less, the operating number of the refrigerator 1 is reduced by one. Increase the number of vehicles. The TCU 61 also controls the capacity of each refrigerator 1 in parallel with the number of operating units so that the operating efficiency of the air conditioning system becomes the best, but the details will not be described here.

As described above, in the present embodiment, the number of operating units is controlled using the control gain (flow coefficient KF) according to the flow rate of the secondary refrigerant, so that hunting can be prevented while improving the control response. became.

The description of the specific embodiment has been completed.
The present invention is not limited to this embodiment. For example, in the above-described embodiment, in order to obtain the operating number increase / decrease amount ΔN, the flow coefficient KF is obtained from the temperature difference ΔTd, and the flow coefficient KF is calculated as the basic operating number increase / decrease amount ΔNB obtained from the inlet temperature gradient ΔTs and the outlet temperature difference ΔT. Although multiplication is performed, a fuzzy calculation may be performed based on the temperature difference ΔTd, the inlet temperature gradient ΔTs, and the outlet temperature difference ΔT to obtain the number of operating vehicles increase / decrease ΔN. Further, in the above embodiment, the value of the control gain (flow coefficient KF) according to the flow rate of the secondary refrigerant is set in the range of 0.8 to 1.2, but may be set in a wider range. You may.

Further, in the above embodiment, a gas heat pump type refrigerator is used as the refrigerator, but a refrigerator equipped with an inverter type compressor, a step control type variable displacement compressor or the like may be used. In addition, the present invention, in addition to the refrigeration system used in the air conditioning system connected to a single indoor unit,
The present invention is also applicable to refrigeration systems used other than air conditioning systems, such as computer cooling systems and cooling systems for various processing machines. Furthermore, the specific configuration of the devices and the specific procedure of control can be appropriately changed without departing from the spirit of the present invention.

[0031]

As described above, according to the refrigeration system of the present invention, the number of refrigerators operated is controlled based on the inlet side temperature and the outlet side temperature of the secondary refrigerant in the heat exchanger. Without using expensive flow sensors, etc.
The number of operating units can be controlled with a control gain corresponding to the flow rate of the secondary refrigerant from the use side device, and hunting can be prevented while maintaining a control response.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of an air conditioning system according to the present invention.

FIG. 2 is a control flowchart according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigerator 3 Indoor unit 5 Compressor 9 Heat source side heat exchanger 17 User side heat exchanger 31-38 Refrigerant piping 41, 43 Secondary refrigerant piping 45 Indoor heat exchanger 51 ECU 55 1st temperature sensor 57 2nd temperature sensor 61 TCU

Claims (2)

[Claims] 1. A refrigeration system for circulating a secondary refrigerant from a use-side device to heat exchangers of a plurality of refrigerators to cool or heat the secondary refrigerant, wherein the heat of the secondary refrigerant is Inlet temperature detecting means for detecting an inlet-side temperature in an exchanger; outlet temperature detecting means for detecting an outlet-side temperature of the secondary refrigerant in the heat exchanger; detection results of the outlet temperature detecting means and a target outlet-side temperature Based on the deviation, the basic increase / decrease amount setting means for setting the basic increase / decrease amount of the number of operating refrigerators, and a correction coefficient based on the deviation between the detection result of the outlet temperature detection means and the detection result of the entrance temperature detection means. Correction coefficient setting means to be set; increase / decrease amount determination means for multiplying the basic increase / decrease amount by the correction coefficient to determine the increase / decrease amount of the number of operating refrigerators; based on the determination result of the increase / decrease amount determination means, Number of operation A refrigeration system comprising: a number-of-operations control means for controlling the number of operating units. 2. A refrigeration system for circulating a secondary refrigerant from a use-side device to heat exchangers of a plurality of refrigerators to cool or heat the secondary refrigerant, wherein the heat of the secondary refrigerant is Inlet temperature detecting means for detecting an inlet-side temperature in an exchanger; outlet temperature detecting means for detecting an outlet-side temperature of the secondary refrigerant in the heat exchanger; and an inlet-side temperature of the secondary refrigerant in the heat exchanger. An inlet temperature gradient detecting means for detecting an amount of change per unit time of the refrigerator; and, based on a deviation between a detection result of the outlet temperature detecting means and a target outlet side temperature and a detection result of the inlet temperature gradient detecting means, A basic increase / decrease amount setting means for setting a basic increase / decrease amount of: a correction coefficient setting means for setting a correction coefficient based on a deviation between a detection result of the outlet temperature detection means and a detection result of the entrance temperature detection means; An increase / decrease amount determining means for determining an increase / decrease amount of the number of refrigerators operated by multiplying the basic increase / decrease amount by the correction coefficient; And a refrigerating system.