JP2012242053A - Refrigeration air conditioning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration air conditioning system that performs load change predictive control capable of suppressing hunting of temperature, which is to be controlled, even during a load change period.SOLUTION: The refrigeration air conditioning system includes an m (m≥1) units of refrigeration air conditioning devices 70 in which n (n≥2) compressors 1a that compress and discharge refrigerant, a condenser 3a which condenses the refrigerant by heat exchange, a throttling device 4a for depressurizing the refrigerant related to the condensation, and an evaporator 5a for cooling an object which is expected to be heat-exchanged by heat exchange with the refrigerant, are connected together by piping to constitute an upper stream side refrigerant circuit 50. It also includes a control circuit 30 which calculates an actual load, determines a load deviation state based on the load deviation which is the absolute value of a difference between the actual load and an average movement of the actual loads at a predetermined frequency, to control a refrigerant circuit that is operated with a control parameter corresponding to the load deviation state being set.

Description

  The present invention relates to temperature control (temperature adjustment) control based on a load in a refrigeration air conditioning system such as an air-cooled heat pump chiller. In particular, the present invention relates to control based on the load of a system having one or a plurality of refrigeration air conditioners equipped with a plurality of compressors.

  For example, in a refrigeration air conditioner using a refrigeration cycle, basically, a heat exchanger serving as a compressor, a condenser, an expansion valve (throttle device), and an evaporator (cooler) are connected by piping. The refrigerant circuit for circulating the refrigerant is configured. And, when the refrigerant evaporates and condenses, it uses heat absorption and heat dissipation from the air to be heat exchanged, and while changing the pressure in the pipe, etc., cooling of the temperature adjustment object, temperature adjustment operation such as air conditioning, etc. Is going.

  In such a refrigerated air conditioner, conventionally, a plurality of (for example, m) heat source devices are connected in parallel, and the capacity is controlled by the number of operating heat source devices to control the air conditioning. There is. In such an apparatus, each time the actual load is measured as a method of controlling the number of operating units that can prevent deterioration in follow-up performance and control delay during the fluctuation period of air conditioning control, a plurality of actual loads up to the actual load are measured. The average of the actual load is calculated as a moving average of the actual load. And the control which determines the number of operation | movement of a heat source machine as a parameter | index for control judgment by adding the difference which subtracted the moving average from the actual load to the actual load is proposed (for example, refer patent document 1).

  In such a unit control, the parameters required for the control are always constant. As for the number of starting units, if all the units are started or if the compressor starting is being restricted, for example, control is performed to start with half the number, and switching by load is not performed.

Japanese Unexamined Patent Publication No. 2007-46857 (first item, FIGS. 1 to 8)

  As described above, in the conventional refrigeration air conditioner, parameters required for, for example, compressor capacity control, etc., are always constant in temperature control. In addition, since all units are normally started, the temperature of the temperature control target (load) hunts due to frequent start, stop, and supercooling of the compressor during the fluctuation period of the load. There was a problem that the delay occurred.

  The present invention has been made to solve the above-described problems. For example, a refrigeration that performs load fluctuation prediction control that can suppress hunting of the temperature of a temperature adjustment target even during a load fluctuation period. The purpose is to obtain an air conditioning system.

  The refrigeration air conditioning system according to the present invention includes a plurality of compressors that compress and discharge a refrigerant, a condenser that condenses the refrigerant by heat exchange, a throttling device that depressurizes the refrigerant related to condensation, and heat exchange with the refrigerant. 1 or a plurality of refrigeration air conditioners that constitute a refrigerant circuit by pipe connection to an evaporator that cools the heat exchange target, calculate an actual load, and a moving average of the actual load and the actual load for a predetermined number of times And a control circuit for setting a control parameter corresponding to the load deviation state based on the load deviation which is an absolute value of the difference between the two and controlling the refrigeration air conditioner according to the operation.

  According to the present invention, the load deviation state is determined based on the load deviation which is the difference between the actual load and the moving average of the predetermined number of actual loads, and the number of compressor starting units and control parameters can be set. Accurate temperature control can be realized, and reliability can be ensured. For example, when the fluctuation range of the load is small, it is assumed that the temperature is close to the target temperature.For example, the control interval is long, the control parameter is set so as to reduce the control amount of the compression capacity, etc. Since the control related to the supply of heat is performed, it is possible to prevent overshooting of the temperature in the temperature adjustment target and suppress hunting. Further, when the load suddenly changes, it is assumed that the load is far from the target temperature. For example, the control parameter is set so that the control interval is short and the control amount is large so as to approach the target temperature quickly. Since the capacity increase / capacity decrease command, the number increase / decrease command, etc. can be output, load followability can be ensured.

It is a figure which shows the structure of the frozen air conditioning apparatus etc. which concern on Embodiment 1 of this invention. 3 is a diagram illustrating a flowchart of processing performed by a control circuit 30 according to Embodiment 1. FIG. It is a figure showing the relationship between the load deviation in Embodiment 1, a compressor starting number, etc. FIG. It is a figure for demonstrating the load deviation state in temperature control. It is a figure which shows an example of a control parameter (setting table). It is a figure which shows the relationship between temperature control and compressor capacity control. It is a figure showing the structure of the frozen air conditioning system which concerns on Embodiment 2 of this invention. It is a figure showing the relationship between the load deviation in Embodiment 2, a compressor starting number, etc. FIG.

Embodiment 1 FIG.
(1.1) Detailed Description of Configuration FIG. 1 is a diagram showing a system configuration centering on a refrigeration air conditioner according to Embodiment 1 of the present invention. Here, an air-cooled heat pump chiller will be described as the refrigeration air conditioner of the present embodiment. As shown in FIG. 1, the refrigeration air conditioner 70 includes an upstream refrigerant circuit 50 and a downstream refrigerant circuit 60. And it has the water circuit 6 which circulates water etc. between the load side apparatus (not shown) and the frozen air conditioning apparatus 70. FIG. The upstream refrigerant circuit 50 (first evaporator 5a) and the downstream refrigerant circuit 60 (second evaporator 5b) are connected in series to the water circuit 6, for example, by a pump (not shown). The water circulating in the water circuit 6 is cooled in two stages. Here, in this embodiment, water or the like circulating through the water circuit 6 (hereinafter referred to as water) is used as a medium for supplying heat to the load. However, the present invention is not limited to water, but other liquids or the like. Can also be used.

  The upstream refrigerant circuit 50 is configured by connecting the first compressor 1a, the first compressor 2a, the first condenser 3a, the first expansion device 4a, and the first evaporator 5a by piping. doing. Similarly to the upstream refrigerant circuit 50, the downstream refrigerant circuit 60 has the second compressor 1b, the second compressor 2b, the second condenser 3b, the second expansion device 4b, and the second evaporation. The refrigerant circuit is constituted by the vessel 5b.

  The first compressors 1a and 2a and the second compressors 1b and 2b suck the refrigerant, compress it, and discharge it in a high temperature / high pressure state. Here, the first compressors 1a, 2a and the second compressors 1b, 2b are constituted by a compressor of a type capable of adjusting the capacity capable of adjusting the discharge amount of the refrigerant, for example, by controlling the rotational speed of an inverter circuit or the like. Suppose you are. Here, in the present embodiment, the first compressors 1a and 2a and the second compressors 1b and 2b are piped in parallel. From the above, the refrigeration air conditioning apparatus 70 of the present embodiment has four compressors. Here, when it is not necessary to distinguish between the compressors, they are simply described as compressors (the same applies to other devices).

  The first condenser 3a and the second condenser 3b are heat exchangers that exchange heat between, for example, air and a refrigerant to condense and liquefy the refrigerant. For example, the first throttling device 4a and the second throttling device 4b such as an expansion valve adjust the flow rate of the refrigerant and reduce the pressure to expand. In the present embodiment, the first evaporator 5a and the second evaporator 5b exchange heat between the water circulating in the water circuit 6 and the refrigerant, thereby evaporating the refrigerant into gas and cooling the water. It is an exchanger.

  As shown in FIG. 1, the inlet temperature sensor 7 is a water temperature detecting means for detecting the temperature (inlet temperature) of water flowing from the load side into the upstream refrigerant circuit 50 (first evaporator 5a). The outlet temperature sensor 8 is water temperature detection means for detecting the temperature (outlet temperature) of water that flows out from the downstream refrigerant circuit 60 (second evaporator 5b) and flows to the load side. The outside air temperature sensor 9 is outside air temperature detecting means for detecting the temperature (outside air temperature) of the air (outside air) around the refrigerant circuit. The control circuit 30 sends drive signals to the first compressors 1a and 2a, the second compressors 1b and 2b, and the expansion devices 4a and 4b to control the driving of these devices. In particular, in the present embodiment, based on the temperatures detected by the inlet temperature sensor 7, the outlet temperature sensor 8, and the outside air temperature sensor 9, the number of compressors to be started is determined before the operation of the refrigeration air conditioner. During operation, the compressor is controlled.

  Next, operation | movement of each refrigerant circuit, etc. are demonstrated based on the flow of a refrigerant | coolant. Here, the levels of temperature and pressure described below are not particularly determined in relation to absolute values, but are based on relationships that are relatively determined in the state, operation, etc. of the device. It shall be written.

  First, the upstream refrigerant circuit 50 will be described. The high-temperature and high-pressure gas refrigerant compressed by the first compressors 1a and 2a flows into the first condenser 3a. The first condenser 3a dissipates heat and condenses by heat exchange with air (outside air). The condensed high-pressure liquid refrigerant flows into the first expansion device 4a. Then, the pressure is reduced by the first expansion device 4a to form a low-pressure two-phase refrigerant and flows into the first evaporator 5a. Then, the first evaporator 5a absorbs heat and evaporates by heat exchange with water or the like serving as a load-side heat medium, becomes a low-pressure gas refrigerant, and is sucked into the first compressors 1a and 2a. On the other hand, in the water circuit 6, the water flowing from the load side device (not shown) is cooled by heat exchange with the refrigerant and flows to the downstream side refrigerant circuit 60.

  Next, the downstream refrigerant circuit 60 will be described. The high-temperature and high-pressure gas refrigerant compressed by the second compressors 1b and 2b flows into the second condenser 3b. In the second condenser 3b, heat is dissipated by heat exchange with air (outside air) and condensed. The condensed high-pressure liquid refrigerant flows into the second expansion device 4b. Then, the pressure is reduced by the second expansion device 4b to form a low-pressure two-phase refrigerant and flows into the second evaporator 5b. Then, the second evaporator 5b absorbs heat by heat exchange with water or the like serving as a load-side heat medium, evaporates, becomes a low-pressure gas refrigerant, and is sucked into the second compressors 1b and 2b. On the other hand, in the water circuit 6, the water flowing from the upstream refrigerant circuit 50 is cooled by heat exchange with the refrigerant and flows to a load side device (not shown).

(1.2) Detailed Description of Operation and Effect The conventional refrigeration air conditioner always maintains constant parameters necessary for compressor capacity control for temperature control. In addition, the number of compressors that are started up is normally 100%. For this reason, for example, during the load fluctuation period, the temperature of the supplied water is hunting due to frequent start and stop, repeated cooling, etc., resulting in follow-up to the load fluctuation and delay in control. .

  Therefore, in order to prevent such a state, the water circuit 6 always detects the inlet temperature, the outlet temperature, and the outside air temperature, and the control circuit 30 performs an operation related to the load based on the temperature related to the detection, Based on the load state, the number of units to be started is determined before starting the compressor, and after starting, a control parameter is set, and based on the control parameter, a control signal is output to the compressor and the expansion device to supply water to the water circuit 6. Supply heat and control the temperature.

  For example, in the judgment before starting the compressor, if the temperature is close to the target temperature (outlet temperature), the amount of heat supplied to the load may be small, so the number of starting units is reduced, and if it is far from the target temperature, the load is high. The number of startups will be increased to supply the amount of heat. In addition, after starting, when the temperature is far from the target temperature, it is necessary to increase or decrease the amount of heat supplied to the load quickly, so control such as increasing the control amount is performed. In addition, when the temperature is close to the target temperature, the fluctuation range of the amount of heat supplied to the load becomes small, so control such as reducing the control amount of the compressor capacity is performed, so that overshoot of the supply water temperature is prevented, and the water circuit Hunting of the supply water temperature to the load side due to 6 can be suppressed.

  FIG. 2 is a diagram illustrating a flowchart of processing performed by the control circuit 30 according to the first embodiment. In the present embodiment, the control circuit 30 sets the values of the inlet temperature related to the detection of the inlet temperature sensor 7, the outlet temperature related to the detection of the outlet temperature sensor 8, and the value of the outside air temperature related to the detection of the outside air temperature sensor 9 to the period of 15 seconds. (S1). Then, the actual load W is calculated based on these values (S2). Also, a moving average Wav for a predetermined number of actual load values W is calculated. Then, a load deviation ΔW that is an absolute value of a difference between the actual load W and the moving average Wav is calculated (S3). Then, it is determined whether it is before the operation of the refrigeration air conditioner (before the compressor is started) (S4).

  FIG. 3 is a diagram illustrating the relationship between the load deviation ΔW and the number of compressors started in the first embodiment. If it is determined that it is before the operation of the air conditioner, the load deviation state is determined based on the load deviation ΔW in order to determine the number of activated compressors (S5). Here, in this embodiment, the load deviation state is set in advance, for example, in three stages of High, Normal, and Low. If it is determined that the load deviation state is High, the number of compressors started is set to 4 (S6). If it is determined that the number is normal, the number of starting compressors is set to two (S7). If it is determined that the number is low, the number of starting compressors is set to one (S8).

  Here, for example, which compressor is activated when Normal or Low is not particularly limited. For example, if a certain compressor is specified, the accumulated drive time of the compressor is biased. Therefore, for example, when making a determination, the number of activated units may be determined so that the compressor is driven by the compressor having the shortest accumulated drive time. Further, in the apparatus configuration in which two refrigerant circuits are connected to the water circuit 6 as in the refrigeration air conditioning apparatus 70 of the present embodiment, for example, two compressors may be driven when cooling is performed. . In such a case, basically, the compressors in the downstream refrigerant circuit 60 and the upstream refrigerant circuit 50 are often started one by one, so when it is determined that the load deviation state is normal, the downstream side You may make it determine the compressor started one by one from the refrigerant circuit 60 and the upstream refrigerant circuit 50. FIG. In the present embodiment, water flowing through the water circuit 6 is cooled. However, for example, when heating is performed, two units may be determined from the upstream refrigerant circuit 50 without being particularly defined.

  FIG. 4 is a diagram for explaining a load deviation state during temperature control. 4A shows a case where the load increases, and FIG. 4B shows a case where the load decreases. If it is determined in S4 that it is not before the operation of the air conditioner, it is determined that the operation is in progress (during temperature control), and the load deviation state is determined based on the load deviation ΔW in order to set the control parameter (S9). The judgment of the load deviation state for setting the control parameter is also judged in three stages of High, Normal, and Low.

  FIG. 5 is a diagram showing an example of control parameters (setting table) such as compressor capacity. As shown in FIG. 5, when the load deviation state is high (when the fluctuation of the actual load W is large), the control interval is shortened and the control amount and the control width are increased as compared with the case where the load deviation state is normal. Y4 is set (S10). On the other hand, when the load deviation state is Low (when the fluctuation of the actual load W is small), Y1 is set to increase the control interval and decrease the control amount and control width (S12). If the load deviation state is Normal, Y2 is set (S11). In this way, the followability to the magnitude of load fluctuation is improved, and the supply water temperature can be kept more constant.

  FIG. 6 is a diagram showing the relationship between temperature control and compressor capacity control. In FIG. 6, in order to make the relationship easy to understand, the control parameter is made constant regardless of the load deviation state. In this Embodiment, the capacity | capacitance of a compressor is controlled based on outlet temperature, for example, and the water temperature control of the water circuit 6 is performed. In the conventional temperature control, the capacity control amount of the compressor is calculated from the target temperature, the current outlet temperature in the water circuit 6, the constant control amount UP coefficient, and the control amount DOWN coefficient regardless of the current load state. Capacity control. At this time, the capacity control holding differential (temperature range in which the capacity is maintained around the target temperature) is also constant. Therefore, frequent start / stop occurs when the load is small, and control follows when the load is large. Was delayed, causing hunting of the supply temperature.

  As described above, according to the refrigeration air conditioning apparatus of the first embodiment, the load deviation state is determined based on the load deviation ΔW that is the difference between the actual load W and the moving average Wav of the actual load. When the width is small and close to the target temperature, the number of compressors to be started is reduced before starting after the start of operation, and the control interval is long due to the control parameter setting even after starting the compressor. By performing capacity control with a small amount, it is possible to prevent overshooting of the temperature of the water to be controlled, and to suppress hunting. Further, for example, even when the load changes suddenly and the temperature in the water to be temperature-controlled moves away from the target temperature (temperature difference widens), the load fluctuation can be always predicted. For example, when it is determined that the load deviation state is High, the control interval can be shortened, the control parameter can be set to increase the control amount, and the capacity increase or capacity decrease command or the number increase or decrease command can be issued. , Load followability can be ensured.

  As described above, the load deviation state is determined based on the load deviation ΔW that is the difference between the actual load W and the moving average Wav, and the number of compressors started and the control parameters can be changed, thereby enabling more accurate temperature control. Can be realized and reliability can be ensured.

Embodiment 2. FIG.
FIG. 7 is a diagram illustrating a configuration of a refrigeration air conditioning system according to Embodiment 2 of the present invention. As shown in FIG. 7, in the present embodiment, a system is configured by connecting m units (m is an integer of 1 or more) of refrigeration air conditioners 101 having n (n is an integer of 2 or more) compressors in parallel. doing. The m refrigerated air conditioners 101-1 to 100-m are the same devices as the refrigerated air conditioner 70 described in the first embodiment. Moreover, it has the pumps 102-1 to 102-m which send the water of the water circuit 6 to the refrigeration air conditioners 101-1 to 100-m, respectively. And it has the header 103 which can make the water which flowed through each refrigeration air conditioning apparatus 101-1-100-m merge and can be made to flow to the thermal loader 104. FIG. Moreover, it has the header 105 which can branch the water which flowed through the heat loader 104 to each refrigeration air conditioning apparatus 101-1 to 100-m.

  Further, the water circuit 6 includes an inlet temperature sensor 106 that detects the temperature of water flowing from the heat loader 104 side to the refrigeration air conditioners 101-1 to 100-m side. Moreover, it has the exit temperature sensor 107 which detects the temperature of the water which flows in into the thermal load machine 104 from the refrigeration air conditioning apparatus 101-1 to 100-m side. And it has the outside temperature sensor 108 which detects the temperature (outside temperature) of the air (outside air) around a refrigerant circuit.

  When applied to a system as shown in FIG. 7 configured by pipe-connecting m refrigeration air conditioners equipped with n compressors, as in the first embodiment, the control circuit 100 uses the inlet temperature. The actual load W and the like are calculated based on the values of the outlet temperature and the outside air temperature, and the number of compressors started, the control parameters are set based on the load deviation state, and the like.

  FIG. 8 is a diagram showing the relationship between the load deviation ΔW and the number of compressors started in the second embodiment. Although the load deviation state is divided into three stages in the first embodiment, it is divided into n × m stages in the present embodiment. This is a balance based on the total number of compressors so that fine control can be performed while preventing the control from becoming too complicated. The largest number of activated units is N (n × m), which is the total number of compressors. As a result, the supply water temperature can be kept constant while ensuring the followability to the magnitude of the load fluctuation.

  As described above, according to the second embodiment, similarly to the refrigeration air conditioner of the first embodiment, not only the number control but also the control parameters such as the compressor capacity can be switched while predicting the load. Since more accurate control can be performed on the capacity control mechanism, for example, when the load fluctuation is small, overshoot can be suppressed. As a result, there is an effect of ensuring the supply water temperature within a certain differential from the target temperature, and preventing compressor damage and failure due to frequent start / stop and overcooling.

  In the above-described embodiment, the medium that transmits heat to the load is water and is a temperature control target. However, the control target is not limited to water, and other liquids, gases such as air, and the like can be used. .

  In the above-described embodiment, the air-cooled heat pump chiller has been described as the refrigeration air conditioner. However, the present invention can also be applied to other air conditioners, refrigeration apparatuses (cooling apparatuses), refrigeration cycle apparatuses, heat pump apparatuses, and the like. .

  1a, 2a 1st compressor, 1b, 2b 2nd compressor, 3a 1st condenser, 3b 2nd condenser, 4a 1st expansion device, 4b 2nd expansion device, 5a 1st Evaporator, 5b Second evaporator, 6 Water circuit, 7 Inlet temperature sensor, 8 Outlet temperature sensor, 9 Outside air temperature sensor, 30 Control circuit, 50 Upstream refrigerant circuit, 60 Downstream refrigerant circuit, 70 Refrigeration air conditioner (Air-cooled heat pump chiller), 100 control circuit, 101 refrigeration air conditioner, 102 pump, 103, 105 header, 104 heat load machine, 106 inlet temperature sensor, 107 outlet temperature sensor, 108 outside air temperature sensor.

Claims (6)

A plurality of compressors that compress and discharge the refrigerant;
A condenser for condensing the refrigerant by heat exchange;
A throttling device for depressurizing the refrigerant for condensation;
One or a plurality of refrigeration air conditioners that constitute a refrigerant circuit by pipe connection to an evaporator that cools a heat exchange target by heat exchange with the refrigerant;
Calculate an actual load, set a control parameter corresponding to a load deviation state based on a load deviation that is an absolute value of a difference between the actual load and a moving average of the actual load for a predetermined number of times, and A refrigeration air conditioning system comprising a control circuit for controlling the refrigeration air conditioning apparatus.   2. The refrigeration air conditioning system according to claim 1, wherein when the compressor is started for operation, the control circuit determines the number of the started compressors corresponding to the load deviation state.   In the case where m (m ≧ 1) refrigeration air conditioners having n (n ≧ 2) compressors are provided, the load deviation state is divided into n × m stages and the control parameters are set. The refrigeration air conditioning system according to claim 1 or 2. A load-side device that supplies heat to the load, and a water circuit that circulates water for conveying the heat supplied by the refrigeration air conditioner to the load-side device. The refrigeration air conditioning system according to any one of the above.   The said refrigeration air conditioning apparatus has a some refrigerant circuit connected along the flow of the water of the said water circuit, The refrigeration air conditioning system of Claim 4 characterized by the above-mentioned. Water temperature detecting means for detecting the temperature of the water before and after the refrigerated air conditioner supplies heat, and an outside air temperature detecting means for detecting the temperature of the outside air in the vicinity of the refrigerated air conditioner,
The refrigeration air conditioning system according to claim 4 or 5, wherein the control circuit calculates the actual load based on temperatures detected by the water temperature detection means and the outside air temperature detection means.

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