GB2555064A

GB2555064A - Refrigeration system

Info

Publication number: GB2555064A
Application number: GB1800132.1A
Authority: GB
Inventors: Yamano Yoshio; Okoshi Yasushi
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2015-07-14
Filing date: 2015-07-14
Publication date: 2018-04-18
Anticipated expiration: 2035-07-14
Also published as: GB2555064B; JPWO2017009955A1; WO2017009955A1; GB201800132D0; JP6681896B2

Abstract

The present invention improves the efficiency of a refrigeration system by accurately ascertaining the amount of heat currently in a load-side apparatus. The present invention comprises: a heat pump chiller 1 that includes a water-refrigerant heat exchanger 12 in which heat is exchanged between a refrigerant and a heat medium, and a compressor 11; a load-side apparatus 2; a water circuit 4 in which the water-refrigerant heat exchanger and the load-side apparatus are connected to each other by a pipe and water is caused to circulate by a pump 3 so as to convey the amount of heat supplied by the heat pump chiller to the load-side apparatus; temperature sensors 23a, 23b that detect the temperature of water; pressure sensors 24a, 24b that detect the pressure of water; a suction temperature sensor 25 that detects a load indicator for determining the load in the load-side apparatus; and a control device 30 that controls the respective operations of the compressor and the pump on the basis of values obtained respectively from the temperature sensors, the pressure sensors and the suction temperature sensor.

Description

DESCRIPTION

Title of Invention

REFRIGERATION SYSTEM

Technical Field [0001]

The present invention relates to a refrigeration system using a heat pump chiller as a heat source.

Background Art [0002]

As a refrigeration system using a heat pump chiller as a heat source device, there is known an air-conditioning system including a water circuit configured to circulate water as a heat medium in a construction, for example, a building or a largescale commercial facility. In the air-conditioning system of this type, water in the water circuit is caused to pass through a fan coil unit or an air handling unit serving as a load-side device so that heat of the water is used for cooling or heating.

[0003]

A plurality of heat pump chillers and a plurality of load-side devices are generally used for one water circuit. Water is circulated by joining the water output from each load-side device at a header, and then distributing the water to each heat pump chiller.

[0004]

In order to save electrical power, it is effective to use a water circulation pump and a heat pump chiller compressor compatible with an inverter. For inverter control of those components, a water temperature inside the header is measured so that optimal control is constructed for the load.

[0005]

Further, in the air-conditioning system including the plurality of heat pump chillers, not only the inverter control but also control of the number of heat pump chillers to be operated is performed to save electrical power.

[0006]

As the related art configured to measure the water temperature inside the header to control the number of heat pump chillers to be operated for electrical power saving, there is known Patent Literature 1. In Patent Literature 1, there is disclosed an air-conditioning system configured to measure the water temperature inside the header to control the number of heat pump chillers to be operated so that only a minimum required number of heat pump chillers is operated.

Citation List

Patent Literature [0007]

Patent Literature 1: Japanese Patent No. 3320631 Summary of Invention Technical Problem [0008]

The related-art air-conditioning system described in Patent Literature 1 controls the number of heat pump chillers to be operated based on only the water temperature inside the header. The water temperature inside the header alone is insufficient as circulating water information of the load-side device. Therefore, a current quantity of heat of the load-side device, that is, a current quantity of heat that can be supplied from the load-side device to an air-conditioning load cannot be accurately detected. Thus, the heat pump chiller may be operated so as to supply extra quantity of heat to the load-side device, and this operation has been a cause of reduction in efficiency of the entire air-conditioning system.

[0009]

The present invention has been made in order to solve the above-mentioned problem, and has an object to provide a refrigeration system capable of accurately detecting the current quantity of heat of the load-side device to improve the efficiency of the refrigeration system.

Solution to Problem [0010]

According to one embodiment of the present invention, there is provided a refrigeration system, including: a heat source device including a compressor and a heat source-side heat exchanger configured to exchange heat between refrigerant and a heat medium; a load-side device; a heat medium circuit in which the heat source-side heat exchanger and the load-side device are connected to each other by a pipe so that the heat medium is circulated by a pump, to thereby convey a quantity of heat supplied by the heat source device to the load-side device; a temperature sensor configured to detect a temperature of the heat medium; a pressure sensor configured to detect a pressure of the heat medium; a load index sensor configured to detect a load index for determining a load in the load-side device; and a controller configured to control an operation of the compressor and an operation of the pump based on a value obtained from each of the temperature sensor, the pressure sensor, and the load index sensor.

Advantageous Effects of Invention [0011]

According to one embodiment of the present invention, a refrigeration system capable of accurately detecting a current quantity of heat of a load-side device to improve the efficiency of the refrigeration system can be provided.

Brief Description of Drawings [0012] [Fig. 1] Fig. 1 is a block diagram for illustrating a configuration of an airconditioning system according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a flow chart for illustrating an operation of the air-conditioning system according to Embodiment 1 of the present invention.

[Fig. 3] Fig. 3 is a graph for showing a relationship between a load factor of a compressor and compressor efficiency.

[Fig. 4] Fig. 4 is a schematic configuration diagram of a hot water supply system according to Embodiment 2 of the present invention.

[Fig. 5] Fig. 5 is a flow chart for illustrating an operation of the hot water supply system according to Embodiment 2 of the present invention.

Description of Embodiments [0013]

Embodiment 1

Embodiment 1 of the present invention is described with an air-conditioning system being given here as an example of a refrigeration system.

[0014]

Fig. 1 is a block diagram for illustrating a configuration of an air-conditioning system according to Embodiment 1 of the present invention. The air-conditioning system includes heat pump chillers 1 that are heat source devices installed outdoors, load-side devices 2 that are indoor units installed indoors, and a pump 3. The airconditioning system further includes a water circuit 4 that is a heat medium circuit configured to circulate water serving as a heat medium. The water circuit 4 is a circuit in which the heat pump chillers 1 and the load-side devices 2 are connected to each other by pipes so that water is circulated by the pump 3, to thereby convey a quantity of heat supplied by the heat pump chillers 1 to the load-side devices 2. Fig.

is an illustration of a case in which two heat pump chillers 1 and two load-side devices 2 are installed, but the illustration does not limit the number of heat pump chillers and load-side devices to be installed.

[0015]

Each of the heat pump chillers 1 includes a compressor 11 whose operation capacity is variable by an inverter, and a water-refrigerant heat exchanger 12 serving as a heat source-side heat exchanger for heating or cooling circulating water to a target temperature with heat of refrigerant, for example, fluorocarbons. Further, the heat pump chiller 1 includes a refrigerant circuit (not shown) including the compressor 11, a pressure reducing device, and a heat exchanger, and functions as a heat source device configured to supply the heat of the refrigerant to the load-side device by exchanging, in the water-refrigerant heat exchanger 12, heat between the refrigerant of the refrigerant circuit through which the refrigerant circulates and the circulating water in the water circuit 4. In the water circuit 4, water circulates between the water-refrigerant heat exchanger 12 of the heat pump chiller 1 and a load-side heat exchanger 21a of a fan coil 21, which is to be described later, of the load-side device 2.

[0016]

Each of the load-side devices 2 includes the fan coil 21 and a motor valve 22. The fan coil 21 includes the load-side heat exchanger 21a and a fan 21b for causing air to pass through the load-side heat exchanger 21a. The fan coil 21 performs a cooling operation of cooling load-side air by exchanging heat between the load-side air and the circulating water in the water circuit 4 in the load-side heat exchanger 21a, to thereby supply the cooled load-side air to an indoor space. The fan coil 21 also performs a heating operation of heating the load-side air by exchanging heat between the load-side air and the circulating water in the water circuit 4 in the load-side heat exchanger 21a, to thereby supply the heated load-side air to the indoor space. The motor valve 22 is configured to adjust an inflow amount of the circulating water to the load-side heat exchanger 21a in the water circuit 4.

[0017]

The load-side device 2 further includes temperature sensors 23 (23a and 23b) that are heat medium temperature sensors, pressure sensors 24 (24a and 24b) that are heat medium pressure sensors, an intake temperature sensor 25 that is a load index sensor, and a humidity sensor 26.

[0018]

The temperature sensor 23a is arranged on a water inlet pipe of the load-side heat exchanger 21a, and is configured to detect the temperature of the circulating water at the inlet of the load-side heat exchanger 21a. The temperature sensor 23b is arranged on a water outlet pipe of the load-side heat exchanger 21a, and is configured to detect the temperature of the circulating water at the outlet of the loadside heat exchanger 21a.

[0019]

The pressure sensor 24a is arranged on the water inlet pipe of the load-side heat exchanger 21a, and is configured to detect the pressure of the circulating water at the inlet of the load-side heat exchanger 21a. The pressure sensor 24b is arranged on the water outlet pipe of the load-side heat exchanger 21a, and is configured to detect the pressure of the circulating water at the outlet of the load-side heat exchanger 21a.

[0020]

The intake temperature sensor 25 is arranged on the windward side of the fan 21 b of the fan coil 21, and is configured to detect the temperature of intake air that is the load-side air. Similarly to the temperature sensor, the humidity sensor 26 is also arranged on the windward side of the fan 21 b of the fan coil 21, and is configured to detect the humidity of the intake air.

[0021]

Detection signals of those sensors 23 to 26 are output to a load-side controller 27 to be described later.

[0022]

The load-side device 2 further includes the load-side controller 27 configured to receive the detection signals of the sensors 23 to 26, and a central controller 50 configured to control the entire air-conditioning system.

[0023]

The load-side controller 27 is configured to transmit the signals of the sensors 23 to 26 in the load-side device 2 to the central controller 30 to be described later via a control signal line 31, and to calculate the quantity of heat necessary in the loadside device 2. The load-side controller 27 may be constructed of hardware, for example, a circuit device for achieving the function of the load-side controller 27, or may be constructed of a calculation device, for example, a microcomputer or a CPU, and software to be executed thereon.

[0024]

The central controller 30 is configured to calculate an optimal operation condition based on information obtained from each of the heat pump chillers 1, the pump 3, and the load-side devices 2 connected by the control signal line 31, and to control the heat pump chillers 1 and the pump 3 by outputting operation instructions thereto. The central controller 30 may be constructed of hardware, for example, a circuit device for achieving the function of the load-side controller 30, or may be constructed of a calculation device, for example, a microcomputer or a CPU, and software to be executed thereon.

[0025]

Description is given here of a configuration in which the operation control of the entire air-conditioning system is performed by performing data communication between the load-side controller 27 and the central controller 30 to achieve cooperative processing, but the present invention may have a configuration in which the central controller 30 also has the function of the load-side controller 27 so that the central controller 30 may perform the operation control of the entire air-conditioning system. The load-side controller 27 and the central controller 30 construct a controller of the present invention.

[0026]

Fig. 2 is a flow chart for illustrating the operation of the air-conditioning system according to Embodiment 1 of the present invention.

In the air-conditioning system configured as described above, the intake temperature sensor 25 and the humidity sensor 26 are used to detect the temperature and the humidity of the intake air (S1). Then, the load-side controller TJ determines whether or not the intake air temperature detected by the intake temperature sensor 25 matches with a target temperature (S2). The intake air temperature detected by the intake temperature sensor 25 corresponds to a load index for determining the current load on the load side. Then, when the intake air temperature does not match with the target temperature, the load-side controller 27 calculates the quantity of heat necessary for causing the intake air temperature to match with the target temperature based on the temperature and the humidity of the intake air obtained by the intake temperature sensor 25 and the humidity sensor 26 (S3).

[0027]

When the intake air humidity is also used in addition to the intake air temperature for the calculation of this necessary quantity of heat, the quantity of heat can be calculated more accurately. That is, for example, when a place having high temperature and high humidity is cooled, the air is cooled while changing the phase of the water vapor in the air into water, and hence heat is required to be removed, including the amount of latent heat. Therefore, when the humidity is high, a larger cooling capacity is required than that when the humidity is low. As described above, with consideration to the latent heat as well, the necessary quantity of heat can be calculated more accurately. From the above-mentioned viewpoint, it is preferred to use the intake air humidity when the necessary quantity of heat is calculated, but at least the intake air temperature may be used.

[0028]

Next, the load-side controller 27 uses the temperature sensors 23 and the pressure sensors 24 to detect the water temperature and the water pressure of the circulating water, to thereby calculate the current quantity of heat that can be supplied from the load-side heat exchanger 21a to the air-conditioning load (S4). In the following, information on the water temperature and the water pressure of the circulating water is sometimes referred to as load-side control information.

[0029]

Then, the load-side controller 27 determines whether or not the necessary quantity of heat can be obtained by adjusting an opening degree of the motor valve 22 to change the flow rate of the circulating water flowing through the load-side heat exchanger 21a (S5). This determination is specifically made through comparison between a difference between the necessary quantity of heat and the current quantity of heat that can be supplied from the load-side heat exchanger 21a to the airconditioning load and a set quantity of heat set in advance. That is, when the difference between the necessary quantity of heat and the current quantity of heat that can be supplied from the load-side heat exchanger 21a to the air-conditioning load is smaller than the set quantity of heat, it is determined that the necessary quantity of heat can be obtained by adjusting the opening degree of the motor valve 22 to change the flow rate flowing through the load-side heat exchanger 21a. On the other hand, when the difference between the necessary quantity of heat and the current quantity of heat that can be supplied from the load-side heat exchanger 21a to the air-conditioning load is larger than the set quantity of heat, the load-side controller 27 determines that the necessary quantity of heat cannot be obtained by adjusting the opening degree of the motor valve 22.

[0030]

When the load-side controller 27 determines that the necessary quantity of heat can be obtained by adjusting the opening degree of the motor valve 22, the loadside controller 27 adjusts the opening degree of the motor valve 22 in accordance with the necessary quantity of heat (S6), and returns to Step S4.

[0031]

When the load-side controller 27 determines that the necessary quantity of heat cannot be obtained by adjusting the opening degree of the motor valve 22, the load-side controller 27 transmits information on this fact, that is, information on a fact that change in operation condition is necessary, to the central controller 30 via the control signal line 31. In this case, when the information on the fact that change in operation condition is necessary is transmitted from the load-side controller 27 to the central controller 30, this information is transmitted together with the current load-side control information (water temperature and water pressure of circulating water), which is obtained in the load-side device 2.

[0032]

The processing from Step S1 to Step S6 described above is performed in each of the load-side controllers 27. Therefore, the information on the fact that change in operation condition is necessary (including the load-side control information) is collected into the central controller 30 from at least a part of the load-side controllers 27 in accordance with the situation of the quantity of heat in each of the load-side controllers 27.

[0033]

Then, the central controller 30 controls the operation of each of the heat pump chillers 1 and the pump 3 based on the operation information obtained from the heat pump chillers 1 and the pump 3, and on the load-side control information (water temperature and water pressure of circulating water) obtained from each of the load9 side controllers 27 of the load-side devices 2. That is, an optimal operation condition is calculated based on the operation information and the load-side control information, and an operation instruction is output to each of the heat pump chillers 1 and the pump 3 (S7). The operation information obtained from the heat pump chillers 1 and the pump 3 specifically corresponds to, for example, a current operation capacity. [0034]

In this case, the efficiency of the compressor 11 has the largest influence on achieving the electrical power saving of the air-conditioning system, and hence the central controller 30 determines the operation instruction so that the plurality of compressors 11 may be operated in a load factor with high efficiency. The load factor of the compressor 11 is shown next in Fig. 3.

[0035]

Fig. 3 is a graph for showing a relationship between the load factor of the compressor and the compressor efficiency. In the case of the compressor 11 having the relationship shown in Fig. 3, when the load factor during the rated operation is 100%, an efficiency of around 50% is preferred. Therefore, for example, when ten heat pump chillers 1 are installed, and a case where all of the ten heat pump chillers 1 are operated at the load factor of 100% is referred to as an operation request of 100%, the operation request of 50% can be achieved by operating five heat pump chillers 1 at the load factor of 100%. However, this compressor 11 has better compression efficiency when the compressor 11 is operated at the load factor of 50% than when the compressor 11 is operated at the load factor of 100%, and hence ten compressors 11 are operated at the load factor of 50%. Further, in the case of the operation request of 40%, eight compressors may be operated at the load factor of 50%.

[0036]

The above-mentioned operation request ratio is determined based on the operation information obtained from the heat pump chillers 1 and the pump 3, and on the necessary quantity of heat obtained by calculating, by the central controller 30, the load-side control information (water temperature and water pressure of circulating water) obtained from the load-side devices 2. The compressors 11 are controlled so that the load factors of the compressors 11 become optimal based on the operation request ratio.

[0037]

The heat pump chillers 1 and the compressors 11 are operated in a number to be operated and an operation capacity, which are optimized based on the abovementioned idea. That is, the central controller 30 determines the optimal operation condition (number of compressors 11 to be operated and operation capacity of compressors 11) so that the compressors 11 are operated within a range of a set load factor including the load factor for obtaining the maximum compressor efficiency (50% in this case).

[0038]

Further, the central controller 30 controls the operation capacity of the pump 3 based on the water pressure obtained from the pressure sensors 10 of the load-side device 2 so that an optimized water circulation amount is obtained in a manner that the outlet water temperature of the heat pump chiller 1 is maintained to a set water temperature while the minimum required water circulation amount is maintained in terms of the operation in the water circuit 4.

[0039]

As described above, according to Embodiment 1, the load-side quantity of heat, that is, the current quantity of heat that can be supplied from the load-side heat exchanger 21a to the air-conditioning load can be detected with use of the water temperature and the water pressure of the circulating water, and hence the load-side quantity of heat can be detected with higher accuracy as compared to that in the related art in which only the water temperature of the circulating water has been used. [0040]

Further, the operation capacity of the compressor 11 and the water amount of the circulating water can be optimally adjusted based on the necessary quantity of heat, on the operation information of the heat pump chillers 1 and the pump 3, and on the load-side control information (water temperature and water pressure of circulating water). Thus, an effect of increasing the efficiency of the entire air-conditioning system can be obtained.

[0041]

Further, when the necessary quantity of heat is calculated, in addition to the intake air temperature detected by the intake temperature sensor 25, the intake air humidity detected by the humidity sensor 26 is further used. Thus, the quantity of heat can be calculated more accurately. When the necessary quantity of heat is calculated with use of humidity as described above at the time of cooling, comfortable air-conditioning can be performed with high efficiency while giving consideration to humidity.

[0042]

Further, when the difference between the necessary quantity of heat and the current quantity of heat that can be supplied from the load-side heat exchanger 21a to the air-conditioning load is smaller than the set quantity of heat, the necessary quantity of heat can be obtained by controlling the motor valve 22 even without changing the operation conditions of the compressors 11 and the pump 3.

[0043]

Further, the pump 3 can be controlled based on the water pressure detected by the pressure sensors 24 so that the outlet water temperature of the load-side heat exchanger 21a is maintained to the set water temperature while the minimum required water circulation amount is maintained in terms of the operation in the water circuit 4.

[0044]

Further, a user interface may be added to the central controller 30 to create a monitoring environment. This configuration provides such an effect that energy management and system monitoring for reliably increasing the efficiency of the entire air-conditioning system can be performed.

[0045]

In Embodiment 1, the heat medium circulating the water circuit 4 is water, but the water may be replaced with, for example, brine obtained by mixing additives for lowering the freezing point into water.

[0046]

Embodiment 2

In Embodiment 1, the air-conditioning system is given as an example of the refrigeration system. In Embodiment 2, an example of a hot water supply system is described.

[0047]

Fig. 4 is a schematic configuration diagram of a hot water supply system according to Embodiment 2 of the present invention.

The hot water supply system includes heat pump chillers 41 that are heat source devices functioning as hot water supply units, a hermetic tank 42 that is a hot water storage tank for storing water heated by the heat pump chillers 41, and a water circuit 44 that is a hot water supply circuit configured to store the water heated by the heat pump chillers 41 to the hermetic tank 42 and to supply the water to hot water supply terminals 43. The hermetic tank 42 corresponds to the load-side device of the present invention.

[0048]

The water circuit 44 includes a water circuit 44a and a water circuit 44b. The water circuit 44a is a circuit in which the heat pump chillers 41 and the hermetic tank 42 are connected to each other by pipes so that water is circulated by a pump 49, to thereby convey a quantity of heat supplied by the heat pump chillers 1 to the hermetic tank 42. The water circuit 44b is a circuit in which the hermetic tank 42 and the hot water supply terminals 43 are connected to each other by pipes so that water is circulated by a pump 45 that is a hot water supply terminal-side pump.

[0049]

The hot water supply terminals 43 are, for example, showers or faucets. Fig.

is an illustration of a case in which three heat pump chillers 1 and one hermetic tank 42 are installed, but the illustration does not limit the number of heat pump chillers and hermetic tanks to be installed.

[0050]

Each of the structures of the heat pump chillers 41 are the same as those described in Embodiment 1 and include the compressor 11 whose operation capacity is variable by an inverter, and the water-refrigerant heat exchanger 12 serving as the heat source-side heat exchanger for heating or cooling circulating water to a target temperature with heat of refrigerant, for example, fluorocarbons. Further, the heat pump chiller 41 includes the refrigerant circuit (not shown) including the compressor 11, the pressure reducing device, and the heat exchanger, and functions as the heat source device configured to supply the heat of the refrigerant to the hermetic tank 42 by exchanging, in the water-refrigerant heat exchanger 12, heat between the refrigerant of the refrigerant circuit through which the refrigerant circulates and the circulating water in the water circuit 44a.

[0051]

The water circuit 44b includes temperature sensors 46 (46a and 46b) that are heat medium temperature sensors and pressure sensors 47 (47a and 47b) that are heat medium pressure sensors.

[0052]

The temperature sensor 46a is arranged on a water inlet pipe of the hermetic tank 42, and is configured to detect the temperature of the circulating water at the inlet of the hermetic tank 42. The temperature sensor 46b is arranged on a water outlet pipe of the hermetic tank 42, and is configured to detect the temperature of the circulating water at the outlet of the hermetic tank 42. The temperature sensor 46b constructs the load index sensor of the present invention.

[0053]

The pressure sensor 47a is arranged on the water inlet pipe of the hermetic tank 42, and is configured to detect the pressure of the circulating water at the inlet of the hermetic tank 42. The pressure sensor 47b is arranged on the water outlet pipe of the hermetic tank 42, and is configured to detect the pressure of the circulating water at the outlet of the hermetic tank 42.

[0054]

Detection signals of those sensors 46 and 47 are output to a load-side controller 48 to be described later.

[0055]

The hot water supply system further includes the load-side controller 48 configured to receive the detection signals of the sensors 46 and 47, and a central controller 50 configured to control the entire hot water supply system.

[0056]

The load-side controller 48 is configured to transmit the signals of the sensors 46 and 47 to the central controller 50 via a control signal line 51, and to calculate the quantity of heat necessary for maintaining the target water temperature in the hermetic tank 42. Further, the load-side controller 48 is connected to the pump 45. The load-side controller 48 may be constructed of hardware, for example, a circuit device for achieving the function of the load-side controller 27, or may be constructed of a calculation device, for example, a microcomputer or a CPU, and software to be executed thereon.

[0057]

The central controller 50 is connected to the heat pump chillers 41 and the load-side controller 48 by a control signal line 51. The central controller 50 is configured to calculate an optimal operation condition based on the information obtained from each of the heat pump chillers 41, the pump 45, and the load-side controller 48 to output the operation instructions to the heat pump chillers 41 and the pump 45. The central controller 50 may be constructed of hardware, for example, a circuit device for achieving the function of the load-side controller 27, or may be constructed of a calculation device, for example, a microcomputer or a CPU, and software to be executed thereon.

[0058]

Description is given here of a configuration in which the operation control of the entire hot water supply system is performed by performing data communication between the load-side controller 48 and the central controller 50 to achieve cooperative processing, but the present invention may have a configuration in which the central controller 50 also has the function of the load-side controller 48 so that the central controller 50 may perform the operation control of the entire air-conditioning system. The load-side controller 48 and the central controller 50 construct a controller of the present invention.

[0059]

Fig. 5 is a flow chart for illustrating the operation of the air-conditioning system according to Embodiment 2 of the present invention.

In the air-conditioning system configured as described above, the temperature sensors 46 and the pressure sensors 47 are used to detect the water temperature and the water pressure of the circulating water (S11). Then, the load-side controller 48 determines whether or not the outlet water temperature of the hermetic tank 42 detected by the temperature sensor 46b matches with a target water temperature (S12). The outlet water temperature detected by the temperature sensor 46b corresponds to a load index for determining the current load on the load side. Then, when the outlet water temperature does not match with the target water temperature, the load-side controller 48 calculates the necessary quantity of heat for causing the outlet water temperature to match with the target water temperature based on detection results of the temperature sensors 46 and the humidity sensors 47 (S13). The necessary quantity of heat is calculated while also giving consideration to the current quantity of heat that can be supplied from the hermetic tank 42 to a hot water supply load. Specifically, the load-side controller 48 performs calculation based on the temperature difference between the outlet water temperature and the target water temperature, and on the detection results of the temperature sensors 46 and the pressure sensors 47.

[0060]

The quantity of heat necessary for maintaining the water temperature inside the hermetic tank 42 to the target water temperature is influenced by the quantity of heat flowing out the hot water supply terminal 43, and this influence appears in the values of the temperature sensors 46 and the pressure sensors 47. Therefore, with use of the values of the temperature sensors 46 and the pressure sensors 47, the quantity of heat necessary for maintaining the water temperature inside the hermetic tank 42 to the target water temperature can be calculated while also giving consideration to the quantity of heat flowing out the hot water supply terminal 43.

[0061]

Then, the load-side controller 48 transmits the information on the calculated necessary quantity of heat to the central controller 50 via the control signal line 51. [0062]

The central controller 50 calculates the optimal operation condition based on the necessary quantity of heat transmitted from the load-side controller 48 and on the operation information of the heat pump chillers 41, and outputs the operation instruction to each of the compressors 11 of the heat pump chillers 41 and the pump 49 (S14), to thereby control the operation capacity of each component. The idea for determining the number of compressors 11 of the heat pump chillers 41 to be operated and the operation capacities of the compressors 11 and the pump 49 is similar to that in Embodiment 1.

[0063]

Further, the load-side controller 48 detects the pressure drop of the water circuit 44b due to the usage of the hot water supply terminal 43 by the pressure sensors 47 arranged in the water circuit 44b. Then, the load-side controller 48 controls the operation capacity of the pump 45 based on the detected water pressure so that an optimized water circulation amount may be obtained in a manner that the water pressure of the hot water supply terminal 43 is maintained to a set water pressure.

[0064]

Further, even when the hot water supply terminal 43 is not used, it is necessary to circulate the water to the vicinity of the hot water supply terminal 43 so that warm water can be provided as soon as the hot water supply terminal 43 is used. At this time, the load-side controller 48 operates the pump 45 at a minimum required level so that the temperature difference of the temperature sensors 46 at the outlet and the inlet of the hermetic tank 42 is maintained constant.

[0065]

As described above, according to Embodiment 2, the current quantity of heat that can be supplied from the hermetic tank 42 to the hot water supply load and the necessary quantity of heat are calculated with use of the load index and the water temperature and pressure of the circulating water. Thus, those quantities of heat can be detected with higher accuracy as compared to that in the related art in which only the water temperature of the circulating water has been used. As a result, the operation capacity and the water amount of the circulating water can be optimally adjusted, and hence an effect of increasing the efficiency of the entire air-conditioning system can be obtained.

[0066]

Further, the hot water supply system capable of maintaining the water pressure of the hot water supply terminal 43 can be obtained by arranging the pressure sensors 47 on the water inlet pipe and the water outlet pipe of the hermetic tank 42, and outputting the operation instruction to the pump 45. When the hot water supply terminal 43 is not used, the electrical power can be saved during the heat-retention operation of the water circuit 44b by arranging the temperature sensors 46 on the water inlet pipe and the water outlet pipe of the hermetic tank 42 and operating the pump 45 at the minimum required level.

[0067]

Incidentally, the systems described in Embodiment 1 and Embodiment 2 are systems in which a heat pump chiller including a heat exchanger for heating or cooling water to a target temperature with heat of refrigerant, for example, fluorocarbons is used as the heat source device, but the refrigeration system of the present invention is not limited to the above-mentioned configuration in which the heat pump chiller is used as the heat source device. Needless to say, the present invention is applicable to a system in which, for example, other chillers, boilers, or electric hot water supply units are used as the heat source.

Reference Signs List [0068] heat pump chiller 2 load-side device 3 pump 4 water circuit 5 control signal line 6 controller 7 relay board 10 pressure sensor 11 compressor 12 water-refrigerant heat exchanger 21 fancoil

21a load-side heat exchanger 21b fan 22 motor valve 23 (23a, 23b) temperature sensor (heat medium temperature sensor) 24 (24a, 24b) pressure sensor (heat medium pressure sensor) 25 intake temperature sensor 26 humidity sensor 27 load-side controller 30 central controller 31 control signal line 41 heat pump chiller 42 hermetic tank 43 hot water supply terminal 44 (44a, 44b) water circuit 45 pump 46 (46a, 46b) temperature sensor (heat medium temperature sensor) 47 (47a, 47b) pressure sensor (heat medium pressure sensor) 48 load-side controller 49 pump 50 central controller 51 control signal line

Claims

CLAIMS [Claim 1]

A refrigeration system, comprising:

a heat source device including a compressor and a heat source-side heat exchanger configured to exchange heat between refrigerant and a heat medium;

a load-side device;

a heat medium circuit in which the heat source-side heat exchanger and the load-side device are connected to each other by a pipe so that the heat medium is circulated by a pump, to thereby convey a quantity of heat supplied by the heat source device to the load-side device;

a heat medium temperature sensor configured to detect a temperature of the heat medium;

a heat medium pressure sensor configured to detect a pressure of the heat medium;

a load index sensor configured to detect a load index for determining a load in the load-side device; and a controller configured to control an operation of the compressor and an operation of the pump based on a value obtained from each of the heat medium temperature sensor, the heat medium pressure sensor, and the load index sensor. [Claim 2]

The refrigeration system of claim 1, wherein the load-side device comprises a fan coil including a load-side heat exchanger and a fan, the load-side heat exchanger being connected to the pipe so that the heat medium of the heat medium circuit circulates therethrough, wherein the heat medium temperature sensor comprises temperature sensors configured to detect temperatures of the heat medium at an outlet and an inlet of the load-side heat exchanger, respectively, wherein the heat medium pressure sensor comprises pressure sensors configured to detect pressures at an outlet and an inlet of the heat medium of the fan coil, respectively, and wherein the load index sensor comprises an intake temperature sensor configured to detect a temperature of intake air to the fan coil.

[Claim 3]

The refrigeration system of claim 2, further comprising a humidity sensor configured to detect a humidity of the intake air to the fan coil, wherein the controller is configured to control the operation of the compressor and the operation of the pump with further use of the humidity detected by the humidity sensor.

[Claim 4]

The refrigeration system of claim 3, wherein the controller is configured to control the operation of the compressor and the operation of the pump with use of the humidity detected by the humidity sensor during cooling in which the fan coil exchanges heat between the heat medium and air to cool the air, to thereby supply the air to an indoor space.

[Claim 5]

The refrigeration system of any one of claims 2 to 4, further comprising a motor valve configured to adjust a flow rate of the heat medium flowing into the load-side heat exchanger of the fan coil, wherein, when a difference between a necessary quantity of heat necessary for causing an intake temperature detected by the intake temperature sensor to match with a target temperature and a quantity of heat that is suppliable from the load-side device to an air-conditioning load is smaller than a set quantity of heat set in advance, the controller is configured to control the motor valve to obtain the necessary quantity of heat, and wherein, when the difference is larger than the set quantity of heat, the controller is configured to control the operation of the compressor and the operation of the pump to obtain the necessary quantity of heat.

[Claim 6]

The refrigeration system of any one of claims 2 to 5, wherein the controller is configured to control the operation of the pump based on the pressure detected by the heat medium pressure sensor so that an outlet water temperature of the load-side heat exchanger is maintained to a set water temperature while a minimum required circulation amount is maintained in terms of an operation in the heat medium circuit. [Claim 7]

The refrigeration system of claim 1, wherein the heat medium comprises water, wherein the load-side device comprises a hot water storage tank, wherein the heat medium circuit comprises a hot water supply circuit configured to store the water heated by the heat source-side heat exchanger to the hot water storage tank, and to supply the water to a hot water supply terminal, wherein the heat medium temperature sensor comprises temperature sensors configured to detect water temperatures at an outlet and an inlet of the hot water storage tank, respectively, wherein the heat medium temperature sensor configured to detect the water temperature at the outlet of the hot water storage tank also serves as the load index sensor, and wherein the heat medium pressure sensor comprises pressure sensors configured to detect pressures at the outlet and the inlet of the hot water storage tank, respectively.

[Claim 8]

The refrigeration system of claim 7, wherein the hot water supply circuit further comprises a hot water supply terminal-side pump configured to circulate the water between the hot water storage tank and the hot water supply terminal, and wherein, when the heat medium pressure sensor detects reduction of a water pressure of the hot water supply circuit during usage of the hot water supply terminal, the controller is configured to control the hot water supply terminal-side pump so that the water pressure of the hot water supply circuit is maintained to a set water pressure.

[Claim 9]

The refrigeration system of claim 8, wherein the controller is configured to operate the hot water supply terminal-side pump at a minimum required level so that a temperature difference of the water between the outlet and the inlet of the hot water storage tank is maintained constant.

5 [Claim 10]

The refrigeration system of any one of claims 1 to 9, wherein the heat source device comprises a plurality of heat source devices, and wherein the controller is configured to determine a number of compressors to 10 be operated and an operation capacity of the compressor with use of information representing a relationship between a load factor of the compressor and compressor efficiency so that the compressors of the plurality of heat source devices are operated within a set load factor range including a load factor for obtaining the maximum compressor efficiency.