JPH07217969A - Refrigerant circulation type air conditioning system - Google Patents

Abstract

PURPOSE:To prevent the phenomenon of cavitation of a pump due to insufficiency of a refrigerant liquid by a method wherein motor operated valves controlling supply of a refrigerant to a heat exchanger are opened and the refrigerant liquid kept in heat exchangers is supplied onto the suction side of the pump, when an inlet temperature of a refrigerant gas carrying pipe becomes the temperature of liquefaction of the refrigerant or below at the time of heating. CONSTITUTION:When a system is switched over to a heating operation, a motor operated valve 6 is closed and a refrigerant passing through heat exchangers of fan coil units 2 and liquefied flows onto the suction side of a pump 5. When the pump 5 is driven then, motor operated valves 21 are opened automatically, a refrigerant gas produced by heating and evaporation in a heat exchanger 1 flows through a refrigerant gas carrying pipe 3 and passes through the heat exchangers of the fan coil units 2 and, on the occasion, the refrigerant liquefied by heat exchange is returned to the heat exchanger 1 via a refrigerant liquid carrying pipe 4. The motor operated valves 21 are controlled to open when an inlet temperature to the units 2 of the refrigerant gas detected by a temperature detector 7 becomes the temperature of liquefaction of the refrigerant or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant circulation type air conditioning system in which a carrier pipe is commonly used for cooling and heating, and a pump capable of returning a refrigerant liquid during heating can prevent a cavitation phenomenon from occurring. The present invention relates to a circulation type air conditioning system.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a heat exchanger is installed at an upper position of a building, and a refrigerant gas carrier pipe and a refrigerant are installed between the heat exchanger and a fan coil unit installed in each room in the building. A closed circuit in which the refrigerant circulates by connecting with a liquid transfer pipe,
When cooling, each room is cooled by natural circulation of the refrigerant liquid in the heat exchanger to the fan coil unit by the action of gravity and the pressure of the vaporized refrigerant gas, and when heating, the liquefied refrigerant liquid is returned to the heat exchanger. There is a refrigerant circulation type air conditioning system with a pump installed in the lower position, but in this system, the refrigerant gas heated by the heat exchanger during the heating operation and vaporized refrigerant gas passes through the refrigerant gas transfer pipe and is a fan in each room. It is supplied to the heat exchanger of the coil unit, cooled by heat exchange with indoor air and liquefied, and this refrigerant liquid flows into the suction side of the pump at the lower position of the building by its own weight, and the heat exchange is performed by driving this pump. A circulation system is formed, which is returned to the reactor, is vaporized there again, and is supplied to the heat exchanger of the fan coil unit in each room.

[0003]

[Problems of the prior art] During so-called full load operation in which all fan coil units are operating, the heat exchanger of all fan coil units is filled with a refrigerant gas, and the refrigerant liquefied through the heat exchanger. The liquid will be sent to the pump,
The amount of this refrigerant liquid is large, and a sufficient amount of the refrigerant liquid will be accumulated in the liquid pipe on the suction side of the pump, and the liquid head can be secured, so that the refrigerant liquid can be smoothly returned to the heat exchanger as the heat source. However, when the fan coil unit stops heating operation, the valve body of the motor-operated valve that controls the supply of the refrigerant to the heat exchanger of each fan coil unit is automatically closed, so that the refrigerant liquid is stored in the heat exchanger. Will stay in.
The amount of refrigerant liquid flowing into the suction side of the pump decreases when the operation of all fan coil units is stopped or during so-called partial load operation in which some fan coil units are operating, and the liquid head of the liquid pipe on the suction side of the pump decreases. Becomes insufficient, causing a so-called cavitation phenomenon, which causes a problem that the refrigerant liquid cannot be smoothly returned to the heat exchanger.

In order to solve the above-mentioned inconvenience, conventionally, a liquid receiver is provided on the suction side of the pump, and the liquid head of the liquid pipe on the suction side of the pump is secured by the refrigerant liquid retained in the liquid receiver. Although the cavitation phenomenon of the pump was prevented, not only the equipment cost becomes high because the receiver and the extra refrigerant retained in the receiver are required during the circuit configuration of the system, but also a large amount of refrigerant leaks. However, there is a problem that the risk becomes large in case of failure.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention measures the inlet temperature of a refrigerant gas carrier pipe to a fan coil unit during heating, and the measured temperature is below the liquefying temperature of the refrigerant. When the fan coil unit heats up, the motor valve that controls the supply of refrigerant to the heat exchanger is energized to open the valve body, and the refrigerant liquid retained in the fan coil unit heat exchanger is transferred to the suction side of the pump. It is an object of the present invention to provide a refrigerant circulation type air conditioning system which can be supplied to prevent the cavitation phenomenon of a pump.

[0006]

DISCLOSURE OF THE INVENTION In a refrigerant circulation type air conditioning system according to the present invention, a heat exchanger is installed at an upper position of a building, and a refrigerant gas is provided between the heat exchanger and a fan coil unit installed in each room in the building. To form a closed circuit in which the refrigerant circulates by connecting the carrier pipe and the refrigerant liquid carrier pipe, and during cooling, naturally circulate the refrigerant liquid in the heat exchanger through the fan coil unit by the action of gravity and the pressure of the vaporized refrigerant gas. In a refrigerant circulation type air-conditioning system in which each room is cooled by, and a pump for returning the liquefied refrigerant liquid to the heat exchanger at the time of heating is provided in the lower position, at the time of heating, the inlet to the fan coil unit of the refrigerant gas transfer pipe The temperature is measured, and when the measured temperature becomes equal to or lower than the liquefaction temperature of the refrigerant, the motor-operated valve that controls the supply of the refrigerant to the heat exchanger of each fan coil unit is energized to open the valve body and blow the fan. The refrigerant liquid which is retained in the heat exchanger yl unit is characterized in that it has to be supplied to the pump side.

[0007]

The inlet temperature of the refrigerant gas carrier pipe to the fan coil unit is measured, and when the measured temperature becomes equal to or lower than the liquefaction temperature of the refrigerant, the refrigerant is supplied to the heat exchangers of all the fan coil units. The valve element is opened by energizing the motor-operated valve for controlling the above, and the refrigerant liquid retained in the heat exchanger of the fan coil unit is supplied to the suction side of the pump to eliminate the cavitation phenomenon of the pump due to insufficient refrigerant liquid.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the system of the present invention will be specifically described with reference to the drawings. FIG. 1 is a schematic configuration diagram of the system of the present invention, in which 1 is a heat exchanger installed in a machine room on the roof of a building, to which cold water is supplied during cooling and hot water is supplied during heating, and an internal heat exchange coil The refrigerant passing through (not shown) is cooled or heated. 2 ... 2 is a fan coil unit installed in each room, 21 is an electrically operated valve that is automatically closed when the operation of each fan coil unit is stopped to shut off the supply of the refrigerant to the heat exchanger (not shown) Therefore, it is preferable to use an auto-return type electric valve in which the valve body opens during energization and automatically closes when the energization is cut off. 3 returns the vaporized refrigerant gas to the heat exchanger 1 after passing through the heat exchanger of the fan coil unit 2 during cooling, and the refrigerant gas heated and vaporized by the heat exchanger 1 during heating to each fan coil unit 2
Refrigerant gas carrier pipes 4 for supplying to the heat exchanger of the fan supply the refrigerant liquid cooled and liquefied by the heat exchanger 1 to each fan coil unit 2 during cooling, and the heat exchanger of each fan coil unit 2 during heating. Refrigerant liquid carrier pipes 5 for returning the liquefied refrigerant liquid to the heat exchanger 1 after passing through the heat exchanger 1 pass through the heat exchangers of the fan coil units 2 during heating to the heat exchanger 1. The pump 6 for returning is an electrically operated valve that opens and closes alternately during cooling and heating to control the flow of the refrigerant. 7 is a fan coil unit 2 of the refrigerant gas carrier pipe 3.
The fan coil unit of the refrigerant gas carrier pipe 3 is a control device installed in each fan coil unit 2 that measures an inlet temperature to the fan gas and outputs an electric signal when the measured temperature becomes equal to or lower than the liquefaction temperature of the refrigerant. The temperature of the inlet pipe to 2 is measured by a temperature detector 71 such as a thermistor, and when the temperature of the refrigerant is below a certain set temperature, an electric current is passed through each motor-operated valve 21. Further, as shown in FIG. 2, the controller 7 measures the temperature of the inlet pipe to the fan coil unit 2 as well as the temperature of the outlet pipe, the outlet of the refrigerant of the heat exchanger, and the temperature detector 72 for measuring the air temperature of the inlet. , 73, 74 for performing various controls during cooling and heating.

In the case of heating, when the system is switched to heating operation, the motor-operated valve 6 is automatically closed, and the refrigerant liquid liquefied by passing through the heat exchanger of the fan coil units 2 ... 2 is directed to the suction side of the pump 5. It comes to flow. When the pump 5 is driven to operate the fan coil units 2 ... 2, the motor-operated valve 21 is automatically opened during the operation of the fan coil unit, so that the refrigerant gas heated by the heat exchanger 1 and vaporized is
Passing through the heat exchanger of the fan coil unit 2 operating through the refrigerant gas carrier pipe 3 in the direction of the dotted arrow, the refrigerant liquid liquefied by heat exchange is sent to the refrigerant liquid carrier pipe 4 by the pump 5, The heat exchanger 1 passing through the carrier pipe 4 in the direction of the arrow
And is again vaporized there and supplied to the fan coil unit through the refrigerant gas carrying pipe 3, and the room in operation is heated by the circulation of this refrigerant.

When the operation of the fan coil units 2 ... 2 is stopped, the motor-operated valves 21 ... 21 are closed, the circulation of the refrigerant is stopped, and the refrigerant gas staying in the refrigerant gas carrier pipe 3 gradually reaches the ambient temperature. It is cooled and liquefied, and the inside of the heat exchanger of the fan coil unit is filled with the refrigerant liquid.

Since the refrigerant gas flows to some extent until the inside of the heat exchanger is filled with the refrigerant liquid, the inlet pipe of the fan coil unit does not fall below the liquefaction temperature of the refrigerant, but when it becomes full, the temperature of the inlet pipe rapidly increases. When each of the temperature detectors 71 detects that the temperature is slightly lower than the liquefaction temperature of the refrigerant, it sends a signal to the control device 7, and each control device 7 causes the motor-operated valve 2 to operate.
Since the valve element is opened by energizing 1 for a certain period of time, the refrigerant liquid retained in the heat exchanger flows into the refrigerant liquid carrier pipe 4, and sufficient refrigerant liquid is accumulated on the suction pipe side of the pump 5. The pump does not cause cavitation phenomenon. Each control device 7 is operated by the motor-operated valve 21 after a certain time has elapsed.
The valve body of the motor-operated valve 21 is closed and the normal operation is resumed.

[0012]

According to the refrigerant circulation type air-conditioning system of the present invention, the inlet temperature to the fan coil unit of the refrigerant gas carrier pipe during heating is measured, and the measured temperature becomes equal to or lower than the liquefying temperature of the refrigerant. At times, the motor-operated valve that controls the supply of refrigerant to the heat exchangers of all fan coil units is energized to open the valve body, and the refrigerant liquid retained in the heat exchangers of the fan coil units is transferred to the suction side of the pump. Since it is designed to eliminate the pump cavitation phenomenon due to lack of refrigerant liquid, it is retained in the receiver and this receiver for compensating for the lack of refrigerant liquid on the suction side of the pump as in the conventional system. No extra refrigerant is needed and the minimum amount of refrigerant is sufficient, so the facility cost can be made extremely low compared to the conventional system, and the risk of refrigerant leakage can be minimized. It is kill things.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a system of the present invention.

FIG. 2 is a schematic diagram showing a relationship between a fan coil unit and a control device.

FIG. 3 is a schematic explanatory diagram of a conventional system.

[Explanation of symbols]

 1 Heat Exchanger 2 Fan Coil Unit 21 Motorized Valve 3 Refrigerant Gas Conveying Pipe 4 Refrigerant Liquid Conveying Pipe 5 Pump 6 Motorized Valve 7 Control Device

Claims (1)

[Claims] 1. A heat exchanger is installed at an upper position of a building, and the heat exchanger and a fan coil unit installed in each room in the building are connected by a refrigerant gas carrier pipe and a refrigerant liquid carrier pipe. It forms a closed circuit in which the refrigerant circulates, and during cooling, the refrigerant liquid in the heat exchanger is naturally circulated in the fan coil unit by the action of gravity and the pressure of the vaporized refrigerant gas to cool each room and to liquefy it during heating. In the refrigerant circulation type air conditioning system in which a pump for returning the refrigerant liquid to the heat exchanger is provided at the lower position, during heating, the inlet temperature to the fan coil unit of the refrigerant gas carrier pipe is measured, and the measured temperature is Refrigerant retained in the heat exchanger of the fan coil unit by energizing the motor-operated valve that controls the supply of the refrigerant to the heat exchanger of each fan coil unit when the temperature falls below the liquefaction temperature of the refrigerant to open the valve body. A refrigerant circulation type air conditioning system characterized in that liquid is supplied to the pump side.