JPH09170824A - Heat conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of overload operation of a liquid pump due to a fluctuation of the load by a method wherein a closed circuit having a plurality of heat-exchangers on the utilization side are connected together in parallel is sealed with a refrigerant the gas liquid phase of which is changed and a bypass device is provided between the delivery side and the suction side of a liquid pump. SOLUTION: A liquid pump 1, a heat-exchanger 2 on the heat source side, heat-exchangers 4a-4c on the utilization side, flow rate control valves 5a-5c, and a liquid receiver 7 having a radiator 8 are connected together, in the order, through a gas pipe 3 and a liquid pipe 6 to form a closed circuit. The closed circuit is sealed with a refrigerant as a medium for conveying a hot heat. A bypass device 9 comprising a differential pressure valve 9a and a bypass pipe 9b is connected in parallel to the liquid pump 1. The bypass device 9 opens and closes the differential pressure valve 9a according to a differential pressure between the outlet and the inlet of the liquid pump 1. This constitution performs operation in a flow rate of a refrigerant corresponding to a heating load and prevents the occurrence of an overload to the liquid pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer device for use in an air conditioner and the like, and more particularly to a heat transfer device using a refrigerant that changes a gas-liquid phase as a medium.

[0002]

2. Description of the Related Art There is known a heat transfer device for supplying a heat source to a load side of an air conditioner or the like, which uses, as a medium, a refrigerant which changes a gas-liquid phase instead of water. For example, the one described in JP-A-4-236063 is known. The heat transfer device is as shown in FIG. 3, and includes a liquid pump 101, a heat source side heat exchanger 102, a use side heat exchanger 104, a liquid receiver 105, a gas pipe 103 and a liquid pipe 1.
06 are sequentially connected to form a closed circuit, and a refrigerant is sealed in the closed circuit as a medium for transferring heat. 1
00 is a heat pump, and this heat pump 100
Is a compressor 90, the heat source side heat exchanger 102, an expansion valve 9
1. An evaporator 92 for pumping heat from the outside air is sequentially connected. The heat source side heat exchanger 102 is a condenser of the heat pump 100, and radiates the warm heat pumped up by the evaporator 92 to the heat transfer device side.

In the above heat transfer device, the liquid refrigerant discharged from the liquid pump 101 is heated and vaporized by the heat source side heat exchanger,
In the use side heat exchanger 104, water, air, etc. are heated to be cooled and liquefied, and then returned to the pump 101 via the liquid receiver 105.
By this cycle, the heat pumped up from the outside air or the like by the heat pump is given to the heat transfer device via the heat source side heat exchanger and added to the object to be heated via the use side heat exchanger.

[0004]

However, in such a device, since the load detecting means of the liquid pump 101 is not provided, the load of the utilization side heat exchanger 104 is reduced, and the heat source side heat exchanger 102 is removed. When the amount of the gas refrigerant flowing to the usage-side heat exchanger 104 becomes larger than the load, the gas refrigerant flows out of the usage-side heat exchanger 104 in a gaseous state, and the refrigerant flows in the liquid pipe 106. There is a problem that the resistance becomes large and the liquid pump 101 is overloaded.
In particular, when a plurality of use-side heat exchangers 104 are connected and the loads are different for each of the plurality of use-side heat exchangers, it is necessary to control the flow rate for each of the use-side heat exchangers according to changes in different loads. Further, the fluctuation of the load on the liquid pump becomes more remarkable, but such a problem has not been solved at all.

The present invention has been made by paying attention to such conventional problems, and its purpose is to:
An object of the present invention is to prevent an overload operation of a liquid pump caused by a change in load in a device that transfers heat of a heat source to a load side such as an air conditioner using a refrigerant as a medium. Further, when a plurality of use side heat exchangers are used, it is possible to distribute the refrigerant flow rate to each heat exchanger according to the load.

[0006]

To achieve the above object, in the invention described in claim 1, a liquid pump, a heat source side heat exchanger, a plurality of utilization side heat exchangers, and a pressure adjusting radiator are attached. The liquid receivers are sequentially connected, and a refrigerant having a gas-liquid phase change is enclosed in a closed circuit formed by connecting the plurality of utilization side heat exchangers in parallel, and the discharge side and the suction side of the liquid pump. And a bypass device having a function of keeping the differential pressure between the suction side pressure and the discharge side pressure constant or within a predetermined range.

According to the second aspect of the invention, the bypass device is constituted by providing a differential pressure valve for maintaining the differential pressure constant or within a predetermined range between the discharge side and the suction side of the liquid pump. It is a thing.

In the invention according to claim 3, between the discharge side and the suction side of the liquid pump, the suction side pressure and the discharge side pressure of the liquid pump are respectively detected to control the opening degree, and the differential pressure The bypass device is configured by providing a control valve that keeps the temperature constant or within a predetermined range.

According to a fourth aspect of the invention, a flow rate control valve for controlling the flow rate corresponding to each heating load is provided in each branch pipe connecting the plurality of utilization side heat exchangers. .

Therefore, in the heat transfer apparatus according to the first aspect, when the heating load decreases and the operating load of the liquid pump increases, the suction side pressure is increased between the discharge side and the suction side of the liquid pump. The bypass device, which has the function of keeping the pressure difference with the discharge side pressure constant or within a predetermined range, is opened, and the differential pressure of the liquid pump is kept constant or within a predetermined value, preventing overload operation of the liquid pump. It

Further, in the heat transfer device according to claim 2,
Since only the differential pressure valve is provided between the discharge side and the suction side of the liquid pump, the above object can be achieved with a simple configuration.

Further, in the heat transfer device according to the third aspect, a control valve is provided for controlling the opening by detecting the suction side pressure and the discharge side pressure, respectively, and keeping the differential pressure constant or within a predetermined range. Therefore, it is possible to apply electronic technology suitable for high-level control.

Further, in the invention of claim 4, since the refrigerant circulation amount of each utilization side heat exchanger is controlled to correspond to the heating load by the action of the flow control valve, the refrigerant flow amount is appropriately distributed. Be seen.

[0014]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described below with reference to FIG. As shown in FIG. 1, the liquid pump 1, the heat source side heat exchanger 2, the plurality of utilization side heat exchangers 4 a, 4
b, 4c, a plurality of flow rate control valves 5a, 5b, 5c, and a liquid receiver 7 provided with a radiator 8 are sequentially connected by a gas pipe 3 and a liquid pipe 6 to form a closed circuit. In the above closed circuit, the use side heat exchangers 4a, 4b, 4c and the flow control valves 5a, 5
Each of b and 5c is connected to a pair of parallel branch pipes branching the liquid pipe 3. Further, a refrigerant is enclosed in the closed circuit as a medium for carrying heat.

In the above cycle, the pressure inside the liquid receiver 7 and the pressure inside the utilization side heat exchanger become saturation temperatures corresponding to the respective temperatures. Further, in order to smoothly circulate the refrigerant, the pressure inside the liquid receiver 7 is set to the use side heat exchangers 4a, 4b,
The pressure of the liquid refrigerant in 4c must be lower than the head difference due to the difference in height between the liquid receiver 7 and the use side heat exchangers 4a, 4b, 4c, and the flow resistance of the liquid refrigerant flowing between the two devices. I won't. The radiator 8 attached to the liquid receiver 7 is provided to make this pressure difference, and cools the liquid refrigerant in the liquid receiver 7 with a cooling medium such as outside air to reduce the pressure.

A bypass device 9 is composed of a differential pressure valve 9a and a bypass pipe 9b and is connected to the liquid pump 1 in parallel. The bypass device 9 opens and closes the differential pressure valve 9a according to the differential pressure at the inlet and outlet of the liquid pump 1. That is, when the differential pressure of the liquid pump 1 is reduced, the opening of the differential pressure valve 9a of the bypass device 9 is decreased, and when the differential pressure is increased, the opening is increased.
The differential pressure between the discharge and suction of the liquid pump 1 is kept constant or within a predetermined range.

The flow rate control valves 5a, 5b and 5c control the flow rates of the refrigerant flowing to the use side heat exchangers 4a, 4b and 4c according to the heating loads of the use side heat exchangers 4a, 4b and 4c. As a method for detecting the heating load, for example, when the use-side heat exchanger heats air, a normal method such as a method of considering the heating load from the difference between the air temperature on the heated side and the set temperature is used.

Next, the operation of the heat transfer device thus constructed will be described. The liquid refrigerant discharged from the liquid pump 1 enters the heat source side heat exchanger 2, where it absorbs heat from a high-temperature heat source, such as hot water, a burner, the waste heat of condensation of the heat pump, and evaporates to become a gas refrigerant. This gas refrigerant is the gas pipe 3
The heat exchanger 4a, 4b, 4c enters the heat exchangers 4a, 4b, 4c through which the heat is radiated to a low-temperature object to be heated, for example, room air, to be condensed and liquefied. The liquid refrigerant enters the liquid receiver 7 through the liquid pipe 6 and is stored in the liquid receiver 7 below. The liquid refrigerant in the liquid receiver passes through the liquid pipe 6 and returns to the liquid pump 1 to repeat the circulation cycle.

Here, the utilization side heat exchangers 4a, 4b, 4
When the temperature of the object to be heated in c all rises and the entire heating load decreases, the refrigerant at the outlets of the heat exchangers 4a, 4b, 4c on the use side becomes gaseous and the pressure difference between the suction and discharge of the liquid pump 1 increases. At this time, since the differential pressure valve 9a of the bypass device 9 is activated and the bypass device 9 is released, the pressure on the suction side of the liquid pump 1 is increased, and the use side heat exchangers 4a, 4b, 4c.
The amount of refrigerant flowing through is also adjusted to correspond to the load.

When the heating load of some of the use side heat exchangers 4a, 4b or 4c is reduced, the refrigerant flow rate control valve connected to the branch pipe of the liquid pipe corresponds to the reduction of the heating load. 5a, 5b or 5c reduces its opening degree and changes the amount of refrigerant gas commensurate with the heating load to the utilization side heat exchangers 4a, 4b, 4
It is controlled to flow to c. For this reason, the amount of refrigerant discharged from the liquid pump 1 increases with respect to the heating load of the heat transfer device, and the refrigerant flow resistance circulating in the circuit increases. In this example, however, the differential pressure valve 9a is used between the suction and discharge of the liquid pump 1. The opening is adjusted so that the resistance is constant, the gas refrigerant on the discharge side is bypassed to the suction side, and the operating load of the liquid pump 1 is prevented from becoming excessive.

Part of the use side heat exchangers 4a, 4b or 4
When the heating of c becomes unnecessary, the refrigerant flow control valves 5a, 5
b or 5c may be completely closed, but in this case, when the outlet side of the use side heat exchanger 4a, 4b or 4c is completely closed and the surroundings of the heat exchanger are gradually cooled,
There is a risk that the liquid refrigerant gradually accumulates in the heat exchanger, and the amount of circulating refrigerant becomes insufficient. In order to prevent this, it is preferable that the refrigerant flow rate control valves 5a, 5b, 5c be opened minutely so that a slight flow rate occurs in the fully closed state.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the bypass device 19 connects the bypass pipe 19b from the discharge side to the suction side of the liquid pump 1, connects the flow control valve 19a in the middle of the pipe 19b, and uses the discharge pressure sensor 19c. The pressure detector 19e detects a pressure difference between the detected discharge pressure and the suction pressure detected by the suction pressure sensor 19d, and adjusts the opening of the flow control valve 19a so that the pressure difference becomes a predetermined pressure difference. . Also in this example, the discharge and suction pressure differences of the liquid pump are kept constant and the overload operation of the liquid pump 1 is prevented as in the above-described embodiment.

The present invention can be modified and embodied as follows. (1) The liquid pump 1 is a reversible pump, and the heat source side heat exchanger 2
A cold heat source is supplied to the tank, the liquid pump 1 is rotated in the reverse direction, and the liquid refrigerant is allowed to flow in the opposite direction to enable the transfer of cold heat. (2) Use-side heat exchangers 4a, 4b, 4c The inlet side flow control valve should be an on-off valve instead of a proportional control valve. (3) In the second embodiment, the discharge pressure sensor 19c
And use a differential pressure sensor instead of the suction pressure sensor 19d. (4) The flow rate control valves 5a, 5b, 5c are configured to be slightly opened in the fully closed state, but instead of this, the flow rate control valves 5a, 5b, 5c are completely fully closed without a minute opening. And, the flow rate control valves 5a, 5b, and 5c should be connected in parallel with the capillary tubes through which a small amount of refrigerant flows.

[0024]

Since the present invention is configured as described above, it has the following effects. According to the invention described in claims 1 to 3, the differential pressure between the discharge pressure and the suction pressure of the liquid pump is kept constant, the operation of the refrigerant flow rate corresponding to the heating load becomes possible, and the overload of the liquid pump is prevented. It can be prevented.

According to the fourth aspect of the present invention, the flow rate of the refrigerant corresponding to the load is distributed to each of the utilization side heat exchangers, and stable operation can be performed.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a heat transfer device according to a first embodiment.

FIG. 2 is a refrigerant circuit diagram of the heat transfer device according to the second embodiment.

FIG. 3 is a refrigerant circuit diagram of a conventional heat transfer device.

[Explanation of symbols]

 1 Liquid Pump 2 Heat Source Side Heat Exchanger 3 Gas Pipe 4a, 4b, 4c Utilization Side Heat Exchanger 5a, 5b, 5c Flow Control Valve 6 Liquid Pipe 7 Liquid Receiver 8 Radiator 9 Bypass Device 9a Differential Pressure Valve 9b Bypass Pipe 19 Bypass device

Claims (4)

[Claims] 1. A liquid pump, a heat source side heat exchanger, a plurality of use side heat exchangers, and a liquid receiver provided with a radiator are sequentially connected by piping, and the plurality of use side heat exchangers are parallel to each other. A connected closed circuit is filled with a refrigerant that changes in gas-liquid phase, and the pressure difference between the suction side pressure and the discharge side pressure is constant or within a predetermined range between the discharge side and the suction side of the liquid pump. A heat transfer device comprising a bypass device having a function of keeping the heat transfer function. 2. The bypass device is constituted by providing a differential pressure valve for maintaining the differential pressure constant or within a predetermined range between the discharge side and the suction side of the liquid pump. The heat transfer device according to claim 1. 3. The pressure difference between a discharge side and a suction side of the liquid pump is controlled by detecting a suction side pressure and a discharge side pressure of the liquid pump, and the differential pressure is kept constant or within a predetermined range. The heat transfer device according to claim 1, wherein the bypass device is configured by providing a control valve that keeps the bypass valve. 4. The flow control valve for controlling the flow rate according to each heating load is provided in each branch pipe connecting the plurality of utilization side heat exchangers. Heat transfer device.