JPH01256770A - Heat pump - Google Patents

Abstract

PURPOSE:To uniformly distribute a coolant to heat exchanger coils preventing a back flow of the refrigerant to a compressor by providing a liquid level sensor to a liquid separator to detect the liquid level in it, and regulating the opening of an expansion valve corresponding to signals from the liquid level sensor so as to maintain the liquid level within a specified range. CONSTITUTION:In heating operation, the refrigerant gas from a compressor 11 gives heat to hot water and liquefies in a heat exchanger 13, and enters a liquid receiver 15 as shown in solid lines and arrows. The high pressure liquid refrigerant is depressurized by expansion valve 16, vapor-liquid separation takes place in a liquid separator 1, and only the liquid refrigerant enters the bottom of heat exchange coils 18 of an air heat exchanger 17. The liquid refrigerant evaporates and the refrigerant gas is sucked by the compressor 11. Signals from a liquid level sensor 3 are transmitted to a control device 5, and the lift of the expansion valve 16 is regulated by the control device 5 so as to maintain the liquid level within a specified range. On the other hand, in cooling operation as shown in dotted lines and arrows, signals from a pressure-temperature sensor 4 are input to the control device 5, and the lift of the expansion valve 16 is regulated so as to keep the degree of overheating constant.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat pump used for heating and cooling a building, for example.

(Prior Art) Conventionally, most large-scale heat pumps for buildings are of a separate type as shown in FIG.

This heat pump has a compressor 1 as shown by the solid arrow.
1 to the first switching valve 12. Water heat exchanger 13゜Second switching valve 1
4. Receiver 15. Expansion valve 16. Second switching valve 14. Air heat exchanger 17. A heating operation flow path which is a circulation flow path for refrigerant returning to the compressor 11 via the first switching valve 12, and a heating operation flow path from the compressor 11 to the first switching valve 12 as shown by the broken arrow. Air heat exchanger 1
7. Second switching valve 14, water heat exchanger 13. First switching valve 12
The cooling operation flow path is a circulation flow path for refrigerant that returns to the compressor 11 via the air conditioner.

Furthermore, in the above-mentioned separate system, the air heat exchanger 17 is usually installed on the roof, and the other parts are installed in the lower part of the building (often underground).

During heating operation, the first. Second switching valve 12゜14
is in the state shown by the solid line, and the refrigerant gas compressed by the compressor 11 is cooled by hot water in the water heat exchanger 13, becomes a liquid, and accumulates in the liquid receiver 15. Furthermore, this accumulated refrigerant liquid is depressurized by an expansion valve 16 and sent to an air heat exchanger 17 installed on the roof, for example, and passes through an internal heat exchange coil 18, where it exchanges heat with the outside air. It is then evaporated, returned to the compressor 11, where it is compressed, and the same cycle as above is repeated thereafter.

In addition, FIG. 2 shows an example in which the expansion valve 16 is a general-purpose temperature-sensing type, and since the distance between the expansion valve 16 and the temperature-sensing part cannot be made large, the temperature-sensing valve is installed on the suction side of the compressor 11. A tube 19 is provided, and the opening degree of the expansion valve 16 is controlled by a signal from the temperature sensing tube 19 so that the degree of superheat of the refrigerant in this portion becomes an appropriate value.

By the way, when using an electrically operated expansion valve instead of the expansion valve 16, the pressure and temperature of the refrigerant are detected at the outlet of the air heat exchanger 17, converted into electrical signals, and the electrical signals are used to operate the expansion valve. control may also be carried out.

Note that during cooling operation, the first The second switching valve 12.14 is switched as shown by the broken line, and the refrigerant gas discharged from the compressor 11 radiates heat in the air heat exchanger 17, is cooled, enters the liquid receiver 15, and passes through the expansion valve 16. The water is completely vaporized in the process of passing through the water heat exchanger 13, and after removing heat from the water in the water heat exchanger 13, it returns to the compressor 11, and the cycle is repeated.

(Problems to be Solved by the Invention) In the separate type heat pump shown in FIG. Because of this, there is a delay in the response of the expansion valve 16 to the temperature change in the air heat exchanger 17, and there is a problem that liquid backflow to the compressor 11 is likely to occur.

In addition, originally, it is desirable to provide the expansion valve J6 at the inlet of the air heat exchanger 17 and control it by the temperature and pressure at the outlet. The pressure at the inlet of the expansion valve 16 decreases, flash gas is generated, and the expansion valve becomes uncontrollable. For this reason, as shown in FIG. 2, conventionally an expansion valve 16 is provided at the outlet of the liquid receiver 15 in the lower part of the building.
The refrigerant is depressurized and fed into a gas-liquid two-phase state to the rooftop air heat exchanger 17, which is generally known for the distribution of the refrigerant to the heat exchange coils 18 of the air heat exchanger 17. Distributors are used in appropriate combinations as special components.

As a result, conventional devices require a special distributor, and the larger the device, the more the heat exchange coil 18
There is a problem in that it becomes difficult to evenly distribute the refrigerant to the

The present invention has been made to address the above-mentioned conventional problems, and has made it possible to eliminate the liquid back-up phenomenon to the compressor and to evenly distribute refrigerant to the heat exchange coil 18 without using any special equipment. The aim is to provide a heat pump.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a first
Switching valve, water heat exchanger, second switching valve, liquid receiver.

A heating operation flow path which is a circulation flow path for refrigerant returning to the compressor via an expansion valve, a second switching valve, an air heat exchanger, and a first switching valve, and a heating operation flow path from the compressor to the first switching valve and air heat exchange. vessel, second
A switching valve, a liquid receiver, an expansion valve, a second switching valve, a water heat exchanger, a cooling operation flow path which is a circulation flow path for the refrigerant returning to the compressor via the first switching valve, and any appropriate one. In the heat pump configured to be switchable to one of the channels, a liquid separator is provided at the outlet of the air heat exchanger in the heating operation channel,
The lower part of the liquid separator is connected to the inlet of the air heat exchanger, and a liquid level sensor is attached to this liquid separator so that the internal liquid level can be detected. A control means is provided to adjust the opening degree of the expansion valve so that the detected liquid level falls within a certain range.

(Example) Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a heat pump according to the present invention, which is substantially the same as the heat pump shown in FIG. 2 except for the inlet/outlet portion of the air heat exchanger 17, the expansion valve 16, and its control system. Corresponding parts are given the same numbers and explanations are omitted.

As shown in the figure, in this heat pump, the expansion valve 16 at the outlet of the liquid receiver 15 is electrically operated, and the liquid separator 1 is provided at the outlet of the air heat exchanger 17 in the heating operation flow path. An on-off valve 2 is provided at the inlet of the heat exchanger 17, and the liquid pool at the bottom of the liquid separator l is connected to the air heat exchanger 17.
and the opening/closing valve 2. In addition, a liquid level sensor 3 is installed in the liquid separator 1 so as to be able to detect the internal liquid level, and a liquid level sensor 3 is installed in the area between the first switching valve 12 and the water heat exchanger 13 to determine the pressure and temperature of the refrigerant in this area. A pressure/temperature sensor 4 is attached to detect the pressure and temperature, and a control means 5 is provided for adjusting the opening degree of the expansion valve 16 in response to a signal from the liquid level sensor 3 or the pressure/temperature sensor 4.

That is, during heating operation, the second
Similar to the device shown in the figure, the high-pressure refrigerant gas discharged from the compressor 11 is liquefied by applying heat to hot water in the heat exchanger 13, and then enters the liquid receiver 15. The high-pressure refrigerant liquid discharged from the liquid receiver 15 is depressurized by the expansion valve 16, becomes a flash gas, and rises in the piping, and is separated into gas and liquid by the liquid separator 1, and only the refrigerant liquid undergoes air heat exchange. It enters from below the heat exchange coil 18 in the vessel 17.

Then, the refrigerant liquid that has entered the heat exchange coil 18 absorbs heat from the outside air and evaporates, enters the upper part of the liquid separator l and is combined with the gas-liquid separated refrigerant gas, from which the refrigerant gas is sent to the compressor. 11, and the same cycle as above is repeated. Then, the signal from the liquid level sensor 3 is input to the control means 5, and the opening degree of the expansion valve 16 is adjusted by the control means 5 so that the liquid level falls within a certain range.

On the other hand, during cooling operation using the flow indicated by the broken line arrow in FIG.
Similarly to the above, the opening degree of the expansion valve 16 is adjusted by the control means 5 so that the degree of superheating at this sensor portion is constant.

Further, the refrigerant liquid in the liquid separator 1 is held in the liquid receiver 15 by opening the on-off valve 2.

(Effects) As is clear from the above description, according to the present invention, the liquid separator is provided at the outlet of the air heat exchanger in the heating operation flow path, and the lower part of the liquid separator is connected to the inlet of the air heat exchanger. At the same time, a liquid level sensor is attached to this liquid separator so that the internal liquid level can be detected, and based on the signal from this liquid level sensor, the detected liquid level is kept within a certain range. A control means is provided for adjusting the opening degree of the expansion valve so that the expansion valve is opened.

For this reason, the liquid level height in the liquid separator is maintained within a certain range, and the responsiveness of controlling the amount of liquid sent to the air heat exchanger is faster than when using the conventional pressure and temperature detection method. Even if unevaporated refrigerant liquid in the coil attempts to flow, it is collected by the liquid separator, making it possible to prevent liquid back-up.

In addition, since the refrigerant liquid enters the heat exchange coil, which has many branched flow paths, in a single-phase flow, it is possible to distribute the refrigerant evenly without using a special distributor, and the performance of the heat exchanger can be improved. This has the effect of making it possible.

[Brief explanation of the drawing]

FIG. 1 is a refrigerant/control system diagram of a heat pump according to the present invention, and FIG. 2 is a refrigerant/control system diagram of a conventional heat pump. l...Liquid separator, 3...Liquid level sensor, 5...Control means, 11...Compressor, 12...First switching valve, 13
...Water heat exchanger, 14...Second switching valve, 15...
Liquid receiver, 16... expansion valve, 17... air heat exchanger. Patent Applicant Kobe Steel Co., Ltd. Agent Patent Attorney Haka Aoyama 1 person Figure 1 Figure 2

Claims (1)

[Claims] (1) Refrigerant returns from the compressor to the compressor via the first switching valve, water heat exchanger, second switching valve, liquid receiver, expansion valve, second switching valve, air heat exchanger, and first switching valve. a heating operation flow path which is a circulation flow path from the compressor to the first switching valve, an air heat exchanger, a second switching valve, a liquid receiver, an expansion valve, a second switching valve, a water heat exchanger, and a second switching valve. In the heat pump, the liquid separator is connected to the cooling operation flow path, which is a circulation flow path for refrigerant returning to the compressor via a switching valve, and is configured to be able to switch to either one of the flow paths as appropriate. The liquid separator is installed at the outlet of the air heat exchanger to communicate the lower part of the liquid separator with the inlet of the air heat exchanger, and a liquid level sensor is attached to the liquid separator to detect the internal liquid level. and a control means for adjusting the opening degree of the expansion valve based on a signal from the liquid level sensor so that the detected liquid level falls within a certain range.