JP2916381B2 - Separate heat pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separate type heat pump suitable as a large building air conditioning system.

[0002]

2. Description of the Related Art Conventionally, a separate heat pump shown in FIG. 2 is known. FIG. 2 shows a state during a heating tone proportional heat recovery operation, in which an oil-cooled compressor 11, for example, an oil-cooled screw compressor, an oil separation and recovery unit 12, a first on-off valve 13, a condenser 14 , First expansion valve 15, and evaporator 1
6 and a portion of a flow path between the condenser 14 and the first expansion valve 15 in the refrigerant circulation flow path through the three-way switching valve 17, and evaporates. At the part of the flow path between the compressor 16 and the compressor 11, and the compressor 11,
Oil separation and recovery unit 12, first on-off valve 13, condenser 14, second
A second refrigerant circulation flow path including the expansion valve 18 and the air heat exchanger 19 is formed. In this heat pump, the flow control valve 20 and the second on-off valve 2 are provided upstream of each flow path at a location where the first refrigerant flow path and the second refrigerant flow path join.
1 is provided. In this operation state, the oil separation and recovery device 12
In the flow path from the flow path to the condenser 14, the flow path that branches off from the upstream portion of the first on-off valve 13 and joins the upstream portion of the second on-off valve 21 is closed.

In this heat pump, a temperature detector 22 and a pressure detector 23 are provided in a portion of the refrigerant flow passage on the downstream side of the evaporator 16, and the degree of superheat is calculated based on signals from the two detectors. Then, a superheat degree controller 24 for adjusting the opening degree of the first expansion valve 15 so that the superheat degree becomes an appropriate state is provided. Furthermore, the air heat exchanger 1 in the refrigerant flow path
9, a temperature detector 25 and a pressure detector 26
The superheat controller 27 that calculates the degree of superheat based on the signals from the two detectors and adjusts the degree of opening of the second expansion valve 18 so that the degree of superheat is in an appropriate state is provided. It is provided. On the other hand, in the flow path of the cold water flowing out of the evaporator 16, a temperature controller that detects the temperature of the cold water in the flow path and adjusts the opening of the flow control valve 20 so that the temperature becomes a set value. 28 are provided.

Then, the refrigerant that has exited the condenser 14 is guided to the first expansion valve 15 and the second expansion valve 18 and circulated in the first and second refrigerant circulation passages. The evaporator 16 produces cold water, and the air heat exchanger 19 radiates heat into the air. Among such heat pumps, for large ones used in hospitals, for example,
It is required to produce cold and hot water even in winter.
The hot water produced by the condenser 14 is always required, whether in summer or winter, whereas cold water is used or not used, especially in winter. When cold water is not used, the opening degree of the flow control valve 20 is reduced by a signal from the temperature controller 28, and the superheat degree controller 24
, The opening degree of the first expansion valve 15 is also reduced, and the flow rate of the refrigerant from the evaporator 16 is reduced. On the other hand, the amount of the refrigerant flowing from the condenser 14 to the air heat exchanger 19 increases, and the opening degree of the second expansion valve 18 is adjusted by a signal from the superheat degree controller 27.

[0005]

In the above-described conventional heat pump, the condenser 14 is turned into the evaporator 16 or the air heat exchanger 1.
The amount of the refrigerant flowing to 9 is controlled by the first and second expansion valves 15 and 18. On the other hand, the condenser 14 and the evaporator 16 are usually installed in a basement, and the air heat exchanger 19 is installed on the roof of a building, and the height difference between them may reach 100 m. Since the secondary side of the second expansion valve 18 has a two-phase flow of the refrigerant gas and the refrigerant liquid, the refrigerant gas and the refrigerant liquid are separated at a certain flow rate or less, and liquid stays at the bottom of the pipe. Thereafter, when a change in the capacity of the compressor 11 and a change in the chilled water load occur, the suction amount of the compressor 11 and the flow velocity of the refrigerant increase. Due to the increase in the flow velocity, the refrigerant in a liquid state returns to the compressor 11, and a liquid back phenomenon occurs, and the compressor 11
The problem of damaging the device. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems. Even under a load condition in which the flow rate of the refrigerant to the air heat exchanger is reduced, the liquid back to the compressor and the accompanying An object of the present invention is to provide a separate heat pump that can prevent the occurrence of a damage accident.

[0006]

In order to solve the above-mentioned problems, the present invention provides a first refrigerant circulating flow path including at least a compressor, a condenser, a first expansion valve, and an evaporator; And branches off from a part of a flow path between the condenser and the first expansion valve, and joins at a part of a flow path between the evaporator and the compressor to form at least the compressor and the compressor. In a separate type heat pump capable of forming a second refrigerant flow path including a condenser, a second expansion valve, and an air heat exchanger, a branch is made at a part of the refrigerant flow path on the inlet side of the condenser, and
In addition to providing a hot gas flow path that merges at the flow path portion on the outlet side of the expansion valve, the flow rate adjustment increases the degree of opening when the amount of refrigerant flowing through the hot gas flow path decreases. It was formed with a valve.

[0007]

With the construction as described above, the required minimum flow rate of the refrigerant to the air heat exchanger can be reduced even under load conditions in which the amount of the refrigerant flowing out of the condenser and flowing to the air heat exchanger side is reduced. Will be secured.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a separate heat pump according to the present invention. Portions common to those of the separate heat pump shown in FIG. In the present embodiment, the hot gas flow path 1 which branches at the refrigerant flow path on the inlet side of the condenser 14 and joins at the flow path on the output side of the second expansion valve 18 is provided. The gas flow path 1 is provided with a flow control valve 2 whose opening is controlled by a superheat controller 27. In the present embodiment, on-off valves 3 and 4 are provided instead of the three-way switching valve 17 in the heat pump shown in FIG.
Works in the same way as

When the degree of opening of the second expansion valve 18 decreases and the amount of refrigerant flowing to the air heat exchanger 19 decreases, the degree of opening of the flow control valve 2 increases, and oil separation and recovery occurs. A part of the hot gas exiting the heat exchanger 12 is transferred to the air heat exchanger 1
9 is introduced in the middle of the pipe to increase the flow rate of the refrigerant in this pipe. Specifically, for example, the second
When the opening degree of the expansion valve 18 decreases and reaches a certain set value, for example, 50%, the flow control valve 2 starts to be opened,
As the opening of the expansion valve 18 further decreases, the opening of the flow control valve 2 increases in inverse proportion to this opening. Further, when the opening of the second expansion valve 18 decreases and reaches a set value, for example, 20%, the flow control valve 2
Becomes fully open.

[0010] In this heat pump, the chilled water load is preferentially dealt with.
When the opening degree of the second expansion valve 18 is 10% or less, the second expansion valve 18 is fully closed in order to avoid flowing the refrigerant to the air heat exchanger 19 as much as possible. . As described above, when the amount of the refrigerant passing through the second expansion valve 18 decreases, the amount of the hot gas sent to the pipe to the air heat exchanger 19 increases, and the two-phase flow of the refrigerant liquid and the refrigerant gas exchanges the air heat. By causing the liquid to flow stably to the compressor 19, the occurrence of a liquid back phenomenon to the compressor 11 and the occurrence of a damage accident of the compressor 11 due to this phenomenon are prevented. Further, in response to the cold water load, it can follow the evaporator 16 side, and can also respond to the hot water load in the condenser 14. In particular, while the hot water is supplied stably, the load of the cold water fluctuates by 0 to 100%. However, stable operation of the heat pump is possible.

[0011]

As is apparent from the above description, according to the present invention, the first refrigerant circulation channel including at least the compressor, the condenser, the first expansion valve, and the evaporator, and the refrigerant circulation channel. In the flow path between the condenser and the first expansion valve, and merges in the flow path between the evaporator and the compressor, and at least the compressor and the condenser. In a separate type heat pump capable of forming a heat exchanger, a second expansion valve, and a second refrigerant flow path including an air heat exchanger, a branch is made at a part of the refrigerant flow path on the inlet side of the condenser, and In addition to providing a hot gas flow path that merges at the outlet side flow path part, a flow control valve that increases the degree of opening is provided in this hot gas flow path when the amount of refrigerant flowing here decreases. It is formed.

For this reason, even if the amount of the refrigerant passing through the second expansion valve is reduced, the hot gas from the hot gas flow path causes the two-phase of the refrigerant liquid and the refrigerant gas in the pipe to the air heat exchanger. The minimum flow rate required for the flow is always maintained, and there is an effect that it is possible to cope with the cold water load and to supply the hot water stably without causing the liquid back to the compressor and the accident of breakage of the compressor accompanying the liquid back.

[Brief description of the drawings]

FIG. 1 is a diagram showing an entire configuration of a separate heat pump according to the present invention.

FIG. 2 is a diagram showing the entire configuration of a conventional separate heat pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot gas flow path 2 Flow control valve 11 Compressor 14 Condenser 15 First expansion valve 16 Evaporator 18 Second expansion valve 19 Air heat exchanger

Claims (1)

(57) [Claims] 1. A first refrigerant circulation channel including at least a compressor, a condenser, a first expansion valve, and an evaporator, and a portion of the refrigerant circulation channel between the condenser and the first expansion valve. A second branch including at least the compressor, the condenser, the second expansion valve, and the air heat exchanger is formed while branching off from the flow path and joining at the flow path between the evaporator and the compressor. In a separate type heat pump capable of forming a refrigerant flow path, a branch is made at a part of the refrigerant flow path on the inlet side of the condenser, and
In addition to providing a hot gas flow path that merges at the flow path portion on the outlet side of the expansion valve, the flow rate adjustment increases the degree of opening when the amount of refrigerant flowing through the hot gas flow path decreases. A separate heat pump characterized by being provided with a valve.