JPH0120707B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pump device including an indoor heat exchanger and a plurality of outdoor heat exchangers.

Conventionally, this type of equipment has a compressor 1, a water heat exchanger 2, and a plurality of units (three in this figure), as shown in Fig. 1, for example.
air heat exchangers 3, 4, 5, four-way valve 6, receiver 7, expansion valves 8, 9, 10, check valves 11, 12,
13, communication passages 14, 15, 16, valves 17, 18,
19, 20, 21, 22, expansion valve 23, check valve 2
4, and these devices are connected to pipes 25, 26, 2.
7, 28, and 29 are connected.

When the four-way valve 6 is placed in the position shown and the heating cycle is in operation, the air heat exchangers 3, 4,
5, a portion of the high-temperature, high-pressure gas (hereinafter referred to as hot gas) discharged from the compressor 1 is sequentially guided to air heat exchangers 3, 4, and 5 for defrosting. That is, first, as shown in the figure, the valve 17 is closed and the valve 18 is opened to introduce the hot gas to the air heat exchanger 3 for defrosting. The condensed refrigerant liquid of the hot gas generated at this time descends and is guided to the secondary side of the expansion valves 9, 10 through the communication passages 14, 16, and the refrigerant gas sent from the receiver 7 and passed through the expansion valves 9, 10. It enters the air heat exchangers 4 and 5 together with the refrigerant liquid and evaporates into the valve 1.
9, 21, and a pipe 28 to the suction port of the compressor 1.

Next, valves 18 and 19 are closed, valves 17 and 20 are opened, and the hot gas is guided to air heat exchanger 4 for defrosting, and then air heat exchanger 5 is defrosted in the same manner.

The above example is an example of returning the condensed refrigerant liquid generated by defrosting to the low-pressure side refrigerant path, but there are also other examples of returning the condensed refrigerant liquid generated by defrosting to the high-pressure side refrigerant path, but all of them had the following drawbacks. .

When returning the condensed refrigerant liquid to the low pressure side: (1) A special pressure reduction device is required for each coil to return the liquid refrigerant from the highest pressure in the refrigerant cycle to the low pressure side.

(2) To coils where the amount of refrigerant evaporation has decreased due to frost formation,
Since liquid refrigerant is supplied, the liquid refrigerant is directly sent to the coil outlet side at the beginning of defrosting. Therefore, the expansion valve of the coil to which the refrigerant liquid has returned operates in the closing direction, and the ratio of the amount of return liquid refrigerant supplied to the coil increases. It is difficult to control the amount of this return liquid refrigerant so that it is not sucked into the compressor as droplets.

(3) As a result, the amount of refrigerant liquid that dissolves in the lubricating oil increases, making the lubrication system more likely to fail.

In addition, when returning condensed refrigerant to the high pressure side, (1) In order to return the condensed refrigerant, create a sufficient pressure difference between the hot gas line and the receiver or refrigerant supply header only during defrosting. Special equipment is required to produce this.

(2) This device for generating differential pressure creates piping resistance during normal operation, increasing the power of the compressor.

(3) During defrosting, if the hot gas pressure is increased to create a differential pressure, the power of the compressor will increase, and if the pressure of the receiver or liquid refrigerant supply header is lowered, the refrigeration capacity will increase even more than the coil reduction. Or heating capacity decreases.

The present invention eliminates the above-mentioned drawbacks of the conventional ones by making the supercooler also function as a differential pressure generator by utilizing the fluid resistance of the supercooler, and uses a special pressure reducing device or differential pressure generator. No need for high pressure side,
The objective is to provide a heat pump device in which the pressure on the low pressure side remains relatively unchanged even during defrosting.

The present invention provides a heat pump device including a compressor, a water heat exchanger, and a plurality of air heat exchangers, in the middle of a refrigerant path between an outlet of the water heat exchanger and an expansion valve at the inlet of the air heat exchanger. A subcooler is installed in the cooling device, and during defrosting, a part of the hot gas discharged from the compressor is allowed to flow into the air heat exchanger to be defrosted, and the condensed refrigerant generated during defrosting is removed. , the supercooler is configured to lead between the outlet of the supercooler and the expansion valve, and the supercooler is configured such that even after the refrigerant liquid is supercooled in the supercooler, the refrigerant liquid remains in a subcooled region. This is a heat pump device characterized by having a fluid resistance that provides a pressure drop as shown in FIG.

The present invention will be explained with reference to the drawings based on examples.
In Figure 2, parts with the same symbols as in Figure 1 are:
It has the same configuration and functions as the one in FIG. A hermetic economizer 30 is provided as a supercooler in the refrigerant path between the outlet of the water heat exchanger 2 and the expansion valves 8, 9, and 10 at the inlets of the air heat exchangers 3, 4, and 5. The gas phase part of the hermetic economizer 30 is connected to the intermediate pressure stage of the compressor 1 by a line 31. 32 is an expansion valve. The refrigerant liquid flowing into the pipe line 33 branched from the pipe line 27 is depressurized by the expansion valve 32 and cooled to a low-temperature refrigerant to become a supercooled state, and then passes through the expansion valves 8, 9, and 10 for air heat exchange The refrigerant enters the containers 3, 4, and 5, evaporates, becomes refrigerant gas, and is sucked into the compressor 1. FIG. 3 is a refrigeration cycle diagram of the above example. is the saturated vapor line, is the saturated liquidus line, is the superheated region, is the supercooled region, and is the wet vapor region. A is the suction port of the compressor 1, C is the point where the refrigerant gas led from the hermetic economizer 30 joins, and D is the discharge port of the compressor 1. Conduit 2
The liquid branched from 7 and enters the expansion valve 32 is depressurized from E and reaches K, is heated by the liquid refrigerant that has entered the pipe 33, evaporates, and reaches C. On the other hand, the liquid refrigerant entering the pipe line 33 is depressurized by the expansion valve 32, is supercooled by the refrigerant whose temperature has dropped, and enters a supercooled region outside the saturated liquidus line. Since there is fluid resistance in the flow path of the closed economizer 30, the refrigerant liquid is supercooled and the pressure is also reduced. Closed economizer 3
The enthalpy at exit point F of 0 is △i compared to point E
As the temperature decreases, the pressure also decreases by △p ₁ . This refrigerant liquid flows through the expansion valves 8, 9, 10
It is depressurized at , passes through point G, enters the wet vapor region again, reaches point J, evaporates in the air heat exchangers 3, 4, and 5, becomes refrigerant gas, reaches point A, and is sucked into the compressor 1 again.

During defrosting, for example, when defrosting the air heat exchanger 3, the valve 17 is closed and the valve 18 is opened. The hot gas enters the air heat exchanger 3 through the valve 18, defrosts it, condenses itself, passes through the check valve 11, reaches the intermediate pressure line 36, joins with the refrigerant liquid that has passed through the sealed economizer 30, and expands. It passes through valves 9 and 10, is evaporated in air heat exchangers 4 and 5, and is sucked into compressor 1.

In this case, the driving force for sending the hot gas to the air heat exchanger 3 and passing it through is the differential pressure △
p ₁ . That is, the sealed economizer 30, which is a supercooler, also serves as a differential pressure generating mechanism for driving force. Therefore, no other special pressure difference generation mechanism is required.

The larger this differential pressure △p ₁ is, the greater the driving force will be, but if it is too large and becomes as shown in △p' ₁ in Figure 3, the H point will enter the wet steam region, causing a flash and reducing the capacity of the expansion valves 9 and 10. This may cause problems such as causing Therefore, the fluid resistance of the hermetic economizer 30 should not be greater than the resistance value that provides Δp ₁ such that point F remains in the supercooled region (Δp ₂ >0).

FIG. 4 shows another embodiment in which a liquid-gas heat exchanger 37 for exchanging heat between the refrigerant liquid and the refrigerant gas sucked into the compressor 1 is used as the subcooler. In this case, as shown in FIG. 3, an enthalpy Δi ₂ equal to the enthalpy Δi ₁ reduced by supercooling is obtained, and the intake steam becomes superheated steam.

The present invention utilizes the fluid resistance of the supercooler to provide an intermediate pressure line to guide the condensed refrigerant liquid generated during defrosting, thereby eliminating the need for a special differential pressure generator and eliminating the need for a special differential pressure generator during defrosting. Therefore, flashing does not occur on the inlet side of the expansion valve of the air-side heat exchanger that is in operation, and a decrease in heating capacity is prevented, which is extremely effective in practical terms.

[Brief explanation of drawings]

FIG. 1 is a flowchart of a conventional example, FIG. 2 is a flowchart of an embodiment of the present invention, FIG. 3 is a refrigeration cycle diagram thereof, and FIG. 4 is a flowchart of another embodiment. 1... Compressor, 2... Water heat exchanger, 3, 4, 5
... Air heat exchanger, 6 ... Four-way valve, 7 ... Receiver, 8, 9, 10 ... Expansion valve, 11, 12, 1
3... Check valve, 14, 15, 16... Communication passage, 1
7, 18, 19, 20, 21, 22... Valve, 23
...Expansion valve, 24...Check valve, 25, 26, 2
7, 28, 29... Pipe line, 30... Sealed economizer, 31... Pipe line, 32... Expansion valve, 33...
Pipeline, 36...Intermediate pressure line, 37...Liquid gas heat exchanger.

Claims (1)

[Claims] 1 In a heat pump device equipped with a compressor, a water heat exchanger, and a plurality of air heat exchangers, supercooling is carried out in the middle of the refrigerant path from the outlet of the water heat exchanger to the expansion valve at the inlet of the air heat exchanger. During defrosting, a part of the hot gas discharged from the compressor is allowed to flow into the air heat exchanger to be defrosted, and the condensed refrigerant generated during defrosting is transferred to the air heat exchanger. The supercooler is configured to lead the refrigerant between the outlet of the cooler and the expansion valve, and the supercooler is arranged so that the refrigerant remains in a supercooled region even after the refrigerant is supercooled in the supercooler. 1. A heat pump device characterized by having fluid resistance that provides a pressure drop.