JPH07127941A - Air heat source heat pump - Google Patents

Abstract

PURPOSE:To prevent the occurrence of local and quantities of frosting in the vicinity of the refrigerant inlet of a heat exchanger on the heat source side during heating operation of an air-conditioner filled with an azeotropic mixture refrigerant. CONSTITUTION:A switching valve 9 for switching the direction of the flow of a refrigerant flowing through a heat-exchanger 5 on the heat source is provided. By switching the switch valve 9 when the temperature of the heat- exchanger 5 on the heat source side is lowered to a set temperature, the direction of the flow of the refrigerant is reversed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air heat source heat pump for an air conditioner, a water heater, a dryer, etc., in which a non-azeotropic mixed refrigerant is enclosed.

[0002]

2. Description of the Related Art A refrigerant circuit of a conventional air conditioner is shown in FIG. 3, and a Mollier diagram of a non-azeotropic mixed refrigerant enclosed in the refrigerant circuit of this air conditioner is shown in FIG. There is.

During heating operation of the air conditioner, the gas refrigerant discharged from the compressor 1 is a four-way valve 2 as shown by a solid arrow.
Through the heat exchanger 3 into the use side heat exchanger 3 in the state of a and exchange heat with the indoor air sent by the indoor fan 6 in the process of passing through the heat exchanger 3 to be condensed and liquefied along the condensation line b.
It becomes the liquid refrigerant in the state of.

This liquid refrigerant is throttled by the throttle 4 and adiabatically expanded along the expansion line (b) to become a gas-liquid two-phase refrigerant in the state of c.

The gas-liquid two-phase refrigerant enters the heat source side heat exchanger 5 in the state of c and exchanges heat with the outside air sent by the outdoor fan 7 in the process of passing through the heat exchanger 5 along the evaporation line c. It vaporizes and becomes a gas refrigerant in the state of d.

This gas refrigerant is sucked into the compressor 1 through the four-way valve 2 and is compressed in the compressor 1 along the compression line 2 to be discharged in the state a.

During the cooling operation of the air conditioner, by switching the four-way valve 2, the refrigerant circulates as indicated by the broken line arrow, contrary to the above.

In FIG. 4, E is a saturated vapor line, F is a critical point, G is a saturated liquid line, and J and L are isotherms.

The non-azeotropic mixed refrigerant is a mixture of two or more kinds of refrigerants having different boiling points, and in a gas-liquid two-phase state, the temperature of the refrigerant changes according to the dryness even under a constant pressure.

Therefore, although the state c of the refrigerant at the inlet of the heat source side heat exchanger 5 is on the isotherm, the dryness increases as the evaporation of the refrigerant progresses, and the temperature of the refrigerant accordingly increases. Since the temperature rises, the state d of the refrigerant at the outlet of the heat source side heat exchanger 5 is located on the isotherm H that is higher than the isotherm L.

[0011]

In the conventional air conditioner described above, when the temperature of the outside air during the heating operation decreases, the moisture in the outside air freezes on the surface of the heat source side heat exchanger 3. Since the non-azeotropic mixed refrigerant is sealed in the refrigerant circuit, the dryness of the gas-liquid two-phase refrigerant is smaller on the refrigerant inlet side of the heat source side heat exchanger 3 than that on the refrigerant outlet side. Since the temperature is lower than that on the outlet side, and therefore the temperature on the refrigerant inlet side of the heat source side heat exchanger 3 is lower than that on the outlet side, there is a problem that the amount of frost near the refrigerant inlet becomes extremely large.

[0012]

The present invention has been invented to solve the above-mentioned problems, and the gist of the invention is to provide a compressor, a utilization side heat exchanger, a throttle, and a heat source side heat exchanger. In an air heat source heat pump in which a non-azeotropic mixed refrigerant is enclosed in a refrigerant circuit including a switching valve for switching the flow direction of the refrigerant flowing through the heat source side heat exchanger and the temperature of the heat source side heat exchanger Is provided with a control means for switching the switching valve when the temperature falls to a set temperature.

The switching valve may be a four-way switching valve.

The switching valve can be constructed by combining four on-off valves.

[0015]

In the present invention, when the temperature of the heat source side heat exchanger drops to the set temperature during the endothermic operation of the air heat source heat pump, the flow direction of the refrigerant flowing through the heat source side heat exchanger by switching the switching valve. To reverse.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the invention is shown in FIG. A temperature sensor 8 for detecting the temperature is attached to the heat source side heat exchanger 5, and the heat source side heat exchanger 5 is provided in the refrigerant circuit.
A switching valve 9 is provided which is a four-way valve for switching the flow direction of the refrigerant flowing through the valve. 10 is a control means and 11 is a setting means. Other configurations and operations are similar to those of the conventional one shown in FIG. 3, and corresponding members are designated by the same reference numerals.

However, when the heating operation is started, the non-azeotropic mixed refrigerant enclosed in the refrigerant circuit circulates in the refrigerant circuit as indicated by the solid arrow. The temperature of the heat source side heat exchanger 5 detected by the temperature sensor 8 is input to the control means 10 and compared with the set temperature input from the setting means 11 here. The temperature at which frost formation on the heat source side heat exchanger 5 starts is set in advance in the setting means 11.

When the temperature detected by the temperature sensor 8 gradually decreases and reaches the set temperature by continuing the heating operation at a low outside air temperature, the control means 10 outputs to the switching valve 9 and this is indicated by a dashed arrow. To switch.

Then, the flow direction of the refrigerant flowing through the heat source side heat exchanger 5 is switched to the opposite direction to the previous one, and as shown by the broken line arrow, it flows in from the previous refrigerant outlet and flows out from the previous refrigerant inlet. To do.

As a result, the previous temperature on the refrigerant inlet side rises, so that the frost on the refrigerant inlet side can be temporarily melted or the progress of frost formation can be suppressed.

By continuing the operation in this state, the switching valve 9 is switched again when the temperature detected by the temperature sensor 8 reaches the set temperature again. By repeating this, if the temperature detected by the temperature sensor 8 becomes equal to or lower than the set temperature,
The frost attached to the heat source side heat exchanger 5 may be melted and removed by defrosting the air conditioner.

A second embodiment of the invention is shown in FIG. In the second embodiment, the four-way valve 9 is replaced by four
One on-off valve 12a, 12b, 12c, 12d is used.

However, during heating operation, the on-off valves 12a and 12d
By opening and closing 12b and 12c, the refrigerant flows through the heat source side heat exchanger 5 as shown by the solid arrow, and the on-off valve 12b
, 12c are opened and 12a, 12d are closed, so that the refrigerant flows through the heat source side heat exchanger 5 in the opposite direction to the above. Other configurations and operations are similar to those of the first embodiment shown in FIG. 1, and corresponding members are designated by the same reference numerals.

[0024]

According to the present invention, during the endothermic operation of the air heat source heat pump, when the temperature of the heat source side heat exchanger drops to the set temperature, the refrigerant flowing through the heat source side heat exchanger is switched by switching the switching valve. The flow direction can be reversed. As a result, it is possible to prevent the local frost that has been generated in the vicinity of the refrigerant inlet of the conventional heat source side heat exchanger and the progress of this frost, and therefore to prevent frost formation on the entire heat source side heat exchanger. Since it can be suppressed and delayed, the cycle of the defrosting operation can be extended.

[Brief description of drawings]

FIG. 1 is a system diagram showing a first embodiment of the present invention.

FIG. 2 is a system diagram showing a second embodiment of the present invention.

FIG. 3 is a refrigerant circuit diagram of a conventional air conditioner.

FIG. 4 is a Mollier diagram of a refrigeration cycle using a non-azeotropic mixed refrigerant.

[Explanation of symbols]

 1 Compressor 3 Utilization side heat exchanger 4 Throttle 5 Heat source side heat exchanger 8 Temperature sensor 9 Switching valve 10 Control means 11 Setting means

Claims (3)

[Claims] 1. An air heat source heat pump in which a non-azeotropic mixed refrigerant is enclosed in a refrigerant circuit comprising a compressor, a utilization side heat exchanger, a throttle, a heat source side heat exchanger, etc. An air heat source heat pump, comprising: a switching valve for switching a flow direction of a refrigerant flowing through the air source; and a control means for switching the switching valve when the temperature of the heat source side heat exchanger drops to a set temperature. 2. The air heat source heat pump according to claim 1, wherein the switching valve is a four-way switching valve. 3. The air heat source heat pump according to claim 1, wherein the switching valve is constituted by a combination of four on-off valves.