JPH0222314B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat pump air conditioning system that takes in heat from the outside air or releases heat to the outside air to condition indoor air.

BACKGROUND ART FIG. 6 shows a cycle of a conventionally used heat pump device. 1 is a compressor, and 2 is a four-way valve. By switching the four-way valve 2, the indoor side is set to low pressure and the outdoor side is set to high pressure in the summer, and the indoor heat exchanger 3 evaporates the refrigerant circulating inside, removing heat from the room and simultaneously transferring heat to the outside. The refrigerant is condensed in the exchanger 6 and heat is discarded outdoors. On the other hand, in the winter season, the four-way valve 2 is switched to reverse the refrigerant pressure compared to the summer season, and heat is released indoors from the indoor heat exchanger 3, and heat is obtained from the outdoors through the outdoor heat exchanger 6. Adjustment of the low pressure and high pressure is mainly performed by the capillary 4 or the expansion valve, and it is common to use the capillary 4 by switching the check valve 5 in summer and winter.

In recent years, the efficiency of heating has improved, and the contribution of such heat pump devices to heating has increased. There are many problems such as fluctuations.

Problems to be Solved by the Invention The present invention is intended to improve the performance of the heat pump device described above during frost formation.By improving the heat pump performance during frost formation, fluctuations in room temperature can be suppressed and indoor This improves comfort.

The deterioration of heat pump performance during frost formation is mainly due to blockage of the air passages of the outdoor heat exchanger due to frost formation. Fifth
The figure shows the state of the outdoor heat exchanger when frost forms. 7 is a copper tube through which a low-pressure refrigerant passes while evaporating, and removes heat from the air 10 flowing between the fins 8 . The fins 8 and the copper tube 7 are configured to be in thermal contact with each other. Therefore, the mass transfer rate is high at the tips of the fins 8, the amount of frost increases on the windward side of the fins 8, and airflow blockage occurs from the tips.
When airflow blockage occurs, the amount of heat taken in from the outdoor heat exchanger decreases significantly, and the amount of heat transported indoors decreases, resulting in a decrease in room temperature.

Therefore, various heat pump devices that are less prone to frost formation have been devised. Figure 4 shows indoor heat exchanger 1
This is an example of a heat pump device in which the sensible heat of the subcooled refrigerant flowing out from the subcooled refrigerant 3 is exchanged with air in the auxiliary heat exchanger 14, and is guided to the outdoor heat exchanger 15. Although this method is well known, the sensible heat that can be released into the outside air by the supercooled refrigerant is about 1000 Kcal/h at most, and the outside temperature can only be increased by about 3°C on average, so it is difficult to melt frost. This was extremely unreasonable and difficult to put into practical use. Furthermore, the difficulty of frost formation due to such supercooled refrigerant is caused by the temperature of the refrigerant liquid gradually decreasing from the inlet to the outlet of the auxiliary heat exchanger 14, and flowing into the outdoor heat exchanger 15 from near the inlet of the auxiliary heat exchanger 14. There was also a problem that there was a large difference between the temperature of the air flowing in and the temperature of the air flowing in from the vicinity of the outlet, resulting in differences in frost melting, uneven air volume, and a decrease in heat exchange capacity.

The present invention solves the above-mentioned problems and provides a heat pump device having a configuration that utilizes the sensible heat of a supercooled refrigerant to prevent frost formation on an outdoor heat exchanger.

Means for Solving the Problems The present invention installs an auxiliary heat exchanger for sensible heat exchange between the supercooled refrigerant discharged from the indoor heat exchanger and the outside air on the upwind side of the outdoor heat exchanger, and The fins of the exchanger are installed between the fin pitches of the outdoor heat exchanger.

Effect A boundary layer and wake are generated on the surface and rear end of each fin of the auxiliary heat exchanger. This wake, which has not sufficiently mixed with the outside air, is guided while still at a high temperature to between the fins of the outdoor heat exchanger at the rear, and melts the frost that forms at the tip of the outdoor heat exchanger. Therefore, unlike conventional frost formation, the phenomenon in which frost only clogs the tips of the fins and blocks the air passages does not occur.

Because the structure is such that the wake of the fins of the auxiliary heat exchanger passes between the fins of the outdoor heat exchanger, even if frost forms on the outdoor heat exchanger, unless the outside temperature drops significantly, the frost will not form. As the surface melts when it comes into contact with relatively high-temperature air, the density of the frost increases, significantly slowing down the rate of frost formation, and improving the thermal conductivity of the frost, reducing the ability of the heat exchanger. Being held down.

Frost develops almost symmetrically between the fins of the outdoor heat exchanger starting from the fins on both sides, connecting near the center and blocking the air passage, but the relatively high temperature air downstream of the fins flowing from the auxiliary heat exchanger always flows near the center between the fins. Furthermore, since the temperature of this air increases as the air volume decreases due to frost, the outdoor heat exchanger is not completely blocked.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings.

FIG. 1 is a perspective view of the heat pump device, outdoor heat exchanger 21, and auxiliary heat exchanger 22 of the present invention. In this embodiment, the outdoor heat exchanger 21 and the auxiliary heat exchanger 22 are integrally fixed to the side plate 27,
Air 28 flows from the direction of the arrow. A refrigerant flows inside the copper pipes A25 and B26, but during heating, the refrigerant in a low-pressure two-phase flow state flows into the copper pipe A25.
A high-pressure refrigerant in a supercooled liquid state flows through the copper pipe B26. Since the temperature of the supercooled refrigerant in the copper pipe B26 is higher than the temperature of the flowing air, heat is transmitted through the fins B24, raising the air temperature. On the other hand, the refrigerant inside the copper tube A25 is evaporating, and heat is removed from the air by the fins A23. Figure 2 shows the outdoor heat exchanger 2 in Figure 1.
1 and the fins and copper tubes of the auxiliary heat exchanger 22 are more specifically shown in a plan view a and a side view b. The numbers for each element in FIG. 2 are the same as in FIG. 1. Copper tube B26 placed in the auxiliary heat exchanger is similar to copper tube A in the outdoor heat exchanger.
By using a diameter smaller than 25,
Pressure loss in the auxiliary heat exchanger is kept to a minimum, and at the same time, the air flow within the fins B24 of the auxiliary heat exchanger approaches a parallel plate flow, achieving a large amount of heat radiation with a small fin surface area. In addition, the pitch of the copper tubes B26 in this auxiliary heat exchanger gradually decreases from the inlet to the outlet of the supercooled refrigerant, so there is no significant change in air temperature due to temperature changes in the supercooled refrigerant, and when frost forms, Fin B24 on the inlet side of supercooled refrigerant
Since the air passes between the air passages, only the frost in the air flow path entering the outdoor heat exchanger is thawed, and there is no phenomenon in which the area near the outlet side is completely thawed, making it possible to achieve almost uniform frost-resistance over the entire surface. On the other hand, the fins B24 are configured to be located between the fins A23 in the outdoor heat exchanger. With this configuration, a relatively high-temperature boundary layer and wake 30 are formed from the surface of the fin B26 to the wake 30 as shown in FIG. 3, and the wake 30 flows between the fins A26 of the outdoor heat exchanger on the leeward side. Go. For this reason, the frost does not have the shape shown in Figure 5 as in the past, but rather a relatively flat frost 2 as shown in Figure 3.
It becomes 9. Further, the surface of this frost 29 is exposed to high-temperature air, and the frost 26 melts and recondenses, thereby increasing its density and slowing down the rate of frost formation. Since this frost layer has a low air content, its thermal conductivity is high, and the fin efficiency improves as frost forms. Therefore, the heat transfer coefficient including the fin efficiency of the fin A23 does not decrease significantly even if the thickness of the frost increases. However, as the air passages become narrowed, the amount of air decreases, so the air temperature rises, and frost formation does not progress beyond the balance point between the refrigerant circulation amount and air flow rate, that is, the air temperature and the amount of frost formation, and the air is constantly circulating. do.

In one embodiment of the present invention, one fin B24 of the auxiliary heat exchanger is installed between the fins A23 of the outdoor heat exchanger, but even if this number is large,
This does not affect the effectiveness of the present invention. Furthermore, this embodiment shows an example in which the fins of the outdoor heat exchanger and the fins of the auxiliary heat exchanger are not connected. However, if a part of the fins of the auxiliary heat exchanger is located between the fins of the outdoor heat exchanger, it is possible to achieve the same effect as this example even if the other parts are connected. It is. Similarly, part of the fins of the auxiliary heat exchanger
It may get between the fins of the outdoor heat exchanger.

Effects of the Invention The present invention provides an auxiliary heat exchanger for sensible heat exchange between the supercooled refrigerant discharged from the indoor heat exchanger and the outside air, which is installed in the same frame on the windward side of the outdoor heat exchanger, and also provides an auxiliary heat exchange. Because the fins of the container are located between the fin pitches of the outdoor heat exchanger, frost adheres uniformly to the fin surface, and the air passage does not close at the fin tip as in the conventional case.The frost surface melts and the frost density increases. becomes higher, and the time it takes for the air flow path to close can be significantly extended. The air content in the frost is reduced, the fin efficiency is improved, and there is less loss of capacity during frost formation. If the outside temperature does not drop that much, even if frost forms, an air passage is secured in the center of the fins and heating operation can continue.

As described above, by implementing the present invention, it is possible to significantly improve the ability to form frosts, and also to sufficiently lengthen the time it takes for air passages to close due to frost formation, thereby improving comfort during heating in winter. This greatly contributes to improvement.

[Brief explanation of drawings]

Fig. 1 is a perspective view of essential parts of a heat pump device according to an embodiment of the present invention, Fig. 2 is a plan view and side view of the same embodiment, and Fig. 3 is a state of frost formation and air flow when the same device is used. 4 is a diagram of a heat pump cycle using an auxiliary heat exchanger, FIG. 5 is a diagram of a conventional frosting state, and FIG. 6 is a diagram of a conventional heat pump cycle. 3,13...Indoor heat exchanger, 6,15,21...
...Outdoor heat exchanger, 14,22...Auxiliary heat exchanger,
25, 26...Copper pipe, 23,24...Fin.

Claims (1)

[Claims] 1 At least a compressor, an indoor heat exchanger, an outdoor heat exchanger, and an expansion valve are connected in an annular manner by a pipe for refrigerant circulation, and auxiliary heat exchange is provided in the refrigerant passage from the indoor heat exchanger to the expansion valve. The auxiliary heat exchanger and the outdoor heat exchanger are constructed of finch tube heat exchangers, and the auxiliary heat exchanger and the outdoor heat exchanger are installed in the same frame, and the auxiliary heat exchanger is arranged on the windward side of the outdoor heat exchanger. , the auxiliary heat exchanger is installed on the windward side of the outdoor heat exchanger, with the fins of the auxiliary heat exchanger being located between the fin pitches of the outdoor heat exchanger, and the pipe diameter of the auxiliary heat exchanger is set to be the same as that of the outdoor heat exchanger. A heat pump device configured to have a pipe diameter smaller than that of the previous one.