JPS6146865A - Outdoor-side heat exchanger for heat pump type air conditioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an outdoor heat exchanger for a heat pump air conditioner that is separated into an upstream heat exchanger and a downstream heat exchanger with respect to an air flow.

Conventional structure and its problems Conventionally, the outdoor heat exchanger of a heat pump air conditioner, which is separated into an upstream heat exchanger and a downstream heat exchanger as described above, is It is becoming increasingly common to reduce the size of heat exchangers by adding refrigerant turbulence grooves to the inner surface (hereinafter referred to as inner grooved tubes) and increasing the inner surface type to improve the heat transfer coefficient on the refrigerant side.

However, in this internally grooved tube, the pressure drop inside the tube of the refrigerant flow becomes large, which causes the evaporation temperature to rise and the condensation temperature to fall, resulting in a decrease in the capacity of the heat exchanger, which leads to a decrease in heating and cooling capacity.

Therefore, the number of refrigerant passages is increased to reduce the pressure drop inside the pipes. However, if the number of refrigerant passages is increased, the refrigerant must also be divided, which increases costs. Since the heat exchanger is still separated into an upstream heat exchanger and a downstream heat exchanger, there is no heat conduction between the two, and the heat passes through the upstream heat exchanger.
The airflow that has radiated or absorbed heat to some extent acts as a heat radiator or absorber in the downstream heat exchanger, so that the heat radiator or heat absorber effect is smaller than that of the upstream heat exchanger. In particular, when used as an outdoor heat exchanger during heating, the evaporation temperature decreases due to a decrease in the heat absorption effect, which has the disadvantage of causing easy frost formation.

Purpose of the Invention The present invention has been made in view of the above-mentioned problems.
The capacity of the heat exchanger is ensured by ensuring a certain degree of heat radiation or heat absorption effect of the air flow passing through the upstream heat exchanger, and by increasing the heat radiation or heat absorption effect in the downstream heat exchanger.
The present invention provides an inexpensive heat exchanger that prevents frost formation due to a decrease in evaporation temperature during heating.

Structure of the Invention That is, the present invention provides an outdoor heat exchanger for a heat pump type air conditioner that is separated into an upstream heat exchanger and a downstream heat exchanger with respect to the air flow, in which a refrigerant tube constituting the heat exchanger is A smooth tube with a flat inner surface is used for the upstream heat exchanger,
By using internally grooved tubes for the downstream heat exchanger, it provides an inexpensive heat exchanger that can prevent frost formation during heating while ensuring condensation and evaporation capabilities.

DESCRIPTION OF EMBODIMENTS The present invention will be explained below with reference to drawings showing one embodiment of the invention. 01 is a compressor, 2 is a four-way valve, and 3 is an outdoor heat exchanger, which is located upstream of the air flow obtained by the blower 4. It is separated into a side heat exchanger 3a and a downstream heat exchanger 3b. 5 is a heating capillary tube, 6 is a check valve provided in parallel with the heating capillary tube 5, and forms a passage that bypasses the heating capillary tube 6 during cooling. 7 is a capillary tube for cooling, 8 is a check valve that forms a passage that bypasses the capillary tube 7 for cooling during heating, and 09 is an indoor heat exchanger, and by connecting these in a ring, a heat pump type air conditioner/heater is created. A refrigeration cycle is constructed as shown in FIG. 1, and a compressor 1, an outdoor heat exchanger 3, and a blower 4 are normally housed in an outdoor cabinet 10 as shown in FIG. FIG. 3 is a side sectional view of the outdoor heat exchanger 3, and the refrigerant tube of the heat exchanger 3a on the upstream side of the air flow is a smooth tube 11 with a flat inner surface.
The refrigerant tube of the downstream heat exchanger 3b is composed of an internally grooved tube 12.

In the refrigeration cycle having such a configuration, during heating operation, the outdoor heat exchanger 3 functions as an evaporator and performs an endothermic action. At this time, the airflow 13b blown to the downstream heat exchanger 3b has a lower heat absorption effect than the airflow 13a blown to the upstream heat exchanger 3a, but the refrigerant tubes of the upstream heat exchanger 3a have inner grooves. This effect is less than in the case of a pipe with a tube, and since the refrigerant tube of the upstream heat exchanger 3a is an internally grooved tube, the heat absorption capacity of the heat exchanger approaches that of the upstream heat exchanger 3a.

Therefore, the evaporation temperature of the downstream heat exchanger 3b is approximately the same as that of the upstream heat exchanger 3a, making frost formation difficult. Still, since the refrigerant tube of the upstream heat exchanger 3a is a smooth tube, the pressure drop inside the tube can be reduced, so there is no need to increase the number of refrigerant passages, and an inexpensive outdoor heat exchanger can be provided.

Effects of the Invention As is clear from the above explanation, the outdoor heat exchanger of the heat pump type air conditioner/heater of the present invention uses a smooth tube as the refrigerant tube of the heat exchanger on the upstream side with respect to the air flow, and the heat exchanger on the downstream side Since the refrigerant tube of the evaporator is an internally grooved tube, the heat dissipation and heat absorption effects of the downstream heat exchanger are improved, and the evaporator becomes resistant to frost formation during heating. Furthermore, since the pressure drop of the refrigerant inside the tubes is reduced, there is no need to increase the number of refrigerant passages, and since smooth tubes are used, an inexpensive heat exchanger can be provided.

[Brief explanation of the drawing]

Fig. 1 is a refrigeration cycle diagram of a heat pump air conditioner equipped with an outdoor heat exchanger according to an embodiment of the present invention, Fig. 2 is a top view of an outdoor unit equipped with the same heat exchanger, and Fig. 3 is a refrigeration cycle diagram of a heat pump type air conditioner equipped with an outdoor heat exchanger according to an embodiment of the present invention. FIG. 3 is a side cross-sectional view of the exchanger. 3...Outdoor heat exchanger, 3a...Upstream heat exchanger, 3b...Downstream heat exchanger, 11...
...Smooth tube, 12...Inner grooved tube.

Claims (1)

[Claims] The outdoor heat exchanger, which serves as a condenser during cooling and an evaporator during heating, is separated into an upstream heat exchanger and a downstream heat exchanger with respect to the air flow, and the refrigerant tubes that make up this outdoor heat exchanger A heat pump type air conditioner/heater in which the upstream heat exchanger uses a smooth tube with a flat inner surface, and the downstream heat exchanger uses an inner grooved tube with refrigerant turbulence grooves on the inner surface. outdoor heat exchanger.