JPH0317183Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a cross-fin type air heat exchanger used in heat pump type air conditioners and the like.

(Prior Art) As a conventionally known cross-fin type air heat exchanger, there is one that has multiple rows of refrigerant systems 3a' and 3b' from the windward side to the leeward side, as shown in FIG. (Refer to Japanese Patent Application Laid-open No. 13247/1983). In an air heat exchanger having such a structure, as shown in FIG.
Common fins 1', 1', . . . are disposed perpendicularly to a', 2b'.

(Problem to be solved by the invention) When the air heat exchanger of the above-mentioned known example is used as an outdoor coil of a heat pump type air conditioner, this outdoor coil acts as an evaporator during heating operation, and the outside air temperature When the temperature decreases, the fin surface temperature becomes 0° C. or lower and frost formation d' occurs. This frost d′ is on the upstream side (i.e.,
As the amount of frost increases from the surface of the fins located on the windward side), as shown in Figure 7, clogging occurs on the windward side of the fins 1', 1', increasing ventilation resistance. , which in turn causes a decrease in air volume. Therefore, as shown by the dotted line in Figure 5, ₁ hour after the start of operation, the refrigerating capacity decreases dramatically.
Normal operation of the refrigeration system cannot be maintained. For this reason, when the amount of frost builds up exceeds a certain limit,
Defrosting operation using a reverse cycle method, etc., in which the refrigerant flow path is reversed, is required. During this defrosting operation, cold air is blown into the room, which causes discomfort due to cold draft, and when the frequency of the defrosting operation increases, a problem arises in that the average heating capacity decreases.

This invention was made in view of the above points,
The purpose of this invention is to delay as much as possible the occurrence of clogging of the fins due to frost formation in a cross-fin type air heat exchanger.

(Means for Solving the Problems) In the present invention, as a means for solving the above problems, as shown in Figs. 3a, 3
In the cross-fin type air heat exchanger having the cross-fin type air heat exchanger, the flow rate of the refrigerant is controlled so that the evaporation temperature of the refrigerant flowing through the refrigerant system 3a on the windward side is relatively higher than that on the leeward side for a predetermined time after the start of operation. The control means 4 is energized to perform the operation.

(Function) In the present invention, the following effects can be obtained by the above-mentioned means.

In other words, until a predetermined period of time has passed after the start of operation,
Since the evaporation temperature of the refrigerant flowing through the refrigerant system 3a on the windward side is higher than that on the leeward side, frost formation d
The frost proceeds from the leeward side of the refrigerant system 3b, and after a predetermined time has elapsed, it proceeds to the windward side of the refrigerant system 3a, so that each fin 1 is uniformly frosted. Therefore, the time until clogging occurs due to frost formation becomes longer.

(Embodiments) Hereinafter, some preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Embodiment 1 FIGS. 1 and 2 show Embodiment 1 of the present invention.

The air heat exchanger of this embodiment is of a cross-fin type having a plurality of rows of refrigerant systems 3a and 3b from the windward side to the leeward side with respect to the air flow W. Refrigerant is distributed to each of the refrigerant systems 3a, 3b via a flow divider 5.

As shown in FIG. 2, a large number of fins 1, 1, . . . are arranged orthogonally in the heat transfer tubes 2a, 2b constituting the refrigerant systems 3a, 3b, respectively.

In this embodiment, a control means 4, which will be described later, is attached to the outlet side of the refrigerant system 3a on the windward side.

The control means 4 includes a capillary reach tube 6;
It is constituted by an on-off valve 7 connected to the capillary reach tube 6 in parallel. The on-off valve 7 is operated until a predetermined period of time has elapsed after the start of operation.
It is designed to be closed and then opened.
Note that the opening timing of the on-off valve 7 may be set using a timer, but it may also be set using other methods, such as
The frost formation state may be detected and determined by a sensor.

The air heat exchanger having the above structure operates as follows.

When this air heat exchanger is used as an outdoor coil of a heat pump type air conditioner, the on-off valve 7 is in a closed state at the beginning of heating operation, so that the refrigerant flowing through the refrigerant system 3a is transferred to the control means 4 at the outlet side. The flow rate is controlled by the pillar reach tube 6, and the evaporation temperature of the refrigerant system 3a becomes higher than the evaporation temperature of the refrigerant system 3b. Therefore, frost d
The frost proceeds from the refrigerant system 3b side in the fins 1, 1, . . . , and frost does not form on the refrigerant system 3a side (as shown in FIG. Then, when frost has formed on the refrigerant system 3b side to some extent, that is, when the on-off valve 7 is opened after the elapse of time _T1 (timing is determined using a timer or sensor, etc.), the refrigerant flowing through the refrigerant system 3a is The capillary reach tube 6 is bypassed, the flow rate is no longer controlled, and the evaporation temperature is reduced to normal. Therefore, frost formation d progresses on the refrigerant system 3a side (as shown in FIG. 2B).

As mentioned above, frost formation d occurs on the leeward side of the refrigerant system 3b.
After that, frost is formed on the windward side of the refrigerant system 3a, so that each fin 1, 1...
The amount of frost on the pipe becomes uniform, and the time T ₂ (see FIG. 5) until clogging occurs due to frost d becomes longer. Therefore, the deterioration in performance during frosting is reduced, and the frequency of defrosting operation is also reduced. In other words, the average heating capacity is improved.

Embodiment 2 FIG. 3 shows an air heat exchanger according to Embodiment 2 of the present invention.

In this case, the control means 4 controls the refrigerant system 3 on the leeward side.
It is provided on the inlet side of the valve b, and is composed of a capillary reach tube 6 and an on-off valve 7, as in the first embodiment. By doing this, the evaporation temperature of the refrigerant flowing through the refrigerant system 3b becomes lower than the evaporation temperature of the refrigerant flowing through the refrigerant system 3a,
Frost formation d advances from the refrigerant system 3b side. after that,
When frost has progressed to a certain extent (after time T ₁ )
When the on-off valve 7 is opened, the evaporation temperature of the refrigerant flowing through the refrigerant system 3b returns to the normal state, and frost formation d progresses on the windward side of the refrigerant system 3a. In other words, frosting progresses uniformly on the fins 1, 1, . . . .

Embodiment 3 FIG. 4 shows an air heat exchanger according to Embodiment 3 of the present invention.

In this case, the first embodiment and the second embodiment are combined, and control means 4, 4 are provided on the outlet side of the refrigerant system 3a and the inlet side of the refrigerant system 3b, respectively. Therefore, for a predetermined period of time after the start of operation, the evaporation temperature of the refrigerant flowing through the refrigerant system 3a becomes high.
The evaporation temperature of the refrigerant flowing through the refrigerant system 3b becomes lower, and the difference in evaporation temperature between the two becomes larger than in the first embodiment or the second embodiment.

In each of the above embodiments, a capillary reach tube and an on-off valve are used as the control means, but it goes without saying that an automatic control valve that can automatically control the opening may be used instead.

Further, the refrigerant system may have two or more rows, and in that case, the evaporation temperature may be different for each row.

(Effect of the invention) As described above, according to the invention, the evaporation temperature of the refrigerant flowing on the windward side is controlled to be lower than the evaporation temperature of the refrigerant flowing on the leeward side until a predetermined time has elapsed after the start of operation. Therefore, since the frost d progresses from the leeward side refrigerant system 3b side to the windward side refrigerant system 3a, the frosting on the fins 1, 1, . . . becomes uniform. Therefore, the reduction in air volume due to frost formation is extremely small, and the time until clogging occurs due to frost formation is lengthened. This contributes to a significant reduction in the frequency of defrosting operations when used as an outdoor coil in a heat pump air conditioner for heating operation at low outside temperatures, contributing to an improvement in the average heating capacity and growth coefficient. It's a big thing to do.

[Brief explanation of the drawing]

FIG. 1 is a side view schematically showing an air heat exchanger according to Embodiment 1 of the present invention, and FIG.
3 and 4 are side views schematically showing air heat exchangers according to embodiments 2 and 3 of the present invention, and FIGS. The figures are characteristic diagrams showing temporal changes in refrigerating capacity in the embodiment of the present invention (shown by solid lines) and the conventional example (shown by dotted lines). Fig. 6 is a side view showing the air heat exchanger of the conventional example. Fig. 7 1 is a sectional view of a main part of a conventional air heat exchanger. 3a, 3b... Refrigerant system, 4... Control means.

Claims (1)

[Scope of utility model registration request] Refrigerant system 3 with multiple rows from the windward side to the leeward side
In the cross-fin type air heat exchanger having the refrigerant system 3a on the windward side, the flow rate of the refrigerant is adjusted such that the evaporation temperature of the refrigerant flowing through the refrigerant system 3a on the windward side is relatively higher than that on the leeward side for a predetermined time after the start of operation. An air heat exchanger characterized in that it is equipped with a control means 4 for controlling the air heat exchanger.