JPS6324384Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a natural air-cooled heat exchanger, and particularly to a natural air-cooled heat exchanger having a condensing pipe arrangement advantageous for plate fin condensers and the like.

Figure 1 explains a natural air-cooled heat exchanger equipped with a Freon-cooled rectifier, which utilizes the heat transfer of boiling and condensing gases such as Freon R-113. A diode element 3 is immersed in the liquefied fluorocarbon liquid 2, and a fin 4 for cooling the element is attached to the diode element 3. When current flows through the diode element 3, heat is generated, this heat is transferred to the element cooling fin 4, and boiling heat transfer is performed on the surface of the fin.
The vaporized Freon is transferred to the heat transfer pipe 5 which is connected to the tank 1.
, enters the gas phase chamber 6 constituting the condenser, and further flows into the condensing pipe 7 . Many of these condensing pipes are installed with the side of the serious gas phase chamber 6 lowered,
In addition, a large number of cooling fins 8 are fixed to these condensing pipes 7. Freon gas is condensed in pipe 7
The condensed liquid is condensed in the inclined condensation pipe 7
and return to the original state. The heat transferred to the condensing pipe 7 is transferred to the fins 8 and released into the atmosphere by natural convection heat transfer.

By the way, when Freon R-113 is used as a refrigerant, the cooling system has a closed structure, so when the temperature of the refrigerant changes from -30℃ to +90℃, the internal pressure will be -0.97Kg/cm ² G~+2.5Kg/ ^cm2
Changes up to G. Therefore, this device has a maximum pressure of 3
It must have strength that can withstand kg/cm ² G.

However, since the condenser is intended to be small and lightweight, aluminum is used, and if there is only one condenser, the gas phase chamber will be large, and the plate will have to be thick to have the strength to withstand high pressure. , the weight is also large. Furthermore, if the condenser is divided into a plurality of parts in an attempt to reduce the plate thickness, there are disadvantages in that the number of welding parts increases, the cost increases, and the reliability decreases.

The purpose of the present invention is to provide a compact and lightweight natural air-cooled heat exchanger that can withstand high pressure.

According to the present invention, the above object is achieved by centrally arranging the condensing pipes in the center of the heat dissipation fins and reducing the size of the gas phase chamber.

Hereinafter, details of the present invention will be explained along with embodiments shown in the drawings.

2 and 3 illustrate an embodiment of the present invention, in which the same parts as in FIG. 1 are designated by the same reference numerals.

In this embodiment, the gas phase chamber 6 is downsized, and the number of condensing pipes, which is approximately half the number of conventional condensing pipes, is arranged in a concentrated manner in the center of the fin 8.

4 and 5 compare the conventional condensing pipe arrangement and the condensing pipe arrangement according to the present invention. In both cases, the diameter of the condensing pipe 7 is
19mm, the material of fin 8 is aluminum, and the thickness is 0.5mm
It is. The vertical and horizontal arrangement intervals u ₁ and h ₁ of the condensing pipes 7 are exactly the same, but in the conventional example shown in FIG. 4 there are 50 pipes, and in FIG. A condensing pipe is used.

By the way, in general, the natural convection transfer rate α _n when a flat plate, which is not very hot, is left in air at one atmosphere near room temperature is expressed by the following equation (1).

α _n = 1.22 (Δt/h) ^0.25 Kcal/m ² h℃ ...(1) Here, Δt = temperature difference between ambient temperature and fin,
h=height of the fin. Now, Δt=50℃, h
= 606mm, the natural convection heat transfer coefficient α _n is 3.7Kal/
m ² h℃.

Here, when calculating the fin efficiency in the conventional condensing pipe arrangement as shown in Fig. 4, if the annular fin is calculated as shown in Fig. 6, the diameter de≒79 mm of the annular fin, and the width W=30mm,
When thickness (half of plate thickness) yb=0.25mm, Therefore, the fin efficiency φ=0.97.

On the other hand, in order to determine the efficiency of the fins shown in FIG. 5, it is easier to understand by considering the efficiency separately in the central part where the condensing pipe is arranged and the efficiency in the outside part without the condensing pipe. It is best to think of the part without the condensing pipe as a direct air fin as shown in Figure 7.
That is, the part without the condensing pipe is W = 100mm, yb
= 0.25 mm, W = α _n /λyb = 0.87, and the fin efficiency φ ₂ = 0.87. Also, the central fin efficiency φ ₁ is calculated as in the case of Fig. 4,
φ ₁ =0.97. Now, assuming that the areas with and without condensing pipes are equal, the overall fin efficiency can be considered to be φ ₁ +φ ₁ ×φ ₂ /2 on average.

In the case of this embodiment, the heat flux from the condensing pipe 7 to the fins 8 is doubled, but since the thermal resistance during this time is extremely small, there is no significant difference in temperature, so it will be ignored.

In this way, when comparing the conventional example and the present example, the fin efficiency only decreases by 6%. As a result, by centrally arranging the condensing pipes at the center of the fin, it is possible to reduce the number of condensing pipes and downsize the gas phase chamber without significantly reducing the fin efficiency. Therefore, both the welding time and the plate thickness can be reduced, the size and weight can be reduced, and it is extremely advantageous economically.

As is clear from the above explanation, according to the present invention, the condensing pipes are concentrated in the center of the fins, and the gas phase chamber is miniaturized. Obtainable.

[Brief explanation of the drawing]

1A and B are front and side views illustrating a conventional structure, 2A and 2B are front and side views illustrating an embodiment of the present invention, 3 is a plan view, and 4 5 and 5 are side views illustrating the arrangement of condensing pipes in the conventional structure and this embodiment, and FIGS. 6 and 7 are explanatory diagrams illustrating the fin effect. DESCRIPTION OF SYMBOLS 1... Tank, 2... Freon liquid, 3... Diode element, 4... Element cooling fin, 5... Heat transfer tube, 6... Gas phase chamber, 7... Condensation pipe, 8...
Finn.

Claims (1)

[Scope of utility model registration request] A plurality of condensing pipes are arranged at an angle with respect to the horizontal direction and parallel to each other, and a plurality of fins are attached to the outer periphery of these condensing pipes so as to be perpendicular to the longitudinal direction of the condensing pipes. A condenser having a gas phase chamber connected to both ends,
In a natural air-cooled heat exchanger in which a gas phase chamber connected to a lower end of a condensing pipe communicates with a closed container containing a condensable cooling medium and parts to be cooled, the condensing pipe is concentrated in the center of the fin. A natural air-cooled heat exchanger characterized in that a surface of the gas phase chamber that is substantially parallel to the fins is smaller than the fins.