JPH09133373A - Sectional shape of heat transfer tube of heat exchanger for domestic air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attempt to improve the heat transfer rate due to increases in the inner and outer surface areas of a heat transfer tube of a heat exchanger and to reduce the sound to the steady state by forming the section of the tube in flat, elliptical or oval shape, and forming a long axis in the air flowing direction and a short axis in the normal direction of the air flowing direction. SOLUTION: The indoor unit for a domestic air conditioner has a heat exchanger 1 having many heat transfer tubes 4 and fins, and an impeller 2 therein. In this case, the section of each tube 4 of the exchanger 1 is formed in a flat, elliptical or oval shape, and the tube 4 is so arranged that a long axis is formed in the air flowing direction and a short axis is formed in the normal direction to the air flowing direction. Thus, the heat transfer amount is improved due to the increases in the inner and outer surface areas of the tube and the sound is reduced to the steady state. Both the ends of the straight heat transfer tube are connected by the adjacent straight tube and U-shaped tube. The end face of the U-shaped tube has the same shape as the end face of the straight tube, but the sectional shape of the center of the U-shaped tube may have a circular or the same shape as the straight tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cross sectional shape of a heat transfer tube of a heat exchanger of an indoor unit of a home air conditioner.

[0002]

2. Description of the Related Art A heat transfer tube of a conventional heat exchanger has a diameter of 6 to 6.
Although a copper circular tube of about 10 mm was used, the heat transfer coefficient was low, and vortices of air were formed downstream of the heat transfer tube, causing noise.

[0003]

[Problems to be Solved by the Invention] Therefore, in order to improve the heat transfer coefficient of the heat exchanger and reduce noise, each manufacturer
I spent a huge amount of money on research and prototyping, but I couldn't come up with a good idea to solve the problem. The present invention was invented in order to meet such a strong demand of users.

[0004]

A heat transfer tube of a heat exchanger has a flat cross section, an elliptical cross section, an oval cross section, an air flow direction is a long axis, and an air flow normal direction is a short axis.

[0005]

If the cross-sectional areas are the same, the shape with the shortest circumference is a circle among all shapes. This is a theorem. However, if the surface shape of the heat transfer tube is complicated,
In some cases, the air resistance flowing on the surface of the heat transfer tube increases, and the heat transfer efficiency decreases on the contrary. As mentioned above, if the cross-sectional area is the same as that of a circular pipe, the flat length, ellipse, and oval length is longer than that of a circular pipe. Moreover, the shape is simple. This means that the surface area is large. Large surface area, large heat transfer. Moreover, since the length on the minor axis side is shorter than that of the circular tube, the pressure loss of the air flowing around the heat transfer tube is reduced, and the flow downstream of the heat transfer tube is smoothed, and the generation of vortices is reduced. The noise generated can be reduced.

[0006]

[Embodiment] The cross section of the heat transfer tube of the heat exchanger is made flat, elliptical, or oval, the major axis of the air flow direction is the minor axis, and the minor axis is the normal direction of the air flow direction. It features improved heat transfer and quietness by increasing the surface area. Since the heat transfer tube can be usually processed by cold drawing, cold extrusion, roll forming, etc., it is not difficult to process the heat transfer tube if the shape is not complicated. The cross-sectional shape of the heat transfer tube can be freely selected as long as it is not complicated. The cost of manufacturing is unchanged. Of course, the holes through which the heat transfer tubes of the peripheral fins pass can be manufactured by punching with a press, so that they can be easily matched to the cross-sectional shape of the heat transfer tubes. Therefore, the fin processing cost does not change. Both ends of the straight tube of the heat transfer tube are
Connect with a letter tube. The end face of the U-shaped pipe has the same shape as the end face of the straight pipe, but the cross-sectional shape of the central portion of the U-shaped pipe may be a circular pipe or the same shape as the straight pipe. Since the cross-sectional shape of the U-shaped pipe is processed by pressing, bending, etc.,
The shape in the middle can be changed freely, so the cost does not change.

[0007]

[Effects of the Invention] By making the cross-sectional shape of the heat transfer tube of the heat exchanger of the domestic air conditioner flat, elliptical, or oval, not only the heat transfer amount is improved with the same cross-sectional area, but also eddies at the downstream of the pipe are reduced. However, it is to reduce noise.

[0008]

[Brief description of the drawings]

FIG. 1 is a sectional view of an indoor unit of a home air conditioner.

FIG. 2 is a cross-sectional view of a heat exchanger

[Figure 3] Cross section of heat transfer tube Flat tube

[Fig. 4] Cross-sectional view of heat transfer tube Elliptic tube

FIG. 5: Cross-sectional view of heat transfer tube Oval tube

[Explanation of symbols]

 1 is a heat exchanger 2 is an impeller 3 is a nose part 4 is a heat transfer tube 5 is a blade

Claims (1)

[Claims] 1. A cross section of a heat transfer tube of a heat exchanger is made flat, elliptical, or oval, and a direction of air flow is a long axis, and a normal direction of the air flow direction is a short axis. It features the improvement of heat transfer coefficient and the noise reduction by increasing the inner and outer surface areas.