On the whole, the tube distance and sheet height of the stainless steel tube heat exchanger will affect the finning ratio, and the finning ratio has a great relationship with the film heat transfer coefficient of the medium inside and outside the tube. If there is a large difference in the heat transfer coefficient between the surface and the inner film of the tube, a finned tube with a relatively large finning ratio should be selected, such as steam heating air. When there is a phase change in the medium on one side, the difference in heat transfer coefficient will be larger.
For example, in order to better realize the exchange of cold and hot air, when the hot air is reduced below the dew point, it is recommended to use a stainless steel tube heat exchanger. In the case of heat exchange between air and air without phase change, or heat exchange between water and water, it is usually more suitable to use a bare tube. Of course, low finned tubes can also be used. Since it is a weak heat supply coefficient at this time, strengthening either side of them has a specific effect. However, the effect of too large finning ratio is not significant, and it is better to strengthen the contact area between the surface and the inside of the tube together, and the equipment can choose threaded tube or fluted tube.
The distance between the pieces of equipment should take factors such as fouling and cleaning into consideration when laying out the equipment, and at the same time, it should also strictly meet the requirements of equipment such as pressure drop. When arranging, the distance between the tubes is not easy to be too large, generally more than 1mm is suitable for pipe layout.
In fact, there is a certain radiative heat transfer in the center between the two stainless steel tube heat exchangers, but it is very small. Since this part has no fins and no resistance, the air can easily penetrate. In the process of air heating, the cold air without heat exchange will be neutralized with the heated hot air passing through the center of the fin, which reduces the effect of heat exchange. It is larger than 0.5mm, which shows the importance of tube distance when finned tubes are arranged.
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