Lord Fin Tube-Finned tube for boiler
Finned tube for boiler
Some principles for understanding the principle of finned tube
After understanding the principles and functions of Finned tube for boiler, there are the following principles for the selection of finned tube
(1) If there is a big difference in the heat transfer coefficient between the two sides of the tube, fins should be installed on the side with small heat transfer coefficient.
Example 1: in the economizer of boiler, water flows in the tube and flue gas flows out of the tube. Fins should be used on the flue gas side.
Example 2: for the air cooler, the liquid flows in the tube and the air flows out of the tube. The fins should be added on the air side.
Example 3: in steam generator, the water boils inside the tube, and the flue gas flows outside the tube, and the fins should be added on the flue gas side. It should be noted that in the design, the side with small heat transfer coefficient should be placed outside the tube to facilitate the installation of fins.
(2) If the heat transfer coefficient on both sides of the tube is very small, in order to enhance heat transfer, fins should be installed on both sides at the same time. If the structure is difficult, fins can not be added on both sides. In this case, if only one side of the fin is added, the increase of heat transfer will not be obvious.
Example 1: in the traditional tubular air preheater, air flows inside the tube and flue gas flows outside the tube. Because of the gas to gas heat transfer, the heat transfer coefficient on both sides is very low, and it is very difficult to add fins in the tube, so we have to use bare tube.
Example 2: Although the heat pipe air preheater still uses flue gas to heat the air, because both the flue gas and the air flow outside the pipe, it is convenient to use finned tubes on both the flue gas side and the air side, which greatly increases the heat transfer.
(3) If the heat transfer coefficient on both sides of the tube is large, it is unnecessary to use finned tube.
Example 1: for water / water heat exchanger, when using hot water to heat cold water, the heat transfer coefficient on both sides is high enough, so it is unnecessary to use finned tube. However, in order to further enhance the heat transfer, the screw tube or corrugated tube can be used instead of the smooth tube.
Example 2: power plant condenser, outside the tube is the condensation of water vapor, water in the tube. The heat transfer coefficient of both sides is very high, so it is not necessary to use finned tube in general.