Plate-fin heat exchangers use flat plates and fins as heat transfer elements. It is mainly composed of plate bundles and heads. There are several channels in the plate bundle. Place fins between the two plates of each channel and seal them with seals on both sides. According to different fluid flow modes, the cold and hot fluid channels are stacked, arranged and brazed into a whole at intervals, that is, a plate bundle is made. The two fluid flow modes include counter-flow, cross-flow and cross-counterflow. The A and B fluids are respectively introduced into the respective plate bundle channels from the inlet head through the guide vane of one distribution section, and then led to the outlet head through the guide vane of the other distribution section. The two fluids exchange heat in countercurrent partition walls. The commonly used fins are straight, porous, serrated and corrugated.
The main advantages of plate-fin heat exchangers are:
①High efficiency. Due to the disturbance of the fin to the fluid, the boundary layer that constitutes the thermal resistance is constantly updated. The heat transfer coefficient is generally 3 times that of the shell-and-tube heat exchanger; and at a small temperature difference (1.5-2℃), the heat (cold) quantity Good recovery effect. The best effect is when used for gas-gas heat exchange.
②Compact. Since most of the heat is transferred through the fins and through the flat plate, the heat transfer area per unit volume of the equipment can reach 1500 m/m.
③Light weight. When the heat transfer area is the same, the weight is close to 1/5 of the shell-and-tube heat exchanger. ④Sturdy. Because the plate bundle is an integral piece and the fins play a supporting role between the two plates, it can withstand higher working pressure.
Because aluminum has good low-temperature performance and light weight, aluminum plate-fin heat exchangers are particularly suitable for deep-low temperature equipment such as oxygen production, ethylene and helium liquefaction, and can also be used in power plants.
