Common Types and Installation Height of Air Heaters
Air heaters are generally classified into two types: bare tube type and finned tube type. The bare tube air heater consists of steel tubes and headers, where the heat medium flows inside the tubes and heats the air through the outer surface of the tubes. The finned tube type uses finned tubes instead of bare tubes, mainly used in air conditioning engineering.
For air heaters on air conditioning ducts, the installation height is usually indicated in the relevant design drawings or specified in the design. If not, you can refer to related drawing materials to obtain the specific value.
An air heater is an electric heating device that can heat gas streams. Its heating element is mainly a stainless steel electric heating tube. Moreover, in the inner cavity of this heater, there are multiple baffles or guide plates to guide the gas flow direction, achieving uniform gas heating. This can improve the heat exchange efficiency of the air heater.
What are the factors affecting air heaters?
1. Increasing the gas inlet velocity of the air heater can enhance convective heat transfer and reduce the surface temperature of the internal electric heating elements. This not only helps to increase the service life of the heating elements but also reduces heat loss, thereby increasing efficiency. However, if the velocity is too high, the pressure loss increases sharply, which is detrimental to improving heating efficiency.
2. If other conditions remain unchanged, changing the surface load will cause the wall temperature of the electric heating elements to change linearly. If the surface load increases, the wall temperature will increase, which will reduce the service life of the heating elements. However, if the surface load is too small and the wall temperature is too low, the efficiency of the heater decreases. Therefore, the selection of the surface load of the electric heating elements is relatively important.
3. When the final air temperature T2 in the air heater increases, the convective heat transfer intensity decreases, and the surface temperature of the electric heating elements rises simultaneously, thereby reducing the efficiency of the heater.
