Heat transfer enhancement in an air process heater using semi-circular hollow baffles

摘要

Air process heater is one of the crucial equipment for many industries. Process heater is used in Baking. Drying, Laminating, Metal Working, Packaging, Plastic Welding, Preheating, Sealing, Soldering, Shrink Fitting, Synthetic Fabric Sewing and in other industries. But heating of air to a very high heat flux is sometimes impossible without the degradation of air quality, because many industries use combustion of gases for the purpose of heating the air to a very high heat flux. Electric healer can be alternative heating equipment, but it requires costly and long heating apparatus for the desired air temperature. In the present study, heat transfer enhancement in an air process heater was investigated both numerically and experimentally. A circular duct with 5 semi-circular hollow baffles and 4 cartridge electric heaters was designed for the process heating. Air was supplied from a wind tunnel at 3.17× 10~4 Reynolds number. Total supplied electric power was 3 kW. The results showed the temperature ratio (Ambient Temperature/Air Temperature) to be decreased up to 0.72 where in many electric air heaters the temperature ratio is about 0.9. The designed air process heater supplies air at velocity 19 m/s and temperature up to 147°C. The experimental results were also matched with the numerical simulation values of the designed heater. The results were also compared with some of the existing air process heater for investigating the enhancement of heat transfer.