Experimental Study of Heat Transfer and Flow Characteristics for a New Type of Air Heater

A new type air heater was developed, and an experimental set-up was built to analyze its characteristics. Within the Reynolds number from 2000 to 15000, the integrated characteristics in air heater channels with and without holed baffles have been studied experimentally. The experimental results show that the average Nu number increases greatly but the friction factor increases only slightly with the Re number. The Webb performance evaluation criterion has been adopted for analysis purposes. It is found that the integrated characteristics of heat transfer and flow friction increase with the hole's diameter at the same hole density (which is equal to the ratio of the hole's total area to the baffle's area), and the heat transfer rate increases with the hole density at the same hole diameter. The C type baffle has the best performance at the same heat transfer surface area and fan power consumption; its heat transfer rate improves about 44 to 69 percent