Abstract
Solar air heaters, because of its simple structure, is one of the most economical devices for building heating in cold regions. However, it has been noted that the thermal efficiency of a solar air heater is low due to the low heat transfer coefficient between the absorber plate and air. To solve this problem and increase the solar absorption rate, a novel solar air heater with aluminum honeycomb is developed. After the comparative experiments, we found it has a high thermal efficiency advantage than the traditional solar air heater in both natural and mechanical air supply conditions. It is founded that the thermal efficiency of aluminum honeycomb solar air heater will increase with the increase of the air flow rate and the ratio of b/a (honeycomb depth/ honeycomb diameter). The highest efficiency is 78%,when the air flow rate is 0.05kg/s and a= 6mm, b = 10mm. In order to explore and predict the parameters affecting the thermal performance of aluminum honeycomb solar air heater, a mathematical simulation, which considered the heat transfer model from honeycomb to the air and solar absorption model of honeycomb, has been developed and experimentally verified. These parameters include the air flow rate, solar elevation angle, the surface radiation absorption rate of honeycomb, the depth and diameters of honeycomb. The experiment and simulation results show the same trend and the average deviation between them is less than 3%. Therefore, these heat transfer models are useful in analyzing and optimized designing the aluminum honeycomb solar air heater.
