Measurement of local wall heat transfer coefficient in randomly packed beds of uniform sized spheres using infrared thermography (IR) and water as working medium

The needs for compact and effective heat transfer equipments are in growing demand and porous media caters to this need. Packed beds are a simple type of porous media devices which help in transport of mass, momentum and heat. The applications of packed beds are in chemical reactors, distillation, catalysis, thermal energy storage, food processing, solar power plants and several other areas. They act as enhancement devices for different transport processes. In the present study, the behavior of wall heat transfer coefficient with randomized packing of uniformly sized spheres is investigated. In the present work, the local wall heat transfer coefficient is estimated from local wall temperature data obtained using infrared (IR) thermography for the packed beds with randomized packing of uniformly sized spheres under steady state conditions with water as the working fluid. Hie experiments are conducted for bed to particle diameter ratios of 6, 3 and 2 using random packing of mono dispersed glass spheres. The two-layer model theory for heat transfer in packed beds is examined in terms of contribution or core zone and wall zone in packed beds. The comparison of heat transfer enhancement aspects with different insert configurations is done and packed beds are found effective. (C) 2017 Elsevier Ltd. All rights reserved.