Extraction of heat transfer parameters in active carbon–ammonia large temperature jump experiments

Abstract

Experimental and theoretical analyses were carried out with the aim of developing a method of extracting heat transfer parameters from active carbon–ammonia large temperature jump data. The approach presented in this paper extracts two thermo-physical properties from the data as opposed to one overall property in previously employed techniques. Active carbon samples were tested using the large temperature jump technique with a step temperature increase from 40 °C to 70 °C. For a loose packed sample, which is about 8 mm thick, the obtained thermal conductivity (k) and heat transfer coefficient (h) were 0.2 W m−1 K−1 and 250 W m−2 K−1 respectively. The effect of changing bulk density through compression was also investigated. The thermal conductivity and contact heat transfer coefficient were found to increase with bulk density. The two physical properties obtained were combined into one single heat transfer figure and were compared to what was obtained using a previous method on the same set of data. Considering the assumptions made in the analytical process, these numbers were in reasonable agreement. A dominance of the thermal conductivity was observed in thicker beds, while contact heat transfer coefficient dominated in thin beds.