TY - JOUR
TI - Improved waste heat recovery through surface of kiln using phase change material
AU - Akram Nouman
AU - Moazzam M Usman
AU - Ali Hafiz Muhammad
AU - Ajaz Ashar
AU - Saleem Arslan
AU - Kilic Mustafa
AU - Mobeen Abdul
JN - Thermal Science
PY - 2018
VL - 22
IS - 2
SP - 1089
EP - 1098
PT - Article
AB - The heat losses that occur from the surface of the rotary kilns during  calcination process are a major source of waste heat in cement production  industry. In order to recover this heat, a multi-shell heat exchanger that  forms an annular duct over the high temperature zone of the kiln is used. The  phase-change material (PCM) paraffin wax with a melting point of 68°C is  filled in between the gap of the two concentric annular steel shells which  are thermally insulated from the outside. In order to draw a comparison and  to establish that phase change material improves the waste heat recovery, the  heat exchanger model made up of mild steel, which extracts waste heat from a  kiln, is experimentally investigated with and without the tertiary shell that  contains the phase-change material. The outer surface of the heat exchanger  is insulated by glass wool, and to facilitate the passage of air between the  shells for heat transfer, a variable speed centrifugal fan (for variable flow  rate) is installed. The results show that the waste heat recovery rate is  increased by 3% to 8% (depending on different air flow rate) with the use of  phase-change material. This implies that phase-change materials such as  paraffin wax can be used in heat exchangers to obtain an improved waste heat  recovery rate.