S.P.Raja, R.Rajavel, D.Navaneethakrishnan
The exhaust gas from an internal combustion engine carries away about 20% of the heat of combustion. The energy available in the exit stream of many energy conversion devices goes as waste, if not utilized properly. The major technical constraint that prevents successful implementation of waste heat recovery is due to its intermittent and time mismatched demand availability of energy. In the present work, heat recovery system consisting of a compact shell and tube heat exchanger and a thermal energy storage (TES) tank with paraffin and ethylene glycol as phase change material (PCM) storage has been designed and fabricated for waste heat recovery from diesel engine exhaust. Castor oil is used as heat transfer fluid (HTF) in the tube side to extract heat from exhaust gas. Cascading mode of heat recovery is tested using those two phase change materials. Heat recovered both during the endothermic and exothermic reactions of phase change material. About 14% of waste heat through the diesel engine exhaust is recovered using this cascaded mode of thermal storage system.