Performance analysis of heat pump and infrared–heat pump drying of grated carrot using energy-exergy methodology

Abstract

In this study, a hybrid drying system that combines all of the advantages of different drying methods was developed. This study aims to compare experimental results of a heat pump dryer (HPD) and an infrared assisted heat pump dryer (IRAHPD), to determine the energy and exergy efficiency of dryers and to analyze the drying kinetic of grated carrot for observing the effectiveness of the dryers. Samples were dried at 45 °C and 50 °C set temperatures and 0.5 m/s air velocity. According to dry basis calculation, initial moisture content amount was 7.06 g water/g dry matter and amount of final moisture content of dry matter was obtained as 0.14 g water/g dry matter. Energy efficiency varied between 5.3% and 50%. Minimum and maximum coefficients of performance for the whole system (COPws) were 2.11 and 2.96 respectively. Maximum exergy efficiency was obtained 66.8% while minimum exergy efficiency was 31.6%. It was concluded that during the time to reach a stable state of system, the exergy efficiency increased in response to exergy loss decreases. This study shows a successful and efficient combination of heat pump and infrared heater in food drying. © 2016 Elsevier Ltd