Numerical simulation of a heat pump assisted solar dryer for continental climates

A numerical model has been proposed in this work for predicting the energy performance of a heat pump assisted solar dryer under continental climates. The model is based on energy and mass balance. The energy performance comparison between heat pump dryer, solar dryer and heat pump assisted solar dryer are presented. The simulation was performed for four different climatic conditions of Almaty city in Kazakhstan. The simulation results showed that, the heat pump assisted solar dryer is more energy efficient when compared to the conventional solar dryers. It is also confirmed that, the conventional solar dryers are not suitable for continental climatic conditions having low ambient temperatures. The heat pump dryer reduces the initial moisture content of banana (on wet basis) from about 74% to the final moisture content (on wet basis) of about 19% in 21 h. Similarly, the solar dryer reduces the initial moisture content (wet basis) from about 74% to the final moisture content (wet basis) of about 20% in 35 h. The specific moisture extraction rate and coefficient of performance of a heat pump assisted solar dryer are estimated to be about 0.6 kg/kWh and 2.72, respectively. (C) 2019 Elsevier Ltd. All rights reserved.