Abstract
The heat pump dryer is an energy-efficient piece of drying equipment, but due to its complicated system of the two interactive working fluids (refrigerant and drying air), the optimum design remains the question. A heat exchanger is the major component influencing the heat pump dryer (HPD) performance. This article reports a study to optimize the condenser coil of the HPD and the component matching in order to obtain optimum performance. The study was carried out by a mathematical model for system simulation and followed by experimental verification. Five HPD configurations were studied, including different designs in air and refrigerant flow paths. It was found that the closed-loop HPD with air bypassing over the evaporator is the most appropriate configuration. The proper coil design is 2-row, 2-circuit configuration with optimum refrigerant mass flow rate of 16–20 g/s/circuit. The optimum air flow rate was found to be in the range of 0.6–0.8 kg/s. The corresponding number of coil modules is 8.
ACKNOWLEDGEMENTS
The authors thank the Thailand Research Fund and the Joint Graduate School on Energy and Environment for the financial support to this project.