Condenser Coil Optimization and Component Matching of Heat Pump Dryer

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.

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