Abstract
Heat pump drying system is prospect technology with high efficiency and energy saving. Stable and efficient operation of heat pump drying systems in cold climate regions is achieved using a separate heat recovery room, which is designed to recover the heat in the exhaust air. Using a separate heat recovery room aims to maintain stable operation through switching between enclosed and partial air-loop modes. This paper analyzes the drying parameters to verify the stability of system, compares the running modes, and evaluate the economy of the dryer. It is found that setting a separate heat recovery room can achieve a higher material uniformity, and the air parameters are less affected by surroundings. Moreover, modes need to be adjusted according to the drying parameters and surroundings. Meanwhile, the proposed system has a great advantage in reducing the exergy loss of the heat exchanger, which can reduce operating costs.