Research On The Structure And Heat Transfer Enhancement Of Heat Pump Dryers

Heat pump dryer provides a good choose for low temperature drying paste type materials. In this paper, a systematic analysis was given on the structure, the applications of heat pump dryers, water-loop heat pump dryer and the process enhancement of heat pump dryer for paste type materials. Experiment was also given in this paper. The specific content of each section was as follows:Analyze the application characteristics place and virtues and defects of three different kinds of heat pump dryers—opened loop heat pump dryers, semi-opened loop heat pump dryers and closed loop heat pump dryers. Two typical widely used closed loop heat pump dryers were introduced in great detail and also were evaluated based on ideal cycle method.The water loop heat pump dryer was composed of heat pump part and dryer part connected by water loop. It is more suitable for mediate and small scale heat pump dryers. The structure, operated characteristics, and method of design were analyzed. A comparison between it and normal heat pump dryers was also made.The basic way to enhance the process of heat pump dryer for paste type materials is to combine the convection and heat conduction, the mechanism, basic parameters, and effect of combined the convection and heat conduction drying.A experimental of normal heat pump dryer and a water loop heat pump dryer were set up, and their operation characteristics and SMER were also studied. The differences between experimental equipment and ideal heat pump dryers was analyzed, and the way to improve experiment equipment—elevate the efficiency, and the drying rate were also given.