Review of heat pump systems for drying application

Heat pump system has been research and developed for different applications and mostly in space heating, cooling and dehumidifying (drying). To improve the performance of the heat pump system, research on modifying heat pump system and combining to other mechanism has been done widely. Heat pump dryer is proven as drying system that ensure the product's quality especially food and agriculture products, able to control drying temperature, relative humidity, moisture contain extraction, drying air velocity, drying period and etc. Factor to be concern in improving a heat pump dryer includes the installation cost, drying performance such as air velocity, drying temperature and relative humidity, performance of the component hybrid to heat pump dryer, power required to run the system and also payback period. By improving the development of heat pump dryer will help increase the product quality and reducing operation cost of drying industry. (C) 2011 Elsevier Ltd. All rights reserved.