Active low-grade energy recovery potential for building energy conservation

With environmental protection and energy source posing as the biggest issue of the global problems, human beings have no choice but to reduce energy consumption. One way to accomplish this is to increase the efficiency of energy consumption and sufficiently exploit the low-grade energy in our lives. Low-grade energy recovery devices are of significance to meet the needs for energy conservation and green environment requirements such as fresh air pre cooling/heating, water heating, drying clothes and humidifying. These devices are also free of motion parts, non-corrosive and environmentally friendly. Various low-grade energy recoveries powered cooling, heating, drying and dehumidifying systems have been tested extensively; however, these systems are not yet ready to compete with the well-known vapor-compression system. The objective of this paper is to provide fundamental knowledge on the low-grade energy usage systems and present a detailed review on the past efforts in the field of low-grade energy recovery and usage subsystems. Lots of attempts have been made by the researchers to improve the performance of the low-grade energy recovery or usage subsystems. It is seen that, for successful operation of such systems, combination of diverse technologies is essential for more effective and multi-purpose applications.