2019 Volume 27 Issue 1 Pages 1-15
Utilization of the widely available low grade heat including the solar thermal energy, waste heat and even the ambient heat offers great opportunities for environmentally friendly energy harvesting. Despite the efforts on developing new low grade heat conversion technologies, heat pump is still one of the most effective ways to utilize low grade heat in the current stage. Regarding the heat pump for efficient low grade heat uses, this paper unrolls a comprehensive view from the thermodynamic cycle, working medium, as well as heat and mass transfer enhancement, to the low grade heat utilization systems. Different heat pumps including vapor compression heat pump, absorption heat pump, and adsorption heat pump are included. The aim of this paper is to share our experience in the evolution from heat pump concept to low grade heat utilization. It is also helpful for researchers who try to build a bridge between thermal science and thermal engineering.