Experimental investigation on heat recovery from condensation of thermal power plant exhaust steam by a CO2 vapor compression cycle

In this paper, a method that utilizes CO₂ vapor compression thermodynamic cycle to recover low‐temperature heat from exhausted water steam of fossil fuel thermal power plants is reported. Experimental investigation was carried out to study the characteristics of low‐temperature heat recovery by liquid CO₂ evaporation process from vacuum exhausted steam condensation occurring at the turbine exit. Furthermore, measured heat recovery performances over one whole year are presented and discussed. Experimental results show that the present heat recovery process by CO₂ vapor compression cycle is able to operate stably. The yearly averaged water temperature at the CO₂ condenser outlet was measured at 87.5 °C with a COP value above 5.0. This high energy efficiency ratio is found to be mainly due to two factors: the transcritical CO₂ vapor compression and steam condensation phase change occurring on the CO₂ evaporator. The findings from this paper provide helpful guidelines for low‐temperature heat recovery system design and improving fossil fuel utilization efficiency. Copyright © 2013 John Wiley & Sons, Ltd.