Experimental investigation on power generation with low grade waste heat and CO2 transcritical power cycle

In this study, a small-scale test rig of CO2 transcritical power cycle (T-CO2) system driven by low-grade heat has been developed and investigated experimentally. The test rig consists of a number of essential components including a CO2 turboexpander with high speed generator, finned-tube air cooled condenser, liquid receiver, CO2 liquid pump and CO2 gas generator. The CO2 is heated in the plate-type gas generator by hot thermal oil flow which is circulated and heated by exhaust flue gases from an 80kWemicroturbine CHP unit. The test rig has been fully commissioned, instrumented, controlled and is ready to operate experiment as required. Subsequently, at constant heat sink (ambient) and heat source (thermal oil) temperatures, a series of experiments have been carried out to examine the effects of various important parameters on the T-CO2 system performance. These include thermal oil flow rate and CO2 mass flow rate etc. Preliminary experimental results show that the CO2 TPC is applicable for the low temperature heat sources to generate power although further efficiency improvements are needed. In addition, the experimental outcomes can instruct future optimal system design and controls.