Thermodynamic characteristics of waste heat utilization system applying S-CO2 partial expansion cycle
In the system realizing waste heat utilization through thermal cycle,there is a mutual restriction relationship between the cycle thermal efficiency and the utilization rate of heat source,solving this problem is the key to build an efficient waste heat utilization system.Taking supercritical carbon dioxide cycle as an example,this paper constructs a new cycle,namely the partial expansion cycle,to broaden the waste heat absorption temperature range,so as to enhance the waste heat utilization rate.After coupling gas turbine exhaust,the waste heat utilization system's power generation efficiency reaches 28.62%,the cycle thermal efficiency reaches 34.03%,and the heat source utilization rate reaches 84.11%.Moreover,to demonstrate the advantages of the partial expansion cycle,a waste heat utilization system is constructed based on the single regenerative Brayton cycle and the recompressed Brayton cycle.Furthermore,the three cycles are compared.Through calculation using the first and second law of thermodynamics,it is found that the power generation efficiency of the partial expansion cycle is higher than that of the other two classical cycles.Via analyzing the circulation process,it is found that the reason for the high efficiency of the partial expansion cycle is that the partial expansion structure broadens the endotherm temperature zone,makes the heat source utilization rate increase greatly,and thus improves the power generation efficiency.
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