Thermodynamic performance study of a pumped thermal energy storage system coupled with low-temperature waste heat recovery
To effectively recover low-temperature waste heat resource in the steel industry,we have integrated the low-temperature sinter cooling flue gas waste heat as a heat source in a pumped thermal energy storage(PTES)system.We constructed thermodynamic calculation models for basic PTES(B-PTES)and regenerative PTES(R-PTES)systems.The R365mfc was selected as the cycle working medium of heat pump(HP),while the R1233zd(E),R245ca and R236ea were set as the working mediums for the organic Rankine cycle(ORC).Our study examined how the HP condensation and evaporation temperatures,as well as the ORC evaporation temperature,affect the thermodynamic performance of B-PTES and R-PTES systems under different ORC working medium conditions.The results show that reducing the HP condensation temperature and increasing the evaporation temperatures of HP and ORC can improve the heating coefficient(COPnew)and power efficiency(ηptp)of the PTES system.However,higher HP condensation temperatures,lower HP evaporation temperatures,and lower ORC evaporation temperatures decrease the system's exergy efficiency(ηex).For identical thermodynamic parameters,the R-PTES system consistently outperforms the B-PTES system in terms of COPnew,ηptp,and ηex.Evaluating the overall performance,the B-PTES system achieves optimal results with R1233zd(E)as the ORC medium,followed by R245ca and R236ea.Conversely,the R-PTES system performs best with R245ca,followed by R1233zd(E)and R236ea.Specifically,when using R245ca as the ORC working medium,increasing the HP condensation temperature by 2℃ results in an average ηex decrease of 0.5％for B-PTES and 0.53％for R-PTES.Conversely,raising the HP evaporation temperature by 2℃ leads to an average ηex increase of 0.2％for B-PTES and 0.21％for R-PTES.Furthermore,a 2℃ in ORC evaporation temperature results in an average ηex improvement of 0.55％for B-PTES and 0.63％for R-PTES.Overall,for systems driven by low-temperature sinter flue gas waste heat,the R-PTES system is recommended,particularly using R245ca as the cycle working medium of the ORC system.
waste heat recoverypumped thermal energy storageorganic Rankine cycleregenerative structurethermodynamic performance
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维普
