Recovering waste heat is essential for primary energy savings and carbon emission reduction.To provide direct and reliable suggestions for factories to recover waste heat,energetic,economic and exergoeconomic comparis...Recovering waste heat is essential for primary energy savings and carbon emission reduction.To provide direct and reliable suggestions for factories to recover waste heat,energetic,economic and exergoeconomic comparison between direct heat exchange(DHE)and open-cycle mechanical heat pump(MHP)under various operating conditions is carried out in this work.The price ratios R_(ES)(electricity to steam)and R_(HS)(hot water to steam)are introduced to quantify regional impacts and conduct quantitative analysis.A semi-empirical formula is obtained to explore the exergoeconomic performance of the two systems.For waste heat within 373.15-423.15 K,the exergy efficiency of the DHE with a temperature difference of 10-90 K is always lower than that of the MHP with a temperature lift of 10-50 K.The economic performance of the two systems has a break-even point,depending on the operating parameters and relative prices of electricity,steam,and hot water.Under the average R_(ES)(3.8)in China,if R_(HS)is higher than 0.748,the annual revenue of the DHE is always higher,whereas the MHP is more economical when R_(HS)is lower than 0.110.In regions where R_(ES)is higher than 4.353,the annual revenue of the MHP will be negative in some cases.展开更多
基金Financial support from the National Natural Science Foundation of China(21736008)。
文摘Recovering waste heat is essential for primary energy savings and carbon emission reduction.To provide direct and reliable suggestions for factories to recover waste heat,energetic,economic and exergoeconomic comparison between direct heat exchange(DHE)and open-cycle mechanical heat pump(MHP)under various operating conditions is carried out in this work.The price ratios R_(ES)(electricity to steam)and R_(HS)(hot water to steam)are introduced to quantify regional impacts and conduct quantitative analysis.A semi-empirical formula is obtained to explore the exergoeconomic performance of the two systems.For waste heat within 373.15-423.15 K,the exergy efficiency of the DHE with a temperature difference of 10-90 K is always lower than that of the MHP with a temperature lift of 10-50 K.The economic performance of the two systems has a break-even point,depending on the operating parameters and relative prices of electricity,steam,and hot water.Under the average R_(ES)(3.8)in China,if R_(HS)is higher than 0.748,the annual revenue of the DHE is always higher,whereas the MHP is more economical when R_(HS)is lower than 0.110.In regions where R_(ES)is higher than 4.353,the annual revenue of the MHP will be negative in some cases.
