摘要
引入无量纲熵产数NS表示换热器热力完善程度,对换热器进行性能熵产分析与评价,研究了表征换热器换热性能的特性参数:进口温度比α、预热温度比β、水当量比W、效能ε、传热单元数NTU及流型对换热性能的影响及相关关系。研究表明,NS值随α增大而增大;提高β值(大于临界值),可降低NS值;NTU值应大于1,考虑经济性,其值不宜过大;W<1的非平衡流是造成有效能损失的原因;应使W趋于1;ε值大于0.5而趋于1,可减少不可逆性及提高换热率。通过熵产分析,可揭示换热器能耗产生的原因,确定热力参数的优化匹配,达到节能目的。
On the basis of the second law of thermodynamics,introduced was a non-dimensional entropy production number Ns to express the thermodynamic perfection degree of a heat exchanger.Through an analysis and evaluation of entropy production studied was the impact of heat exchanger characteristic parameters,such as inlet temperature ratio α,preheat temperature ratio β,water equivalent ratio W,effective energy ε,heat transfer units NTU and flow pattern,on heat exchange performance and mutual relations.The results of the study indicate that the entropy production number Ns will increase with the increase of inlet temperature ratio α.The increase of preheat temperature ratio β to a value greater than a critical one can decrease the value Ns.The number of heat transfer units NTU should be greater than 1.On account of cost-effectiveness,this value should not be excessively large.The non-equilibrium flow representing water equivalent ratio W being less than 1 is a major cause leading to a loss of effective energy,therefore efforts shall be made to enable W tend to be 1.The value ε should be greater than 0.5 and tend to be 1,thus reducing the irreversibility and enhancing the heat exchange rate.Through an analysis of the entropy production,the cause of energy consumption in a heat exchanger can be revealed and an optimized matching of thermodynamic parameters identified,thereby attaining the energy-saving objective.
出处
《热能动力工程》
EI
CAS
CSCD
北大核心
2007年第4期399-403,共5页
Journal of Engineering for Thermal Energy and Power
基金
国家自然科学基金资助项目(50476080)
关键词
换热器
热力特性参数
熵产分析
热力性能评价
heat exchanger,thermodynamic parameters,entropy production analysis,thermodynamic performance evaluation
