基于天然气发动机排气余热回收系统的非共沸混合工质性能分析

Performance Analysis of Non-azeotropic Mixture Based on CNG Engine Waste Heat Recovery System

针对一台车用天然气发动机排气能量的变化规律,建立了带回热器有机朗肯循环系统,对比分析了采用纯工质R245fa和非共沸混合工质R416A时,带回热器有机朗肯循环系统的净输出功率、热效率、效率和单位工质能量输出密度。结果表明,采用非共沸混合工质R416A时上述各项性能指标均优于采用纯工质R245fa。最后,构建了天然气发动机-带回热器有机朗肯循环联合系统,采用非共沸混合工质R416A,分析了联合系统的热效率。结果表明,加装带回热器有机朗肯循环系统后,发动机热效率最大可提高7%。

A set of organic Rankine cycle （ORC） system with internal heat exchanger （IHE） was designed to recover exhaust energy of a compressed natural gas （CNG） engine .The net output power ,heat release efficiency ,exergy efficiency and energy output density of ORC system for R245fa and R416A organic working fluids were compared and analyzed .The results show that the performance of R416A zeotropic mixture surpasses that of R245fa .Finally ,the CNG engine and ORC combined system with IHE is built and the thermal efficiency of R416A non‐azeotropic mixture is analyzed .It is found that the thermal efficiency of engine can increase by 7% at most .