二氧化碳逆循环中气体冷却器的传热窄点分布

为了揭示二氧化碳逆循环气体冷却器中的传热窄点分布特征,探明二氧化碳和换热流体间温差的沿程变化规律,以及如何防止传热窄点的产生进行相应的理论分析.建立二氧化碳的冷却换热模型,明确冷却过程中传热窄点产生的条件,并利用状态方程得到不同压力下二氧化碳温度与焓值的对应关系,分段计算焓随温度的变化率进而得到多种压力下发生传热窄点现象的机率.根据换热器的最小传热温差,确定不同压力下进出气体冷却器的换热流体的物性参数和窄点分布规律.在气体冷却过程中,传热窄点的位置随压力的增加而逐步向换热后程移动;换热流体在气体冷却器出口的温度随二氧化碳压力的升高呈现先降低再升高的趋势.此外,还给出6种压力下避免发生传热窄点现象的换热流体温差控制范围,为合理选择二氧化碳逆循环工况提供理论依据.

Distribution of Heat Transfer Pinch Point of Gas Cooler in CO_2 Inverse-cycle

In order to reveal distribution characters of heat transfer pinch point of gas cooler in CO2 inverse-cycle,and explore the change rule of temperature difference between CO2 and heat-transfer fluid,and how to avoid the occurrence of pinch point inside heat exchangers,corresponding theoretical analysis are carried out.A cooling model of CO2 is built,so the occurrence condition of pinch point is obtained,also the situation equation of CO2 is used to compute some relationship between temperature and enthalpy,gr...