Abstract:

The research on heat transfer pinch point (between refrigerant and heat-transfer fluid) was carried out in a condenser with airconditioning operation to investigate the change in temperature difference from condenser inlet to outlet and to avoid the occurrence of pinch pointFirstly, a model of refrigerants condensation was built, and the condition of pinch point occurrence was determinedThe condensation parameters of 15 commonly used refrigerants were decided for standard airconditioning operationSecondly, the equations of state of refrigerants were used to compute and obtain some relationships between temperature and enthalpy and the probability of pinch point occurrence of 15 refrigerants was obtainedLastly, the ranges of temperature difference from condenser inlet to outlet were recommended to avoid the occurrence of pinch point for 10 refrigerantsSuch information might be helpful to choosing refrigerants and adjusting the operation of condenser in airconditioner units.

Key words:

非共沸制冷剂, 冷凝, 传热窄点, 空调工况

摘要：

为了揭示15种常用非共沸制冷剂在空调工况下冷凝器中的传热窄点特征;探明它们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;进行了相应的理论分析。首先;建立了制冷剂的冷凝换热模型;明确了冷凝过程中传热窄点产生的条件;并根据标准的空调工况确定了15种制冷剂的冷凝物性参数。然后;利用制冷剂状态方程得到冷凝过程中温度与焓值的对应关系;并分段计算了焓随温度的变化率;进而得到15种制冷剂冷凝过程中发生传热窄点现象的概率。最后;针对10种可能发生传热窄点现象的制冷剂给出了换热流体温差控制范围;为合理选择制冷剂和设计运行工况提供了一定的理论依据。

关键词:

非共沸制冷剂, 冷凝, 传热窄点, 空调工况