The pinch point is important for analyzing heat transfer in thermodynamic cycles. With the aim to reveal the importance of determining the accurate pinch point, the research on the pinch point position is carried out ...The pinch point is important for analyzing heat transfer in thermodynamic cycles. With the aim to reveal the importance of determining the accurate pinch point, the research on the pinch point position is carried out by theoretical method. The results show that the pinch point position depends on the parameters of the heat transfer fluids and the major fluid properties. In most cases, the pinch point locates at the bubble point for the evaporator and the dew point for the condenser. However, the pinch point shills to the supercooled liquid state in the near critical conditions for the evaporator. Similarly, it shifts to the superheated vapor state with the condensing temperature approaching the critical temperature for the condenser. It even can shift to the working fluid entrance of the evaporator or the supereritical heater when the heat source fluid temperature is very high compared with the absorb- ing heat temperature. A wrong position for the pinch point may generate serious mistake. In brief, the pinch point should be founded by the itcrativc method in all conditions rather than taking for granted.展开更多
基金Project 51306198 supported by National Natural Science Foundation of China is gratefully acknowledged
文摘The pinch point is important for analyzing heat transfer in thermodynamic cycles. With the aim to reveal the importance of determining the accurate pinch point, the research on the pinch point position is carried out by theoretical method. The results show that the pinch point position depends on the parameters of the heat transfer fluids and the major fluid properties. In most cases, the pinch point locates at the bubble point for the evaporator and the dew point for the condenser. However, the pinch point shills to the supercooled liquid state in the near critical conditions for the evaporator. Similarly, it shifts to the superheated vapor state with the condensing temperature approaching the critical temperature for the condenser. It even can shift to the working fluid entrance of the evaporator or the supereritical heater when the heat source fluid temperature is very high compared with the absorb- ing heat temperature. A wrong position for the pinch point may generate serious mistake. In brief, the pinch point should be founded by the itcrativc method in all conditions rather than taking for granted.
