Investigation on the Pinch Point Position in Heat Exchangers

• Published in: Journal of thermal science Vol. 25; no. 3; pp. 258 - 265
• Main Authors: Pan, Lisheng, Shi, Weixiu
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.06.2016
• Subjects: Classical and Continuum Physics; Engineering Fluid Dynamics; Engineering Thermodynamics; Heat and Mass Transfer; Physics; Physics and Astronomy; 临界条件; 临界温度; 位置; 夹点技术; 换热器; 流体性质; 热力学循环; 蒸发器; supercritical condition; phase transition; heat exchanger; heat transfer; pinch point position
• ISSN: 1003-2169; 1993-033X
• DOI: 10.1007/s11630-016-0858-7

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.