Mi Tingcan,Li Yanzhong
(School of Energy and Power Engineering,Xi'an Jiaotong University,Xi'an ¡¡710049,China)
Abstract:A group of governing equations for a counter-flow plate-fin heat exchanger(HX) with double cold channels were put forward on the basis of theoretical analysis and eventually solved by using finite difference method in order to confirm the longitudinal heat conductivity effects on cryogenic HX.A dimensionless longitudinal heat diffusion coefficient(¦Õ) was proposed to indicate the effect of longitudinal heat conductivity in cryogenic HX, which could simplify the model from two dimensions to one dimension and be more convenient for calculation.The results show that the effect of the longitudinal heat conduction on HX increases along with the increase of ¦Õª« and heat transfer unit, and degrades the performance of HX.The cross-sectional area should be reduced as small as possible for alleviating the heat loss.It is also revealed quantitatively that higher heat conductivity of solid walls enhances the heat loss according to this model.
Keywords:longitudinal heat conduction;plate-fin heat exchanger;finite difference method
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