The influence of the moments of probability density function for flow maldistribution on the thermal performance of a fin-tube heat exchanger

The work presented in this paper reports the quantitative study on the influence of the statistical moments of probability density function, i.e., mean, standard deviation, skew and kurtosis, for an air flow maldistribution profile on the thermal performance of a fin-tube heat exchanger. The effects of the geometrical parameters of the heat exchanger, i.e., tube diameter, fin pitch, row pitch, tube pitch, number of rows and fin surface pattern, are also investigated. The thermal performance is found to be noticeably affected by mean, standard deviation and skew but not the kurtosis. In addition, the interaction between the external and internal thermal resistances has a significant effect. All the geometrical parameters examined, except for the number of rows and fin pattern, have either a weak or an insignificant effect on the thermal performance degradation factor. Physical reasoning has been provided to explain the trends of the degradation with respect to the moments and geometrical parameters. From these trends, a new set of correlation equations is proposed to predict the degradation effect of the flow maldistribution on wavy fins. The correlation agrees well with experimental data within ±10%.