Characteristics of heat transfer for tube banks in crossflow and its relation with that in shell-and-tube heat exchangers

Abstract

The thermodynamics performances for tube banks in crossflow and for the shell sides of shell-and-tube heat exchangers were investigated, and the relation of fluid flow and heat transfer between them were analyzed. The results indicate that the incline degree of tube does not lead to obvious change on characteristics of fluid flow and heat transfer for fluid flowing across tube banks. Under different incline degrees of tubes, the characteristics of fluid flowing across tube banks are similar concerning fluid velocity components and local heat transfer along across angles. The ratios of vertical velocity component to parallel velocity component remain about 4.2 in the banks. Decreasing of impacting angle in the model reduces average fluid velocity crossing tubes, which weakens heat transfer. Characteristics for fluid flowing across tube bundles in shell sides distinguish from that for tube banks in crossflow with different impacting angles. At the same mass rate, the values of parallel velocity components in different shell sides are equivalent, but the vertical velocity components vary greatly. The ratios of vertical velocity component to parallel velocity component change from about 0.33–0.92 in the three types of shell sides. Many different leakage paths and bypass streams leads complicated fluid flow in shell sides of heat exchangers. The complicated flow pattern is not a simple combination of fluid flowing across tube banks with different impacting angles. The thermodynamics performance of shell side depends greatly on the vertical velocity component of fluid. The achievement in the paper can be a reference for study and development of heat exchanger.