Abstract
Heat exchangers usually involve two or more fluids having different temperatures. The performance of heat exchangers depends critically on the nature of the participating fluid flows. Over the years of traditional heat exchanger design, the most accounted feature of the fluid flow has been its magnitude. This is because design procedures for heat exchangers have been closely connected to fan/blower/pump curves in which the magnitude of the delivered flow is linked to the pressure rise. However, those characteristic curves do not take into account swirl, eddies, backflow, cross-sectional nonuniformities, and unusually high turbulence, almost all of which are embedded in actual fluid flows delivered to heat exchangers. The focus of this chapter is to quantitatively demonstrate the necessity of taking into account all of the characteristic features of the fluid flow that is delivered to the heat exchanger. This is accomplished by treating the fan/blower/pump and the heat exchanger as a single interactive system. In such a treatment, it is mandatory that fan rotation is fully considered to ensure that all rotation-based flow characteristics are included. The composite system, consisting of the fluid mover and the heat exchanger, is solved by numerical simulation. The fluid flows produced by this approach are a more true representation of reality.
Heat exchangers usually involve two or more fluids having different temperatures. The performance of heat exchangers depends critically on the nature of the participating fluid flows. The focus of this chapter is to quantitatively demonstrate the necessity of taking into account all of the characteristic features of the fluid flow that is delivered to the heat exchanger. This is accomplished by treating the fan/blower/pump and the heat exchanger as a single interactive system. The composite system, consisting of the fluid mover and the heat exchanger, is solved by numerical simulation. The chapter presents evidence of the importance of taking into account the realistic interactions between a fluid mover and the heat exchanger, which is the recipient of the fluid flow. The two types of fans that generally are encountered in connection with heat exchangers are axial and centrifugal.