Abstract
M.Ing.
Tube-in-tube heat exchangers have wide industrial application. From fields as diverse as food and beverage to automotive industries these devices are used extensive to enable heat exchange. In many cases they are manufactured by coiling two tubes placed one within the other. This method often results in the tubes not sharing the same centre line and in some cases annular contact occurs. Comparison of such heat exchangers to aligned (concentric) devices was done experimentally to quantify the influence annular contact has on the heat exchange capabilities.
By comparison of the Nusselt numbers calculated for each vessel in each experiment, it was concluded that annular contact diminishes the capability of a counterflow tube-in-tube heat exchanger to transfer energy from a hot to a cold fluid. This effect becomes more profound at higher Reynolds and Prandtl numbers respectively.