Abstract:
The performance of heat-exchange equipment can be considerably improved by using heat transfer --..:Qt mentation techniques. Several investigators have proposed the use of twisted tapes as an appropriate means of enhancement of thermal performance of such systems.
The enhancement of heat transfer has been found to be accompanied by a considerable increase in friction power losses. In view of this, the system and operating parameters of such a heat-exchange system have to be selected on the basis of best thermohydraulic performance i.e. the maximum gain in, heat transfer accompanied by a minimum possible enhancement of friction power losses.
In this work, the effect of various system and operating parameters like flow Reynolds number twisted tape pitch, pipe diameter and Prandtl number on heat transfer coefficient and friction factor has been investigated. The value of thermohydraulic optimisation parameter has been determined in the range of flow, tape geometry and thermo-physical properties of fluid studied. From these values, optimum pitch diameter ratio for given set of values of Prandtl number and Reynolds number has been evaluated. These values have been presented in the form of
a design plot which can be utilized by a designer to obtain a thermohydraulically optimum heat-exchange system.
