Numerical Study on the Heat Transfer and Torsional Behavior of Flow in Helical HeatExchangers

Helical coil heat exchangers were widely used inindustrial applications ranging from cryogenic processes,air-conditioning, nuclear reactors and waste heatrecovery due to their compact size and high heat transfercoefficient. In this kind of heat exchangers, flow andheat transfer are complicated. In the current study,numerical methods was utilized to study the influence ofdifferent parameters such as coil radius and coil pitch onthe torsional behavior of flow through the helical heatexchangers and their impact on heat transfer andhydrodynamic characteristics. Modeling of the study wasimplemented based on the principles of heat transfer,fluid mechanics and thermodynamics. By applyingsuitable boundary conditions and selection of appropriategridding, analysis was done with Computational FluidDynamics software and results were compared withexisting experimental results in literature. The resultsindicated that heat transfer augments by increasing ofinner dean number, curvature ratio and by the reductionof pitch of the coils. It is shown that, the torsionalbehavior of flow is changed directly with the variation ofthe radius and pitch of the coils. With increase of loop'sradius, fluid’s torsional behavior approaches to linearbehavior and helical tube turns to straight tube and itseems to be the reason of what happens to the frictionfactor to be decreased. Tube pitch is a parameter thatdoesn’t have a great influence on analysis trend. Thetorsional behavior of flow is invigorated when the coilspitch and loops radius is reduced and the helical heatexchanger becomes more compact one.

کلیدواژه ها:

Helical heat exchanger ، Curvature ratio ، Dean Number ، Torsional behavior.