Analytical Design of Helically Coiled Heat Exchangers Used for Transient Heat Transfer Applications

In the present study, a special application of a helical heat exchanger, i.e. its usage in the cooling process of a reservoir’s hot fluid at a specified finite time was considered. An analytical approach was developed to anticipate the required heat transfer area of the heat exchanger. Also, the effects of the various flow and geometry parameters of the heat exchanger like the mass and initial and target temperatures of the reservoir fluid, mass flow rate and inlet temperature of the tube-side fluid, the diameter, curvature and pitch of the coiled tube, etc, and also the finite time allocated to heat transfer were investigated. Next, the effects of different parameters upon the required length were examined in appropriate curves. It was generally observed that transition from laminar to turbulent regime, enhanced heat transfer coefficient and consequently, reduced the required length of the heat exchanger.