Numerical studies of a double-pipe helical heat exchanger

A double-pipe helical heat exchanger was numerically modeled for laminar fluid flow and heat transfer characteristics under different fluid flow rates and tube sizes. Two different tube diameters were used. The overall heat transfer coefficients were calculated for both parallel flow and counterflow. Validation of the simulations was conducted by comparing the Nusselt numbers in the inner tube with those found in literature; the results fell within the range found in the literature. The greatest thermal resistance was found in the annular region. The annulus Nusselt number was correlated with a modified Dean number, and showed a strong linear relationship.