The model used for the following simulations was validated
against a cylindrical source model, as well as by comparison with
the models developed by Kujawa et al. [35] and Bu et al. [2]. A more
specific breakdown of the model validation is detailed in Templeton
et al. [34]. Additionally, the proposed model simplifies the velocity
profile of the fluid within the heat exchanger to a uniform profile.
This assumption was considered due to the laminar nature of the
flow, the relatively low fluid velocity, and comparison with results
obtained from implementing a parabolic velocity profile for the
fluid in the inner pipe and outer annulus. By verifying the Reynolds
Fig. 2. Geometric properties of the double pipe heat exchanger model. number of mass flow rates considered in the investigated scenarios