Experimental Verification of the Thermal Component of a User-Defined Source-Term CFD Model of Heat and Mass Transfer in a Thin Liquid Layer

A modular computational fluid dynamics (CFD) framework for heat and nonequimolar mass transfer in a thin liquid layer is formulated in ANSYS Fluent using user-defined source terms. The sensible thermal module rewrites the near-wall Fourier heat flux as a volumetric energy source, SE,th = λeff(Tw − T)/(δy hc), where λeff is the local effective thermal conductivity, Tw and T are the boundary and cell temperatures, and δy and hc characterize the wall-adjacent source layer. The mass-transfer module uses the structurally analogous source ṁpc = k0(Y0,b − Y0), with k0 = Dmρ0/(δy hc), and the phase-change energy contribution is SE,pc = −ṁpc hfg. A full-scale gasketed plate heat exchanger with a 3 mm interplate gap was used to verify the single-phase thermal component implemented through source_thermal_energy; mass-transfer, species, transient UDS, and latent-heat source terms were disabled. The thermal CFD calculation predicted cold- and hot-stream outlet temperatures of 338.01 and 350.81 K versus measured values of 338.15 and 349.65 K, corresponding to relative deviations of 0.041% and 0.332%. The experimental comparison therefore verifies the sensible thermal component under single-phase conditions, whereas evaporation, condensation, nonequimolar species transfer, and latent-heat coupling remain outside the experimentally verified scope.