NUMERICAL SIMULATION OF CONJUGATE HEAT TRANSFER IN THE RECTANGULAR COOLING CHANNEL AT SUPERCRITICAL PRESSURES

In the present study, the conjugate heat transfer in a rectangular cooling channel is numerically simulated in supercritical pressure conditions. The compressible methane flow is considered as a working fluid. A finite volume scheme is utilized for the discretization of the governing equations on a collocated grid. Moreover, the central differencing scheme is employed for the discretization of the diffusion fluxes and density approximation on the control volume boundaries. Upwind and hybrid schemes are used for the density correlation approximation and the convective fluxes discretization on the control volume surfaces, respectively. An iterative solution method based on the SIMPLEC (Semi-Implicit Method for Pressure Linked Equations-Consistent) algorithm is adopted to solve the equations. The solver is developed based on the thermodynamic and transport property relations corresponding to the coolant flow conditions in the transcritical regime. The solver is validated with the experimental data of the MTP test, and the thermal behavior of methane inside the rectangular cooling channel is investigated. Moreover, a relation is derived to calculate the pseudo-critical temperature of methane according to pressure. The relative error of this relation with NIST data is less than 0.5 percent, and it operates in a range of pressure from 4.6 MPa to 30 MPa. Furthermore, the Nusselt relations presented for coolant flow with supercritical pressures are studied and corrected for the methane coolant in supercritical pressure conditions in 3D rectangular cooling channels. The relative error of modified Nusselt relations with numerical data is less than 1.0 percent.