Experimental and numerical investigations on a solar tracking concentrated photovoltaic–thermal system with a novel non-dimensional lattice Boltzmann method

A Non-Dimensional Lattice Boltzmann Method for direct and porous medium model simulations of 240-tube bundle heat exchangers in a solar storage tank

“…Based on the Chapman-Enskog expansion on the dimensionless Navier-Stokes and energy equations, similar to the analysis with units [21], we obtain the dimensionless relaxation times for the flow s à f and heat transfer s à g based on Re ' , and Pe ' ¼ Re ' Pr ' as discussed in [23]. In the present study, the computational velocity scale is the natural convection velocity scale, hence Ri ref ¼ 1.…”

“…7. From left to right, the recorded isotherms are for dimensionless time from 1  10 3 to 1:5  10 5 , with time scaleDt ¼ 1:1866  10 À2 s.Similar as the scale analysis of[23,3], when t à 6 the present NDLBM, the heat transfer is dominated by conduction. The first picture from the left side ofFig.…”

“…The NDLBM applied in the present study is extended from that developed by Su et al [23] for a concentrated PV system to the present applicator, by replacing the governing parameters Re ' with ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Ra ' =Pr ' p and adding an extra body force term for the volume averaged drag between tube surfaces and fluid, and an extra supplementary term for the convection term of the momentum equation due to the definition of Darcy velocity. For the direct simulations, the two extra body force terms are equal to zero, and the bounce back boundary conditions are applied on every cylindrical wall to represent the no-slip velocity on the tube walls [34,35].…”

“…Similar to the NDLBM in [23], using the computational length 2 3 , and the density scale q f 0 , we can obtain the dimensionless coordinate…”

“…dimensionless governing parameters and the size of mesh on computational accuracy and speed. In order to overcome the above limitations of the conventional LBM, a novel Non-Dimensional Lattice Boltzmann Method (NDLBM) was developed by Su et al to simulate the conjugate mixed convection heat transfer inside a concentrated photovoltaic thermal receiver [23]. Compared to the conventional LBM, the NDLBM can reveal the relationships of dimensionless governing parameters based on macroscopic, microscopic, and mesoscopic length scales.…”