Radiation heat transfer within a solar system considering nanofluid flow inside the absorber tube

Abstract

Purpose

This paper aims to model solar unit equipped with mirrors with numerical simulation. To augment the efficiency of system, absorber pipe was equipped with fins and nanomaterial was used as carrier fluid. Existence of secondary reflector results in better optical efficiency.

Design/methodology/approach

Finite volume approach is used for modeling which is done in two steps. The first one is done to achieve the heat flux distribution and second step to model turbulent flow inside the pipe. Verification has been presented for calculation of important functions (f and Nu). Outputs reveal the impacts of fin height (HF), number of fin (NF), inlet temperature (T_in) and velocity on irreversibility, thermal treatment.

Findings

Surface temperature decreases by 0.498, 0.07 and 0.017% with intensify of Re, HF and NF, respectively, when other factors were minimum. With augment of T_in, wall temperature increases about 9.87%. Given NF = 8, HF = 3 mmm, growth of Re makes Darcy factor to decrease about 28.28%, but it augments the Nu by 2.63%. Nu augments with rise of NF and HF about 2.63 and 7.66%. Irreversibility reduces about 29.5 and 11.65% with augment of NF and HF, respectively.

Originality/value

Numerical simulations for solar unit equipped with mirrors were reported in this modeling. To augment the efficiency of system, absorber pipe was equipped with fins and nanomaterial was used as carrier fluid. Existence of secondary reflector results in better optical efficiency. Finite volume approach is used for modeling which is done in two steps. The first one is done to achieve the heat flux distribution and second step to model turbulent flow inside the pipe. Verification has been presented for calculation of important functions (f and Nu). Outputs reveal the impacts of fin height (HF), number of fin (NF), inlet temperature (T_in) and velocity on irreversibility, thermal treatment.

Citation

Ebrahimpour, Z., Sheikholeslami, M., Farshad, S.A. and Shafee, A. (2022), "Radiation heat transfer within a solar system considering nanofluid flow inside the absorber tube", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 32 No. 2, pp. 469-487. https://doi.org/10.1108/HFF-07-2020-0453