Computational Fluid Dynamics (CFD) Based Simulation

    The aim of the present study is to evaluate the thermos-hydraulic performance parameter (THPP) and thermal approaches on the basis of simulation by using the response surface methodology (RSM). The parameters of analysis are the design of inclined fins in the solar air heater (SAH).

    The simulation of SAH is carried out by using CFD based software (ANSYS Fluent v16.1). The simulation model is two dimensional RNG k-𝜀 turbulence model. The results after implementation of RSM are measured by the finite volume method. The parameter optimizations are done for the SAH. The Finite Volume method is used for the simulation.

        The increase in the pumping power is due to the higher drop of pressure. In the present work, the main purpose of the simulation was to determine the higher thermal performance with the minimum drop in pressure. The proposed conditions can be achieved by suitable geometry, flow parameters, and optimization of geometry.

    The statistical analysis of ANOVA is used for the identification of all the interactions on the individual basis. The control factors are analyzed for the design outcomes.

    The design factors are determined by the equation and the factors including analysis are friction factors, Nusselt number, and THPP of the solar air heater. The accuracy of all the parameters is an essential part of the analysis. In the graphical representation, the computed values and the predicted values of friction factors, Nusselt numbers, and THPP are compared. The graph represents that computed and predicted values are in good agreement and it is important for the model verification. The normal probability for the residuals is represented by the straight line along with the residual errors. From the analysis, it can be concluded that the prediction of friction factor, THPP, and Nusselt numbers are in good agreement with the measured values. The accuracy of these parameters is dependent on the response surface methodology.

        The graphical representation is used to show the impact of Reynold numbers, angle and pitch, length on the THPP of the solar air heater. The inclined fins at a certain angle are considered for the analysis. The results show an increase in THPP values with the increase of Reynold numbers and after reaching the maximum values the Reynold numbers decrease. In the previous research, Saini and Prasad proposed the reason, according to them the increase in the roughness height is due to higher values and the reattachment of the shear layer can induce impact on it. The friction factor is not directly related to the rate of the heat transfer. According to the graph, the gradual increment in the fin length results in the decreased of THPP and the main cause is fin length. With the change in the friction factors, higher Nusselt number provides less THPP.

    The design and the geometric parameters can be validated by the development of the RSM model and the numerical results of CFD simulations are compared with experimental results. The graph and values show the comparison of numerical results obtained by the CFD simulation and the RSM model. The validation test was used to determine the error between the actual and the simulated values at 0.41%. The results of the numerical model and the RSM models are in good agreement.

        The results show that inclination of fins induces impact on the practical applications of the absorber plates. The prior researches identified the methods for the improvement of thermal performance in certain ways, particularly by the artificial roughness. The increase in the pressure drop results in the higher power of pumping. The main objective was to maintain the thermal performance with further pressure drop. The appropriate results can be obtained by the accurate flow parameters and the optimized geometric conditions.

    In the previous researches and the literature, there are different modifications proposed in the designs to improve the coefficient of heat transfer. The heat transfer is considered between the air and the absorber plate. The inclined fins are considered for the absorber plate in the heaters. The sufficient research is required for the design parameters of the solar air heater.

    The use of inclined fins for the absorber plate significantly increases the heat transfer in the solar air heater.

    The increase in the Reynold numbers results in the increase of Nusselt number. The Nusselt numbers are directly proportional to the fin length, pitch, and the slant angle. The increase in the slant angle of the fins at the fixed pitch as well as length results in the increase of Nusselt numbers. At a particular point, the increase in the pitch values (P) results in a decrease of Nusselt numbers and increases the slant angle and value of length.

    In the present analysis different values, Reynold numbers were obtained and the Reynold numbers are directly proportional to the friction factors. The trend of friction increases with the increase of fin length (e) and reaches to constant values for the pitch and the slant angle. The friction factor decreases with the increase of pitch values at the constant values.

    The ratio was evaluated for the average Nusselts numbers and measured ratio was 2.780 at certain parameters of the fins and the geometry. The parameters for the Nusselt number evaluation are mentioned below,