Mathematical modeling of the thermofluid characteristics of solar collector for variable solar radiation in climatic condition of Bangladesh

Abstract

A mathematical model was developed for the flat plate solar collector with variable solar radiation. In this study, the governing equations were derived applying the energy balance for each control volume of the solar collector and the storage tank. The solar thermal collector was divided into five nodes, namely glass cover, air gap, absorber, working fluid, and insulation. For each node, the discretization equations were derived applying the control volume method. The forward and backward finite difference method was employed to solve the system of nonlinear equations. The time derivatives were replaced by a forward difference scheme, whereas the dimensional derivatives were replaced by a backward difference scheme. In this work, the influence of different types of parameters such as the number of nodes, flow rates, time intervals, initial temperature and the amount of working fluid was studied to optimize the performance of the flat plate solar collector especially suitable for the climatic condition of Bangladesh. The software package MATLAB version R2015a was used for coding and the derived results were shown graphically. Flat plate solar collector operation with variable solar radiation may be designed using the proposed model that could be utilized for supplying hot water in the industrial and household works having a maximum temperature of 51℃ and thereby would help in conserving the fossil fuel/electricity maintaining harmony with the environment. The model may be used to predict the temperature of the working fluid that could be raised to its maximum level subject to the local ambient temperature and variable solar radiation.