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

Abstract

Bangladesh being a tropical country, solar radiation is available over the whole year. A good number research on the solar collector with constant radiation have been reported already but there is hardly any model available in the relevant literature focusing on flat plate solar collector operation for variable solar radiation. In this study, a mathematical model will be developed for the flat plate solar collector with variable solar radiation. In this study, the governing equations will be derived applying the energy balance for each control volume of the solar collector and the storage tank. The solar thermal collector will be divided into five nodes namely glass cover, air gap, absorber, working fluid, and insulation. For each node, the discretization equations will be derived applying control volume method. The forward/ backward finite difference method will be employed to solve the system of nonlinear equations. The time derivatives will be replaced by a forward difference scheme whereas the dimensional derivatives will be replaced by a backward difference scheme. In this work, influence of different types of parameters such as number of nodes, flow rates, time intervals, initial temperature and amount of working fluid will be 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 will be used for coding and the derived results will be 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.