Modeling, Analysis, Evaluation and Selection of Flat Plate Liquid Solar Collector System

Abstract

Solar energy is the best alternative to fulfill the increasing energy demand and to overcome the drawbacks of conventional sources like environment pollution. Flat plate solar collector is the device used to convert solar energy into heat energy. Flat plate liquid solar collectors are the most commonly used collectors today all over the world in commercial and domestic water heating applications. However researches are going on to make this collector useful for other applications like water distillation, heat pump, solar cooling system, effluent evaporation system, solar oven etc. A number of models are developed by different researchers to evaluate the only thermal performance of the system. Thermal performance is the important factor but not only sole criteria for the selection of FPLSC. A new procedure is developed for the selection and evaluation of flat plate liquid solar collector (FPLSC) using multi attribute decision making approach. A cause and effect diagram is developed for the attributes identification, those are sufficient to describe the system. Attribute based characterization of the systems make the classification of the systems more precise. Coding of attribute is done to convert the information into useful form. Information developed from the quantification of attributes is useful to the designer, manufacturer and the user in their respective areas. The three stage selection procedure is used for the evaluation and ranking of the FPLSC system. First the limited numbers of alternative systems are sorted out on the basis of user requirements using elimination search. Weighted normalize matrix is developed for the selected systems in the 2nd step which takes into account of the relative importance of attributes. TOPSIS and graphical techniques (spider and line graph) are applied for the evaluation and ranking of the systems in step 3rd. This methodology is explained with an illustrative example. The results obtained from the three techniques are not consistent with each other. Further sensitivity analysis is carried out to see the effect of individual attribute on the ranking of FPLSCs. Sensitivity results come from the three techniques are also different. So it is concluded that results from the TOPSIS are taken to be right as it is the standard procedure for the evaluation and ranking of systems. Graphical techniques are inconsistent with the TOPSIS so do not use these for the selection purpose. These techniques can be used for the visual inspection of the systems. Final selection of FPLSC system is not only the basis of ranking of the systems. The final selection is made by the management by considering other factors effecting the selection. This approach is useful to designer and manufacture to get the information about the attribute those are more useful for the selection of FPLSC so that those attributes are considered more while designing and manufacturing. A structural model of the FPLSC is developed using graph theoretic approach to analyze the FPLSC from different prospective. The different constituents and the interaction between the constituents are identified. A graph is developed which represent the constituents and the interactions between the constituent. The information of the graph is converted into matrix form. Further this information of the graph is converted into a mathematical function using viii matrix algebra. This function includes the effect of all constituents and the interaction between the constituents. If the information about the FPLSC structure is in qualitative form then this function is used for the comparison of the different FPLSCs. If the information of FPLSC structure is given in numerical values then this function is useful to analyze the different FPLSC properties like quality, reliability etc.