Multi Objective Optimization on Insulated Residential Roof with Solar Water Heating System Using Grey Relation Analysis (RESEARCH NOTE)

In this work, a multi-objective optimization on novel insulated roof with solar water heating system at low material cost has been carried out through Taguchi based grey relational analysis technique. The novel roofs have concrete, insulating polyurethane, and a channel of water in a metallic pipe tunneling the chromium block. Chromium block is used to conduct more heat to raise the water to relatively high temperature. On the other hand, roof with such high conductive material gains more indoor heat and this can be reduced by providing insulation material at the bottom of the roof. Performance of such a novel roof on water heating and heat insulation have been studied and provided for the months of December and May. In this multi-objective optimization study, chromium block thickness, polyurethane layer thickness, pipe material and pipe diameter are considered as control parameters and varied for three levels. Taguchi’s L9 orthogonal array has been employed and the performance of novel roof patterns is studied through numerical simulation. The optimized novel roof  raises the water temperature by 44°C in December and maintains the room temperature at 28°C in the month of May which is 3°C less than the conventional roof. Finally, ANOVA is employed to identify the contribution of each control parameter on overall multiple objective function.