Rectified solar wall development

Abstract

Protection of our environment, and greater use of renewable energy are two major topics discussed throughout the world in recent years. It is imperative that every one understands the importance of leading a sustainable life-style. This project was aimed at utilising solar energy for domestic space heating. A conceptual design of solar wall was proposed. It was suggested that the disadvantages of the Trombe wall could be largely overcome by using heat pipes as a thermal diodes between the solar energy source and the thermal mass of the wall. A computer model of such a wall was developed to predict its performance and this model was used to optimise the geometry and the materials in the design of the solar panel and the wall into which it was to be incorporated. A prototype panel of this design was manufactured and subjected to an experimental testing program. In the first phase of the testing program the panel was heated by a hot water bath and the heat output was measured in another cold water tank. As a result of these first tests, some modifications were made to the panel which was then tested again to ensure that it would meet the design requirements. In the second testing phase, the panel was subjected to solar radiation as the heat input, and its behaviour as a solar panel determined and compared with typical flat plate collectors. After obtaining satisfactory results from these experiments, a prototype wall was constructed. To measure the useful space heating effect of the wall, a calorimeter box was constructed on the room side of the wall. Auxiliary equipment and instrumentation enabled monitoring of the net energy requirement of maintaining this box at the same temperature as the surrounding room. Time constraints required that the wall be tested during summer time, but the temperature distribution across the wall and the average energy output from the wall to the room was able to be obtained under these conditions and compared with the predictions of the computer model. From this comparison, the model was modified to match the actual results as closely as possible. The modified model then able to be used to predict the winter performance of the wall. Both quantitative and qualitative conclusions about the wall concept and its performance were able to be drawn, and some recommendations for further work made.