The techniques of computer modeling and simulations are used to develop a design procedure for greenhouse solar heating systems. In this study a flexible computer program was written based on mathematical models that describe the various subsystems of the solar heating system that uses the greenhouse as the solar collector. Extensive simulation runs were carried out for predicting system thermal performance, and subsequently correlations were established between dimensionless variables and long term system performance. The combined greenhouse thermal environment - thermal storage model along with the empirical relationships and the values of constants approximated in the simulation yielded reasonably accurate computed results compared to observed data. The computer model was then applied to predict the system behaviour using long-term average climatological data as forcing functions. A parametric study was made to investigate the effects of various factors pertinent to greenhouse construction and thermal energy storage characteristics on system performance. The key performance indices were defined in terms of the 'total solar contribution' and the 'solar heating fraction'. Correlations were developed between monthly solar load ratio and total solar contribution, and between total solar contribution and solar heating fraction. The result is a simplified design method that covers a number of alternative design options. It requires users to obtain monthly average climatological data and determine the solar heating fraction in a sequence of computational steps. A crop photosynthesis model was used to compute the net photosynthetic rate of a greenhouse tomato canopy; the result may be used to compare crop performance under different aerial environments in greenhouses equipped with a solar heating system. This research program had attempted to generate technical information for a number of design alternatives, and as design optimization of greenhouse solar heating is subject to three major criteria of evaluation: thermal performance, crop yield and cost, recommendations were put forward for future work on economic analysis as the final step required for selecting the most cost effective solution for a given design problem. / Graduate and Postdoctoral Studies / Graduate

An analytical procedure to determine the effectiveness of greenhouse, as solar collectors was presented. This procedure was used to predict the effect of several construction parameters on solar radiation input to greenhouses. The orientation of the greenhouse was found to be the most effective construction parameter controlling solar radiation input to greenhouses. The effective albedo of the plant canopy was also found to be a significant factor. A new solar greenhouse design, suitable for high latitude regions was developed. The results showed that an internal solar collector could be incorporated as an integral part of the greenhouse design. The concept developed could be used as a free-standing greenhouse or in a combination with livestock building. The efficiency of the solar input was investigated for the conventional and the shed greenhouses, both as a free-standing unit and a greenhouse-animal shelter system, using computed simulation analyses. The results indicated that the efficiency of solar input is highly dependent on location; the effect of location on the shed type design is more profound. A typical case of a greenhouse-hog barn production system was investigated using computer simulation analyses. The results showed that such a food production system achieves a significant reduction in conventional fuel consumption due to both animal waste heat recovery and solar energy utilization. / Graduate and Postdoctoral Studies / Graduate

The Hayes Arboretum Solar Greenhouse located in Richmond, Indiana, at 39° 50' N latitude, 84° 50' W longitude has been operational since December 1, 1976. Temperatures inside the 1000 square foot greenhouse were maintained at 55°F. minimum, 85°F. maximum. Data on gas usage was collected over a 24 month period (December 1, 1976 - November 30, 1978). Temperature data was collected during months when auxiliary heat was necessary to supplement the greenhouse.The solar greenhouse was designed by the author to test the feasibility of solar energy in Indiana. Solar energy provided 27% of heating needs during the two year period. A total of 77% of the energy needed to run a convencial design features."Fuel" (natural gas + collector pump electricity) costs were 11.8 ¢ /sq. ft./year for the solar greenhouse compared to 51 ¢ /sq. ft./year for conventional greenhouses during the same period.Ball State UniversityMuncie, IN 47306

M. Tech. Architectural Technology / The aim of this study was to investigate the climate influence of a conservatory added to an existing building. The interior temperature and relative humidity levels were measured, analysed and compared with that of the exterior, to determine in which seasonal cycle the conservatory was more effective as an interior climate enhancement system. The building on which the case study was based is a farmhouse, retrofitted with a conservatory, situated in KwaZulu-Natal, near Bergville in the Drakensberg region. The owner added a conservatory to the existing building, in an attempt to achieve a more temperate indoor climate by harnessing natural energies. The South African climate is typified by varying high diurnal temperatures, with some climatic zones experiencing high summer and/or low winter temperatures. The conservatory was therefore used as a design measure to create a passive solar environment within an enclosed intermediate area.

MSc (Physics) / Department of Physics / Titanium dioxide (TiO2) is considered to be an ideal semiconductor for photocatalysis because of its high stability, low cost and safety towards both humans and the environment. Doping TiO2 with different elements has attracted much attention as the most important way of enhancing the visible light absorption, in order to improve the efficiency of the dye sensitized solar cells (DSSCs). In this study, first principle density functional theory was used to investigate electronic and optical properties of bulk anatase TiO2, undoped, and ruthenium (Ru) and strontium (Sr) doped anatase TiO2 (1 0 0) surface. Two different doping approaches i.e., substitutional and adsorption mechanisms were considered in this study. The results showed that absorption band edges of Ru and Sr-doped anatase TiO2 (1 0 0) surface shift to the long wavelength region compared to the bulk anatase TiO2 and undoped anatase TiO2 (1 0 0) surface. Also, the results revealed that the band gap values and the carrier mobility in the valence band, conduction band and impurity energy levels have a synergetic influence on the visible-light absorption and photocatalytic activity of the doped anatase TiO2 (1 0 0) surface. Furthermore, according to the calculated results, we propose the optical transition mechanisms of Ru and Sr-doped anatase TiO2 (1 0 0) surface. Thus, we conclude that the visible light response of TiO2 can be modulated by doping with both Ru and Sr. However, Sr-doped system shows higher photocatalytic activity than the Ru-doped system. The study has successfully probed the interesting optical response mechanism of TiO2 (1 0 0) surface. / NRF