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published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

The aim of this Engineering Doctorate is to design, build and test novel environmental retrofit technologies to reduce energy consumption in existing buildings. Three contributions to knowledge are documented. The first contribution is the technical verification of a novel proof-of-principle prototype incorporating translucent silica aerogel granules to improve the thermal performance of existing windows without blocking out all of the useful natural light. The study demonstrates that a 10 mm thick prototype panel can reduce heat loss by 80 %, without detrimental reductions in light transmission. Payback periods of 3.5-9.5 years are predicted if applied as openable shutters or removable secondary glazing. The second contribution is a streamlined life cycle assessment of silica aerogel following the ISO 14000 standards. The study assesses the raw materials and electricity use associated with two of the three known methods of aerogel production. Despite being produced in a laboratory that had not been refined for mass manufacture, the production energy and CO2 burden from aerogel production can be recovered within 0-2 years when applied in a glazing application. The third contribution is the development and verification of a novel solar air heater incorporating granular aerogel, retrofitted to an external south facing wall, preheating the air in a mechanical ventilation system with heat recovery on a hard4to4 treat domestic property. During the 7-day in-situ test, peak outlet temperatures up to 45 °C were observed and validated to within 5 % of predictions, preheating the dwelling’s fresh air supply up to 30 °C, facilitating internal temperatures of 21-22 °C without auxiliary heating. The predicted financial and CO2 payback for a range of cover thicknesses is 7-13 years and 0-1 years, respectively. Efficiency up to 60 % and a financial payback of 4.5 years is predicted with an optimised design incorporating a 10 mm thick granular aerogel cover.

Thesis (M.Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography: p. 202-205. / Until now, passive solar energy has been overlooked as a viable alternative for home heating in urban subsidized housing. Rather ironically, in housing whose residents could most benefit from the use of solar energy, such concepts and technologies are not utilized. This thesis demonstrates how passive solar heating and energy conscious design can be economically implemented in low- and moderate-income subsidized housing. The research and design work presented explain the well-integrated system of natural environmental tempering that includes passive solar heating, natural daylighting, natural ventilation and energy conservation. A crucial aspect of the thesis is the method of dollar-for-dollar tradeoffs that is used to keep the cost of the natural environmental tempering components within the strict budget constraints of subsidized housing. Also, the housing is designed with careful attention paid to the needs of the inhabitants. Thus, in addition to the energy concerns, the design reflects new attitudes toward subsidized housing. The resulting solar architecture is a significant answer to the need for economical public housing that allows low-income urban residents to benefit from the sun's abundant energy. / by Karen M. Duncan. / M.Arch.

Thesis. 1977. M.Arch.--Massachusetts Institute of Technology. Dept. of Architecture. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH. / Bibliography : leaves 98-100. / by James S. Day. / M.Arch.

The results of a combined theoretical and experimental study of the kinetics of a hot-liquid energy-storage tank are presented. A physical model is developed which accurately describes the thermal stratification behavior in a storage tank. The governing differential equations are developed for the physical model. A numerical solution to the system of equations is presented. Some existing models were examined and the predicted results of each are discussed. The concepts developed can be used to predict the thermal stratification behavior in a storage tank under most conceivable operating conditions. These conditions include flow configurations at the top and the bottom of the tank which both have inversionary tendencies. Inversionary behavior could conceivably occur in both the top and the bottom regions of the tank during a combined storage and usage mode which might occur at non-peak storage hours. Although the work was done primarily for the utilization of solar energy, the results are not limited to such application. The results are more significant as a contribution to applied fluid dynamics.

A Solar Radiation Concentrating System for generation of high temperature heat for a solar oven was developed and evaluated at the University of KwaZulu-Natal, Westville Campus, Durban - South Africa. The system concentrates direct solar radiation on a small area receiver which absorbs the radiation and converts it into thermal energy that may be stored and used for several applications where food preparation and water pasteurization is the priority. The concentrator, area 2.2 m², is a half satellite communication dish covered with trapezoidal acrylic mirror tiles. The receiver/absorber is a spiral coil of blackened stainless steel pipe. Oil is circulated as heat transfer fluid. To determine the optimal dimension and position of the receiver, two experimental methods were used: (1) The tiles were scanned using a vertical, self adjusting laser beam to get a distribution of reflected radiation across the focal volume. (2) A thin, blackened stainless steel plate was placed at appropriate distances in the focal volume, and temperature distribution scanned using a temperature gun. The latter method proved to be the more useful. Results of the analysis of system performance showed that the system has the capability to produce high temperatures for domestic purposes. The efficiency of the system is about 35 %. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

There is the potential to use solar energy as an energy efficient method of heating water, instead of using electricity. This study investigated the current barriers to the mass rollout of solar water heaters in South Africa and provided possible solutions to reduce these barriers. Local experts have already identified the key barriers to the rollout of solar water heaters and this study drew from the findings of international practises and applied these findings to the South African context. The barriers that are preventing the industry from developing are: the high price of solar water heaters, the lack of awareness of the technology, the absence of legislation, a tedious process for rebates, non–mandatory standards, insufficient training facilities leading to a shortage of skills and the low price of electricity. The research methodology was a blend of qualitative and a quantitative study including relevant theory supported by seven open-ended questionnaires completed by recognised industry specialists. The information gathered from the questionnaires was analysed and compared to the theory and international experience. The barriers to solar water heating can be overcome by having more government involvement in the development of policies to promote and educate the public on alternative energy sources. This lack of awareness on the technology can be improved by having awareness programmes in schools and frequent broadcasts on radio and television. There is a dire need for the development of cost effective financing mechanisms because the high costs of production influences the price of solar water heaters. Financial incentive models such as rebates, could be more effective in assisting the low and middle-income groups with partial funding for the purchase of the solar water heater. / Thesis (MBA)-University of KwaZulu-Natal, 2010.

This document presents the energy analysis and simulation of central solar heating plants with seasonal storage (CSHPSS) designed for covering a part of residential heat demand required for SpaceHeating (SH) and Domestic Hot Water (DHW) oriented to reduce the consumption of fossil fuels.The main objectives of this thesis are to simulate and analyse in POLYSUN software a defined systemof CHSPSS already built in TRNSYS, in order to compare the results of both programs and to analyse and simulate these systems in different cities of Spain. In carrying out the objectives, some limitations have been found. Ones of these are the limitations of POLYSUN program, which have forced to reduce the number of housings. The document starts with a revision of the state of art, in which it is shown the number of plants in Europe and specially, in Sweden and Spain observing the differences between them, for example, Spain has not any CSHPSS plant and Sweden was the first country of building one. In addition, in the theory section, it has been studied the main elements of these plants, such as different types of solar collectors and seasonal storages, and different simulation programs commercially available for the simulation and analysis of this type of plants. According to this, POLYSUN program is more intuitiveand user-friendly in some extent than TRNSYS, but its applications are more specific and more appropriate for small district heating systems. Steps followed for obtaining the analysed system and main characteristics of it have been explained.These steps have been used to analyse the results of POLYSUN and to compare results betweenTRNSYS and POLYSUN. According to the obtained results, it can be remarked that the results obtained from POLYSUN are coherent, with the exception of Space Heating demand, which is calculated by the program and has a very important difference between the calculated value and the Space Heating demand introduced by the user. When comparing with TRNSYS, it has been observed that POLYSUN‘s boilers have a high thermal losses and low efficiency and POLYSUN’s pumps have high energy consumption and thermal losses.

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