Thesis (M. Sc.)--University of Hong Kong, 1982.

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In this thesis, heat powered ejector cooling systems was investigated in two ways: to store the cold energy with energy storage system and to utilize low grade energy to provide both electricity and cooling effect. A basic ejector prototype was constructed and tested in the laboratory. Water was selected as the working fluid due to its suitable physical properties, environmental friendly and economically available features. The computer simulations based on a 1-0 ejector model was carried out to investigate the effects of various working conditions on the ejector performance. The coefficients of performance from experimental results were above 0.25 for generator temperature of lI5°C-130 °C, showing good agreements with theoretical analysis. Experimental investigations on the operating characteristics of PCM cold storage system integrated with ejector cooling system were conducted. The experimental results demonstrated that the PCM cold storage combined with ejector cooling system was practically applicable. The effectiveness-NTU method was applied for characterizing the tube-in-container PCM storage system. The correlation of effectiveness as the function of mass flow rate was derived from experimental data, and was used as a design parameter for the PCM cold storage system. In order to explore the possibility of providing cooling effect and electricity simultaneously, various configurations of combined power and ejector cooling system were studied experimentally and theoretically. The thermal performance of the combined system in the range of 0.15-0.25 and the turbine output between 1200W -1400W were obtained under various heat source temperatures, turbine expansion ratios and condenser temperatures. Such combined system was further simulated with solar energy as driving force under Shanghai climates, achieving a predicted maximum thermal efficiency of 0.2. By using the methods of Life Saving Analysis, the optimized solar collector area was 30m2 and 90m2 respectively for the system without and with power generation. The environmental impacts and the carbon reductions of these two systems were discussed.

Increasing concern with the amount of energy required to maintain static indoor conditions in hot-humid climates is encouraging designers to again contemplate passive methods of indoor environmental control. Yet prevailing cultural perceptions of acceptable comfort levels make building occupants wary of any suggestions to reduce the mechanical control of building interiors. The rapid deployment of air-conditioning in the building sector over the past fifty years and its consequent pervasiveness nearly guarantees that most Americans have had little conscious experience with non-conditioned space. This thesis considers the potential for historic sites in Texas to interpret pre-air-conditioned indoor environmental conditions and to demonstrate historical approaches to climate mitigation. Within the context of preservation practice and theory, this study examines the historical context for these sites, particularly the professional and cultural constraints on architectural design in the nineteenth-century American South and architects’ strategies for managing environmental conditions within the limits of prevailing stylistic modes. Three case study sites are explored as potential venues for discovery and interpretation of traditional or transitional methods of cooling and ventilation: Historic Texas (Goliad and Comal county) courthouses, Galveston Historical Foundation’s Gresham House (Bishop’s Palace), and the University of Texas at Austin’s Battle Hall. Issues of historical interpretation are discussed and strategies that could be deployed in an indoor-climate interpretive program are proposed. With the rest of the world poised to follow America’s lead into a fully air-conditioned existence, it is critical to understand the modes and methods building designers used in the past in order to imagine alternate futures. Historic buildings and sites are well positioned to be the interpreters of those conditions and activities that made life in a hot-humid climate manageable. However, the ways in which preservationists value and evaluate historic buildings may have to change in order to participate meaningfully in this discussion. / text

The overall aim of the research reported here was the development of a simple, low-cost passive solar heating system for operation in the Portuguese climate. The performance of this device is critically dependent on the rate of convective heat exchange across the cavity behind the heater plate. Both computational and experimental studies of the heat transfer characteristics of this new storage device, have been conducted. An experimental installation in full scale was designed and constructed to enable the measurement of local heat transfer rates. Computer simulations of the laminar flow under solar-driven conditions were made using an existing steady, threedimensional computational fluid dynamics (CFD) code based on the finite-volume method (PHOENICS Code shareware version 1.S). A boundary-fitted co-ordinate system was developed to fit the non-rectangular geometry of the cavity, that represented the water store, which provided the computational grid for the CFD code. The experimental data from the test rig was used to validate the CFD model. A solar water heating system was built to test the design under realistic weather conditions. The experimental thermal performance was evaluated in 48% while the theoretical was estimated in 51 %.

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

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