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

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A numerical model for isothermal and non-isothermal flat-plate liquid-desiccant dehumidifiers and regenerators was developed and implemented. The two-dimensional model takes into account the desiccant, water and air flow streams. A parametric analysis was performed to evaluate the influence of some of the most important operational parameters on mass transfer performance, such as flow configuration, water mass flow rate and inlet temperature, and desiccant mass flow rate. The results indicate that the water temperature and mass flow rate have a strong effect on the performance of the dehumidifier and regenerator, with the isothermal wall case acting as an upper limiting case. Increasing the desiccant mass flow rate improves the water transfer performance, but the improvement is asymptotic with mass flow rate. An experimental rig with a single channel prototype was also built and tests were run for 18 different cases, with varying water mass flow rate, desiccant mass flow rate and flow configuration. The results show trends similar to those observed in the numerical results. However, the discrepancies between the numerical and experimental results are larger than the estimated experimental uncertainty at a 95% confidence level. There is some indication that poor desiccant wetting of the channel walls was partially responsible for the discrepancies. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2007-12-31 22:12:39.184

A thermal liquid desiccant air handling machine was procured, installed, and field tested. The goal of the present investigation is to evaluate the field performance of the machine and characterize its operation for the temperature range of a solar thermal array. The system studied includes a natural gas boiler supplying the heat, and a cooling tower for heat rejection. System performance was evaluated for the 50 to 90 C temperature range, the operating range of solar thermal collectors. Cooling power varied between 4.3 kW and 22.8 kW for this range of temperature, with a latent heat ratio between 1.1 and 1.9, confirming that the unit is significantly dehumidifying the process air stream. Electrical COP varied between 0.58 and 4.48. Performance data indicates higher temperature solar collectors such as evacuated tube or double glazed flat plat collectors would be optimum in a solar cooling application with this system. Empirical correlations for the regenerator and conditioner components were obtained using a multivariate linear regression model. 5 empirical relations were derived and can be used to characterize the thermal dehumidification concept. These relations and methods will be used in future work to simulate and optimize a solar thermal driven dehumidification system for dedicated outdoor air systems. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-09-28 04:36:36.26

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