Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
2 results
Search Results
Item Development and analysis of micro polygeneration systems and adsorption chillers(2012) Gluesenkamp, Kyle; Radermacher, Reinhard; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)About a fifth of all primary energy in the US is consumed by residential buildings, mostly for cooling, heating and to provide electricity. Furthermore, retrofits are essential to reducing this consumption, since the buildings that exist today will comprise over half of those in use in 2050. Residential combined heat and power (or micro CHP, defined by <5 kW electrical generation capacity) has been identified as a retrofit technology which can reduce energy consumption in existing homes during the heating season by 5-30%. This thesis investigates the addition of a thermally-driven chiller/heat pump to a CHP system (to form a trigeneration system) to additionally provide savings during the cooling season, and enhance heating season savings. Scenarios are identified in which adding thermally-driven equipment to a micro CHP system reduces primary energy consumption, through analytical and experimental investigations. The experimental focus is on adsorption heat pump systems, which are capable of being used with the CHP engines (prime movers) that are already widely deployed. The analytical analysis identifies energy saving potential off-grid for today's prime movers, with potential on-grid for various fuel cell technologies. A novel dynamic test facility was developed to measure real-world residential trigeneration system performance using a prototype adsorption chiller. The chiller was designed and constructed for this thesis and was driven by waste heat from a commercially available natural gas-fueled 4 kW (electric) CHP engine. A control strategy for the chiller was developed, enabling a 5-day experiment to be run using a thermal load profile based on moderate Maryland summer air conditioning loads and typical single-family domestic hot water demand, with experimental results in agreement with models. In this summer mode, depending on electrical loads, the trigeneration system used up to 36% less fuel than off-grid separate generation and up to 29% less fuel than off-grid CHP without thermally driven cooling. However, compared to on-grid separate generation, the experimental facility used 16% more primary energy. Despite high chiller performance relative to its thermodynamic limit, this result is primarily due to the electrical efficiency of the prime mover being lower than the grid. A residential trigeneration system utilizing a high temperature fuel cell is predicted to save up to 42% primary energy relative to the grid.Item DISTRESS TOLERANCE AS A PREDICTOR OF EARLY TREATMENT DROPOUT IN A RESIDENTIAL SUBSTANCE ABUSE TREATMENT FACILITY(2005-03-15) Daughters, Stacey Brooke; Lejuez, Carl W; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A large percentage of individuals entering residential treatment for substance abuse dropout of treatment early, often leading to subsequent relapse. Although a number of studies have investigated the predictors of treatment dropout, the particular characteristics that affect one's ability to cope with the initial stages of treatment and abstinence have not been addressed. As one line of research, the concept of distress tolerance, defined as one's ability to tolerate either psychological or physical distress, has been shown to be related to early lapse in abstinence attempts in illicit drug users, smokers, and gamblers. Although clearly applicable, the relationship between distress tolerance and early treatment dropout has yet to be examined. Thus, in the current study it was hypothesized that levels of distress tolerance would predict whether individuals dropout of treatment within 30 days. Specifically, 122 individuals entering a residential substance abuse treatment facility completed a battery of selfreport measures assessing characteristics previously demonstrating a relationship with residential substance abuse treatment dropout, namely demographic variables, mood variables, levels of psychopathology, substance-use severity, social support, and treatment readiness. Additionally, participants completed behavioral measures of psychological and physical distress tolerance. As hypothesized, logistic regression analyses indicated that psychological distress tolerance predicted early treatment dropout above and beyond relevant self-report variables. There was no relationship between physical distress tolerance and early treatment dropout. Implications for future studies and treatment development/modification are discussed.