Browsing by Subject "Thermal analysis"
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Item An analysis of endothermic solid state decompsitions: cylindrical case(Texas Tech University, 1976-12) Busby, John FNot availableItem Effects of selected parameters on thermal performance of earth sheltered housing(Texas Tech University, 1983-08) Young, Ren-tsengNot availableItem Item Improved CBM of top drives using advanced sensors and novel analysis techniques(2015-08) Adams, Douglas Alexander; Van Oort, Eric; Ashok, Pradeepkumar, 1977-Although technology in the oil and gas industry is always advancing, there are still numerous tools, sensors, and analysis techniques used regularly in the field that have remained unchanged for many years. This is especially true when observing critical drilling components such as the top drive. Top drive monitoring techniques today are only effective after a severe problem occurs on the top drive. The consequence of this is that when the top drive fails, it is always unexpected, resulting in unnecessarily high repair costs (an average of $60,000 - $120,000 per failure) and, even more importantly to operators, downtime to the operations (which ranges from $100,000 / day for land operations to larger than $1,000,000 /day for large-scale offshore operations). These costs arise from the fact that when the top drive fails, drilling is effectively shut down until a repair is made. A solution to this problem is to change the fundamental way in which top drives are monitored. Rather than using traditional time-based preventative maintenance, monitoring strategies can be changed to encourage condition based maintenance (CBM). CBM varies from scheduled or preventative maintenance in that it fundamentally relies on data analyzed from the machinery to ascertain whether maintenance is required. CBM has been applied in many industries throughout the past half century and opens up a new dimension in performance by quantifying the ongoing health of a monitored machine. Three separate analysis techniques are recommended for implementation onto top drives: vibration analysis, oil analysis, and thermal analysis. Vibration analysis and oil analysis have proven successful in other industries to detect mechanical faults in components such as shafts, gears, bearings, and motors. For thermal analysis, a novel methodology is introduced which relies solely on temperature sensors already installed on most operational top drives. When model-based expected temperatures deviate sufficiently far from measured temperatures it is assumed that the system has thermally failed, triggering an alarm to the operator. The software code to implement such a procedure has been developed for a programmable logic controller (PLC) and is currently being tested in the field to obtain real-time analysis results.Item The mechanism of the thermal rearrangement of enol ester epoxides(Texas Tech University, 1962-05) Heilman, William JNot availableItem Thermal analysis of plutonium storage containers(Texas Tech University, 1999-08) Stevkovski, SasoExperimental results were obtained for four different values of heat generation rate (15, 20, 25 and 30W), and three different values of outside container temperature (20, 25 and 30°C). A constant temperature boundary condition was imposed on the outside surfaces of the container by circulating a constant temperature fluid. The purpose of the outside boundary condition was to enable basis for comparison between the experimental and numerical results. Heat generation caused by the decay of the plutonium was simulated by passing an electric current through a resistor placed in the center of a hollow bowling ball sized stainless steel sphere, referred to as the plutonium pit simulator. Experiments were performed with air, argon and helium as the backfill gases. The lowest temperatures were recorded with heHum as the backfill gas. The maximum temperatures registered in the ALR8(SI) container exceeded the safety Hmit of 60°C for most of the cases. According to the results, only using helium as a backfill gas can guarantee that the maximum temperature wiU not exceed the safety Hmit, for heat generation rates less than 20W. For higher heat generation rates, the limit will be exceeded for any tested backfill gas.Item Three dimensional computational modeling of electrochemical performance and heat generation in spirally and prismatically wound configurations(2012-08) McCleary, David Andrew Holmes; Meyers, Jeremy P.; Ezekoye, OfodikeThis thesis details a three dimensional model for simulating the operation of two particular configurations of a lithium iron phosphate (LiFePO¬4) battery. Large-scale lithium iron phosphate batteries are becoming increasingly important in a world that demands portable energy that is high in both power and energy density, particularly for hybrid and electric vehicles. Understanding how batteries of this type operate is important for the design, optimization, and control of their performance, safety and durability. While 1D approximations may be sufficient for small scale or single cell batteries, these approximations are limited when scaled up to larger batteries, where significant three dimensional gradients might develop including lithium ion concentration, temperature, current density and voltage gradients. This model is able to account for all of these gradients in three dimensions by coupling an electrochemical model with a thermal model. This coupling shows how electrochemical performance affects temperature distribution and to a lesser extent how temperature affects electrochemical performance. This model is applicable to two battery configurations — spirally wound and prismatically wound. Results generated include temperature influences on current distribution and vice versa, an exploration of various cooling environments’ effects on performance, design optimization of current collector thickness and current collector tab placement, and an analysis of lithium plating risk.