No description available.

No description available.

The aluminosilicate materials kaolinite, calcium montmorillonite and emathlite have been tested as solid sorbents for alkali vapour in controlled gaseous environments, in order to study their sorption characteristics. The study used pan pelletised and extruded pellets in single pellet and fixed bed reactor systems under gaseous environmental conditions containing water vapour, hydrogen chloride and nitrogen at a temperature of 850°C. The means of producing the pellets and the composition of the gaseous environment were shown to determine the sorption performance of the sorbent pellets. The physical properties of the pellet (particle size, total pore volume, surface area, crush strength) significantly affect the sorption effectiveness, while the formation of reaction products is dependent upon the sorbents' chemical composition and on the sorption conditions. Reaction products identified under the various sorption conditions indicated possible pathways for alkali capture. Hydrogen chloride mixtures were shown to cause a reverse of the sorption process for some sorbents. A leaching method for extracting sodium from treated pellets enabled the type of bonding to be determined but not necessarily the prime sorption mechanism. With the introduction of water vapour, some evidence was presented that the alkali sorption rate can change significantly. The previously reported effect of hydrogen chloride upon alkali capture by the sorbent material, calcium montmorillonite; shown by McLaughlin (1990) was confirmed and the effect was also investigated for emathlite and kaolinite. Reversibility depended upon the presence or absence of hydrogen chloride. Both water vapour and hydrogen chloride determine sorption activity and capacity. Likewise the structural characteristics of the pellet influences the sorption activity and capacity. The sorption process is not due to aluminosilicate reaction alone but also due to replacement mechanisms. Conclusions are drawn regarding mechanism and theoretical model proposed.

Den här rapporten handlar om en ändring i livsmedelsföretaget Freezing Food Småland Öland AB:s avfrostningsrutin för deras förångare i frysrummet. Ändringen gick ut på att avfrostningstiden och maxtemperaturen sänktes samt att tiden mellan avfrostningarna nu sker varannan i stället för varje natt. Syftet var att undersöka om ändringen av rutinen hade bidragit till en minskad energiförbrukning i förhållande till innan ändringen gjordes genom att också granska andra faktorer än själva avfrostningen som kunde tänkas påverka energiförbrukningen. Metoden gick ut på att insamla och analysera stora datamängder tillhandahållna av företaget för att sedan reducera dem till hanterbara siffror. Även data för lokala utomhustemperaturer samlades in. Med hjälp av detta beräknades medelvärden för en given tidsperiod för energiförbrukning, lagerhållning och utomhustemperatur. Resultatet visade en sänkning av energiförbrukningen, hur stor andel som berodde på avfrostningens ändrade rutiner lämnade undersökningen obesvarat. Utomhustemperaturen bör ha minskat effektbehovet, samtidigt bör lagerhållningen ökat den. Slutsatsen blev att mer tid behövde passera och en ny undersökning behöver framställas efter att avfrostningsrutinen ändrades för att möjliggöra en säkrare bedömning. / This report is about a change in the food company Freezing Food Småland Öland AB’s defrosting routine for their evaporators in the freezer warehouse. The change was that the defrosting time and maximum temperature were reduced and that the time between defrostings now takes place every other night instead of every night. The aim was to examine whether the change in the routine had contributed to a reduction in energy consumption compared to before the change was made by also examining factors other than defrosting itself that might affect energy consumption. The method was to collect and analyze large amounts of data provided by the company and then reduce them to manageable figures. Data for local outdoor temperatures were also collected. This calculated averages for a given time period for energy consumption, warehousing and outdoor temperature. The results showed a decrease in energy consumption, the proportion due to the change in defrosting procedures left the investigation unanswered. The outdoor temperature should have reduced the power requirement, at the same time the storage should have increased it. It was concluded that more time needed to pass,and a new study needed to be produced after the defrosting routine was changed to allow for a safer assessment.

<div>Vapor compression cycles are the most common method used to provide cooling to environments. In the residential area, refrigerator/freezers as well as air conditioners/heat pumps almost exclusively use vapor compression cycles. The driving force behind a vapor compression cycle is the compressor, where a variety of compressor types are used in the same application. While reciprocating compressors are found in the majority of refrigerator/freezers, scroll compressors are predominantly used in residential air conditioners. Yet other compressors have emerged as replacements due to increased efficiency. A R134a oil-free prototype scroll compressor and a R134a reciprocating compressor are operated in a hot-gas bypass test stand under refrigerator/freezer conditions to compare performance. Additionally, a R407C scroll compressor and a R410A rotary compressor are operated in a compressor calorimeter under air conditioning/heat pump conditions to compare performance. Experimental results show that the reciprocating compressor far outperforms the prototype scroll compressor in the refrigerator/freezer application, while the performance between the scroll and rotary compressors are almost equal in the air conditioning application.</div><div>Pressure fluctuation at compressor discharge is also measured in the compressor calorimeter to determine feasibility of applying a novel muffling design to air conditioning compressors, although it was found that traditional muffling methods currently used are effective to a degree such that this new method is unwarranted. Data from the compressor calorimeter is also used to investigate the accuracy of the AHRI 540 10-Coefficient Correlation compressor map in predicting performance both inside and outside the tested operating conditions. The AHRI 10-Coefficient Correlation achieves high accuracy inside tested operating conditions but is inept in extrapolating performance, where other map correlations are more accurate.</div>

The work presented in this thesis was carried out with a particular view of enhancing the of coal fired fluidised bed hot gas generator (HGG) at the Cantley factory of British Sugar. It covers combustion of coal and biomass and their blends also called co-firing in a fluidised bed combustor. Particularly it focuses on the effect of introduction of moisture as part of fuel or injection of water into the bed on the reduction of excess air to get a stable bed temperature. Although this thesis is focused on increasing the throughput of the HGG, the study has a broad application and can be beneficial in utilising relatively cheap, poor quality, unprepared biomass materials. The results of this study can be helpful in devising systems to deal with wastes from different industries in co-combustion with a fuel of higher calorific value such as coal. Thus the study will have dual impact on the industry; addressing waste management issues on one hand and producing useful energy on the other. This may contribute towards meeting the targets of Kyoto Protocol by reducing emissions of carbon dioxide (COi) as biomass is thought to be COa neutral. The fluidised bed at Cantley is used to dry animal feed and has a design capacity of 40 MW but due to limitations of flow of fluidising gases caused by high flow resistance through sparge pipes, the combustor is running under capacity. Consequently, some of the animal feed has to be dried by using expensive oil fired drier. In any combustion system excess air is used to control combustion temperature. In fluidised bed combustion excess air is used to control bed temperature. If the bed is cooled by other means the requirement of excess air can be reduced. This is the basic idea behind this study which is aimed at enhancing the capacity of the HGG by cooling the bed and thus reducing excess air requirements. The excess air thus spared can be used to combust more coal in the bed and thus will reduce dependence on oil fired dryer and will have financial benefits for British Sugar. Different fuels including wood pellets, wood chips and sugar industry by-products such as vinasse, raffinate and pressed pulp were fired/cofired with Thoresby coal in a fluidised bed test rig installed at the University of Glamorgan. The blends of wood chips and pressed pulp with coal are co-fired at different moisture contents. The tests were conducted at different thermal inputs at a wide range of excess air levels. Most of the work is focusedon the combustion of blends of coal and pressed pulp in different proportions. It was found that the maximum proportion of the pressed pulp in the blend with coal which could be burned successfully in the fluidised bed is 50%. During combustion of different coal-pulp and coal-wood chips blends it was found that excess air requirement is reduced by around 20% in comparison to coal only firing, over the range of the operating conditions tested. Because of the presence of potassium in pressed pulp, which could cause agglomeration during combustion in fluidised beds, longer term tests were carried out with 50/50 blend of coal and pulp. No signs of agglomeration were observed when the rig was fired for 8 days for almost 7 hours a day. However, Scanning Electron Microscopy (SEM) analyses of bed samples taken at the end of every day have shown the accumulation of potassium in the bed up to 1%. For comparison purposes tests were also carried out by co-firing coal with raffiante and vinasse and then it was observed that the bed defluidised relatively quickly, within 40 minutes of co-firing. Post experiment SEM analysis confirmed the accumulation of potassium in the bed which was found to be around 8% for raffinate and around 10% for the vinasse experiment. It was found that the pulp is difficult to deal with and particularly its feeding into the fluidised bed could be a potential problem. Therefore, injection of water into the bed, a relatively cheaper and adaptable option, was also investigated. It was found that emissions of carbon monoxide due to incomplete combustion or water gas shift reaction would not be a problem as long as the bed temperature is controlled above 800 °C. It was found that the injection of water at a rate of 4.5 1/h into the bed fired at 17 kW reduced the air flow requirement by around 7.5 m3/h which corresponds to a reduction of almost 20% which agrees with the finding with coal-pulp blends co-firing. This excess air can be used to burn around 5 kW equivalent of more coal and thus result in an increase in the thermal capacity by around 30%. Therefore, it may be possible to enhance the thermal capacity of the HGG at Cantley by 30% by injecting water into the bed or by co-firing coal and pulp.

No description available.

Presented in this thesis is the development of a high-fidelity aerothermal model for GE T700 turboshaft engine. The model was constructed using thermodynamic relations governing change of flow properties across engine components, and by applying real component maps for the compressor and turbines as well as empirical relations for specific heats. Included in the model were bleed flows, turbine cooling and heat sink effects. Transient dynamics were modeled using inter-component volumes method in which mass imbalance between two engine components was used to calculate the inter-component pressure. This method allowed fast, high-accuracy and iteration-free calculation of engine states. Developed simulation model was successfully validated against previously published simulation results, and was applied in the simulation of inlet distortion and engine deterioration. Former included simulation of steady state and transient hot gas ingestion as well as transient decrease in the inlet total pressure. Engine deterioration simulations were performed for four different cases of component deterioration with parameters defining engine degradation taken from the literature. Real time capability of the model was achieved by applying time scaling of plenum volumes which allowed for larger simulation time steps at very little cost of numerical accuracy. Finally, T700 model was used to develop a generic model by replacing empirical relations for specific heats with temperature and FAR dependent curve fits, and scaling T700 turbine maps. Developed generic aerothermal model was applied to simulate steady state performance of the Lycoming T53 turboshaft engine.

ABSTRACT REMOVAL OF HYDROGEN SULFIDE BY REGENERABLE METAL OXIDE SORBENTS Karayilan, Dilek M.S., Department of Chemical Engineering Supervisor : Prof. Dr. Timur Dogu Co-Supervisor: Prof. Dr. G&uuml / lSen Dogu June 2004, 166 pages High-temperature desulfurization of coal-derived fuel gases is an essential process in advanced power generation technologies. It may be accomplished by using metal oxide sorbents. Among the sorbents investigated CuO sorbent has received considerable attention. However, CuO in uncombined form is readily reduced to copper by the H2 and CO contained in fuel gases which lowers the desulfurization efficiency. To improve the performance of CuO-based sorbents, they have been combined with other metal oxides, forming metal oxide sorbents. Sulfidation experiments were carried out at 627 oC using a gas mixture composed of 1 % H2S and 10 % H2 in helium. Sorbent regeneration was carried out in the same reactor on sulfided samples at 700 oC using 6 % O2 in N2. Total flow rate of gas mixture was kept at 100 ml/min in most of the experiments. In this study, Cu-Mn-O, Cu-Mn-V-O and Cu-V-O sorbents were developed by using complexation method. Performance of prepared sorbents were investigated in a fixed-bed quartz microreactor over six sulfidation/regeneration cycles. During six cycles, sulfur retention capacity of Cu-Mn-O decreased slightly from 0.152 to 0.128 (g S)/(g of Sorbent) while some decrease from 0.110 to 0.054 (g S)/(g of Sorbent) was observed with Cu-Mn-V-O. Cu-V-O showed a very good performance in the first sulfidation and excessive thermal sintering in the first regeneration prevented further testing. Sulfur retention capacity of Cu-V-O was calculated as 0.123 (g S)/(g of Sorbent) at the end of the first sulfidation. In addition, SO2 formation in sulfidation experiments was observed only with Cu-V-O sorbent.

Indiana University-Purdue University Indianapolis (IUPUI) / Ignitability and the ignition delay time of a combustible mixture in a long combustion chamber, ignited by a hot combustion torch jet generated in a pre-chamber was investigated experimentally in relation to application as a viable igniter method for wave rotor combustors. Methane-air, ethylene-air, and propane-air in varying equivalence ratios were investigated as the combustible mixture in the combustion chamber. The effects of variation in the torch jet fuel, initial equivalence ratio in the pre-chamber, and nozzle geometry on the ignitability and the ignition delay time of combustible mixtures were observed and analyzed. The single-channel wave-rotor combustion rig at Combustion and Propulsion Research Laboratory at the Purdue School of Engineering and Technology at Indiana University-Purdue University, Indianapolis was used for this study. High-speed video imaging techniques to observe the ignition and flame propagation in the combustion chamber and fast-response pressure transducers to measure the dynamic pressure fluctuations in the combustion chambers were used in the current study. The present work explains how the experimental procedure and preliminary testing was carried out in order to conduct the necessary testing to find the ignitability and ignition delay time of a combustible mixture. Ignitability of methane, ethylene, and propane were much broader in range compared to conventional spark ignitable lean and rich limit equivalence ratios. The methane and propane ignition lean limits were similar to radical activated ignition lean limits found in previous studies of the same fuels. Ethylene exhibited the widest range in equivalence ratios from 0.4 to 2.4, while methane had the narrowest ranging from equivalence ratio 0.4 to 1.4. The ignition delay studies indicated both chemical kinetics and mixing between the combustion torch jet and the combustible mixture were critical. The mixing phenomena dominated chemical kinetics; unlike in ignition delay studies conducted using shock heated ignition techniques. Ethylene-air mixtures had the shortest ignition delay times ~1 ms for lean but near-stoichiometric mixtures. Methane and propane indicated similar ignition delay time characteristics with lean near-stoichiometric mixtures. The fuel-air equivalence ratio which was used to generate the combustion torch jet and the torch jet nozzle geometry had a direct influence over the ignition delay time in the main chamber combustible mixture. The slightly rich fuel-air ratios used to generate the combustion torch jet had the lowest delay times in igniting the main chamber fuel-air mixtures.