The diploma thesis deals in the theoretical part with various types of sys-tems for the preparation of hot water and specifies the types of solar sys-tems. In the calculation part, it solves the design of kindergarten heating by a system of heating elements. It also solves two variants of hot water preparation in the hot water tank. The design also includes all the equip-ment needed for the proper functioning of the heating system. The exper-imental part compares flat panel and evacuated tube solar collectors.

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Freeze-drying (lyophilization) is a drying process which is used to remove water from heat sensitive products, usually for the purpose of preservation. By removing water, the product becomes more stable at room temperature. This is a common process in the pharmaceutical industry because freeze-drying offers the advantage of drying at low temperatures and producing very low residual moisture contents. Often the materials dried in this manner are heat sensitive and require the highest possible quality. However, freeze-drying is a very slow process, often requiring 24 to 48 hours. During the process, vacuum pumps and refrigeration systems run continuously, making freeze-drying a very expensive process. The goal of this project was to show that volumetric heating can be used in pharmaceutical freeze-drying and that this mode of heating offers some advantages. There were two approaches taken to the work, one experimental and one analytical. The experimental approach was broken into two phases, one focused on comparing microwave and conventional freeze-drying and the other focused on demonstrating the advantages of volumetric heating. In the analytical approach, a mathematical model was used to confirm the trends observed in phase II of the experimental work. Experiments were conducted in a conventional laboratory freeze-dryer and the drying rate results were compared to the results obtained with an experimental microwave freeze-drying apparatus. Experiments were also conducted with the vaccine strain <i>A. pleuropneumoniae</i>. A viability study was conducted, comparing the viability loss caused by each process. The viability study showed a slightly higher viability loss for the microwave process. A comparison of drying curves showed that the microwave process resulted in a slight improvement in primary drying time: 2.5 hours for the microwave process compared to 3 hours for the conventional process. There was a significant difference in overall drying times: 4 hours for the microwave process compared to 11 hours for the conventional process. This result was caused by a lower residual moisture content at the start of secondary drying and a higher secondary drying temperature for the microwave process. Experiments were also conducted to show that using lower chamber pressure results in higher drying rates. This is not the case in a conventional freeze-dryer since heating is dependent on the chamber pressure in the low pressure environment of freeze-drying. Thus, an advantage of volumetric heating was demonstrated. The results show that a modest increase in pressure, from 0.05 to 0.3 Torr, caused a one third reduction in primary drying time. The mathematical model developed in the analytical work relied on the D'Arcy equation to describe the flow of vapor in the porous dried layer. The results of the model confirm trends seen in the measured temperature and weight profiles. Analyzing the effect of varying the chamber pressures shows that lowering the pressure in the range of 1 to 0.01 Torr results in a significant increase in drying rate giving as much as a two thirds reduction in drying time for the case studied. A model incorporating mass transport equations derived from the dusty gas model was also presented. This model offers the benefit of a more accurate prediction of mass transport through the porous dried layer. NOTE: (09/2008) An updated copy of this ETD was added after there were patron reports of problems with the file. / Ph. D.

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published_or_final_version / Mechanical Engineering / Master / Master of Science in Engineering

Summer brooding often requires some form of air modification in addition to maximizing ventilation rate to prevent animal heat stress and possible death due to hyperthermia. A rockbed thermal storage module was designed and constructed to provide sensibly cooled air for a broiler space under summer brooding conditions. A mathematical model of rockbed thermal storage module was developed to predict performance of the prototype module. Experiments to evaluate the rockbed module under different weather conditions and operating schedules were conducted. The results were presented and compared with the mathematical simulation. A microprocessor control system was designed and assembled to control the ventilation air that would enter a broiler house during warm weather periods. The system was capable of taking temperature samples from thermocouples and then operate a damper arrangement which determined the mixture of outdoor and sensibly cooled air from rockbed thermal storage module. The cost and feasibility of utilizing a rockbed thermal storage module and a microprocessor control ventilation system were discussed. / Graduation date: 1989

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Experimental and numerical investigations were carried out on air-filled cavities containing heated inner cylinders. The effect of varying the position of radial spacers on a single cylinder was studied. It was concluded that for central positioning of the cylinder within the cavity. the rate of heat-transfer was minimised at a radial spacer angle of 480 (measured from the vertically downwards radius vector). When the cylinder was positioned at displacement ratio of 0.7, the rate of heat-transfer was minimised at a corresponding spacer angle of 520. The corresponding reductions in the total rate of heat-transfer were found to be 25% and 31% less than that obtained for the system with no spacers at a cylinder displacement ratio of zero. Following this research investigation, the behaviour of a two-pipe arrangement, consisting of a hot supply and cooler return pipe within a rectangular sectioned cavity, was studied. Eccentric positioning of both supply and return pipes showed that minimum rates of heat-transfer occur at supply and return pipe displacement ratios of 0.45 and -0.33 respectively. This value of heat-transfer is approximately 20% less than that obtained for a system where supply and return pipe displacement ratios are 0.7 and zero respectively. As experimental testing has proved to be excessively time consuming (e. g. due to having to wait until a steady-state ensued before measurments were taken) and laborious, a finite-element numerical model was developed and used to predict the heat-transfer between a heated inner cylinder and a cooled outer square duct. This study investigated eccentricity effects on the rate of heat-transfer for different ratios of duct height to cylinder radius. Solutions were obtained for Rayleigh numbers 1 to 300 and optimal pipe eccentricity for minimum heat-transfer was predicted. These predictions were in good agreement with previous experimental results.

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