No description available.

Two types of solar collecting systems are frequently employed--flat plate collectors with spectrally selective windows which trap sunlight with the "greenhouse effect" and focusing systems with curved mirrors which concentrate the sun's rays on an absorbing surface. The flat plate collector is the simpler of the two designs, but cannot readily provide temperatures as high as the focusing collector. Both of the collectors are candidates for absorption cycle solar air conditioning systems. This role dictates higher temperature than are normally required of solar collectors, particularly the flat plate design. Focusing systems of interest here are those which are fixed in orientation and require no elaborate solar tracking mount. Such collectors might be economically competitive with flat plate configurations if the higher energy "quality" or delivery temperature they can provide permitted a smaller installation than would be possible with a flat plate collector. An analysis of the two collector candidates is undertaken here to assess the merits of a fixed orientation focusing collector and a more traditional flat plate system. This analysis indicates that the focusing design is superior to the flat plate for solar air conditioning. The study of the two designs includes selection of system configurations and the development of their mathematical descriptions. The analytical approach was to incorporate mathematical models of the collectors into a computer program which predicts the performance of both the flat plate and focusing systems. The program has been designed to permit convenient variation of important parameters so that their effect on collector performance may be determined. The results of the collector analysis and the computer program are presented with sufficient information to permit the reader to use the program for his own analyses.

The purposes of this thesis were to investigate the contemporary field of air conditioning in industry and education; to determine what equipment should be recommended for installation in the Mechanical Engineering Laboratory of the Virginia Polytechnic Institute; and to design the components and controls for a unit which will be modern, practical, and educational. The components of the unit were designed or selected on the basis of the research summarized in this thesis in Chapter II, ”Review of Literature.” A central fan system was designed. Within the necessary design limitations, every effort was made to incorporate as many different methods as possible which demonstrate air conditioning processes, and every effort was made to enhance the effectiveness and attractiveness of the unit for its intended purposes of demonstration and research. The main part of the conditioning apparatus will be supported in ductwork about four feet above the floor level so that weigh tanks, scales, condensate coolers, and drain lines may be placed underneath, thereby allowing the processes to be controlled and observed at normal eye level. In order to keep within the prescribed area, the air measurement chamber and fan will be mounted at a higher level. Ducts will carry air from the existing insulated test room to the unit and return conditioned air to the test room. A duct to extend from an existing roof opening will be large enough to carry 2000 cfm and will contain a freeze-resistant tempering coil. Manually adjusted opposed blade dampers control air quantities at the junction of the outside air duct and the return air from the test room. Air passing through the built-up unit will pass through the following components: disposable filter, electronic filter, activated carbon filter, steam preheater coll, direct expansion coll, hot or chilled water coil, opposed blade face and bypass dampers, washer, steam reheater coil, air temperature measuring chamber, air flow measuring chamber, and centrifugal fan with inlet vanes. Among the accessory components are a Refrigerant 12 refrigeration unit with water-cooled condenser, water chiller, steam water heater, high-head circulated pump, and a wide assortment of valves and actuators for automatic control on any one of the many cycles being run. Each piece of conditioning equipment operating on the summer cycle was designed for a nominal cooling capacity of five tone when the system is circulating the equivalent of 2000 standard cfm of air. The winter cycle equipment was designed to supply humidified air to the test chamber at not less than 100°F when 9000 pounds per hour of outside air at 0°F enters the equipment. The apparatus will be capable of maintaining within close limits any reasonable air temperature and humidity under all conditions of operation on both cooling and heating cycles. / Master of Science

Vita. / Digitized by Kansas Correctional Industries

Sanden international, an automobile air conditioning compressor manufacturer, was facing a problem in its incoming material inspection procedures. Although the company had designed and was using its own sampling plan, some managers and supervisors where not confident of its reliability. Sanden recently established a goal for its total number of defects per supplier as one part per million. Achievement of this target required reviews of the existing sampling plan. The purpose of this project was to help Sandra identify the best alternatives for its incoming material inspection procedures. To do that considerations were made about the usefulness of sampling inspections, theoretical aspects of inspection sampling plans were examined, current sampling plans were analyzed and recommendations were made.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

No description available.

The following report investigates district cooling systems. This form of technology provides an alternative means of providing cooling. In a traditional cooling system each building would include cooling equipment to serve only that building. District cooling differs in that water is chilled at one location and pumped to two or more buildings. District cooling has many benefits over traditional cooling systems. This report, however, aims to determine the economic benefits (if any) of district cooling systems. The location chosen as a model for this study was the University of Natal (Durban) campus. This campus currently operates a district cooling system serving six buildings. This study is hypothetical in nature, as the cooling system is already finalized and operational. The aim of this dissertation is to answer the question of which would be the more attractive alternative if the University were in a position of having to install a completely cooling system. One of the most important steps in this process is the calculation of cooling loads. The cooling load was estimated for each of the buildings associated with the district cooling system. The LOADEST software package was used to derive these cooling loads. The accuracy of LOADEST software was also validated in this study. The bulk of this report is composed of the preliminary work required to obtain capital and operating costs for cooling systems, including validation of cooling load calculation software. It was felt that this prelimiinary work justified inclusion in the final report to provide accurate representation of the steps taken before any economic evaluation could be reached. The capital and operating costs of the district cooling system and a more traditional system were compared. It was found that the district cooling system reduces operating costs significantly, although it's capital cost is higher than the traditional system against which it was compared. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

In South Africa, a significant amount of electrical energy is used for air conditioning in commercial buildings, on account of the high humidity experienced. Due to its geographical location, the levels of solar irradiation and the demand for air-conditioning of commercial buildings reach maximum levels simultaneously. The South African region daily solar radiation average varies between 4.5 and 6.5 kWh/m2 and when compared to the United States 3.6 kWh/m2 and Europe’s 2.5 kWh/m2 , solar thermal powered cooling technologies has significant potential as this solar irradiation is also available all year around [1]. Utilizing solar energy for an air conditioning system has the advantage that the availability of solar radiation and the need for cooling reach maximum levels simultaneously and proportionally. This type of air conditioning system has an electrical energy saving benefit in light of increasing energy tariffs and the energy crisis currently facing Eskom in South Africa. Solar-assisted Absorption Cooling systems decreases the peak electricity consumption, is less noisy and vibration free, since it does not contain a compressor and this gives a higher reliability, low maintenance and its electricity consumption is approximately four times less (21.8kW versus 5.5kW for 35kW of Cooling) than that of an electric driven chiller containing a mechanical compressor [2]. However, due to the high capital cost of solar powered air-conditioning plants, it is essential that a feasibility analysis be undertaken to indicate and establish a return on capital investment. The main objective of the present study is to investigate and establish the feasibility of a solar-assisted air-conditioning system based on Lithium Bromide and Water (LiBr/H2O) absorption chillers on a medium scale for commercial buildings in terms of energy saving and performance. This study presents the results of the experiment on a solar-assisted air-conditioning facility constructed and installed in October 2009 at Pretoria’s Netcare Moot Hospital. This study has confirmed that a payback period of 13 months can be achieved and the performance parameters of the manufacturer’s specifications for a solar-assisted air conditioning system are exceeded for the South African climate. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2012.

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