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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Environmental impact : a critical review of implementing evaporative cooling system in Hong Kong /

Ho, Mei-kim. January 2002 (has links)
Thesis (M. Sc.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 58-59).

Optimum dry cooling tower-cooling pond combinations for power plant heat rejections

Gupta, Arun Kumar, 1943- January 2010 (has links)
Digitized by Kansas Correctional Industries

Solar cooling of buildings in a Swedish climate : Analysis and design of solar cooling in Building 45 at Högskolan i Gävle.

Moreno Fernandez, Marcos January 2014 (has links)
Nowadays Solar Energy is one of the engineering fields most exploited, due to the ongoing need to developing new technologies based on renewable energy or improving the existing ones. One particular application of this kind of energy is Solar Cooling, which consist in generating cold from the heat received from the Sun. A common installation of solar cooling requires solar collectors, an absorption/adsorption chiller, fan coils, piping, valves and pumps. It calls for a minimal preventive maintenance which should allow keeping operating conditions within certain limits.The aim of this work is to analyze the viability of the installation of a solar cooling system in a roof. It has been chosen the Building 45 of the University of Gävle (Hus 45) as a pattern design. It was built in 2008, thirteen years after Högskolan i Gävle was inaugurated. This building uses electric compression coolers for its cooling demand. According to their heating demand, this is solved by using District Heating.This work is focused on the determination of the cooling demand of this particular building and the proposal of a solar cooling system that could supply it. Calculating the cooling demand means applying most of the concepts learnt during the whole speciality of the degree, like thermal loads in buildings. This calculation has been possible by using IDA ICE, which is a software that allows the user to develop a new construction through defining all structure parameters. After having defined all the contour conditions, the simulation shows all kinds of parameters in detail, in particular, the cooling demand of the respective building. Moreover, creating a new solar cooling system for this building means reviewing all the concepts related to refrigeration cycles and solar energy that have been learnt during the intensification. To do it, it has been necessary to use POLYSUN, another program that let the user to create solar thermal systems, photovoltaic systems or any other installation for getting heating, cooling or hot water.In addition, another important point to discuss is the usage of a solar cooling system based on absorption/adsorption technology instead of using photovoltaic as a way of providing to the current cooling units.The simulation about the cooling demand of the building shows that for covering the 95,22% of the operation hours (within the study), it is required to solve a cooling peak demand of 100 kW, which is in terms of energy a value of 68437,6 kWh. Regarding the designs of the solar cooling systems, two variants have been analyzed. While the first one is based on using the absorption technology, the second one has two subdivided proposals: a stand-alone photovoltaic system and a net metering installation. The absorption system could cover the cooling demand with the exception of July. The viability of this installation is questioned because of the low operation hours of the absorption machine, which is not working as it was expected since it is the cooling tower who really carries out the cooling function. On the other hand, the stand-alone system allows the building to cover all of its cooling demand, but the system is oversized and no profitable within a period of 30 years although it supposes a reduction of 100% in CO2 emissions, which is obvious since this option considers an electrical consumption from the grid of 0 kWh. Finally, the net metering system is probably the best option for covering the cooling demand of this building, as it has the shorter pay-back (18 years), the less visual impact when the solar modules are installed on the roof and requires less maintenance.Since there are no advantages in using an absorption machine for a cooling system in a Swedish climate, the next step would be analysing a system like the one proposed into another climate, where the solar radiation has more influence, thus, the absorption machine could work because of the inlet water (coming from the solar loop) is hot enough.

Two-phase flow of water and steam in a liquid metal fast breeder reactor pipe

Kane, Stephen James January 1994 (has links)
No description available.

Computer assisted design of humidification equipment

Harvey, Glenn B. 29 October 1990 (has links)
A computer assisted design model, developed for undergraduate students to teach the basic principles of humidification design, is developed and presented. Beginning with the development of the differential equations, the conversion to numerical code is presented, followed by a series of applications to mechanical draft in cooling towers, natural draft cooling towers, and packed columns. Extensions of the program to other uses is also discussed. Several calculation options are presented which allow students to understand the effect of design options at a practical level. A user's manual, flow charts, program listing, and other design information are also included. / Graduation date: 1991

A critical evaluation and refinement of the performance prediction of wet-cooling towers /

Kloppers, Johannes Christiaan. January 2003 (has links)
Thesis (Ph. D.)--University of Stellenbosch, 2003. / Includes bibliographical references. Also available via the Internet.

Laser cooling of solids /

Rayner, Anton. January 2002 (has links) (PDF)
Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Forced draft cooling tower

Merryman, Ralph E. 05 1900 (has links)
No description available.

Effects of vacuum rate on the vacuum cooling of lettuce

Rennie, Timothy J. January 1999 (has links)
The deterioration of freshly harvested horticultural crops can be minimised by precooling prior to storage. This technique of quickly cooling the produce does not only increases the shelf life, but it also reduces the size of the refrigeration system needed for storage facility. Vacuum cooling is an effective method of precooling leafy vegetables, but has a major drawback of requiring substantial initial capital investment. Thus, vacuum coolers are generally limited to large-scale or co-op operations where the initial investment can be spread across a large quantity of produce. / The conventional philosophy behind precooling design is to establish systems to cool produce as quickly as possible; this concept is more so with vacuum coolers. By changing certain design criteria of a vacuum cooler, it may be possible to reduce the capital cost of vacuum coolers by reducing the rate of vacuum. Though the time to cool the produce may be increased, the reduction in the size of the vacuum pump and the refrigeration system, and hence the capital cost of the cooler, may be beneficial to small-scale producers who can not justify the large expenses incurred when purchasing a conventional system. / Experiments were performed on a modified vacuum cooler in which the rate of vacuum could be controlled. The cooling characteristics, including the temperature distribution and mass loss, and the lettuce quality were determined for different rates of vacuum. A relationship between the speed of the vacuum and the peak product refrigeration load was developed and tested with experimental data. The results suggest that slower vacuum coolers can be successfully designed and built for small-scale operations.

The optimization of cooling of underground cable systems

Fedoroff, Vitaly L. January 1970 (has links)
A novel, idealized mathematical description is presented of the cooling process of electric power cable system by an integral liquid coolant configuration. A model is first obtained for constant fluid velocities, by the use of Laplace transform and subsequent solution of an ordinary differential equation. A simple integral expression is obtained, which is numerically integrated by the Simpson's rule. The set of curves so obtained, clearly show the delay of the temperature peak vs. the peak of the power demand. A steady state form of control is proposed. Block diagrams of two implemetations are shown. These control systems are designed to maintain the temperature of the effluent constant. An optimization algorithm based on developments given by Sage is presented. This algorithm will optimize the transfer of the cooling system from the initial condition of zero velocity to the steady state operation described above. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

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