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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.
1

Design, modeling and performance of miniature reciprocating expander for a heat actuated heat pump

Herron, Thomas G. 21 September 2004 (has links)
A miniature reciprocating expander is being developed as part of a larger program to develop a heat actuated heat pump for portable applications. By utilizing the higher energy density of liquid hydrocarbon fuels relative to batteries, a heat actuated heat pump would be able to provide cooling for much longer than motor driven units of equal weight. A prototype expander has been constructed and demonstrated to produce up to 22 W of shaft power at 2500 rpm using 60 psig, room temperature nitrogen as the input. Assuming adiabatic conditions, the expander appears to operate at up to 80% isentropic efficiency. However, when heat inflow to the expander is accounted for, the resulting polytropic efficiency is about 10% lower. In addition to experimental results, models of expander performance with different loss mechanisms are presented. These mechanisms include over- and under-expansion, in-cylinder heat transfer, clearance volume, friction, and valve pressure drop. / Graduation date: 2005
2

An analytical study of the performance characteristics of solid/vapor adsorption heat pumps

Fuller, Timothy Alan 05 1900 (has links)
No description available.
3

Design and modelling of novel absorption refrigeration cycles / by Stephen David White.

White, S. D. January 1993 (has links)
Nine pages of Addenda and eight pages of Errata in back pocket. / Includes bibliographical references. / vii, 192, [78] : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1994
4

Constrained thin film desorption through membrane separation

Thorud, Johnathan D. 17 February 2005 (has links)
A constrained thin film desorption scheme has been experimentally tested to determine the desorption rates for water from an aqueous lithium bromide mixture through a confining membrane. Variable conditions include the inlet concentration, pressure differential across the membrane, and channel height. Desorption takes place in a channel created between two parallel plates with one of the walls being both heated and porous. A hydrophobic porous membrane creates a liquid-vapor interface and allows for vapor removal from the channel. Inlet concentrations of 32 wt%, 40 wt%, and 50 wt% lithium bromide were tested at an inlet sub-atmospheric pressure of 33.5 kPa. Pressure differentials across the membrane of 6 kPa and 12 kPa were imposed along with two channel heights of 170 μm and 745 μm. All cases were run at an inlet mass flow rate of 3.2 g/min, corresponding to Reynolds numbers of approximately 2.5 to 4.5. The membrane surface area for desorption was 16.8 cm². A maximum desorption rate (vapor mass flow rate) of 0.51 g/min was achieved, for the 32 wt%, 12 kPa pressure differential, and 170 μm channel. Increasing the pressure differential across the channel allowed for higher desorption rates at a fixed wall superheat, and delayed the transition to boiling. As the inlet concentration increased the desorber's performance decreased as more energy was required to produce a fixed desorption rate. Results are also presented for the variation in the heat transfer coefficient with the wall superheat temperature. The increase in the channel height had a negative influence on the heat transfer coefficient, requiring larger superheat values to produce a fixed desorption rate. / Graduation date: 2005 / Best scan available for tables and computer code in the appendices. The original is faded.

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