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Title: Heat driven adsorption cooling utilising enhanced effective thermal conductivity monolithic adsorbent generators for refrigeration and ice production in developing countries
Author: Davies, Gareth N. L.
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2000
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An experimental and numerical study is presented on the design, construction and evaluation of a prototype heat driven adsorption cooling system utilising the carbon- ammonia adsorption pair. The primary objective of the research was to enhance the effective thermal conductivity of the monolithic carbon material so as to enable more rapid thermal cycling and provide increased' specific cooling power. The overall design was guided towards the goal of a system appropriate for refrigeration and ice production in developing countries. A novel carbon-aluminium laminate structure was selected to enhance the effective thermal conductivity of the monolithic carbon. A two dimensional finite difference model was applied in order to determine the optimal internal geometry for this laminate. The laminate consists of a stainless steel shell containing alternate activated carbon and aluminium disc layers formed in situ. Sample sections of the laminate viewed under the microscope indicate good thermal contact between the constituent laminate materials. A prototype cooling rig was constructed based on two generators operating 180" out of phase, each containing one metre lengths of the carbon-aluminium laminate. Experimental results indicate that for a twenty minute thermodynamic cycle duration the specific cooling power achieved is 144 W kg'1 which is an improvement in performance over the previous results of 30-60 W kg '. The total semi-continuous cooling power for both generators is 458 W with a cooling coefficient of performance (COP) of 0.35 and a Carnot COP of 3.12. The numerical model was validated against the temperature, pressure and concentration data obtained from the experimental rig. A good correlation was seen between the numerical and experimental data for an external heat transfer coefficient during heating of 1000 W m 2K' and an external heat transfer coefficient during cooling of 500 W m'2K'. Performance predictions utilising the validated numerical model suggest that significant further improvement in the specific cooling power should be obtained by reducing the cycling time and increasing the generating temperature. Future design modifications will focus on reducing thermal mass, utilising heat pipes for generator cooling and adapting the system for use in developing countries.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry ; TA Engineering (General). Civil engineering (General) ; TJ Mechanical engineering and machinery ; TP Chemical technology