Limitations on water utilization are turning into an expanding issue for the power and electricity generation industry. As a contribution to the solution of water consumption problems, utility companies are shifting toward using air-cooled condensers (ACC) in replace to the typical water-cooling methods of once-through cooling and the surface condenser/wet-cooling tower combination. Although the ACC is a dry cooling method, the industry is quite hesitant to switch over to ACC mainly for three reasons: (a) lower power output, (b) higher capital cost, and (c) larger physical footprint. All these drawbacks are because of the high overall thermal resistance of condensing steam to the ambient air compared to condensing it to water. In this study, detailed mathematical equations were derived to model the heat transfer process through the fined tubes of the ACC. The total thermal resistance model was analyzed and investigated theoretically. The model was used to identify the design components with the most significant effect on the overall thermal resistance of the ACC system. This study proposed a feasible cooling system based on heat pipe technology, using a novel disc-shaped heat pipe design. The solution addresses the three problems highlighted in using the air-cooled condensers in steam powerplant condensers. The analysis covered design and manufacturing considerations, in addition to the thermal performance and the limitations of the proposed annular disc-shaped heat pipe. The proposed annular disc-shaped heat pipe was investigated using three analysis techniques. The first is a theoretical investigation of the heat transfer limitations of the proposed annular disc-shaped heat pipe. This analysis was used to predict the capillary and boiling thermal limitations of the proposed heat pipe design. Secondly, an annular disc-shaped heat pipe was designed and built for the experimental investigation using de-ionized water as the working fluid. The results obtained by the parametric analysis were used as the input for the experimental design. Third, A detailed mathematical set of equations was derived to model the heat pipe thermal resistance. The experimental setup was validated by comparing the results to well-referenced experimental results of similar disc-shaped heat pipe with different evaporator configurations. The experimental results were compared to the thermal resistance model developed in this study. The results showed a starting regime of the heat pipe, where the thermal resistance is decreasing until it reaches a steady performance before it starts to increase again when it reaches the heat transfer limits. The experimental results showed a good agreement with the model prediction in the steady-state regime for heat inputs over 300 w. The data identified two thermal performance regimes of the heat pipe, a single-phase, and a two-phase regime. The second regime starts when the vapor region reaches the isothermal state.
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Doctor of Philosophy (Ph.D.)
College of Engineering and Computer Science
Mechanical and Aerospace Engineering
Length of Campus-only Access
Doctoral Dissertation (Open Access)
Saleh, Ahmad, "Design of an Annular Disc-shaped Heat Pipe for Air-cooled Steam Condensers" (2020). Electronic Theses and Dissertations, 2020-. 619.
Restricted to the UCF community until February 2021; it will then be open access.