Analysis of thermosyphon/heat pipe integration for feasibility of dry cooling for thermoelectric power generation

• Thermal resistance network analysis for two-phase thermosyphon heat exchangers.
• Feasibility of thermosyphon integrated direct condenser and indirect cooling tower.
• Parametric sensitivity study of dry-cooling for thermoelectric power generation.
• System comparison of flow dynamics, heat transfer, cost and resource utilization.

Areas of minimal freshwater often struggle to provide the large amounts of water required for industrial processes, such as for the cooling of thermoelectric power plants. In an effort to decrease the water losses of a typical 500 MWe thermoelectric plant, two concepts are investigated: (i) replacing the existing steam condenser with a direct-dry condenser, to provide the phase change and heat rejection of previous once-through and re-circulation cooling systems, and (ii) replacing the conventional wet cooling towers with completely dry indirect cooling of the recirculation water stream. For each concept, innovative hybridization of existing systems with closed two-phase thermosyphons allows for the necessary heat transfer of the power cycle. A modular top-down approach to system design allows for manufacturing and installation simplification, and system performance is considered in terms of thermal and cost analysis. The proposed direct steam condenser with heat rejection to ambient air yields an effectiveness, coefficient of performance, and cost per kWth of 0.55, 376, and $31/kWth, while the dry indirect cooling tower performance specifications are 0.77, 206, and a cost per kWth of $54/kWth, respectively. These values are near-to or exceed federally proposed standards for dry cooling of thermoelectric plants and outperform existing dry-cooling systems, proving the feasibility of each heat rejection design. Hybrid arrangements of the dry condenser and dry cooling towers are also presented and analyzed, which provide easier retrofit, along with lower costs and greater water savings if combined with existing conventional wet cooling components.