Currently nine out of ten power plants in the United States that generate electricity from steam power require condensate cooling which accounts for approximately 40% of the nation's total freshwater withdrawals and approximately 3% of the nation's total freshwater consumption. In order to significantly reduce or eliminate the use of water for cooling power plants, the proposed research will demonstrate a new generation of ejector-based cooling technology that can result in significant reductions or elimination of the use of water for cooling power plants.
Using low-grade thermal energy of steam, an ejector can create a supersonic flow and low pressure zone that can be used to produce cooling. Combining an innovative evaporation/condensation compact condenser, that utilizes hybrid hydrophobic and hydrophilic condensing surfaces and thin film evaporation, an innovative concept of ejector-based cooling technology will be demonstrated. This innovative and potentially transformative system can significantly reduce or eliminate the use of water and significantly reduce the condenser size; furthermore, and it can significantly reduce condensation temperature from 50 °C to 35 °C at an ambient temperature of 30 °C. In addition, this system can be easily integrated into ongoing cooling systems.
The proposed cooling system integrates state-of-the-art technologies of ejector refrigeration powered by a low-grade thermal energy, hybrid hydrophobic and hydrophilic condensing surfaces, thin film evaporation, and efficient low-cost oscillating heat pipes. The low-grade thermal energy of steam is utilized to power the ejector refrigeration system. Fundamental understanding of supersonic flow in nozzles, mixing chambers, and diffusers, and its effect on the entrainment in particular, is a missing piece that has restrained ejector refrigeration from wide-spread application. Thermodynamic analysis and fluid dynamic modeling of the supersonic flow will be conducted resulting in a better understanding of ejector performance. A prototype of 5 kW with optimized nozzle, mixing chamber, and diffuser will be demonstrated. The effect of a hybrid hydrophobic and hydrophilic condensing surface on the condensation heat transfer will be conducted in order to provide an insight into fluid flow and condensation mechanisms. Optimization of thin film evaporation can further push the evaporating heat transfer limit to the next level. Low-cost fins embedded with no-wick oscillating heat pipes will be demonstrated to increase the heat transfer efficiency of the air side. The resulting ejector-based compact condenser, if successful, will have significant impact on power plant cooling.
