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A novel pressurized CHP system with water extraction and refrigeration.

Author(s) : KHAN J. R., LEAR W. E., SHERIF S. A., et al.

Type of article: Article

Summary

A novel cooling, heat, and power (CHP) system has been proposed that features a semi-closed Brayton cycle with pressurized recuperation, integrated with a vapor absorption refrigeration system (VARS). The semi-closed Brayton cycle is called the high pressure regenerative turbine engine (HPRTE). The VARS interacts with the HPRTE power cycle through heat exchange in the generator and the evaporator. Waste heat from the recirculated combustion gas of the HPRTE is used to power the absorption refrigeration unit, which cools the high-pressure compressor inlet of the HPRTE to below ambient conditions and also produces excess refrigeration in an amount which depends on ambient conditions. Water produced as a product of combustion is intentionally condensed in the evaporator of the VARS, which is designed to provide sufficient cooling for the inlet air to the high-pressure compressor, water extraction, and for an external cooling load. The computer model of the combined HPRTE/VARS cycle predicts that with steam blade cooling and a medium-sized engine, the cycle will have a thermal efficiency of 49% for a turbine inlet temperature of 1400°C. This thermal efficiency is in addition to the large external cooling load generated in the combined cycle which is 13% of the net work output. In addition it also produces up to 1.4 kg of water for each kg of fuel consumed, depending upon the fuel type. When the combined HPRTE/VARS cycle is optimized for maximum thermal efficiency, the optimum occurs for a broad range of operating conditions. Details of the multivariate optimization procedure and results are presented in the paper. Previous studies have demonstrated the following attributes of the combined HPRTE/VARS cycle: attaining high part power efficiency in a compact package, threefold specific power increase over the state of the art, reduced IR signatures due to lower exhaust temperature, significant reduction of exhaust particulates and smoke, constant high-pressure compressor inlet temperature and order-of-magnitude reductions in emissions such as NOx, CO and unburned hydrocarbons. The integrated nature of this system allows overall reduction in size and weight of approximately 50% relative to conventional equipment. The combination of positive attributes makes the HPRTE combined cycle engine attractive for future mobile power applications in terms of performance as well as life cycle cost. [Reprinted with permission from Elsevier. Copyright, 2009].

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