Design and optimization of a distributed generation system with the production of water and refrigeration.

摘要

A novel cooling and power cycle that combines a semi-closed cycle gas turbine called the High Pressure Regenerative Turbine Engine (HPRTE) with a Vapor Absorption Refrigeration System (VARS) is investigated for power, water extraction and refrigeration. The refrigeration cycle, VARS, interacts with the power cycle, HPRTE, through the generator and 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. The combined HPRTE/VARS cycle is modeled using zero-dimensional steady-state thermodynamics, with conservative values of polytropic efficiencies and pressure drops for the turbomachinery and heat exchangers. The cycle is shown to operate with a thermal efficiency approaching 40.4% for a turbine inlet temperature of 1400°C while producing about 1.5 kg of water for each kg of fuel (propane) consumed. The thermal efficiency does not take into account the cooling effect produced in the evaporator of VARS. The combined cycle efficiency at the above operating condition was found to be 44%.; Experiments were conducted on two simplified versions of the combined HPRTE/VARS cycle to validate the models and demonstrate the working of HPRTE. In the first simplified version a one ton vapor compression refrigeration unit was used in the place of the VARS. In the second simplified version two heat exchangers were used each in the place of the generator and the evaporator of the VARS. The values of cycle parameters obtained from the model are compared with the experimental values. The difference between the two values is found to be within acceptable limits.; The combined HPRTE/VARS cycle is optimized using the thermodynamic model for a medium sized engine with conservative values of the design parameters. The optimization variable considered was the high pressure turbine exit temperature, the low pressure compressor ratio, the temperature of the gas exiting the evaporator and the generator temperature of the VARS. The objective function, maximized in the optimization process, consists of a linear combination of three different outputs of the combined cycle. They are the thermal efficiency representing power output, refrigeration ratio representing external refrigeration load and ratio of mass flow rate of water extracted to mass flow rate of fuel burnt.