A Comparative Analysis of the Thermal Efficiency of 1977 and 1978 Model Year Vehicles Under Chassis Dynamometer Conditions

Emissions are reported for four heavy-duty trucks, which were converted to operate on compressed natural gas fuel. Two 1988 model year Ford F700 Series trucks equipped with 7.0 L gasoline engines and two 1986 model year GMC trucks equipped with DDC 8.2 L diesel engines were tested on a heavy-duty chassis dynamometer in a baseline condition and again after conversion to natural gas. The vehicles were tested over the EPA Urban Dynamometer Driving Schedule for Heavy-Duty Vehicles and at no-load curb idle. Regulated emissions of NOx, CO, HC, and diesel particulate, along with nonmethane hydrocarbons, are reported in grams/mile. Fuel economy is reported in energy-equivalent miles per gallon of gasoline or diesel fuel.

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Comparative analysis of the Allam cycle and the cycle of compressorless combined cycle gas turbine unit

E3S Web of Conferences ◽

10.1051/e3sconf/202020903023 ◽

2020 ◽

Vol 209 ◽

pp. 03023

Author(s):

Mikhail Sinkevich ◽

Anatoliy Kosoy ◽

Oleg Popel

Keyword(s):

Comparative Analysis ◽

Gas Turbine ◽

Thermal Efficiency ◽

Power Plants ◽

Thermal Power ◽

District Heating ◽

Combined Cycle ◽

Working Fluid ◽

District Heating System ◽

Wide Range

Nowadays, alternative thermodynamic cycles are actively studied. They allow to remove CO2, formed as a result of fuel combustion, from a cycle without significant energy costs. Calculations have shown that such cycles may meet or exceed the most advanced power plants in terms of heat efficiency. The Allam cycle is recognized as one of the best alternative cycles for the production of electricity. Nevertheless, a cycle of compressorless combined cycle gas turbine (CCGT) unit is seemed more promising for cogeneration of electricity and heat. A comparative analysis of the thermal efficiency of these two cycles was performed. Particular attention was paid to ensuring equal conditions for comparison. The cycle of compressorless CCGT unit was as close as possible to the Allam cycle due to the choice of parameters. The processes, in which the difference remained, were analysed. Thereafter, an analysis of how close the parameters, adopted for comparison, to optimal for the compressorless CCGT unit cycle was made. This analysis showed that these two cycles are quite close only for the production of electricity. The Allam cycle has some superiority but not indisputable. However, if cogeneration of electricity and heat is considered, the thermal efficiency of the cycle of compressorless CCGT unit will be significantly higher. Since it allows to independently regulate a number of parameters, on which the electric power, the ratio of electric and thermal power, the temperature of a working fluid at the turbine inlet depend. Thus, the optimal parameters of the thermodynamic cycle can be obtained in a wide range of operating modes of the unit with different ratios of thermal and eclectic powers. Therefore, the compressorless CCGT unit can significantly surpass the best steam turbine and combined cycle gas turbine plants in district heating system in terms of thermal efficiency.

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