Characteristic requirements of a closed-cycle gas turbine (CCGT) working fluid were identified and the effects of their thermodynamic and transport properties on the CCGT cycle performance, required heat exchanger surface area and metal operating temperature, cycle operating pressure levels, and the turbomachinery design were investigated. Material compatibility, thermal and chemical stability, safety, cost, and availability of the working fluid were also considered in the study. This paper also discusses CCGT working fluids utilizing mixtures of two or more pure gases. Some mixtures of gases exhibit pronounced synergetic effects on their characteristic properties including viscosity, thermal conductivity and Prandtl number, resulting in desirable heat transfer properties and high molecular weights. Typical examples of such synergetic gas mixture are helium-xenon and helium-carbon dioxide.

Characteristic requirements of a closed-cycle gas turbine (CCGT) working fluid were identified and the effects of their thermodynamic and transport properties on the CCGT cycle performance, required heat exchanger surface area and metal operating temperature, cycle operating pressure levels, and the turbomachinery design were investigated. Material compatibility, thermal and chemical stability, safety, cost, and availability of the working fluid were also considered in the study. This paper also discusses CCGT working fluids utilizing mixtures of two or more pure gases. Some mixtures of gases exhibit pronounced synergetic effects on their characteristic properties including viscosity, thermal conductivity and Prandtl number, resulting in desirable heat transfer properties and high molecular weights. Typical examples of such synergetic gas mixture are helium-xenon and helium-carbon dioxide.

General characteristics equations for cogeneration cycle thermodynamic performance were derived and expressed as functions of the power-to-heat ratio. Based on these equations, design point performance of indirect-fired open-cycle and closed-cycle gas turbine/cogeneration systems were analyzed and compared with those of steam turbine/cogeneration system. Effects of gas turbine pressure ratio and inlet temperature on design point performance were evaluated. Off-design partial load performances of the three cogeneration systems using various control modes were also investigated. Results indicated significant efficiency advantage of the closed-cycle gas turbine/cogeneration system over the others for both design and off-design operations.

The coal-fired, closed-cycle gas turbine (CCG T) heat engine cycle is being developed for the cogeneration of process heat and power. The coal burning heater that Rockwell International/Rocketdyne Division, provides the heat input to the gas turbine cycle is one of the more costly and Canoga Park, CA technically challenging components of such systems. This paper discusses the interrelationships between the technical and economic feasibility of the heater and the CCG T cycle parameters, i.e., temperature, pressure ratio, working fluid, pressure level, etc. A mathematical relationship between the cycle parameters and the heaters' working fluid side heat transfer coefficient is presented. Conclusions are presented regarding the zones of applicability of the available heater concepts to the spectrum of possible CCGT cycle parameters.

Cogeneration systems capable of utilizing our abundant coal resources are now especially attractive, as petroleum products are relatively expensive. However, coal-fired systems must inevitably cope with the abrasive and fouling character of the noncombustible ash content of all coals. This paper discusses the characteristics and cogeneration potential of the coal-fired, closed-cycle, gas turbine system (in which the working fluid is isolated from the products of coal combustion). Many closed-cycle, gas turbine thermodynamic cycles may be adapted to cogeneration. Parametric performance data are presented. The advantages of closed-cycle, gas turbine system/cogeneration cycles are explored, and comparisons are made between such systems and the more conventional steam-turbine based cogeneration cycles. The technology of closed-cycle fired heaters, including pulverized coal and fluidized bed firing is discussed. The key technical features of the fired heaters are discussed.