1 The Special Characteristics of Closed-Cycle Gas Turbines Available to Purchase
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Published:2005
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Charging the gas turbine cycle gives rise to the following special properties:
• The volume flows and therefore the flow sections required are reduced in inverse proportion to the degree of charging.
• Charging increases the convective heat transfer coefficients such as (p/p0)0.75 at constant relative pressure drops in flow. This results in smaller heat exchanging surfaces for coolers, recuperators and heaters. In the latter, the increased convective heat transfer in the heat pipes allow a more intensive input of radiated heat.
• Charging has a negligible effect on the flow ratios (velocity triangles) in the compressor and the turbine. The pressure ratios and enthalpy differences in the machines and apparatus remain constant throughout the charging process and therefore at any load.
• Thus, the output can be easily controlled while maintaining a more or less constant efficiency by varying the pressure level, in other words letting gas in or out of the system.
• Other gases can be used instead of air, such helium, with its great specific heat and very high sound velocity.
• Indirect heat supply via the exchange surfaces of the gas heating pipes allows almost any fossil or nuclear fuel to be used, as well as efficient connection to solar energy.