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The efficiency depends primarily on size (different manufacturtes have use similar designs). Bigger Gas Turbines tend to more effiecient. Additional factors such as waste heat recovery and heat exchangers can improve the system efficiency (but not the effiecency of the actual Gas Tubine).

Smaller gas turbines such as the Rolls Royce Avons have around 25% Thermal Efficiency while larger units such as the Rolls Royce Trent-50 have efficiencies of around 42%. A full list of Tubine Efficiencies for different manufacturers can be found at

Note that the above comment does not make the Avon a bad unit its simply the case that it is designed primarily for a high power to weight ratio. Some people will also quote very high figures for G.E Frame machines (+50%) but these numbers usually include co-gen (a steam turbine used to recover waste heat) and are therefor not just Gas Turbine Efficiency.

The full calculation for calculating Gas Turbine effieciency is avalaible at VibroNurse at the following page ( and program which does the calculation is available at We use this program at our oil and gas platforms and it works well particlauarly as a condition monitoring tool.

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โˆ™ 2011-09-13 15:22:41
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Q: Thermal efficiency of gas turbine?
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Related Questions

What is the efficiency of thermal power plant?

A modern combined cycle gas turbine/ steam turbine power plant can reach almost 60% efficiency.

How inefficiencies of compressor and turbine affect back work ratio and efficiency of gas turbine?

Inefficiencies in the compressor of a gas turbine cycle increase the back-work ratio and decrease the thermal efficiency of the gas turbine cycle, since they increase the compressor work.

How do you increase a Thermal efficiency of brayton cycle?

by increasing the turbine inlet gas temperature

What are the effects of humidity on gas turbine performance?

an increase in relative humidity will increase the Gas turbine output. and thermal efficiency. when the ambient tempeature is high at that time also if RH is high it will have a slight positive impact on GT output & Efficiency.

What is the effect or reheater in the gas turbine?

1.Turbine output is increased for same compressor work. 2.As more heat is supplied,thermal efficiency decreases.

How do I calculate Gas turbine efficiency calculation?

output /input

What is the efficiency of a Turbine?

The efficiency of a Turbine, is roughly 40%.

What is the difference between combined cycle and cogeneration?

In Cogeneration Plant : The generated steam in boiler is used for both power generation & process heating, thereby reducing the condenstion losses compared to thermal power plant. In combined cycle first is gas turbine , rather than wasting the flue gas from gas turbine, we are sending it into boiler and again generating steam for running steam turbine. Both the ways we are increasing the thermal efficiency of the plant

Do you use HHV or LHV for gas turbine efficiency calculation?

Gas turbine manufacturers generally state the efficiency of their turbines using LHV. However, natural gas in the U.S. is bought and sold on an HHV basis, so be careful that you don't mix units. Otherwise, you will buy a gas turbine that is too small for your anticipated needs.

Why the temperature and the pressure of gas are decreasing after flowing out from turbine?

The gas (working fluid) having flown through the turbine does some work on the turbine, converting its thermal energy into mechanical work produced by the turbine and coming out as an expanding gas with lower temperature and pressure.

How can I run a gas turbine power generator efficiently? discusses many factors affecting gas turbine efficiency. It specifically addresses GE turbines, but the factors discussed are relevant to all gas turbine power generators.

Is it true that thermal efficiency of a diesel engine equals indicated thermal efficiency - brake thermal efficiency?


How do you calculate specific fuel consumption of gas turbine?

A simple-cycle gas turbine used for power generation has a thermal efficiency of about 34 percent. Since 1 kwh is theoretically equivalent to 3,415 Btu, the simple-cycle gas turbine has a fuel connsumption of: 3,415 / 0.34 = about 10,000 Btu/kwh. Given the heating value (i.e, heat of combustion) of a fuel, we can easily calculate the simple-cycle gas turbine fuel usage. For example, natural gas has a net heating value of about 21,500 Btu/pound. Thus, the natural gas consumption in a simple-cycle gas turbine would be: 10,000 / 21,500 = 0.47 pounds/kwh = 0.21 kg/kwh. As another example, a typical diesel oil has a net heating value of 130,000 Btu/gallon. Thus, the diesel oil consumption in a simple-cycle gas turbine would be: 10,000 / 130,000 = 0.077 gallon/kwh. (The gallon used just above is the U.S. gallon rather than the Imperial gallon) A combined-cycle gas turbine will have a higher thermal efficiency and, hence, lower fuel consumptions.

A steam turbine has an efficiency of 40 percent A steam engine has an efficiency of 25.0 percent Suppose both devices are provided with 1000J of thermal energy How much more useful work will the ste?

The steam turbine will produce 400 J of output, and the steam engine 250 J. That's what the efficiency figure means.

Why steam turbine is used in thermal power plant?

A steam turbine extracts thermal energy for steam, hence it's use in a thermal power plant.

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Gas turbine generator?

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A free turbine engine is a type of gas turbine engine, where the power turbine and the gas producer turbine are not connected by a solid shaft

How superheating of steam improves the efficiency of thermal power plant?

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Is natural gas thermal or electric energy?

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How do you calculate only turbine efficiency not turbine cycle efficiency?

by calculating the inlet steam enthalpy-outlet steam enthalpy we will know the total kcal consumed for output mw required kcal for 1 kwh=860 now campare this with your turbine kcal for 1kwh now you came to know how much is your turbine efficiency................................................................................

What does thermal energy convert to?

Thermal energy is just heat. To convert it to mechanical energy you need some sort of heat engine, like an internal combustion engine or a gas turbine.

What is the defferences between a steam turbine gas turbine?

steam turbine having more efficinency and using direct steam, wheras gas turbine using used gas .

What is the differences between gas turbine and a steam turbine?

Gas turbine works on bryton cycle where as steam turbine works Rankine cycle. Construction, operation of a gas turbine are entirely different to steam turbine. Gas turbine has a compressor to compress the combustion air, a combustion chamber to burn the fuel and a turbine section to extract the work for burning fuel. Steam turbine is just has a turbine section to extract the work from steam.

Why is the gas turbine called as the power plant?

A gas turbine is one type of power plant. It produces power by burning gas to turn the turbine.