Gas turbine efficiency is most favorable under which ambient temperature condition?

• A. Moderate temperatures
• B. Hot temperatures
• C. Humid conditions
• D. Cold temperatures

Answer: (D)

Ambient temperature affects air density, and that density directly influences how efficiently a gas turbine can convert fuel into useful work. Cooler air is denser, so for a given intake and compressor speed the engine draws in more air mass. With more air available at the same turbine inlet temperature limit, you can burn fuel more effectively to produce the same power, improving specific fuel consumption and overall cycle efficiency. In hot conditions, the air is less dense, so the mass flow is reduced for the same intake, which tends to raise fuel use for the same output and lowers efficiency. Humidity has a smaller impact than temperature. Therefore, the most favorable efficiency occurs in cold ambient conditions.