A gas turbine: Which statement best describes how output responds to intake air density?

• A. Expands hot gases through the compressor
• B. Output increases when using air of maximum density
• C. Operates the best when the inlet air is hot
• D. Output increases when equipped with an air preheater

Answer: (B)

Gas turbine output hinges on how much air mass is entering the compressor. Denser intake air means more air mass per second, which provides more oxygen for combustion. That allows more fuel to be burned and pushes the turbine inlet temperature higher, producing more shaft power. So the highest output occurs with maximum air density (cold, dense air). If the intake air is hot, its density is lower, reducing mass flow and thus output. Heating the incoming air with a preheater lowers density as well, which doesn’t increase output (though it can improve overall efficiency by reducing fuel use for a given power).