Question

A simple Brayton Cycle using air as the working fluid has a pressure ratio of 10 and works with a volumetric flow of fᵥ = 4 m³/s. The minimum and maximum temperatures in the cycle are 295 and 1240 K. The Compressor efficiency is 83% and the turbine efficiency is 87 %.

Will the gas turbine perform the same way in Mexico City altitude (Patm = 75 kPa) and at sea level (Patm =101 kPa)?

Answer 1

The Brayton cycle gas turbine will not perform the same in Mexico City as it would at sea level, because the lower atmospheric pressure at higher altitudes leads to a reduced air density, which affects the mass flow rate and ultimately decreases the power output and efficiency of the turbine.

Step-by-step explanation:

The student's question is related to the performance of a Brayton cycle gas turbine operating at different atmospheric pressures which are notable at Mexico City altitude and at sea level. Atmospheric pressure affects the density of the air, which in turn affects the mass flow rate of air entering the compressor of a gas turbine. Since the performance of a Brayton cycle depends on the mass flow rate of the working fluid, it can be deduced that the gas turbine will not perform in the same way at Mexico City's altitude as it would at sea level. Lower atmospheric pressure at higher altitudes leads to lower air density and thus a reduced mass flow rate, which could result in decreased power output and efficiency of the gas turbine.Specifically, the air is less dense at higher altitudes like in Mexico City compared to sea level, leading to a lower mass flow rate through the gas turbine system, despite the volumetric flow rate remaining constant at fᵥ = 4 m³/s. Therefore, the gas turbine is likely to generate less power and have decreased efficiency at the higher altitude in Mexico City than at sea level due to the reduced density of air.