A gas with a specific heat of 9.2 cal/mol · °C is compressed from 25°C and 1 atm to 8 atm in a single-stage adiabatic compressor that is 75 percent efficient. (a) What is the work done per mole of gas? (b) If a two-stage compressor is used with intercooling to 20°C, how does the total work compare with that for single-stage compression?

A portion of a turbojet engine is shown in the figure below. Air flowing at 25 kg/s at 240 K and 80 kPa (State 1) enters an adiabatic and reversible diffuser with a velocity of 250 m/s. It leaves the diffuser with negligible velocity (State 2). As a result, you may assume the velocity of the air leaving the diffuser is small compared to the velocity of air entering the diffuser. The air is then compressed in an adiabatic compressor with an isentropic efficiency of 80%. The compressor requires 7 MW of power (work input). You may assume air is an ideal gas with constant specific heats. Use the correct specific heats in the table below in analyzing the different processes. Air Properties Cp Cy R kJ/kgK kJ/kgK kJ/kgK Diffuser (Process 1 to 2) Compressor (Process 2 to 3) 1.003 0.716 0.287 1.014 0.727 0.287 1. Calculate the pressure of the air in kPa leaving the compressor (State 3).

The question: A gas turbine has an isentropic efficiency of 83% and induces air in at atmospheric pressure and a temperature of 18 oC. The air is compressed to 5.5 bar before being heated to 827 oC at constant pressure conditions, and subsequently expanded through two stages in series back to atmospheric pressure. The compressor is powered by the high-pressure turbine, and the low-pressure stage powers an external load producing 150 kW of power. For both stages, the isentropic efficiency is 86%. Assume that the mass of the fuel is negligible. Taking γ for the turbine and compressor as 1.3 and 1.4, respectively, and the gas constant as 0.287 kJ kg-1K-1.  I need help answering the following: 1. You need to calculate the inter-stage pressure of the turbines. 2. You need to calculate the mass flow rate of air. 3. You need to calculate the thermal efficiency of the cycle.

Steam enters a turbine at 70 bar, 500C, and leaves at 2 bar as a saturated vapor. Calculate the isentropic efficiency of the turbine. Assume adiabatic process and negligible changes in kinetic energy and potential energy.