MAE 204 Lecture Notes - Lecture 20: Isentropic Process

• School: University at Buffalo
• Department: Mechanical & Aerospace Engr
• Course: MAE 204
• Professor: Salac David

Document Summary

We want to compare an actual open system to the ideal case. Each ideal system will be reversible, most ideal systems are adiobatic. -> ideal system = reversible + adiabotic = isentropic. Define efficiency by comparing the actual system to an sientropic one. n = actual work out/ isentropic work out = wa / ws n = isentropic work in/ actual work in = ws/wa. The input sate for the actual and isentropic system are the same. The output state will have one common proporty, the other properties will differ: turbine: convert flow energy into work generic turbine: assume both actual and isentropic turbines are adiabotic. Assume steady flow, uniform flow , neglect ke and pe dm/dt = 0 =m. 1 -m. 2 m. de/dt = q. om -w. out +m. in in -m. out out. W. a = m. (h1-h2a) nt = w. a/w. s = m. (h1-h2a)/(m. (h1-h2s) = (h1-h2a)/(h1-h2s) = nt. Compressor: purpose is to rasise the preessure of a gas.