UNIFIED ENGINEERING Fall 2004

Ian A. Waitz

Problem T12 (Unified Thermodynamics)

a) In problem T5 you evaluated the work obtained through three different adiabatic processes. Calculate the change in entropy for those same three processes. What is the relationship between entropy change, work and irreversibility?

b) In problem T7 you were asked to calculate the pressure and temperature at each point in the cycle for MIT's ABB Cogeneration Plant. Calculate the change in entropy of the system for each leg of the cycle and sketch the cycle on a T-s diagram.

c) On the T-s diagram, sketch how you would represent non-isentropic behavior (e.g. flow with friction) in the compressor and turbine . Assume that the engine still maintains the calculated pressure ratios across the two components--other properties may be different.