THE UNIVERSITY OF MICHIGAN
Department of Mechanical Engineering
ME 235 Thermodynamics I / Winter 2014 / Section 002
HW 5 Solutions
Due date: Feb. 14 2014
3.124 A piston cylinder (0.5 kg steel altogether) maintaining a constant pressure has 0.2 kg R -134a as
saturated vapor at 150 kPa. It is heated to 40°C and the steel is at the same temperature as the R -134a at
any time. Find the work and heat transfer for the process.
3.160 A piston/cylinder arrangement of initial volume 0.025 m contains saturated water vapor at 180°C.
The steam now expands in a polytropic process with exponent n = 1 to a final pressure of 200 kPa, while
it does work against the piston. Determine the heat tr ansfer in this process.