文档介绍：Thermal Energy Quiz #2 – Fall 2002
Date: 11/22/02
Do all three problems. All problems count the same.
1. The power plant shown in the figure bines a Brayton cycle and a Rankine
cycle. ponents are ideal, ic energy effects can be neglected and air can
be assumed a perfect gas with cp=1 kJ/kgK.
a) Determine pressor exit temperature T2 .
b) Find the air mass flow rate m& air of the ideal Brayton cycle.
c) Determine the turbine exit temperature T4 .
GT
d) What is power output of the ideal Brayton cycle ?
e) How much heat Q&exchanger is transferred in the heat exchanger?
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f) What is power output of the Rankine cycle ?
g) What is the overall thermal efficiency of bined cycle?
2. The sketch below shows a perfectly insulated container with partments
separated by a non-adiabatic, frictionless piston. partments are at the same
pressure (pA = pB) and contain an equal amount of the same gas (mA = mB). Initially
compartment A is at a higher temperature partment B (TA > TB).
a) Which way, if at all, does the piston move? Indicate by an arrow on a drawing in
your exam book (A sentence or two is expected, perhaps bolstered by some
equations).
b) Is the final internal energy Ufinal of the system (partments together)
lower, equal or higher than the initial internal energy Uinitial