A heat engine with 29.0% efficiency produces 3.05 10 4 W of power while exhausti
ID: 1410332 • Letter: A
Question
A heat engine with 29.0% efficiency produces 3.05 104 W of power while exhausting 1.50 104 J to the cold reservoir during each cycle.
(a) How much energy does the engine absorb from the hot reservoir during each cycle?
kJ
(b) How long does each cycle take?
s
The figure below illustrates the cycle ABCA for a 2.10-mol sample of an ideal diatomic gas, where the process CA is a reversible isothermal expansion.
In 1816, Robert Stirling, a Scottish minister, patented an engine now known as the Stirling engine. The Stirling engine follows a four-process cycle: two isothermal processes and two constant-volume processes as shown in the figure below. The working substance used in the Stirling engine never leaves the engine. There are no exhaust valves and no internal combustion; instead, the Stirling engine uses an external hot reservoir. Thus, the Stirling engine is very quiet and is used in applications where a quiet engine is important, such as on submarines. Today, the engine is being developed for a wider range of applications.
Explanation / Answer
formula for effeiciency,
e = W/Q_H
e = QH- QC/ QH
e = 1- QC/QH
QC/QH = 1-e
QH = QC/ 1-e
=1.5 * 10^4 J/ 1- 0.29
=2.11 * 10^4 J
(b)
P = W/t
P = QH - QC/ t
t = QH- QC/ P
= 2.11 * 10^4 - 1.5 * 10^4 J/3.05 * 10^4 J
=0.2 s
As per guide lines I worked first problem , please post remaining posts again