Question

A heat engine receives 5 kW of heat from a source at 800 K and 10 kW from another at 1000 K, while rejecting heat to a reservoir at 600 K. If the process can be assumed to be reversible, Determine the power output from the engine. ​

Answer 1

Solution:-

C.V. The heat engine, this is in steady state

To find:-

Energy Eq...

➸0 = Q¹ + Q² - QL - W

Entropy Eq...

$➸0 = \frac{Q1}{T1} + \frac{Q2}{T2} - \frac{QL}{TL} + 0$

Now solve for QL from

the entropy equation

$➸QL = \frac{TL}{T1} Q1 + \frac{TL}{T2} Q2$

Substitute into the energy equation

and solve for the work team

$➸W = Q1 + Q2 - QL$

$= 5 + 10 - 9.75 = 5.25kW$

For a low temperature of 298 K

we can get

$➸QL2 = \frac{298}{600} QL = 4.843kW$

$➸W = Q1 + Q2 - QL$

$= 5 + 10 - 4.843 = 10.16kW$