A real (non-Carnot) heat engine, operating between heat reservoirs at temperatures of 650 K and 270 K, performs 4.3 kJ of net work and rejects 8.0 kJ of heat in a single cycle. What is the thermal efficiency of this heat engine?

Respuesta :

Answer:

[tex]n_{thermal-efficiency}=0.6[/tex]

Explanation:

Given data

Temperature T1=270K

Temperature T2=650K

Work=4.3 kJ

Heat rejects=8.0 kJ

To find

Thermal efficiency

Solution

The thermal efficiency is given as:

[tex]n_{thermal-efficiency}=\frac{n^{|}_{real-cycle} }{n^{||}_{Carnot-cycle} }[/tex]

For Carnot cycle efficiency

[tex]n^{||}=1-(T1/T2)\\n^{||}=1-(270K/650K)\\n^{||}=0.584\\[/tex]

For real cycle efficiency

[tex]n^{|}=\frac{4.3}{4.3+8.0}\\n^{|}=0.35\\[/tex]

So the thermal efficiency is:

[tex]n_{thermal-efficiency}=\frac{n^{|}_{real-cycle} }{n^{||}_{Carnot-cycle} }\\n_{thermal-efficiency}=(0.35/0.584)\\ n_{thermal-efficiency}=0.6[/tex]