Carnot Engine Problem

Lliño Del Rosario

@llino-f7euoM • Oct 26, 2024

Oct 26, 2024

1.8K

QUESTION
A Carnot Engine operating between 900 Fahrenheit and 90 Fahrenheit produces 40,000 ft-lb of work. Determine (a) the heat supplied, (b) the change in entropy during heat rejection and (c) the thermal efficiency of engine. (answers should be in BTU)

MY ATTEMPT
(a) 22.74 BTU
(c) 60%

Am i leading to correct answers

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yadavundertaker mohit

@yadavundertaker-0p3HBs • Oct 10, 2009

LindellQUESTION
A Carnot Engine operating between 900 Fahrenheit and 90 Fahrenheit produces 40,000 ft-lb of work. Determine (a) the heat supplied, (b) the change in entropy during heat rejection and (c) the thermal efficiency of engine. (answers should be in BTU)

MY ATTEMPT
(a) 22.74 BTU
(c) 60%

Am i leading to correct answers

I don't know in BTU but i atleast can try it

T1=900 F
T2=90F
W=40,000 ft-lb

n=(T1-T2)/T1

(900-90)/900

=98.88%

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antenna

@antenna-3JkwKK • Oct 10, 2009

Yadavundertaker, youhave use that formula(1-t1/t2) with t in kelvin.
Use that,you would get the right ans.Any way the efficiency of a heat engine can reach 60% to 65% at max.

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Lliño Del Rosario

@llino-f7euoM • Oct 11, 2009

1 ft-lb = 9.478* 10^-4 BTU

(a) 22.74 BTU
W=N QH
=.60(40000 ft-lb * (9.478* 10^-4 BTU / 1 ft-lb)
= 22.74 BTU

am i correct?

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raj87verma88

@raj87verma88-ZpL2Wn • Oct 11, 2009

T1 = 755.222 K
T2 = 305.222 K

1) Heat Supplied Qc = nRT1 ln(Vb/Va)
ab is the initial Isothermal path.

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