Carnot Engine Problem

Replies

• 

  yadavundertaker mohit

  Lindell

  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

  
  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%
• 

  antenna

  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.
• 

  Lliño Del Rosario

  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?
• 

  raj87verma88

  T1 = 755.222 K
  T2 = 305.222 K
  
  1) Heat Supplied Qc = nRT1 ln(Vb/Va)
  ab is the initial Isothermal path.