In Rankine cycle there is a concept of Tm(mean temp of heat
addition)For calculating the efficiency of the cycle we
generally use
n=1-T2/T1
again Tm taking into consideration we get
n=1-T2/Tm
as T1>Tm so he efficiency will be different for same cycle.
Can anybody explain how is it possible?
advance appriciation for your effort
Answers were Sorted based on User's Feedback
Answer / balajee
in the rankine cycle
t1 is greater and t2 will be lesser in temperature.
therefore the mean temp tm will be less then t1 and greater
than t2.
hence the efficiency will be differ
Is This Answer Correct ? | 5 Yes | 1 No |
Answer / ab_ina7
sorry i didn't get your question...i think (1-t2/t1) is used for reversible cycle like carnot cycle...for rankine cycle
(h1-h2)/(h1-hf4) is used....
Is This Answer Correct ? | 2 Yes | 1 No |
Answer / palash
thanks for the reply Balajee.Yes the efficiency will differ in he two calculations.
But my question was how can there be different efficiency for a same cycle?
Can you help?
Is This Answer Correct ? | 0 Yes | 0 No |
Answer / shubham
n(carnot)=1-t2/t1 which is an ideal cycle.and n(carnot)is grater than n(rankine)both being in ideal condition.so in question u have used a wrong formula for n(rankine)-1 equat.u cannot use this for rankine cycle.
Is This Answer Correct ? | 0 Yes | 0 No |
Answer / hisham tariq
eff=1-(T2/T1)---------CARNOT EFFICIENCY (IDEAL CYCLE)
eff=1-(T2/TM)-------------RANKINE CYCLE EFFICIENCY
CARNOT EFF > RANKINE EFF
If you know the rankine cycle and molliers diagram there you will find turbine entry temperature (T1) and economizer entry temperaure (T4). TM is the mean of both values.
PS: eff of rankine cysle can also be calculated by
(h1-h4)/(h2-h3)
Since, h=U+PV and U=TS -PV .So h=TS ,if you plug this guy in above formula with T replaced by Tm yoy gonna get same eff
Is This Answer Correct ? | 0 Yes | 0 No |
Answer / palash dolai
I understand the difference now.All have explained in nicely.
I thought both formula can be used for same cycle.
Is This Answer Correct ? | 0 Yes | 0 No |
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