Use app×
Join Bloom Tuition
One on One Online Tuition
JEE MAIN 2025 Foundation Course
NEET 2025 Foundation Course
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
307 views
in Physics by (47.1k points)
closed by

A vapour, in a certain process, while condensing at 400°C, transfers heat to water at 200°C. The resulting steam is used in a power cycle which rejects heat at 30°C. 

What is the fraction of the available energy in the heat transferred from the process vapour at 400°C that is lost due to the irreversible heat transfer at 200°C ?

1 Answer

+1 vote
by (41.5k points)
selected by
 
Best answer

Temperature of vapour, T1 = 400 + 273 = 673 K 

Temperature of water, T2 = 200 + 273 = 473 K 

Temperature at which heat is rejected, T0 = 30 + 273 = 303 K. 

LMNP  would have been the power cycle, if there was no temperature difference between the vapour condensing and the vapour evaporating, and the area under NP would have been the unavailable energy. RTWP is the power cycle when the vapour condenses at 400°C and the water evaporates at 200°C. The unavailable energy becomes the area under PW. Therefore, the increase in unavailable energy due to irreversible heat transfer is represented by the area under NW.

Now, Q1 = T1∆s = T1′∆s′

\(\cfrac{∆s'}{∆s}\) = \(\cfrac{T_1}{T_1'}\)

W = Work done in cycle LMNP 

= (T1 – T0) ∆s ...per unit mass 

W′ = Work done in cycle RTWP 

= (T1 – T0) ∆s′ ...per unit mass 

The fraction of energy that becomes unavailable due to irreversible heat transfer

Hence the fraction of energy that becomes unavailable = 0.346 or 34.6%.

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...