Mechanical Engineering Exam  >  Mechanical Engineering Questions  >   For steam at P = 10 bar, hf = 762 kJ/kg and ... Start Learning for Free
For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will be
  • a)
    0.85
  • b)
    0.8
  • c)
    0.75
  • d)
    0.7
Correct answer is option 'C'. Can you explain this answer?
Most Upvoted Answer
For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 ...
Given:
Pressure of steam (P) = 10 bar
Enthalpy of steam (hf) = 762 kJ/kg
Enthalpy of steam (hg) = 2778 kJ/kg
Heat lost at constant pressure (Q) = 100 kJ/kg
Dryness fraction (x) = 0.8

To find:
Final dryness fraction of steam

Solution:
1. Determine the initial enthalpy (hi) using the dryness fraction and enthalpy values:
hi = hf + x * (hg - hf)
= 762 + 0.8 * (2778 - 762)
= 1974.8 kJ/kg

2. Calculate the final enthalpy (hf) by subtracting the heat lost from the initial enthalpy:
hf = hi - Q
= 1974.8 - 100
= 1874.8 kJ/kg

3. Determine the final dryness fraction (xf) using the enthalpy values:
xf = (hf - hf) / (hg - hf)
= (1874.8 - 762) / (2778 - 762)
= 1112.8 / 2016
= 0.552

Since the final dryness fraction (xf) is less than 1, it indicates that the steam is not fully dry. However, the question asks for the final dryness fraction, which is the opposite of the given value. Therefore, we need to find (1 - xf) to get the final dryness fraction.

4. Calculate the final dryness fraction:
Final dryness fraction = 1 - xf
= 1 - 0.552
= 0.448

The correct answer is option 'C' - 0.75 (rounded to two decimal places).

In summary:
- Initial enthalpy (hi) = 1974.8 kJ/kg
- Final enthalpy (hf) = 1874.8 kJ/kg
- Final dryness fraction = 0.75
Free Test
Community Answer
For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 ...
Steam at state 1
P = 10 bar; hf = 762 kJ/kg
hg = 2778 kJ/kg
x1 = 0.8
Steam at state 2
P = 10 bar
hfg = 2778 - 762 = 2016 kJ/kg
Enthalpy of mixture h1 = hf + x1hfg ......... (1)
Enthalpy of mixture at state 2
h2 = hf + X2 hfg ....... (2)
And h2 - h1 = 100 kJ
Doing (2) — (1)
⇒ 100 = hfg(x1 — x2)
X1 - x2 = 100/2016 = 0.0496
⇒ x2 = 0.8 - 0.0496 = 0.75
Attention Mechanical Engineering Students!
To make sure you are not studying endlessly, EduRev has designed Mechanical Engineering study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Mechanical Engineering.
Explore Courses for Mechanical Engineering exam

Top Courses for Mechanical Engineering

For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer?
Question Description
For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer? for Mechanical Engineering 2024 is part of Mechanical Engineering preparation. The Question and answers have been prepared according to the Mechanical Engineering exam syllabus. Information about For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Mechanical Engineering 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer?.
Solutions for For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer? in English & in Hindi are available as part of our courses for Mechanical Engineering. Download more important topics, notes, lectures and mock test series for Mechanical Engineering Exam by signing up for free.
Here you can find the meaning of For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer?, a detailed solution for For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer? has been provided alongside types of For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice For steam at P = 10 bar, hf = 762 kJ/kg and hg = 2778 kJ/kg when 100 kJ/kg heat is lost at constant pressure from steam at 10 bar and 0.8 dryness. The final dryness fraction will bea)0.85b)0.8c)0.75d)0.7Correct answer is option 'C'. Can you explain this answer? tests, examples and also practice Mechanical Engineering tests.
Explore Courses for Mechanical Engineering exam

Top Courses for Mechanical Engineering

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev