In these notes Air leakage and Condenser Performance are discussed.

1. Steam condensers - Part 5
Presentation by:
Avdhesh Tyagi
Asst. Prof.
Department of Mechanical Engineering
G. L. Bajaj Institute of Technology & Management, Greater Noida
Disclaimer: The materials provided in this presentation and any comments or information
provided by the presenter are for educational purposes only. Nothing conveyed or provided
should be considered legal, accounting or tax advice.

2. Name of Subject: Applied Thermodynamics
Subject Code: KME401
Department of Mechanical Engineering
G. L. Bajaj Institute of Technology and Management,
Greater Noida, Uttar Pradesh
College code: 192
Affiliated to Dr. A.P.J. Abdul Kalam Technical University (Formerly UPTU Lucknow).
Unit 3
Topic covered: Steam condensers –
Air leakage and Condenser Performance

3. Air leakage in Steam condenser
Generally, a steam condenser operates at a
pressure lower than atmospheric pressure.
Hence, the leakage of air is practically always
there in condensers.
The presence of air inside a condenser is always
undesirable as it causes many adverse effects on
condenser performance and efforts must be
made to detect the sources of air leakage.

4. Sources of air leakage in Steam
condenser
The main sources of air found in condensers are
given below :
1. Joints of the various parts on condenser
body.
2. Air dissolved in feed water.
3. A little quantity of air dissolved in the
injection water (in Jet condensers).

5. Effects of air leakage in Steam
condenser
Following are the main effects of air leakage in
Steam condensers:
1. Reduced thermal efficiency
2. Increased requirement of cooling water
3. Reduced heat transfer
4. Corrosion

6. Condenser performance parameters
The performance of a steam condenser can be
measured by following two parameters:
1. Vacuum efficiency
It indicates the ability of a steam condenser to
produce vacuum within itself.
2. Condenser efficiency
It indicates the ability of a steam condenser to
raise the temperature of cooling water.

7. Vacuum efficiency
Vacuum efficiency is defined as the ratio of the
actual vacuum to the maximum obtainable
vacuum.
The maximum vacuum is obtained when there is
only steam and no air is present in the
condenser.
Vacuum efficiency =
Actual vacuum
Maximum obtainable vacuum

8. Vacuum efficiency
Let
pb = Barometric pressure
ps = Partial pressure of steam
pa = Partial pressure of air
pc = Absolute condenser pressure = ps + pa
Actual vacuum (pv, act.) = pb − pc = pb − (ps+pa)
Maximum obtainable vacuum (pv, max.) = pb − ps
Hence,
ηvacuum =
(pv, act.)
(pv, max.)
=
pb − (ps+pa)
pb − ps

9. Condenser efficiency
Condenser efficiency is defined as the ratio of Actual rise
in cooling water temperature to the Maximum possible
temperature rise. Mathematically,
Condenser efficiency =
Actual rise in cooling water temperature
Maximum possible temperature rise
Let
ti = Inlet temperature of cooling water
to = Outlet temperature of cooling water
t 𝑠𝑎𝑡 = Saturated temperature corresponding to
condenser pressure

10. Condenser efficiency
Actual rise in cooling water temperature = t 𝑜 − ti
Maximum possible temperature rise = = tsat − ti
η 𝑐𝑜𝑛𝑑𝑒𝑛𝑠𝑒𝑟 =
t 𝑜 − ti
tsat − ti

11. Condenser efficiency
Hence, It may also be defined as the ratio of the
difference between the outlet temperature and
inlet temperature of cooling water to the
difference between the temperature
corresponding to the condenser pressure and
inlet temperature of cooling water.

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