3. What is Condenser
A condenser is a heat exchanger that removes heat from a gas
or vapor, converting it into a liquid. It plays a crucial role in
thermal and refrigeration systems by facilitating the phase
change from vapor to liquid.
4. NEED OF CONDENSER
I. In Rankine cycle , to facilitate the constant
pressure heat rejection ,a Condenser is
required to maintain necessary
thermodynamic conditions for the cycle.
II. The condenser enables vacuum pressure
operation, lowering the back pressure at
turbine exit ( say 1.013 to 0.074 bar) thus
increasing specific work output of turbine,
the plant efficiency and reduces steam flow
for given output.
III. Condensate is reused as high-quality feed
water for the steam generator , without any
further treatment.
5. Working Principle of Condenser
•Hot Vapor Enters: The vapor from the system (e.g., steam from
turbines in power plants or refrigerant gas in air conditioners) enters the
condenser.
•Heat Transfer to Cooling Medium: The condenser has a network of
tubes where a cooling medium (air or water) absorbs heat from the
vapor.
•Condensation Occurs: As heat is extracted, the vapor loses energy
and transitions into a liquid state.
•Liquid Collection & Removal: The condensed liquid (water or
refrigerant) is collected and either drained out or recirculated into the
system.
10. In this, the cooling water is sprayed into the steam. Steam by mixing directly with
cold water gets condensed. The exhaust steam from the turbine mixes with the
cooling water to produce saturated water.
12. A barometric condenser is a type of jet condenser where the condenser is placed
at a height of around 10-12 meters (33-40 feet) above the hot well. This height
creates a natural vacuum due to the weight of the water column, eliminating the
need for an external air pump to remove condensate and cooling water.
14. A jet-type condenser, also known as a mixing condenser, is a type of condenser
where the exhaust steam from a turbine or engine directly mixes with the cooling
water. This process results in the immediate condensation of steam into water,
which is then removed by a pump.
16. Surface Condenser
These are shell-and-tube heat exchangers where the two fluids do not come in
direct contact and the heat released by the condensation of steam is transferred
through the walls of the tubes into the cooling water continuously circulating inside
them
17. Generally, the condenser pressure is maintained
below the atmospheric pressure so there is always a
chance of air leakage in condenser. This air affects the
condenser performance in the following way –
1. As the air –water vapor mixture approaches
the cold tube surface, water vapor condenses.
Air , being non-condensable, forms film
around the condensate film and act like a
thermal resistance ( since k value is less). Thus,
the heat transfer is generally reduced.
FACTORS AFFECTING THE
PERFORMANCE OF CONDENSER
18. As the condenser receives a mixture of air and steam, reducing the condenser
vacuum and increasing turbine exhaust pressure which results in less work
output.
{Dalton's law of Partial pressure }
Pt is Total pressure in shell
Pair is Partial pressure of air
Psat,steam is Saturation pressure of steam at that temperature
Note: The rate at which air leaks in the condenser, same has to be continuously
removed from the condenser shell.م
FACTORS AFFECTING THE
PERFORMANCE OF CONDENSER
19. Vacuum Efficiency and
Condenser Efficiency
This two parameters are used to determine the performance of a
Condenser _____________
(i) Vacuum efficiency - It is the ratio of actual vacuum to maximum
obtainable vacuum.
η =
vacuum
Pv,act
Pv,max
=
Patm – (Psteam+Pair)
Patm - Psteam
=
Psteam
Psteam + Pair
(ii) Condenser efficiency - It is the ratio of actual rise in cooling water
temperature to maximum possible temp rise.
η =
cond
ΔTact
ΔTmax
20. • In an ideal situation when the venting system properlyremoves air from
the condenser i.e. zero air leakage , the achievable condencing pressure is
determined by the temperature of cooling water
• The lower the cooling water temperature ,lower will be condenser
pressure ,hence plant efficiency will be more
• Since the naturally available cooling water has a specific range(-20˚C-30˚C)
hence can not varied accroding to our need ,but we can vary the cooling
water flow rate
• For a specific cooling water temperature as the mass flow rate of water
increases the mean temperature difference ( Tm) in the condenser
∆
decreases ,hence decrease in condenser pressure and increase in plant
efficiency
FACTORS AFFECTING THE
PERFORMANCE OF CONDENSER
22. From Energy Balance ,
• Heat lost by steam = Heat gained by cooling water
ms[xhfg + Cp,w(Tsat –Tsubcooled)]= mw.Cp,w(Tco – Tci)
mw =
(Assumption: whole steam is condensed)
FACTORS AFFECTING THE
PERFORMANCE OF CONDENSER
23. References
■ P.K. Nag, Power Plant Engineering, McGraw Hill, 2017
■ Shah, Syed Haider Ali. "EFFECT OF CONDENSER
CONDITIONS ON PERFORMANCE OF A STEAM POWER
PLANT." (2012).
![From Energy Balance ,
• Heat lost by steam = Heat gained by cooling water
ms[xhfg + Cp,w(Tsat –Tsubcooled)]= mw.Cp,w(Tco – Tci)
mw =
(Assumption: whole steam is condensed)
FACTORS AFFECTING THE
PERFORMANCE OF CONDENSER](https://image.slidesharecdn.com/powerplantppt-250625133907-fb427e89/85/POWER_PLANT-BASIC-INTRODUCTIONAND-DISCUSSION-22-320.jpg)
