NOTES BY AAFTAB M 9619468502 SUB: TEN 1

CHAPTER 5: STEAM CONDENSERS

CHAPTER NO.5

STEAM CONDENSER

SUB: TEN

NOTES BY: AAFTAB A.Z.M

MOB.: 9619468502

Email I.d: aaftab.mukadam21@gmail.com

NOTES BY AAFTAB M 9619468502 SUB: TEN 2

CHAPTER 5: STEAM CONDENSERS

STEAM CONDENSERS

Q. Define condenser and write Classification of steam condensers:

Condenser:

It is a device which maintains pressure below atmospheric pressure by rejecting heat.

Classification of steam condensers

A) Jet condenser/contact type condenser

a) Parallel flow condenser

b) Counter flow condenser

c) High level condenser

d) Ejector condenser

B) Surface condenser/non contact type

a) Down flow surface condenser

b) Central flow surface condenser

c) Regenerative surface condenser

d) Evaporative surface condenser

e) Double pass surface condenser or shell and tube type

Q. What are Sources of Air- leakage in condenser?

Sources of Air- leakage in condenser:

1) Air leakage from the joints of parts

2) Air comes with steam from boiler

3) Air comes with cooling water.

Q. Define: Condenser efficiency:

It is defined as the ratio of difference between the outlet and inlet temperature of cooling water

to maximum rise in cooling water temperature.

Condenser efficiency= 𝐀𝐜𝐭𝐮𝐚𝐥 𝐫𝐢𝐬𝐞 𝐢𝐧 𝐜𝐨𝐨𝐥𝐢𝐧𝐠 𝐰𝐚𝐭𝐞𝐫 𝐭𝐞𝐦𝐩𝐞𝐫𝐚𝐭𝐮𝐫𝐞

𝐌𝐚𝐱𝐢𝐦𝐮𝐦 𝐫𝐢𝐬𝐞 𝐢𝐧 𝐜𝐨𝐨𝐥𝐢𝐧𝐠 𝐰𝐚𝐭𝐞𝐫 𝐭𝐞𝐦𝐩𝐞𝐫𝐚𝐭𝐮𝐫𝐞

Max rise = (saturation temperature corresponding to condenser pressure) – (inlet temp.)

Q. Define : Vacuum efficiency: It is defined as the ratio of actual vacuum to the ideal

vacuum.

NOTES BY AAFTAB M 9619468502 SUB: TEN 3

CHAPTER 5: STEAM CONDENSERS

Q. What is Regenerative type condenser?

Regenerative type condenser:

1. When the condenser has provision or arrangement to reheat the condensed steam it is

known as regenerative type heat condenser.

2. This is down by passing the condensate through the exhaust steam from the prime mover

(turbine) to increase the condensate temperature before it is fed to the boiler.

Q. Write functions of Cooling Tower and classify them

Function is to cool hot water from condenser by exposing it to the atmospheric air, so that the

cold water may be used again by circulation.

1. Natural draught towers :

(a) Natural draught spray filled towers:-

The air enters through the lower sides & flows across the unit in a transverse direction.

The capacity varies from 50 to 100 lit/ min/m2 of base area depending upon the air velocity.

NOTES BY AAFTAB M 9619468502 SUB: TEN 4

CHAPTER 5: STEAM CONDENSERS

(b) Natural draught packed type towers: Similar to above except that water distributing toughs or fills are used which helps to break the

water into small droplets .

(c) Hyperbolic cooling tower :

It is ferro concrete structure & filled 10 m above the ground level.

NOTES BY AAFTAB M 9619468502 SUB: TEN 5

CHAPTER 5: STEAM CONDENSERS

2. Mechanical draft towers

(a) Forced draught towers: The fan is located at the base & air is blown by the fan up through

the descending water.

(b) Induced draught towers: The fan is located at the top of the tower.

NOTES BY AAFTAB M 9619468502 SUB: TEN 6

CHAPTER 5: STEAM CONDENSERS

Q. State Daltons law of Partial pressures:

This law states that “The total pressure exerted by a mixture of air and water vapour on the

walls of container is the sum of partial pressure exerted by air separated and that exerted by

vapour separately at common temperature of the condenser”.

P = Pa + Ps

Where,

Pa= partial pressure exhausted by air

Ps = partial pressure exhausted by vapour

P = total pressure of mixture at temperature

NOTES BY AAFTAB M 9619468502 SUB: TEN 7

CHAPTER 5: STEAM CONDENSERS

Q. Explain Surface condenser:

1) In surface condenser cooling wat4er and an exhaust steam do not come in direct contact

with each other.

2) They are essentially shell and tube condenser consisting of steel shell with water boxes on

each side. Water flows for two passes.

3) At the end there are tube sheets into which water tubes are rolled to prevent leakage of

water into steam.

Vertical plates are provided to support to the long tubes and prevent tube vibration. Hot well

acts as reservoir of condensate.

Q.Give the Classification of surface condenser:

i. Down flow type

ii. Center flow type

iii. Inverted flow type

iv. Regenerative type

v. Evaporative type

NOTES BY AAFTAB M 9619468502 SUB: TEN 8

CHAPTER 5: STEAM CONDENSERS

1., Down flow type

2. Center flow type

NOTES BY AAFTAB M 9619468502 SUB: TEN 9

CHAPTER 5: STEAM CONDENSERS

3.Evaporative

type

Q. Write continuity equation of steam nozzle.

The Law of Conservation of Mass states that mass can be neither created nor destroyed. Using the Mass

Conservation Law on a steady flow process - flow where the flow rate do not change over time - through

NOTES BY AAFTAB M 9619468502 SUB: TEN 10

CHAPTER 5: STEAM CONDENSERS

a control volume where the stored mass in the control volume do not change - implements that-inflow

equals outflow. This statement is called the Equation of Continuity.

Q. Function of Heat exchanger-

1. A heat exchanger is a device, which transfers thermal energy between two fluids at

different temperatures.

2. In most of the thermal engineering applications, both of the fluids are in motion and main

mode of heat transfer is convection.

3. Examples are automobile radiators, condenser coil in refrigerator, air conditioner, solar

water heater, chemical industries, domestic boilers, oil coolers in heat engine, milk chillers in

pasteurizing plant.

Q. Explain the working of shell and tube type heat exchanger with neat sketch.

Shell and tube heat exchanger:

1. Shell and tube heat exchanger consists of large number of tubes having parallel

arrangement inside the shell.

2. The ends of the tube on both sides are connected to a plate called as tube sheet. The whole

assembly is called bundle of tubes.

3. The shell should be a house of all the tubes and it should be leakage free. It is closed on

both sides.

4. The one fluid flow inside the tube it is called as tube side fluid and the other one

which flows outside the tube known as shell side fluid.

NOTES BY AAFTAB M 9619468502 SUB: TEN 11

CHAPTER 5: STEAM CONDENSERS

5. The transfer of heat takes place between the two fluids through the medium of tube

surfaces.

6. Naturally heat flow takes place from hot fluid to the cold fluid. The arrangement of inlet

and outlet for hot and cold fluid is shown in figure

Q. Define:

Mach number :

It is defined as velocity at point in a fluid to velocity of sound at that point at a given instant

of time.

M = 1 Sonic flow

M > 1 Supersonic flow

M< 1 Subsonic flow

Critical pressure – the pressure at throat in nozzle is known as critical pressure.

NOTES BY AAFTAB M 9619468502 SUB: TEN 12

CHAPTER 5: STEAM CONDENSERS

Q. Difference between:

Natural draught cooling Tower Forced draught cooling Tower

1. Circulation of ir is provided by

inside pressure difference in tower.

2. Cooling capacity is less.

3. Operating cost is less.

4. Less Maintenace

5. size is large and

1. Fan is used for air circulation.

2. Cooling capacity is more.

3. Operating cost is more

4. More maintenance

5. size is small.