Presented By:

Ameer Hamza DDP-SP13-BEC-10M. Atif Rauf DDP-SP13-BEC-48Hafiz Tariq javid DDP-SP13-BEC-22Fakhar Hayat DDP-SP13-BEC-18

Thermodynamics 2

Comsats institute of information and technology Lahore

Pumps

Pump:

Pump is a mechanical device, pumps increases the mechanical energy of fluid, Increasing its velocity, pressure or elevation.

Positive Displacement pump Centrifugal Pump

Positive Displacement Pump:

PD pumps apply pressure directly to the fluid by reciprocating motion.

Types of PD Pump:

Positive displacement pump

Reciprocating

Apply direct pressure to fluid by reciprocating piston

Contain moveable piston or plunger to displace fluid

Rotary

The chamber moves from inlet to discharge and back to the inlet

Reciprocating pump:

Piston pump Plunger pump Diaphragm Pump

Rotary Pump:

Gear Pump Lobe pump Van Pump Peristalic Pump

Piston Pump:

Discharge pressure up to 50 atm

Application:High pressure purpose

Plunger pumps :Use to produce 1500 atm or more

Mostly motor drivenSingle acting

Diaphragm pumps :Use to produce 100 atm

Application:Corrosive or toxic liquid handling

Mechanical Efficiency of Reciprocating:

For small pumps: 40 to 50 % For large pumps: 70 to 90% Efficiency independent of speed under normal conditions. Decrease slightly with a increase suction pressure

Volume efficiencyThe ratio of the volume of fluid discharge to the volume swept by the piston or plunger is called volumetric efficiency

Gear Pump:

Minimize leakage due to close tolerance between moving and stationary parts

Liquid must be clean, moderately viscous fluids i.e. light lubricating oil

Spur-gear pump Internal-gear pump

Lobe pump:

Vane Pump :

Peristalic Pump:

Use for small flow rates and constant flow rates No air leakage or possibility to air (leakproof)

ApplicationProduction of biomedical, pharmaceuticals etc.

Centrifugal Pump:

Centrifugal force generates high rotational velocities, then convert the resulting K.E of the fluid to pressure energy.

Parts of Centrifugal Pump:

Stationary components

Casing Volute Circular

Seal chamber and stuffing box

Moving Components

Impeller

Shaft

Types of Centrifugal pump:

Multistage centrifugal pump Leak proof centrifugal pump

Canned-rotor pump

Magnetic-derive pump

Multistage Centrifugal Pump:

When a head greater than 200 ft (60 m) is needed, two or more impeller sCan be mounted in series on a single shaft multistage pump is obtained, the Discharge from the first impeller provides suction for the 2nd and second for The 3rd, and so forth.

Leakproof centrifugal pump:

Used for handling dangerous liquids.

Canned-rotor pumpsA canned like stainless steel structure cover the rotor which keep the pumped fluid away from the rotor.

Magnetic-derive pumpImpeller carries magnetic is driven by the magnetic disk on the other side of casing walls.

If the suction pressure is slightly greater than vapor pressure of the liquidSome liquid may flash to vapors inside the pump

It greatly reduces the pump capacity

Causes serve erosion

Cavitation:

Disadvantages:

Selection parameters:

Amount of the fluid

The fluid properties

Head required

Type of the flow

Power supply

Cost compared to efficiency

Pressure developed by the pump :

Depends on, Impeller dia No. of impeller Size of the impeller eye Shaft speed

Size of Pump:depends on,

Head capacity

Key parameters for determining efficiency:Depends on, Flow Head Power

Head:

Head is the height at which a pump can raise water up.

Power requirement:

Power supplied to the pump derive from external source

PB= mWp

Power delivered to the fluid is calculated by mass flow rate and head developed

Pf=mΔH

Pump Priming:

To remove the entrapped air inside the pump is called pump priming

When we do it? First start up after a long time First start up after maintenance First start up for a new pump

How we do it ?

If there is any air entrapped in the suction line, we need to replace this air with liquid.

Air can be displaced by liquid from any tank into the suction line and submerge the pump impeller

Note: Positive displacement pump can compress the gas to a required discharge pressure, that’s why they are known to self priming