Two Phase Flows(28082)

By: Prof. M. H. Saidi

Center of Excellence in Energy ConversionSchool of Mechanical EngineeringSharif University of Technology

Outline of Course

v Introduction, Fundamental concepts and definitionvPrinciple Model of Two phase Flow (Method of Analysis)vExperimental Model of Two phase FlowvPool BoilingvHeat Transfer in Sub cooled BoilingvVoid Fraction and Pressure LostvHeat Transfer in Saturated Boiling

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Example of Multiphase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

12

3

4

5 1. Liquid- Solid Two Phase Flow

2. Gas- Liquid Two Phase Flow

3. Liquid- Liquid Two Phase Flow

4. Gas- Solid Two phase Flow

5. Three- Phase Flow

Multiphase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Multiphase Flow

Example of Multiphase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Gas- Solid

Nature Sand Storm . Volcano . Avalanche

Living Body Aerosol

IndustriesPneumatic Conveying. Dust Collector. Fluidized BedSolid Propellant Rocket. Spray Drying. Spray Casting

Solid- Liquid

NatureMotion Of Sand In Rivers And Sea. Mud Flow Debris Flow. Ice Berge

Living Body Blood Flow

IndustriesSlurry Transport. Flotation Fluidized Bed. Water Jet Cutting

Liquid- GasNature Rain. Mist

Industries Nuclear reactor. Boiler

Liquid- Liquid Industries Emulsion

Three Phase Flow Industries Airlift Pump

Natural Application of Gas- Solid Two Phase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Industrial Application of Gas- Solid Two Phase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Application of Gas- Solid Two Phase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Application of Solid- Liquid Two Phase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Industrial Application of Solid- Liquid Two Phase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Industrial Application of Three Phase Flow

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

IntroductionvMultiphase flow occurs in many industrial processes

– Petroleum, power and manufacturing processes (food, drug)vMajor goal of this course is to provide a basic working

knowledge of multiphase flow and where to learn morevExpected outcomes for this course:

– Ability to develop a conceptual picture of multiphase flow– Familiarity with definitions and nomenclature – Familiarity with basic balances and correlations – Understand when to use more complex approaches– Recommendations are made for particular situations

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Method Of Two Phase Flow Analysis

• Homogeneous Model (HM)equal velocity, pressure, temperature• Separated Model (SM)non-equal velocities => emp. correlation• Flow Pattern Model (FPM)non-equal velocity and temperature

– Balance equations for each fluid and interface coupling relations describing interfacial momentum and heat transfer

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Definition

Multiphase Flow Research GroupSchool of Mechanical Engineering IntroductionA

AAA fg =−= )1(, αα

Void Fraction for Gas- Liquid Two

Phase Flow

Definition

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

, (1 )g f

g f g f

W Wx xW W W W

= − =+ +

Mass Quality

W uG uA

ρυ

= = =

Mass velocity

, (1 )g fW GAx W GA x= = −

,g fg f

g g f f

W Wu uA Aρ ρ

= = ,g fg f

g f

Q Qu uA A

= =

(1 ),(1 )g f

g f

Gx G xu uρ α ρ α

−= =

−

Definitions

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

, (1 )g f

g f g f

Q QQ Q Q Q

β β= − =+ +

, ,g fg f

Q QQj j jA A A

= = =

(1 ), (1 ) (1 )g g f fg f

Gx G xj u j j u jα β α βρ ρ

−= = = = − = − =

, (1 ) ,g g g f f f g fG J Gx G j G x G G Gρ ρ= = = = − = +

1( )( )( )1

g f f g f

f g g f g

u A W xu A W x

ρ ρ αρ ρ α

−= =

−

Volumetric Quality

Superficial Velocity

Slip Ratio

Measurement Classification

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

PrincipalMeasuredQuantity

METHOD

1. Opticalattenuation reflection/refraction interference diffractionimage sensor PIV LDV

Particle velocity

Particle density

Particle flow rate

Fluid velocity

Particle size

Flow Structure

2. Mechanicalpressure resistance/impact rotation weight

3. Electrical Resistance charging capacitance

4. Radiation Attenuation tracer tracking

5. Acoustic ultra-sonic noise

6. Thermal hot wire (film) thermal response

7. Electrochemical

electrolyte

8. Other Microwave MRI

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction

Multiphase Flow Research GroupSchool of Mechanical Engineering Introduction