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Fluid Thermodynamics: Phase Diagrams, Enthalpy, Heat, Compressibility, and Liquid Approx., Schemes and Mind Maps of Thermodynamics

Various thermodynamic concepts related to fluids, including phase diagrams, enthalpy, specific heat, compressibility, and the compressed liquid approximation. Topics include phase determination, energy balance at constant pressure, incompressible flow, and the use of the compressed liquid approximation for estimating properties of compressed liquids.

Typology: Schemes and Mind Maps

2021/2022

Uploaded on 09/27/2022

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We will cover,
Phase Diagrams
Enthalpy
Specific Heat Constant
Incompressible Fluid
Compressed Liquid (subcooled)
Molar Base and Universal Gas Constant
Critical State and Reduced Coordinate
Compressibility
Session-6
pf3
pf4
pf5
pf8
pf9
pfa

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Download Fluid Thermodynamics: Phase Diagrams, Enthalpy, Heat, Compressibility, and Liquid Approx. and more Schemes and Mind Maps Thermodynamics in PDF only on Docsity!

We will cover,

-^

Phase Diagrams

-^

Enthalpy

-^

Specific Heat Constant

-^

Incompressible Fluid

-^

Compressed Liquid (subcooled)

-^

Molar Base and Universal Gas Constant

-^

Critical State and Reduced Coordinate

-^

Compressibility

Session-

Flow Chart

Determine phase of substance

Determine quality

Compressed LiquidDirect look up

Superheated Vapor

Direct look up

Compare with saturation table Interpolate other properties

Two-phase Mixture

energy required to raise the temperature of a system by one degree (at constant pressure orconstant volume).

p

p

v

v

h T

c

u T

c

p c v c

k^

Specific Heat Constants

Specific Heat Ratio

When density is assumed to be constant throughout a process the process is called“incompressible” and the fluid is called “incompressible fluid.”

(^

) 1

2

1

2

1

2

(^21)

(^21)

v

v P

cdT

h

h

cdT

u

u

cdT

du

u T

c

c

c

c

u T

h T

T T

T T

v

v

v

p

v

p

Incompressible Flow

(^

)^

(^

)

,^

Pv

T u

P T h

=

Interpretation of Compressed Liquid Approximation

exact state

approximate state

constant temperature line

P-v

diagram

Constant pressure line

exact state

approximate state T-v

diagram

Compressed Liquid Approximation

-^

However, the compressed liquid approximation for enthalpy isexceptional. It is due to the intrinsic definition of enthalpy beingexplicitly dependent on pressure:

-^

It is incorrect to neglect the pressure variation in enthalpyevaluation. Hence,

Pv

u

h

(^

P

T

Pv

P T u P T h

(^

T

Pv

T

u

f

f^

) (

T

v T

P

T

Pv

T v T P T u

f

sat

f

T h

f

sat

f

f

(^

)^

(^

T v T P P T h f

sat

f^

Two-phase

dome

Superheated

vapor

Comp.liquid

Saturated vapor line

Saturated liquid line

Critical Point

Vapor Liquid

Solid

Sublimation

Vaporization (^) Melting

Critical Point

Critical State and Reduced Coordinate

-^

Recall the phase diagrams of a general substance:

cr

R^

P P

P

reduced pressure:

cr

R^

T T

T^

=

reduced temperature: ,

The critical temperature is the maximum temperature at which liquid and vaporphases can coexist in equilibrium. •^

Base on the thermodynamic properties associated with the critical point, a non-dimensional reduced coordinate can be defined for each substance:

Compressibility Chart

(Taken from Figure 3-56 in Cengel & Turner)

T R

v P

T R

v P

Z

=

CompressibilityFactor:= Ideal Gas:

1

Z Good for:• low pressure• high temperature

critical point

Ideal Gas