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Thermodynamics > chapter 3 and 4 > Flashcards

chapter 3 and 4 Flashcards

1
Q

Phase

A

Matter which is homogeneous throughout in both its chemical and physical structure. ex- air = single phase
water with ice = 2 phase

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2
Q

Homogeneous

A

Matter is all the same state, solid, liquid, or gas

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3
Q

Pure Substance

A

A substance that is uniform and invariable in chemical composition. ex- helium, water and ice

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4
Q

liquid to gas

A

Vaporization

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5
Q

gas to liquid

A

Condensation

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6
Q

solid to liquid

A

Melting (fusion)

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7
Q

liquid to solid

A

freezing

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8
Q

solid to gas

A

sublimation

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9
Q

gas to solid

A

deposition

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10
Q

Phase Rule

A 
f=c-p+2
f= degrees of freedom
c=number of components
p=number of phases
 at equilibrium for a system of any composition.
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11
Q

The ______ state of a closed system at equilibrium is its condition as described by the values of its intensive thermodynamic properties.

A

intensive

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12
Q

For a simple compressible system, specifying any _____ independent intensive thermodynamic properties will fix the other intensive thermodynamics properties of the system.

A

2

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13
Q

Examples of intensive properties

A

(Doesn’t depend on amount of matter or size)

Pressure, Temperature, Density, Specific Volume, Internal Energy, Enthalpy, Entropy.

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14
Q

saturation temperature

A

temp at which a phase change happens for a specific pressure

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15
Q

True or false. Within two-phase regions, pressure and temperature ARE independent.

A

False

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16
Q

Critical point

A

the point where saturated liquid and saturated vapor lines meet

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17
Q

isotherms

A

line of constant temperature

High left to low right on p-v

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18
Q

isobar

A

line of constant pressure

low left to high right t-v

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19
Q

true of false. while in dome if p-v or t-v diagram temp and pressure remain constant from specific volume changes

A

true

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20
Q

compressed liquid

A

a liquid with a temp lower than saturation temp for

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21
Q

quality (x) equation

A

percent of mixture that is vapor

x=mvapor/(mliquid+mvapor)

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22
Q

superheated vapor

A

when temp is higher than the sat temp for corresponding pressure

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23
Q

total volume saturated liquid formula

A

V=vf+x(vg-vf)

vf=liquid vg=vapor

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24
Q

specific enthalpy (h)

A

h=u+pv

enthalpy= internal energy + work due to expansion

25
Q

linear interpolation

A

vactual= v@ref1 +[(v@ref2 - v@ref1)/(ref2-ref1)] (actual-ref1)

26
Q

Extensive form of internal energy and enthalpy

A

U and H (uppercase is important)

27
Q

Intensive form of internal energy and enthalpy

A

u and h (lowercase is important)

28
Q

Constant volume process equation

A

u2-u1=cv(T2-T1)

29
Q

Constant pressure process equation

A

h2-h1=cp(T2-T1)

30
Q

specific heat ratio

A

k=cp/cv

31
Q

True of False. For a liquid, there is little change in v,u,h,and s at different Temperatures and fixed Pressure.

A

False

there is little change at different Pressures and fixed temperature.

32
Q

incompressible substance

A

any substance whose properties do not change with pressure, or have very minor changes.

33
Q

generalized compressibility only applies to _____

A

gases

34
Q

what does a horizontal line above a variable mean

A

molar unit.

unit times molar weight (g/mol)

35
Q

what does it mean when z=1

A

ideal gas
P is much less than Pc
T is much greater than Tc

36
Q

pressure and temp reduced equations

A

Pr=P/Pc Pc=critical pressure

Tr=T/Tc Tc=critical temp

37
Q

ideal gas equation (3 forms)

A

pv=RT (lowercase v is important)
pV=mRT m=mass
pV=nRT (with line above R) n=number of moles

38
Q

if a gas behaves as an ideal gas, then its specific internal energy and specific enthalpy, depends only on _____

A

temperature

39
Q

polytropic process formula and process for N=1,0,and k

A

pv^N=constant or pV^N=constant
N=1 - isothermal pv=Constant
N=0 isobaric process p=Constant
N=k adiabatic process Q=0

40
Q

Mass rate balance

A

the rate at which mass accumulates in the control volume is the difference between mass flow in and flow out

41
Q

Energy rate balance

A

the rate at which energy accumulates. the difference between heat flow rate in and power out AND difference between mass carries energy into and out of control volume

42
Q

1st law of thermodynamics for open system

A

rate of energy accumulation= Qdot - Wdot +mdot-i (ei) - mdot-e (ee)

43
Q

Flow work

A

work done BY the flow (Wdot)

44
Q

control volume work

A

work done BY the control volume (Wdot-cv) integral of pdv

ex - work done by turning a shaft or electricity

45
Q

work done ON system by mass entering

A

negative

46
Q

work done On environment as mass exits

A

positive

47
Q

steady state Qdot=0 if

IMPORTANT

A

small surface area
system is insulated
small time interacting with system and environment

48
Q

steady state Wdot=0 if

IMPORTANT

A

no change in system volume (fixed container)

no turbines/pumps or electrical devices

49
Q

steady state gz=0 if

IMPORTANT

A

no significant change in elevation from inlet and outlet

50
Q

vi^2-ve^2=0 if

IMPORTANT

A

inlet and outlet are the same size

51
Q

Nozzle

A

passage where velocity increases in direction of flow
Ve greater than Vi
Pe less than Pi
Enters wide end exits narrow end

52
Q

diffuser

A

passage where velocity decreases in direction of flow
Ve less than Vi
Pe greater than Pi
enters narrow end, exits wide end

53
Q

Turbine

A

a device in which –power is developed– as a result of a gas or liquid passing through a set of blades attached to a shaft free to rotate.

54
Q

compressors and pumps

A

devices in which –work is done on the substance– flowing through them to change the state of the substance, typically to –increase the pressure and/or elevation–

55
Q

difference between compressor and pump

A

compressor- uses gas

pump - uses liquid

56
Q

Heat exchanger

Direct contact

A

a mixing chamber in which hot and cold streams are –mixed directly–
ex- water faucet

57
Q

heat exchanger

tube-within-a-tube counterflow

A

a gas or liquid steam is –separated– from another gas or liquid by a wall through which energy is conducted. heat transfer occurs from the hot stream to the cold stream as the streams flow in opposite directions.
ex- radiator

58
Q

specific heat (c) definition

A

The heat required to raise the temperature of a unit mass of a substance by a certain amount. (usually 1 degree)

Thermodynamics (2 decks)

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