Thermodynamics Flashcards

1
Q

Any and all substances can exist in 1 of these 4 states:

A

Solid
Liquid
Gas
Plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

State of matter is determined by what 2 things?

A

Temperature

Pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Matter in a gaseous state has no definitive _____ or _____.

A

Size

Shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

The process when a substance changes from a solid to a vapor.

A

Sublimination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 3 states of water?

A

Solid
Liquid
Gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Some scientist say heat is _____ _____.

A

Molecular motion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Water in its natural state is in the liquid/solid form. By removing heat from a given quantity of water the molecules slow down/speed up and the cohesion and adhesion between the molecules decrease/increase pulling the molecules close together and increasing its density. If enough heat is removed, the water will reach its densest point at 39/49°F.

A

Liquid
Slow down
Increase
39°F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

When heat is added to water at atmospheric pressure, the molecules will decrease/increase in speed.

A

Increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is used to identify heat quantity in the English measuring system?

A

British Thermal Unit (BTU)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The specific heat of any substance is the amount of heat required to lower/raise 1 lb of the substance 1°F at a given temperature and pressure.

A

Raise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

A good conductor has a specific heat capacity of less than _____.

A

1.0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The ability of a substance could get so cold that it’s molecules would cease to move and it could get no colder because there is no lower temperature.

A

Absolute zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 3 ways heat transfer occurs?

A

Radiation
Conduction
Convection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the ability of a substance to conduct heat or the rate of conduction?

A

Thermal conductivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

If adding or removing heat causes a change in the temperature of a material, the heat is called what?

A

Sensible heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When we are changing water to gas (steam) the same conditions exist. In this case we are evaporating or vaporizing the liquid into its vapor or gaseous state. The heat required for this change of state is called what?

A

Latent heat of vaporization

17
Q

Between points C and D, 970 BTU/lb were added and the temperature did not change. This heat was required to change the water to steam. This heat is called _____ _____ _____. When cooling the steam to water, the latent heat removed is called the _____ _____ _____.

A

Latent heat of vaporization

Latent heat of condensation

18
Q

What is a fluid that picks up heat by evaporating at a low temperature and pressure and gives up heat by condensing at a higher temperature and pressure?

A

Refrigerant

19
Q

What do you call the temperature at which refrigerant oil change state from liquid to a vapor or vice versa?

A

Saturation temperature

20
Q

A substance is said to be at its critical point when it is at its critical/non-critical pressure and temperature when at this point the properties of a liquid and vapor are indistinguishable.

A

Critical

21
Q

Steam in its purest form is _____ to the eye.

A

Invisible

22
Q

What are the 2 kinds of steam?

A

Saturated

Superheated

23
Q

It’s temperature or heat content is above that of dry saturated steam at the same pressure.

A

Superheated steam

24
Q

What is the excepted reference temperature for enthalpy?

A

32°F

25
Q

What is the enthalpy of 1 pound of water at 212°F assuming zero enthalpy be at 32°F?

A

Specific heat of water is sp. ht. = 1BTU/lb/°F

Heat to raise temperature of 1 pound of water from 32°F to 212°F = 212-32 = 180°F

H=M x sp. ht. x 🔼T

H=1 x 1 x 180

H=180 BTU (total enthalpy @ 212°F)

26
Q

What component is not on the high side?

A

Metering device

27
Q

What are the 4 basic components of a typical compression refrigeration system?

A

Evaporator
Compressor
Condenser
Metering device

28
Q

The substance flowing around the evaporator tubes (air) is cooler/warmer than the refrigerant flowing through the tubes, so the substance transfers its heat to the refrigerant and leaves the evaporator at a higher/lower temperature than that at which it entered.

A

Warmer

Lower

29
Q

What is a coil of metal tubing that is exposed to air or water?

A

Condenser

30
Q

The absorbed heat comes from the air passing through the _____ fins.

A

Evaporator

31
Q

When the vapor reaches the _____, the condenser coil will be hotter than the outside air being forced through the condenser coil. The result will be a heat transfer from the coil to the outside air. This heat transfer removes the _____ _____ of the refrigerant vapor as it condenses and removes latent heat of condensation.

A

Condenser

Latent heat

32
Q

What is the reverse of evaporation whose purpose is to expel heat absorbed by the refrigerant?

A

Condensation

33
Q

What boils in the evaporator at low temperature as it absorbs heat from the air or from the substance that you want to cool?

A

Refrigerant

34
Q

In condensing, the refrigerant accepts/rejects the heat that it absorbed during boiling. The condensed liquid refrigerant is then metered back to the refrigerated area to absorb/dissolve more heat by boiling again.

A

Rejects

Absorbs