[ILM] 102C Flashcards

1
Q

condenser coil

A

dissipates heat from the refrigerant

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2
Q

evaporator coil

A

absorbs heat from the warm air passing across it

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3
Q

enthalpy

A

the amount of heat in 1lb of a substance starting from a zero-base point and at a universally accepted temperature

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4
Q

base point for refrigerants

A

-40F

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5
Q

entropy

A

a measure of change in a refrigerant’s molecular activity w/o a change in molecular structure while passing as a vapour through a refrigeration compressor

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6
Q

flow rate

A

the amount of fluid in motion passing a given point per a unit of time

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7
Q

Pascal’s law

A

the internal pressure of a gas remains the same throughout a closed system

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8
Q

static pressure

A

the pressure of a stationary fluid or the pressure perpendicular to the flow direction of a moving fluid

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9
Q

psia =

A

psig + 14.7

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10
Q

Dalton’s Law

A

the total pressure of a mixture of gases is the sum of each individual gas pressure

PT = p1 + p2 + p3 + … + pn

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11
Q

Bernoulli’s Law

A

an increase in fluid flow result in a decrease in the lateral or static pressure applied by that fluid

PT = static pressure + velocity pressure

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12
Q

up 2ft ==
up 1ft ==

A

1psi
0.5psi

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13
Q

Charles’ First Law

A

an increase in the absolute temperature of an ideal gas whose volume is constant will also result in a proportional increase in the pressure of that gas

p1 x T2 = p2 x T1 (Volume Constant)

convert to absolute pressure +14.7

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14
Q

Charles’ Second Law

A

an increase in the absolute temperature of an ideal gas whose pressure is constant will result in a proportional increase in the volume of that gas

V1 x T2 = V2 x T1 (Pressure Constant)

convert to absolute temperature +460

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15
Q

Boyle’s Law

A

p1 x V1 = p2 x V2 (Temperature Constant)

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16
Q

General or Combined Gas Law

A

a combination of the 2 Charles’ Laws and Boyle’s Law

p1V1T2 = p2V2T1

17
Q

The standard in the refrigeration industry for static fluid pressure gain or loss is

A

0.5 psi/foot

18
Q

Fluids that move through tubes and pipes lose pressure because of friction loss. Common factors are

A
  1. Tube length
  2. Tube diameter
  3. Tube internal smoothness
  4. Fitting type & shape
  5. Fluid weight
  6. Fluid viscosity (점성)
19
Q

The long radius elbow has far lower friction losses than the short radius elbow

T or F

A

True

20
Q

Refrigeration is measured by its

A

outer diameter

21
Q

NRE ==

A

Evap outlet enthalpy - TXV outlet enthalpy

h3 - h1

22
Q

HoC ==

A

Comp outlet enthalpy - Comp inlet enthalpy

h5 - h4

23
Q

HoR ==

A

Comp outlet enthalpy - TXV inlet enthalpy

h5 - h1

24
Q

Mass Flow Rate ==

A

m = system capacity/NRE

25
Q

CoP ==

A

NRE/HoC

Higher CoP values result in effective system performance

26
Q

CR ==

A

Saturated Discharge Absolute Pressure / Saturated Suction Absolute Pressure

Lower CR values result in greater system performance

27
Q

Critical Point

A

a refrigerant’s condition where its liquid and vapour forms coexist and cannot change state