Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
15 Cards in this Set
- Front
- Back
- 3rd side (hint)
|
How is Compression Ratio determined?
|
Can be caculated by dividing the absolute discharge (condenser) pressure by the absolute suction (evaporator) pressure.
|
|
|
|
What is Net Refrigeration Effect (NRE)?
|
Is the difference in enthalpy (heat content in btu/Lb) of the refrigerant that enters the evaporator and the refrigerant that enters the compressor. It is the cooling effect received from evaporating one pound of refrigerant at the observed conditions.
|
|
|
|
How is Refrigerant Flow Rate used and how is it calculated?
|
Is the amount of flow (Lb/Min) required to satisfy the system load conditions. It can be calculated by dividing the system tonnage by the NRE.
|
|
|
|
How is Compressor Horsepower determined?
|
A Vapor compression systems horsepower per ton requirements vary depending upon system operating conditions. The Hp/Ton ratio can be caculated by multiplying the heat of compression, times the flow rate, times .02357 Btu/Hp/Min.
|
|
|
|
How is Coefficient of Performance (COP) used?
|
It is the ratio of the useful refrigerating effect compared to the energy expended in compressing the refrigerant. COP bears a fixed relationship to Hp/Ton. It can be calculated by dividing the system's NRE by the heat of compression.
|
|
|
|
In reference to the Pressure-Enthalpy Diagrams, How are pressures stated?
|
Pressures are stated in PSIA,
Once condensing and evaporating pressures are known, saturation temperatures for each can be read from the diagram. |
|
|
|
Describe Compression Displacement:
|
It is the volume of suction gas (cubic Ft./Min) that must be pumped by the system's compressor. It can be calculated by multiplying the specific volume (cubic Ft./Lb) of the suction vapor as it enters the compressor, by the system flow rate (Lbs/Min).
|
|
|
|
Heat rejected in the condenser is described as:
|
The refrigerant's enthalpy difference as it passes through the condenser.
|
|
|
|
[Conversion of Units]
1 Btu/Min = _____ Hp |
1 Btu/Min = .02357 Hp
|
|
|
|
[Conversion of Units]
1 Hp = _____ Btu/Min. |
1 Hp = 42.44 Btu/Min.
|
|
|
|
[Conversion of Units]
1 Ton = _____ Btu/Hr. |
1 Ton = 12,000 Btu/Hr.
|
|
|
|
[Conversion of Units]
1 Ton = _____ Btu/Min. |
1 Ton = 200 Btu/Min.
|
|
|
|
[Conversion of Units]
1 Ton = _____ Hp. |
1 Ton = 4.716 Hp.
|
|
|
|
[Conversion of Units]
COP = _____ Divided by _________. |
COP = NRE Divided by Heat of Compression.
|
|
|
|
[Conversion of Units]
Hp/Ton = _____ Div. By _____. |
Hp/Ton = 4.716 Div. By COP.
|
Hp/Ton = Heat of Comp (Btu/Lb) x Flow Rate (Lbs/Min) x .02357 (Hp/Btu/Min)
|
