Chapter - 113,114,115 Flashcards
What is the saturation temperature of water and what is the atmospheric temperature?
100*C
101.325 kPa
In a closed vessel, the boiling point of water and the condensing point of its vapour can be raised by…
Increasing the pressure in the vessel, and also lowered by decreasing the pressure
Definition of: Sensible heat
The heat removed from the substance
Definition of: Latent heat
The heat absorbed by the refrigerant
What is 1 degree Celsius equal to in Fahrenheit?
1.8 degrees Fahrenheit
Definition of: Capacity of a Refrigeration System
Capacity of any Refrigeration system is the rate at which it will remove heat from the refrigerated medium.
Which system of measurement is Fahrenheit, Tons, Btu, and pounds (lbs)?
Which system of measurement is Celsius, Joules, Kilojoules, Kilowatts, Tonnes, and Kilograms?
- Imperial
- Metric
A metric tonne of refrigeration is approximately _____ greater than an imperial ton of refrigeration.
- 30%
- 15%
- 85%
- 10%
10%
The rate at which a system will remove heat from the refrigerated medium is defined as
Net Refrigeration Effect
Definition of: Coefficient of Performance (COP)
Is the ratio of heat absorbed from the refrigerated medium by the evaporator to the amount of energy used to drive the compressor.
Definition of: Compression Ratio
Is the clearance volume plus the piston displacement divided by the clearance volume.
Name and describe the groups of refrigerants
Groups A1, A2, A3 are non-toxic but flammable
Groups B1, B2, are highly-toxic but nonflammable
Group B3 is highly-toxic and highly flammable
Thermodynamic properties of refrigerants are…
The properties that directly affect the movement of heat
EXAM QUESTION
The saturation temperature (boiling temperature) of a liquid in a closed vessel can be raised or lowered by…
Raising or lowering the pressure in the closed vessel
Define miscibility
The ability of a refrigerant to be dissolved
What is leakage tendency
The bigger the mass, the harder it is to escape small openings
EXAM QUESTION
What are two reasons moisture she be avoided?
1- it will cause ice to form between the expansion valves
2- may cause acid formation resulting in corrosion
What are the five parts of a closed type refrigerator?
Expansion valve Evaporator Compressor Condenser Receiver
EXAM QUESTION
What is another term for a direct refrigeration system?
Direct expansion systems
What is the Difference between a direct system and an indirect system?
The evaporator in a direct system is inside the refrigerated area
What is the role of an economizer?
It controls the amount of refrigerant flowing from the condenser to the evaporator
What are the two parts of an economizer?
Upper and lower
What refrigeration unit uses an economizer?
Centrifugal unit
What are the three types of compressors
Reciprocating
Rotary
Centrifugal
Explain a reciprocating compressor
It is very similar to a piston, which has two strokes, a suction and discharge stroke
What are the two types of suction and discharge valves
Flexible reed and none flexible
