Lesson 3 Flashcards
What is the cooling substance in a refrigerator or in air-conditioning unit.
Refrigerant
Heat-carrying medium that absorbs heat and low temperature
Refrigerant
What are the properties of refrigerant?
Low boiling point
Safe and non-toxic
Ease of liquefy action at moderate pressure and temperature
High latent value
Ability to operate under positive pressure
No effect on moisture
Mix well with oil
Non-corrosive to metal
What are the common refrigerant used in household and air-con units?
R-12 (Dichlorodifluoromethane)
R-22 ( Mono chlorodifluoromethane)
R-134a (Tetrafluoroethane)
Commonly used in refrigerators and automotive air-con units
Dichlorodifluoromethane R-12
Commonly used in domestic air conditioning units
Mono chlorodifluoromethane R-22
Refrigerant used to substitute to R-12 and R-22 which are known to be environmental friendly
Tetrafluoroethane R-134a
What are the basic operations in refrigeration cycle?
Diagnosing
Leak testing
Vacuuming
Two types of vacuuming
Self-vacuuming
Using a vacuum pump
When will vacuuming should perform?
Before charging or recharging with refrigerant
The process of filling or refilling the system with a cooling agent also known as refrigerant to an amount equivalent to the full load rating of the system.
Charging the system
Determining the status of the system.
Diagnosing
This the process of determining a break or a hole in the sealed tube where the refrigerant escapes causing abnormality in the refrigeration cycle.
Leak testing
This is the process of removing air gas in an enclosed space
Vacuuming
A process of removing air, gas, moisture, dirt, and other foreign materials in the refrigeration system using its motor compressor to pump them out
Self- vacuuming
This the method of vacuuming uses a vacuum pump instead of the motor compressor of the refrigerator unit.
Using a vacuum pump
What is the chemical formula of R-12 (Dichlorodifluoromethane)
CCl2F2
What is the chemical formula of R-22 (Mono chlorodifluoromethane)
CHCLF2
R-134a (Tetrafluoroethane) also known as
HFC 134a
Reduces volume and creates high pressure gas causing the temperature to rise.
Compressor
Hot gas is cooled by water before being condensed to become a hot liquid
Condenser
Hot liquid cools due to pressure decrease resulting in cold refrigerant
Expansion valve
Cold refrigerant chills equipment as it vapors; turning back into a gas it draws the heat away from the refrigerator’s contents before existing the evaporator
Evaporator
