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Refrigeration

QuestionAnswer
What is the chemical name for R-22? Monochlorofifloromethane...A low temperature refrigerant with a boiling point of -41 degrees F at atmospheric pressure.
Name 3 qualities of a good refrigerant. Inexpensive, Low boiling point and low freezing point.
Where is the filter-dryer located? On the liquid line just after the receiver. It is used to remove moisture and small foreign particles.
Where is the sight glass located? On the liquid line. On the compressor. On the receiver.
What is Gay-Lussac's Law Pressure of a specific volume of gas is directly proportional to its absolute temperature. An increase in temperature will give an increase in pressure. A decrease in pressure will decrease in temperature.
What is entropy? Mathematical factor used in engineering calculations. Energy in a system.
What is enthalpy? Total amount of heat in a pound of a substance calculated from expected temperature base. Temperature of 32 degrees F is expected base for water vapor calculation. For refrigeration calculations acceptable base is -40 degrees F.
What is a shaft packing or seal? Sealing device consisting of soft material or mating soft element. Compressing to form a leak-proof seal.
What is adiabatic compression? Compressing refrigerant gas without removing or adding heat.
What is isothermal compression? A change in volume or pressure under conditions of constant temperature.
Define what cold means. The absence of heat.
1st law of thermodynamics? Heat and mechanical energy are mutually compatible.
2nd law of thermodynamics? Heat travels to cold. Heat will flow only to a material at a higher temperature to a lower temperature.
What is Dalton's Law? Vapor pressure created in a container by a mixture of gasses equal to the sum of individual vapor pressures of the gasses contained in the container.
What is Boyles law? With constant temperature the volume of a perfect gas varies inversely as a pressure is applied.
What device adds heat to the refrigerant? The compressor adds heat to the refrigerant.
What device removes heat to the refrigerant? The condenser removes heat from the refrigerant.
What is the temperature for absolute zero in Celsius? -273 degrees Celsius.
What is the temerature for absolute zero in Fahrenheit? -460 degrees Fahrenheit
How many BTU's are in a ton of refrigerant? 288,000
What is standard ton condition? Used as a basis for air conditioning calculations; Temperature 68 degrees Fahrenheit, pressure 29.92 inches of mercury and 30% relative humidity.
What is superheat? Temperature of vapor above its boiling point as a liquid at that pressure. No liquid is present.
What does the term saturation mean? When a substance contains all of another substance it can hold for that temperature and pressure.
Name the 5 latent heats. Fusion, Melting, Sublimation, Condensation, and Vaporization.
What is the specific heat of water? Heat required to raise 1 pound of water 1 degree.
Name the 3 states of physical matter. Gas, liquid, and solid.
Name the 3 methods of heat transfer. Radiation, convection, conduction.
How does the color of a material effect radiant heat transfer? Darker colors absorb more heat.
What is a BTU? British Thermal Unit
What is sensible heat? Heat that causes a change in temperature of a substance. Can be measured with a thermometer.
What is the Celsius to Fahrenheit formula? F=9/5C+32
What is latent heat? Hidden heat. Heat energy absorbed. A change in state but no change in temperature.
What is absolute zero? Temperature at which all molecular motion ceases.
What is thermodynamics? Part of science which deals with the relationship between heat and mechanical action.
What is oil sag? When oil forms a "tear drop sag bottom."
If oil gets too hot it will first start to? Foam up
What is a halocarbon system? All refrigerants except ammonia.
The oil in the evaporator is expected to do what? Be swept back through the suction line to the compressor.
Where does the oil accumulate in the evaporator? It settles at the bottom where it must be periodically drained.
In the evaporator, what happens to oil in very cold conditions? Wax begins to separate from it.
What problems does the oil create in the evaporator? Oil thickens due to the lower temeperature, it thickens and coats the evaporator walls reducing heat transfer.
What is another name for an oil separator? Oil trap.
How is oil selected for a specific refrigerant? It is rated by its viscosity and compatibility with such refrigerant.
At what temerature will oil began to break down? 225 degrees Fahrenheit
Describe what the cloud point looks like. Opaque. Transluscent. Cloudy appearance.
What happens at the 'cloud point' with oil? Wax will begin to separate from the oil.
The flash point regarding oil is an indication of what? Oil is beginning to break down.
What does pour point mean? The temperature at which a given amount of oil thickens to the point where it will not pour out when the vessel is turned on its side.
What does flashpoint mean regarding oil? The temperature at which an inflammable vapor is distilled from oil it will not ignite unless a flame is provided.
What is foaming? The process in which the bubbles form on the top of the oil surface. Which can reflect an improper oil level for example the foam that forms on the surface of beer.
What is the refrigeration process? No more that heat exchange.
What mediums are used for refrigeration? Air and water.
What do metering devices do? Regulate the amount of refregerant to the evaporator.
The type of oil is used? In relation to the kind of refrigerant.
Connecting piping consist of? The suction line, the discharge line, and the liquid line.
The suction line piping is located where? Between the outlet of the evaporator and the inlet (suction valve) of the compressor.
The liquid line is the piping that connects the? Condenser outlet to the receiver inlet, the receiver outlet to the inlet side of the metering device the outlet of the metering device to the inlet of the evaporator.
The piping in the refrigeration system is also known as? The suction line to discharge line and liquid line.
So that the suction line, the liquid line and the dsicharge line don't gain or lose heat or temperature what is used? Insulation is used.
What state is a refrigeration in when it is in the system? Both liquid and solid.
What component absorbs heat from the medium? The evaporator. Heat causes liquid refrigerant to boil changing the state to vapor.
What is darkness? The absence of light.
What is the Fahrenheit to Celsius formula? C=5/9(F-32)
What is humidity? A quanitity representing the amount of water vapor in the atmosphere or a gas.
What is absolute humidity? The actual weight of water vapor in a given amount of air usually in grains of moisture per pound or grains per cubic foot.
What is relative humidity? The amount of water vapor present in air expressed as a percentage of the amount needed for saturation at the same temperature.
How is humidity measured? In grains of sand and weigh 1/7 of a pound.
What measures the humidity in the air? A sling psychometer. Wet bulb and dry bulb temperature.
Post of duty? Under the supervision of a license operator in responsible charge. Possessing at least a 3rd class refrigeration oerators license.
Requirements for a 3rd class refrigeration operator? Horspower does no exceed 125 hp. Refrigerant does not exceed 500 pounds.
Wet bulb? Wick needs to be dipped in water. And then compared to dry bulb temperature.
Created by: geralddixson
 

 



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