[Refrigeration Systems] Flashcards
Instantaneous evaporation of liquid refrigerant in an evaporator
Flash gas
What may be closed to prevent toxic or dangerous vapors from entering the vessel?
Dampers
Carries the refrigerant vapor from the evaporator to the compressor
Suction line
Four variables that the design of a capillary tube depends on
- Tube length
- Inside diameter
- Tightness of tube windings
- Temperature of tubing
Two types of piston rings
- Compression ring - upper ring
* Oil ring - lower ring designed to control the oil “flow” past the piston
What type of thermometer detects infrared rays produced by a substance?
Radiometer
Three types of compressors
- Hermetic
- Semi-hermetic
- Open type (externally driven)
Amount of heat required to raise the temperature of one pound of water one degree Fahrenheit
BTU
Process in which a gas is compressed without losing heat to the surroundings
Adiabatic compression
Safety device that prevents liquid refrigerant from flowing into the suction line and compressor
Accumulator
Serves as a pressure plate in a cylinder, supporting and holding the valves and valve plate in position
Cylinder head
Connects to the lower end of the piston by means of a floating bearing in a Scotch yoke mechanism
Crankthrow (crankshaft pin)
1) Maintains proper flow of refrigerant; provides and controls refrigerant
2) What are the two types?
1) Refrigerant metering device
2) Thermostatic-controlled expansion valves and capillary tubes
Vapor formation in a capillary tube
Vapor lock
Leak-proof container that houses crankshaft
Crankcase
Back-and-forth action in a straight line
Reciprocating
Heat is a form of what?
Energy
SI metric unit of heat
Joule (J)
Connecting rods that are shorter than the master connecting rod
Articulated rods
Four components of refrigeration
- Compressor
- Condenser
- Refrigerant control device
- Evaporator
What is the most damaging condition of refrigeration operation?
Refrigerant slugging (allowing liquid refrigerant to enter the compressor)
What discharge air from the vessel to the atmosphere?
Exhaust system and fans (axial and centrifugal)
What measures the heat intensity or heat level of a substance?
(measures the speed of motion of the atom)
Temperature
What is happening when a fluid evaporates?
Heat is absorbed
Coils cooled by brine or any fluid which does not evaporate in the coil
Cooling coils
Contact device with a remote bulb mounted in the duct or plenum of an air handling unit to measure air temperature in such a way that it does not see radiant heat directly from the heater
Duct thermostats
How is temperature measured?
Thermometer
Part of refrigerator mechanism where liquid refrigerant boils or evaporates and absorbs heat
Evaporator
Volume of space between piston and cylinder head at TDC
Clearance space
Motor-driven device which removes the heat-laden vapor refrigerant from the evaporator
Compressor
Expendable refrigerant usually used in an expendable refrigerant refrigeration system
Liquid nitrogen
What is the moisture level?
Humidity
What consists of duct heaters, unit heaters, and convection heaters?
Heating system
What maintains correct operating temperature by controlling the motor electrical circuit?
Thermostat
What are the major supply systems feeding air into the vessel?
Air intake trunks (ducts)
What are the major components in an air conditioning cooling cycle?
- Cooling coil
- Compressor
- Condenser
- Expansion valve (or capillary tube assembly)
Temperature of the air surrounding a motor, control mechanism, or any other device
Ambient temperature
What provides local filtering and reheating or cooling of air?
Recirculating (return air) system
Mechanical refrigeration cycle
- Closed system
- Continuously circulating
- Condensation
- Evaporation
Temperature control device that is mounted on the wall in the area which it serves
Room thermostats
What is the SI unit of temperature?
Kelvin (K)
When does the HVAC process begin?
As weather air enters the HVAC supply intakes
Pressure of a vapor in contact with a liquid
Vapor pressure
Instrument used when accurate readings at various temperatures are needed
Thermometer-pyrometer
Pyrometer means “high temperature
Three safety considerations
- Safety of operator
- Safety of equipment
- Safety of content
What is the American conventional unit of temperature?
Fahrenheit
What move the air through the supply ducts to ventilate compartments and to heat or cool the air?
Supply fans
Amount of heat required to raise the temperature of one gram of water one degree Celsius
Calorie
What is often done to the connections of a capillary tube?
Brazed
What removes air from the galley along with all cooking smoke and odors?
Galley exhaust fan
Unit which equals 100,000 BTU
Therm
Sequence of events
- Liquid line
- Expansion valve
- Evaporator
- Suction line
- Compressor
- Discharge line
- Condenser
What does the operation of a mechanical refrigerator rely on?
Heat absorption property of a fluid passing from the liquid to the vapor state
Shaft section which is larger and has a different center than the shaft
Eccentric
Type of refrigerant control that consists of a length of seamless tubing with a small and accurate inside diameter
Capillary tube
What is the thermal energy of the atom multiplied by the number of atoms (mass)?
Heat
What does a substance state consist of?
- Pressure
- Heat content
- Temperature
What is the American conventional unit of heat?
British Thermal Unit (BTU)
Temperature where molecular motion stops (all heat is removed)
*lowest temperature possible
Absolute zero
What happens when a gas is compressed?
Temperature rises (heat of compression)
1) Insulated cabinet equipped with a tray or tank at the top for holding blocks or pieces of ice
2) What is the advantage?
1) Typical ice refrigerator
2) Maintaining the interior of the cabinet at a fairly high humidity
Keeps moisture, dirt, metal, and chips from entering the refrigerant flow control
Liquid line filter-drier
How does natural air enter a room?
Door louvres
