Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
HVACR
| Question | Answer |
|---|---|
| Matter | (Everything we touch) Solids, Liquids, Gases |
| Energy | The ability to effect a change in matter/ ability or capacity to perform work |
| Energy Types | Chemical, Thermal, Light, Electrical, & Mechanical |
| Subdivision of Energy | Potential & Kinetic |
| Potential | Stored energy/ idle objects |
| Kinetic Energy | Energy doing work/ objects in movement |
| Law of conservation of energy | Energy cannot be created or destroyed but can be altered |
| Gravitational force exerted by the earth on an object | Weight |
| Mass | Used to express that the quantity of material is the same regardless of the change in the force of gravity. |
| US Customary Units of Weight | Ounce, Pound, & Ton |
| SI Units of Weight | Kilogram |
| Density | A substances mass per unit volume |
| US Customary System Density | Pounds per Cubic Foot |
| Specific Volume | Volume of a specific amount of gas under standard conditions |
| Standards Conditions of Volume | 68 Degrees F, 20 degrees C, & 14.7 psia |
| Specific Gravity | Ratio of the mass of a certain volume of a liquid or a solid compared to the mass of an equal volume of water |
| Relative Density | Ratio of the mass of a certain volume of gas as compared to the mass of an equal volume of hydrogen |
| Force | Energy applied to matter that unless counteracted by opposing forces, causes a change in the matters velocity |
| Acceleration Constant | 32.2 ft/s squared |
| SI Unit of Force | Newton |
| Newton | That force which applied to a 1-kg mass will accelerate the mass at a rate of 1m/s squared. |
| Heat | A form of energy that results in the motion of atoms. |
| Atoms | The smallest indivisibl part of an element |
| All substances are made up of | tiny atoms |
| Tiny atoms combine to make up | Molecules |
| Cold | Low temperature or lack of heat |
| SI Units Temperature | Celcius |
| US Units Temperature | Fahrenheit |
| Absolute Temperature Scale | A temperature scale that uses absolute zero as a starting point |
| Two Absolute Temperature Scales | Rankine Scale ( Fahrenheit Absolute Scale) & Kelvin Scale (Celsius Absolute Scale) |
| Ambient Temperature | The temperature of the air surrounding an object |
| US Customary Units of Heat | British Thermal Units/ BTUS |
| SI Units of Heat | Specific Heat Capacity |
| Enthalpy | Total amount of heat in a substance (calculated from an accepted reference temperature) |
| Specific Enthalpy | Enthalpy per unit of mass |
| Radiation | Transfer of heat by heat rays. |
| Conduction | Flow of heat through a material due to molecular vibrations in the material/ contact of materials |
| Convection | The movement of heat from one place to another by way of a liquid or gas. |
| Solid | Definite Shape & Volume |
| Liquid | Definite Volume, No Definite Shape |
| Gas | No definite shape or volume |
| Latent Heat | Heat that brings about a change of state with no change in temperature |
| Latent heat of fusion | The heat required to change a substance from a solid to a liquid or from a liquid to a solid |
| Latent Heat of Vaporization / Condensation | Latent Heat added to a liquid to change it into a gas or the latent heat removed from a gas to change it into a liquid |
| Sensible Heat | When heat is added to a substance and temperature rises as the heat is added. (The increase of heat) |
| Superheat | The difference in temperature between a vapor and its condensation point |
| Subcooling | Measures the difference in temperature between a liquid and its boiling point |
| Saturated Vapor | A condition of balance on an enclosed quantity of a vaporized fluid |
| A Ton of Refrigeration | The amount of heat energy absorbed when one ton of ice melts during one 24-hour day |
| Volume | The physical space that a substance occupies |
| Pressure | Force per unit area |
| Pascal | A Newton per Square Meter |
| Pascals Law | Pressure applied upon a confined fluid is transmitted eaually and undiminished in all directions |
| Heat of Compression | Energy added to the gas by compression |
| Adiabatic Compression | A gas is compressed without gaining heat from or losing heat to its surroundings |
| Critical Temperature | The highest temperature at which it can be liquified |
| Critical Pressure | The pressure at which the gaseous form of the substance liquifies when the substance is at its critical temperature |
| 0 psi Gauge pressure | 14.7psia at sea level |
| 14.7 psia | One Atmosphere |
| Gauge Pressure Scale | Pressure above atmospheric pressure |
| Atmospheric Pressure | Pounds per unit of area, Inches of liquid column height, or in atmospheres |
| Zero Point | Absolute Pressure |
| Gauge Pressure | Atmospheric Pressure at sea level as the zero point |
| Absolute Pressure | Gauge pressure plus atmospheric pressure |
| PSIG/PSI | Gauge Pressure |
| PSIA | Absolute Pressure |
| Perfect Vaccum | 0 PSIA/ Zero point for Absolute Pressures |
| Partial Vaccum | Any pressure below atmospheric pressure |
| Inches in Mercury | US customary units for pressure above atmospheric pressure |
| Inches or Feet of Water Column | US customary units for pressure below atmospheric pressure |
| Manometers | Pressure measuring devices |
| Torrs | A unit of measure that has been devised for measuring high vaccums (pressure close to an absolute vaccum) (1= 1mm pressure of Mercury |
| Bar | 14.5PSIA |
| SI units of atmospheric pressure | Kilopascals(kPa) |
| Compound gauges | Measures both pressure and vaccum in the same system |
| Boyles Law | Pressure and Volume Relationship (Pressure increases, Volume Decreases) |
| Charles Law | Volume & Temperature Relationship ( Temperature increases, Volume increases) |
| Gay-Lussacs Law | Pressure and temperature relationship ( Pressure increases, Temperature increases) |
| Combined Gas Law | States the ratio among a gases pressure, volume, & temperature |
| Avogeadros Law | Equal volumes of gases at equal pressures and temperatures contain equal numbers of molecules regardless of the mass of the gases |
| Ideal gas laws | Provides a formula for calculating the pressure, temperature, or volume for a known quantity of gas |
| Daltons Law | To determine the total pressure of a confined mixture of gases, the pressure for each gas involved must be added |
| Hermetic Compressors | When the motor is sealed inside the same dome or housing as the compressor (shaft seal is not needed) the motor is directly connected to the compressor often through a shared shaft |
| Fully hermetic compressors | Fully welded and cannot be serviced without cutting open the shell |
| Semi-Hermetic Compressors | Combines a motor and a compressor inside a multipart shell that is bolted together. The shell can be unbolted |
| Types of compressors | Reciprocating, Rotary, & Scroll |
| Reciprocating Compressor | A compressor that functions by changing the rotational movement of a crankshaft into the reciprocsting motion of the pistons within cylinders |
| Rotary Compressors | A compressor in which vapor compression takes place in spaces between the cylinder wall and sides of an off-center rotor that spins inside the cylinder |
| Scroll Compressor | Produces vapor compression between the walls of a fixed scroll and an orbiting scroll |
| Compressor Windings | Common, Run, & Start |
| Crankcase heater | Turns on when compressor/system is on the off cycle |
| Capacitor Windings | Common, Fan Hertz |
| Herm | Compressor |
| Fan | Outdoor condenser fan |
| P.A.S.S (Fire Extinguisher) | Pull the pin, aim the nozzle at the base, squeeze the lever, sweep back and forth. |
| Line side | Brings power into the device |
| Load side | Takes power out of the device |
| 240v side | Primary/ Common |
| 24v side | Control/Secondary |
| Metering devices types | Cap tubes, fixed orifices, TXV, AXV, EEV, LSF, & HSF |
| Safety devices | Used to ensure clean oil at proper levels and sufficient vapor flow for cooling |
| Open-drive compressors | Compressors driven by an external source of mechanical power |
| Compressors are | Mechanical devices that require lubrication and cooling for safe and efficient operation |
| Compressor protection devices may stop operation based on | Current on the compressor motor, head pressure, temperature of the compressor dome, and temperature of the discharge line |
| Overcurrent protection for compressors are in the forms of | fuses, circuit breakers, and internal overload devices such as the thermal overload |
| Metering Devices | Restrict refrigerant flow from the liquid line into the evaporator maintaining the proper pressure drop between the high and low side |
| Fixed Metering devices | Has a fixed diameter passage |
| Fixed metering device | Has a fixed diameter passage |
| Air cooled evaporators | Designed to cool the air circulating through a conditioned space |
| Types of air cooled water evaporators | Natural draft or forced draft |
| Types of air cooled water evaporators constructions | Fin & tube, Plate, & Microchannel |
| Types of condensors | Air cooled, water cooled, or evaporative |
| Sight Glass | A small viewport in a refrigerant line used to visually inspect the circulating fluids in a system |
| Service Valves | Manual valves that provide a connection to a system so that technicians can take a pressure readings, charge the system, or evacuate the system |
| Liquid line driers are installed | between the liquid received and the metering device |
| Evaporators and Condensers are | Heat Exchangers |
| Air Cooled Evaporator | Used to directly cool the air within a cabinet or other conditioned space |
| Liquid Cooled Evaporator | Used to cool a body of liquid that is the used to cool other substances (More commonly used on commercial systems |
| Three groups of Evaporators for applications used in refrigeration | Low Temperature , Medium Temperature, & High Temperature |
| Low Temperature Applications | (-10F/-23C to 28F/-2.2C) |
| Medium Temperature Applications | 28F/-2.2C to 40F/-4.4C |
| High Temperature Applications | 40F/-4.4C to 60F/-15.5C |
| The two main subclasses of air-cooling evaporators | Natural Draft & Forced Draft |
| Natural Draft Evaporator | Depends on gravitational circulation |
| Gravitational Circulation | When cold air is denser than warm air and sinks below the warmer, less dense air. (Hot air rises, Cold air falls) |
| Forced Draft Evaporator | An Evaporator equipped with a fan that blows air over the Evaporator coil’s tubes & fins |
| ACR (Air conditioning and refrigeration) tubing is designated by | its outside diameter. |
| ACR tubing is usually | charged and sealed with gaseous nitrogen, keeping the tubing clean and dry until it is used |
| Annealing | A process in which a substance is heated to a specific temperature range and then cooled slowly (used on soft ACR tubing) |
Created by:
leii