Refrigeration

Air conditioner

Equipment that conditions air by cleaning, cooling,heating, humidifying,dehumidifying. A term applied to comfort cooling equipment.

Air conditioning

A process that maintains comfort conditions in a defined area.

Ambient temperature

Surrounding air temperature.

Atmospheric pressure

The weight of the atmosphere's gasses pressing down on the earth. Approximately 14.696 psi at sea level.

Boiling point

The temperature level of a liquid at which it begins to change to a vapor. The boiling temperature is controlled by the vapor pressure above the liquid.

Btu

The amount of heat required to raise one pound of water 1degree.

Celsius scale

A temperature scale with 100-degree graduations between the freezing point 0 degrees C. And the boiling point 100 C of water.

Change of state

The condition that occurs when a substance changes from one physical state to another such as ice to water or water to steam.

Cold

The word used to describe heat at lower levels of intensity.

Condensing pressure(Saturation)

The pressure that corresponds to the condensing temperature in a refrigeration system.

Condensing Temperature

The temperature at which vapor changes to a liquid.

Conduction

heat transfer from one molecule to another within a substance. Or from one substance to another.

Conductivity

The ability of a substance to conduct electricity from one substance to another.

Controlled Environment

The conditioned space the HVAC system is trying to maintain.

Convection

Heat transfer from one place to another using a fluid.

Crank Case Pressure Regulator

A refrigerant control device located in the suction line that controls the maximum suction pressure allowed to a compressor by reducing refrigerant flow.

Density

The weight per unit of volume of a substance.

Dew Point Temperature

The exact temperature at which moisture begins to form.

Dry-Bulb Temperature

The temperature Measured using a regular thermometer.

Energy

The capacity for doing work.

Enthalpy

The amount of heat a substance contains from a predetermined base or point.

Evaporation

The condition that occurs when heat is absorbed by liquid and it changes to vapor.(Evaporation is a cooling process.)

Evaporator Pressure Regulator

A refrigerant control device, located in the suction line, that limits the minimum pressure of an evaporator coil by reducing refrigerant flow.

Fahrenheit Scale

The temperature scale that places the boiling point of water at 212F. And the freezing point at 32F

Gas

The vapor state of matter.

Heat

Energy that causes molecules to be in motion and to raise the temperature of a substance.

Heat Transfer

The transfer of heat from a warmer substance to a colder substance.

Hidden Heat

Latent heat

High Temperature Refrigeration

A Refrigeration temperature range starting with evaporator temperatures no lower than 35Fahrenheit. A range usually associated with air conditioning.

humidity

Moisture in the air.

Kelvin Scale

A Temp Scale that has the same graduations as the Celsius scale but has absolute zero as a starting point or o (460 below)

Kilowatt

A unit of power = to 1000 watts.

Latent Heat

Heat energy absorbed or rejected when a substance changes state and there is no change In temperature.

Latent Heat Of Condensation

The latent heat given off when a gas condenses to a liquid.

Latent Heat Of Condensation

The latent Heat Given off when a gas changes to a liquid.

Latent Heat Of Vaporization

The latent heat absorbed when a liquid changes to a vapor

Low Temperature Refrigeration

A refrigeration range starting with evaporator temps no higher than 0 F. Commonly used for storing frozen foods.

Mass

Matter held together to the extent that it is considered one body.

Matter

A substance that takes up space and has weight.

Medium Temp Refrigeration

Refrigeration range where the evaporator temperatures are above 32 degrees F. Normally used for preserving fresh food.

Melting Point

The temperature at which a substance will change from a solid to a liquid.

Molecular Motion

The movement of molecules within a substance.

Natural Convection

The natural movement of a gas or fluid caused by differences in temperature.

Power

The rate at which work is done.

Pressure

Force per unit of area.

Pressure Temperature Relationship

refers to the relationship of a liquid and vapor in a closed container. If the temp increases, the pressure will increase. If the temp is lowered, the pressure will decrease.

PSI

Pounds per square inch

PSIa

Pounds per square Inch absolute

PSIg

Pounds per square inch gage

Radiant Heat

Heat that passes through air, heating solid objects that in turn heat the surrounding area.

Rankin

The absolute Fahrenheit scale with 0 at the point where all molecular motion stops.

Refrigerant

THe fluid in a refrigeration system that changes from a liquid to a vapor and back to a liquid at practical pressures.

Refrigeration

The process of removing heat from a place where it's not wanted and transferring that heat to a place where it makes little or no difference.

Relative Humidity

The amount of moisture contained in the air as compared to the amount the air could hold at that temperature.

Saturated Vapor

The refrigerant when all of the liquid has just changed to a vapor.

Saturation

A term used to describe a substance when it contains all of another substance it can hold.

Saturation Temperature

The temp at which both liquid and vapor exist.

Sensible Heat

Heat that causes change in temperature

Solid

Molecules of a solid are highly attracted to each other forming a mass that exerts all of it's weight downward.

Specific Gravity

The weight of a substance compared to the weight of an equal volume of water.

Specific Heat

The amount of heat required to raise the temperature of 1lb of a substance 1degree F.

Specific Volume

The volume occupied by 1lb of fluid.

Standard Atmosphere of Standard Conditions

Air at sea level at 70 degrees F, when the atmosphere's pressure is 14.696. PSIa(29.92in.hg). Air at sea level has a volume of 13.33ft squared/lb.

Steam

The vapor state of water.

Subcooled

The temperature of a liquid when it's cooled below it's condensing temperature.

Super heat

The temp of a liquid when it's above it's saturation(change of state) temp.

Temperature

A word used to describe the level of heat or molecular activity, expressed in Fahrenheit,Rankin,Celsius, or Kelvin units.

Temperature Difference(air-conditioning)

The difference between the air entering the evaporator coil and the air leaving the evaporator coil.

Temperature Difference(Refrigeration)

The difference between the saturated suction temperature and the temperature of the conditioned space.

Temperature/Pressure Relationship

This refers to the temperature/pressure relationship of a liquid and vapor in a closed container. If the temp increases, the pressure will increase. If the temp is lowered the pressure will decrease.

Ton Of Refrigeration

The amount of heat required to melt a ton of ice at 32 degrees F. In 24hrs, 288,000 btu/24. 12btu an hour.

Vapor

The gaseous state of a substance.

Vapor Pressure

The pressure exerted on top of a saturated liquid.

Vaporization

The changing of a liquid to a gas or vapor.

Watt

A unit of power applied to electron flow. 1Watt= 3.414BTU

Weight

The force that matter (liquid,solid,or gas)applies to a supporting surface when it is at rest.

Wet Bulb Temperature

A wet bulb temperature of air is used to evaluate the humidity in the air. It is obtained with a wet thermometer bulb to record the evaporation rate with an air stream with an air stream passing over the bulb to help in evaporation.

Boyles Law

The volume of gas varies inversely with the absolute pressure,provided the temperature remains constant.

Charles Law

At a constant pressure, the volume of gas varies directly with the absolute temperature, and at a constant volume ,the pressure of a gas varies directly with the absolute temperature.