Hvac Intro To Cooling

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Absolute Pressure

Back 1

Positive pressure measurements that start at zero (no pressure at all). Also gauge pressure plus the pressure of the atmosphere (14.7 psi at sea level at 70F

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Atmospheric Pressure

Back 2

The pressure exerted on all things on the earth as a result of the weight of the atmosphere

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Btu (British thermal unit)

Back 3

The amount of heat needed to raise the temp of one lb. of water one degree F

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Cold

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A relative term for temperature. Having less heat heat energy than another by means of direct contact

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Conduction

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A means of heat transfer in which heat is moved from one material to another by means of direct contact

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Conductor

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A material in which the transfer of heat by conduction occurs easily

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Convection

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The transfer of heat by the flow of liquid or gas caused by temperature differential

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Enthalpy

Back 8

The total heat content (sensible and latent) of a refrigerant or other substance

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Floodback

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Refrigerant returning to the compressor in the liquid state

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Fluorocarbons

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Halocarbons in which at least one or more of the hydrogen atoms has been replaced with fluorine

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Halogens

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Substances containing chlorine, fluorine, bromine, astatine, or iodine

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Heat

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A form of energy. Causes molecules to be in motion and raises the temp of a substance. Other forms of energy like electricity, light, and magnetism deteriorate into heat

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Hydrocarbons

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Compounds containing only hydrogen and carbon atoms in various combinations

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Insulators

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Materials that resist heat transfer by conduction

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Latent Heat

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Heat energy absorbed or rejected when a substance is changing state but maintaining its measured temp

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Latent Heat of Condensation

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heat given up or removed from a gas in changing back to a liquid state (steam to water)

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Latent Heat of Fusion

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heat gained or lost in changing to or from a solid

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Latent Heat of Vaporization

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heat gained in changing from a liquid to a gas

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Pressure

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Force per unit of area

Front 20

Radiation

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the movement of heat in the form of invisible rays or waves, similar to light

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Refrigerant

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a liquid or gas that picks up heat by evaporation at a low temp and pressure, and gives up heat by condensing at a higher temp and pressure

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Refrigeration

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the transfer of heat from a space or object where it is not wanted to a space or object where is is not objectionable

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Sensible Heat

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heat that can be measured by thermometer or sensed by touch. the energy of molecular motion

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Sensible heat

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heat that can be measured by a thermometer or sensed by touch. the energy of molecular motion

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Slug

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large amount of liquid refrigerant or oil engineering a compressor cylinder

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Specific Heat

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the amount of heat required to raise the temperature of one pound of a substance one degree Fahrenheit

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Subcooling

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cooling a liquid bellow its condensing temperature

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Superheat

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the measurable heat added to the vapor or gas produced after a liquid has reached its boiling point and completely changed into vapor

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Thermistor

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a semiconductor device that changes resistance with a change of temp

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Thermocouple

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a device made of two different metals that generates electricity when there is a difference in temperature from one end to the other

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Ton of refrigeration

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large units for measuring the rate of heat transfer. One ton is defined as 10k Btu's