BU 2: Mechanical Systems (TERMS)

Air conditioning

defined as the simultaneous control or air temperature, humidity, motion and purity of air in a confined space.

Air conditioner

a device which provides air conditioning

Heat

a form of energy that is transformed by the temperature difference

Enthalpy

quantity of heat in BTU/ min. in a fluid glass

Condenser

A heat-exchange device in a refrigeration system; consists of a vessel or arrangement of pipes or tubing

Compressor

a machine for drawing refrigerant from the evaporator at a relatively low pressure, COMPRESSES IT and the DISCHARGES IT to the condenser.

Evaporator

part of the refrigeration system in which the refrigerant is vaporized, thereby taking up external heat at producing cooling.

Humidity

water vapor within a confined space or environment.

Relative humidity

the RATIO of the weight of water vapor in humid air to the maximum possible weight of water vapor that the air could contain at the same temperature.

Humidity ratio

weight of water IN A MIXTURE PER POUND OF DRY AIR.

Humidistat/ Hygrostat

A regulatory device actuated by changes in humidity.

Thermostat

a device which responds to changes in temperature.

Adiabatic saturation

the introduction of water into an unsaturated air to increase humidity ratio but without transfer of heat to or from an outside source.

Dew point

the temperature at which air-water vapor mixture will become saturated and begins to yield drops of condensed water.

Latent heat

amount of heat absorbed/evolved in changing the stae of the substance without changing its temperature

Latent heat of fusion

one where change is from LIQUID to SOLID.

Latent heat of vaporization

one where change is from LIQUID to GAS

Sensible heat

Heat in BTU absorbed by a substance in changing its temperature without changing its stae

Wet bulb temperature

Temperature shown by a thermometer with a wetted bulb

Dry bulb temperature

Temperature in air-water vapor mixture as measured in the normal way with °F thermometer.

Desicant

an absorber which could be liquid or solid that CAN REMOVE WATER VAPOR FROM A MATERIAL.

Damper

A device used to VARY THE VOLUME OF AIR passing through an air outlet, inlet or duct

Duct, Air conditioning duct, Air duct

A passageway usually fabricated of metal, fiberglass, concrete and asbestos fibers; USED TO TRANSFER AIR from one location to another.

Filter

A device USED TO SEPARATE solid such as dirt, dust, and other particles from air.

Refrigerant

A substance which PRODUCES REFRIGERATING EFFECT by absorbing heat while expanding or evaporating.

Freon

a synthetic chemical refrigerant

Ventilation

the process of SUPPLYING OR REMOVING AIR by natural/mechanical methods to or from any space.

Ton of refrigeration

the useful refrigerating effect equal to 211 KJ/min or 288,000 BTU/ 24 hrs or 12,000 BTU/ hr.

Condensing unit

A specific refrigerating machine combination for a given refrigerant

Expansion coil

an evaporator constructed with a pipe or tubing.

Generator

Any device equipped with heating element used in the refrigerating system to increase the pressure of the refrigerant.

Air conditioning Machinery

Equipment including any or all of the following: condenser, generator, evaporator, absorber, receiver, connecting pipe, air handling units, etc.

Unit air conditioner

a type of system used for SMALL INSTALLATION such as residences and small offices.

Split type air conditioner

A type of system COMPOSED OF 2 SEPARATE SECTIONS, one installed inside the room and the other one is mounted outside the building.

Centralized type air conditioning system

A type of air conditioning system used for LARGE INSTALLATIONS with the use of ducts.

Cooling tower

A structure usually on the roof of the building over which water is circulated so as to cool it evaporatively in contact with air.

Annual Fuel Utilization Efficiency (AFUE)

The ratio of annual fuel output energy to annual input energy.

Coefficient of Performance (COP)

for cooling- ratio of rate of heat removal to rate of energy input

for heating- ratio of rate of heat delivered to rate of energy input

Energy Efficiency Ratio (EER)

the ratio of net equipment cooling capacity in BTU/hr to the rate of electric input in watts.

Integrated Part Load Value (IPLV)

A single number figure of merit based on part-load EER or COP.

Seasonal Energy Efficiency Ratio (SEER)

The total cooling output of an air conditioner during its normal annual usage.

Conduction

transfer of heat from one place of higher temperature to a place of lower temperature which IT IS IN CONTACT WITH.

Convection

transfer of heat by MOTION OF THE PARTICLES of the heated substance

Radiation

the process of transmitting rays of heat through the air.

Thermal transmission loads

heat transferring from walls, doors, floors, ceilings, etc.

Infiltration and Ventilation Load

Entry of outside air into the space to be conditioned.

Solar load

heat gained due to heat energy incident on the surface.