2nd Year Finals Flashcards
form of energy that is transformed by temp difference
heat
quantity of heat in BTU/min in a fluid or gas
enthalpy
a heat exchange device in a refrigeration system
condenser
machine for drawing refrigerant from the evaporator at a relatively low pressure, compresses it then discharges it
compressor
part in which refrigerant is vaporized
evaporator
heat transmission by currents resulting from differences in density due to temperature differences
convection
water vapor within a confined space
humidity
ratio of the weight of water vapor actually in humid air to the max possible weight of water vapor that air could contain at the same temp
relative humidity
weight of water vapor in a mixture per pound of dry air
humidity ratio
regulatory device actuated by changes in humidity
humidistat/ hygrostat
device which responds to changes in temp
thermostat
introduction of water into an unsaturated air to increase humidity ratio but without transfer of heat
adiabatic saturation
temp in which air-water vapor mixture will become saturated and begins to yield drops of condensed water
dew point
amount of heat absorbed in changing the state of the substance without changing its temp
latent heat
one where change is from liquid to solid state
latent heat of fusion
one where change is from liquid to gas
latent heat of vaporization
heat in BTU absorbed by a substance in changing its temperature without changing its state
sensible heat
temp shown by a thermometer with a wetted bulb rotated rapidly in the air
wet bulb temperature
temp of air-water vapor mix as measured in the normal way with Fahrenheit thermometer
dry bulb temperature
an absorber that can remove water vapor from a material
desiccant
device used to vary the volume of air passing through an air outler
damper
substance that produces refrigerating effect by absorbing heat
refrigerant
synthetic chemical refrigerant
freon
process of supplying or removing air
ventilation
useful refrigerating effect equal to 211 KJ/min or 12000BTU/hr
ton of refrigeration
specific refrigerating machine combination for a given refrigerant
condensing unit
evaporator constructed with a pipe or tubing
expansion coil
device equipped with heating element
generator
equipment including: compressor, condenser, generator, evaporator, etc.
air conditioning machinery
type of system used for small installation such as residences
unit air conditioner
aircon system used for large installations with the use of ducts
centralized type air conditioning system
structure usually on the roof in which water is circulated so as to cool it
cooling tower
ratio of annual fuel output energy to annual input energy
AFUE annual fuel utilization effieciency
the ratio of heat removal/delivered to the rate of the energy input
COP (coefficient of performance)
ratio of net equipment cooling capacity in BTU/hr to the total rate of electric imput in watts
EER energy efficiency ratio
single number figure of merit based on part-load EER or COP
IPLV integrated part load value
total cooling output of an aircon during its normal annual usage divided by the total energy input
SEER seasonal energy efficiency ratio
transfer of heat from one place of higher temp to lower temp
conduction
transfer of heat by motion of the particles
convection
process of transmittin rays of heat through the air
radiation
comfortable cooling temperature
68-74 Fahrenheit
based upon the alternate liquefying and evaporating of a volatile liquid refrigerant with a low boiling point
mechanical refrigeration
self-contained unit which houses all the necessary air conditining components such as the compressor condenser evaporator
unitary/ room airconditioner
unitary type ac is composed of the ff:
fan coil unit, air cooled condensing unit ACCU
fan coil unit FCU is composed of the ff:
fan, coil, filter
ACCU is comprised of the ff:
air cooled condenser ACC, compressor
ACC is composed of the ff:
ACC fan, condensing coil
commonly known as piston type compressor
reciprocating type
defined as the simultaneous control of air temp, humidity, motino, and purity or air in a confined space
air conditioning
used for humidifying and cleaning the air
air washer
power unit to raise and lower an elevator
drive machine
grooved wheel of a traction-type machine over which the hoist rope motion is imparted to the car
drive sheave
average time between departure of cars from the lobby
interval or lobby dispatch time
waiting time at an upper after registering a call
registration time
an electric device that is designed to interpret input conditions
relay
group of floors
zone
elevator with cables fastened to and would around a drum
winding drum machine
consists of a dc motor, shaft directly connected to the break wheel and driving sheave
gearless traction machine
the power from the motor is transmitted through reduction gears
geared traction machine
used to guide rails
guide shoes
ropes that hang from the bottom of the car to the bottom of the counterweight
compensator
carries current to and from the car
brush
causes car and counterweight to stop in case of emergency
governor
gives stability to a governor rope
tension sheave
18” above or below landing
landing zone
