Unit 36 Refrigeration Applied to Air Conditioning
3450, 1750
Compressor Speeds (RPM) Older small and medium-size compressors Single-speed pumps and turned at standard motor speeds of ________ or ________ rpm
outside, outside
Installation Procedures Equipment is located _______________ the structure so service can be done ______________
firm foundation, ductwork, electrical
Installation Procedures To install, mount on a ___________________ and connect _________________ and _______________ service
Package systems, window unit
Installation Procedures ____________________ (whole air conditioner in one cabinet) Example:
Package air-conditioning
Package-Type and Split-Type Air-Conditioning Systems Self-contained; all components in one cabinet with air ducted to and from the unit
A
Package-type air-conditioning units are intended to be located A. either on the roof of a structure or at ground level B. only on the roof of a structure C. only in the attic of a residence D. only at ground level
higher
Structural Heat Gain Summer solar load on a structure is _____________ on east and west sides
Attic ventilation, powered, natural-draft
Structural Heat Gain _____________________ can help relieve solar load on the ceiling Accomplished with _________________ or ________________ ventilation systems
55, 95%, cooled, mixed
The Evaporator: Humidity and Airflow Air leaves the coil at about _______ degrees F dry-bulb and about _______ humidity Humidity is high because air has been __________; relative humidity will all when ___________
A coil, slant coil, H coil
Three common evaporator coil configurations are the ____________, ________________, and ___________
D
What refrigerant lines are field installed on the typical package-type-air-conditioning unit? A. Liquid line and suction line B. Discharge line and liquid line C. Discharge and suction line D. Package-type equipment has no field-installed refrigerant lines
Compressor, condenser, metering device, evaporator
Air-Conditioning Uses the same four components as other refrigeration systems ___________________, ____________________, __________________, and ____________________
indoor blower, supply, return
Air-Side Components Consist of _____________________ as well as the ___________ air and __________ air ducts
40 degrees F, sensible, latent
Air-conditioning evaporators operate at about _______ (at design conditions) and remove __________ heat and __________ heat
rattling
Condenser Cabinet Design Fasten screws tightly when installing equipment in the field to prevent ____________
A
The temperature of the evaporator is affected A. only by the amount of air passing through the coil B. only by the temperature of the air passing through the coil C. by both the temperature and amount of air passing through the coil D. by neither the temperature nor the amount of air passing through the coil
D
The two types of heat transfer that are facilitated by the evaporator are A. superheat and subcooling B. sensible heat and superheat C. subcooling and latent heat D. sensible heat and latent heat
C
Three common evaporator coil configurations found on air-conditioning systems are A. slant, A, and V B. A, V, and H C. slant, A, and H D. A, H, and V
A
What refrigerant lines are field installed on the typical split-type air-conditioning system? A. Liquid line and suction line B. Discharge line and liquid line C. Expansion line and discharge line D. Suction line and expansion line
B
When sizing and selecting air-conditioning equipment, which of the following must be taken into account? A. Dirt content B. Moisture content C. Smoke content D. Pollen content
B?
Which of the following best describes the air that enters the structure after being treated by an evaporative cooler? A. Warm and humid B. Warm and dry C. Cool and humid D. Cool and dry
indoors, outside
Air-Conditioning Absorbs heat _______________ and puts it _____________
comfort cooling
Air-Conditioning Refrigeration process applied to _____________________
conduction, infiltration, radiation
Structural Heat Gain Heat leaks into a structure by ________________, _________________, and ________________
reciprocating, rotary, scroll, centrifugal, screw, commercial refrigeration
The Compressor Types include _________________, ___________, __________, _______________, and ____________ Use same designs as similar types used in ___________________________
low, high, Increases, compressing vapor
The Compressor Vapor pump that pumps heat-laden vapor from the _________-pressure (evaporator) side of the system to the ___________-pressure (condenser) side by ___________________ _________________ temperature and pressure of vapor
rejects
The Condenser Component that _________ heat from the air-conditioning system
air-cooled
The Condenser Most equipment is ________________ and rejects to the air
copper, aluminum, heat exchange
The Condenser The coils are made of ______________ or _______________ and have aluminum fins to increase the _______________________ surface area
New coil designs
The Condenser _______________ are used in some units to make them lighter and more efficient
local design practices
Design Conditions Be familiar with ______________________________
Hermetic
Cooling the Compressor and Motor ______________ compressors suction-gas-cooled
interconnecting piping, cool gas, liquid, Cool gas
Installation Procedures: Split Systems Install __________________________ (____________ line and __________ line) ______________ should be insulated
close together
Installation Procedures: Split Systems Locate condensing unit and air handler as ___________________ as possible
Take care, insects, sharp objects, weak ceilings, lines
Installation Procedures: Split Systems ______________ handling equipment Watch out for ___________, _________________, _________________, and _________ carrying refrigerant
air temperature, moisture
Removal of sensible heat lowers the______________________; removal of latent heat removes __________________
Hot air, noise, Motor, vertical
Top-Air-Discharge Condensing Units Most popular configuration for condensing units in residential equipment ____________ and__________ discharge from the top _____________ on tope should be protected with a rain shield Bearings mounted in ________________ position need thrust surface
Package equipment
A refrigerating system where all major components are located in one cabinet
compressor motor speed
Compressor Speeds (RPM) Most systems today use variable refrigerant flow technology to vary the __________________________ to control and adjust capacity
efficient
Compressor Speeds (RPM) Newer single-speed compressors Operated at the faster speed and more ______________ refrigerants
low
Evaporative Cooling Used primarily in climates with ________ humidity
D
Heat leaks into a structure by which three methods A. Conduction, convection, and radiation B. Infiltration, convection, and radiation C. Conduction, convection, and radiation D. Conduction, infiltration, and radiation
side
Side-Air-Discharge Condensing Units Discharge air out the _________ of the unit
factory, factory, efficient
The package unit is charged at the ____________ and is _______________ assembled. Under similar conditions, it is more _____________ than the split system
subcooling, below, Adds
Condenser Coil Design Bottom rows of coil may be used for ___________________ Lowers condensed refrigerant temperature ____________ the condensing temperature ___________ to the efficiency of the system
B
Evaporative cooling systems are best suited for which type of climate? A. Hot, humid climate B. Hot, dry climate C. Cool, humid climate D. Cool, dry climate
A coil, slant coil, H coil, pressure drops, multiple circuits, Microchannel
Evaporator Coil Configurations Common evaporator coil types: __________, ____________, and ___________ Coils may operate in parallel to avoid large _____________________ and may each use________________ with a distributor ____________________ (flat-plate-and-fin) technology: coil designs that resemble automobile radiators
Control flow
Expansion Devices ___________________ of refrigerant into the evaporator
B
Multicircuit evaporators are equipped with which of the following components? A. A refrigerant distributor located at the inlet of the metering device B. A refrigerant distributor located at the outlet of the metering device C. A refrigerant receiver located at the outlet of the metering device D. A refrigerant receiver located at the outlet of the evaporator coil
A?
On average, each tone of system capacity has the ability to remove approximately how much moisture from the air? A. One cup B. One pint C. One quart D. One gallon
airstream
Side-Air-Discharge Condensing Units Noise generated inside cabinets discharged in ________________
positive, evaporator, condenser
The compressor is the ___________ displacement pump that pumps the heat-laden vapor from the ______________ to the _____________
high-temperature
Air-Conditioning Classified as a ___________________________ refrigeration system
demand
High-Efficiency Condensers The HVACR industry and the federal government ____________ higher efficiency
head pressure, greater surface area, lower compression ration
High-Efficiency Condensers Best method is to lower __________________ Physically larger coils -> __________________________-> lower head pressure -> _______________________ and less power consumed
air, moisture
High-temperature refrigeration, air-conditioning, or comfort cooling cools the ________ and removes the _______________
increasing, Two, mild, hot
Higher condenser efficiency is achieved by ________________ the condenser surface area. _________ speed fans may be used ----- one speed for __________ weather and the other for ________ weather
assembled, charged
Installation Procedures Completely factory _________________ and ________________ with short, efficient refrigerant lines
roof, wall, duct
Package air conditioners are installed through the ___________ or through the __________ at the end of a structure, wherever the __________ can be fastened
40 degrees F
The Evaporator Evaporator coil operates at about __________
Split-system
A refrigeration or airconditioning system that has the condensing unit remote from the indoor (evaporator) coil
compressor oil
Cooling the Compressor and Motor Lack of cooling results in damage and breakdown of _______________________
Infiltrating air
Structural Heat Gain: Conduction and Infiltration ________________ has different characteristics (humidity), depending on location, that must be taken into account
B
A typical multihead, ductless split system is configured with A. multiple outdoor units and one indoor unit B. multiple indoor units and one outdoor unit C. multiple outdoor units and multiple indoor units D. one indoor unit and one outdoor unit
average climates, 350 cfm/ton, desert areas, 55, 75, well-insulated, high
Air-Side Components Airflow is normally about 400 cfm/ton in ____________________, __________________ in coastal areas, and 450 cfm/ton in __________________ Air leaves at _____ degrees F returns at about ____ degrees F Ductwork for handler running through unconditioned space must be ____________________ Cool air distributes better from supply registers located _________ in the room
D
Air-conditioning is classified as which type of refrigeration? A. Ultra low temperature B. Low Temperature C. Medium Temperature D. High Temperature
A
Air-conditioning is often referred to as A. comfort cooling B. comfort heating C. mechanical exhausting D. mechanical ventilating
outside, waterproofing, salty
Condenser Cabinet Design Cabinets are usually located _____________, so they need ____________________ Aluminum is lightweight, but susceptible to rust in ____________ environments
small equipment
Condenser Cabinet Design Most _____________________ is assembled with self-tapping screws made of weather resistant sheet metal
grass, dirt, clean
Condenser Coil Design Vertical condenser coils may become clogged with _____________ and _________ Coils must be __________ to operate efficiently
water, evaporation, outlet, pressurize, Drip, spray or singer, rotary
Evaporative Cooling Uses fiber mounted in a frame with __________ running over the fiber as cooling media Fresh air is drawn through the fiber and cooled by _________________ Must be an _____________ for air that has entered to leave the structure or it will ________________ Three common configurations: _________-type swamp cooler, the ___________________-type swamp cooler, and the ___________-type swamp cooler
temperature, humidity
Evaporative cooling may be used in areas where the _______________ is high and the _____________ is low
fixed-bore, TXV, Electronic expansion valves (EEVs), more, faster, off, high-starting
Expansion Devices Most common types are ________________ and __________ _____________________________ are used on almost all ductless split systems TXVs are _________ efficient Evaporator reaches peak performance _________ Refrigerant pressures in TXV systems typically do not equalize during the _______ cycle, requiring compressors to use____________________-torque motors
operate, same
Package-Type and Split-Type Air-Conditioning Systems Air-conditioning, comfort cooling, or high-temperature refrigeration systems _______________ with the ____________ four main system components
Split-system air-conditioning, popular
Package-Type and Split-Type Air-Conditioning Systems Condenser outside; removed from evaporator; connected by refrigerant lines Ductless split system very __________
kill plants
Side-Air-Discharge Condensing Units Heat from the condenser coil can be hot enough to _______________ it blows on
Fan, motor
Side-Air-Discharge Condensing Units __________ and ___________ are located under top panel
walls, closed windows, closed doors, cracks
Structural Heat Gain: Conduction and Infiltration Heat enters through ________, ________________, and _____________________ by conduction, and by infiltration through ____________ around the doors and windows
air, refrigerant, sensible, latent
The Evaporator Transfers heat from _______ to ______________ Absorbing ____________ heat lowers air temperature Absorbing ___________ heat removes moisture by changing water vapor to condensate, which is drained
75 degrees F, 50%, 62.5 degrees F
The Evaporator Typical room conditions: _________ dry-bulb temperature, ________ relative humidity, ________ wet-bulb temperature
lower
The Evaporator: Humidity and Airflow When climate is humid, coil temperature may be _____________ to remove more humidity
suction gas, air
The Reciprocating Compressor Mainly cooled by _________________ and _______ passing over the shell of the compressor
hermetic, suction-gas
The Reciprocating Compressor Usually the fully _____________, ____________________ - cooled type
reciprocating, refrigerant
The Rotary Compressor More efficient than ____________________ compressors Discharges all __________________ that enters it
Stationary vane, Rotary vane
The Rotary Compressor Two basic design types ____________________________ rotary compressor ____________________________ rotary compressor
Small, light
The Rotary Compressor __________ and __________, sometimes cooled with compressor discharge gas
axial, radial
The Scroll Compressor High performance depends on good __________ and _________
highly
The Scroll Compressor Several compression stages occur simultaneously; ______________ efficient
stationary, orbiting, pockets, trapped, smaller
The Scroll Compressor Uses two spirals, one _______________ one _______________ The two scrolls form multiple individual "_____________" where refrigerant is ______________ The pockets get ______________ as refrigerant passes through the compressor
C
The condensing unit of a split-type air-conditioning system is made up of the A. metering device and evaporator coil B. compressor and metering device C. condenser coil and compressor D. evaporator and condenser coils
outside, reject
Condensers are located ____________ in order to _____________ the heat to the outside
higher
Cooling the Compressor and Motor Newer compressor motors can run at _________ temperatures
discharge
Cooling the Compressor and Motor Rotary compressors cooled with ________________ gas leaving the compressor
Technician, 225 degrees F
Cooling the Compressor and Motor _____________ should determine that discharge temperature is correct (not over ___________)
full load, 1%, 5%, 2.5%
Design Conditions Choose equipment using climate condition charts Single-speed, non-inverter-controlled equipment performs most efficiently when running at ______________ Many designers compromise between selecting for _____ and _____ conditions by choosing _______ conditions or by using variable capacity systems
Coil temperature, Airflow
The Evaporator: Humidity and Airflow ___________________ is controlled by airflow across the coil _____________ affects coil temperature
positive-displacement
The Reciprocating Compressor They are ________________________ compressors using R-22, R-410A, or R-407C refrigerants
residential, light
The Reciprocating Compressor Used in ___________________ and __________ commercial air-conditioning
Evaporative Cooler
Devices that provide this type of cooling use fiber mounted in a frame with water slowly running down the fiber. Fresh air is drawn in and through the water-soaked fiber and cooled by evaporation to a point close to the wet-bulb temperature of the air
aluminum, copper, aluminum, increase
Evaporator Coil Configurations The evaporator is a refrigeration coil made of __________________ or ________________ with __________________ fins to ______________ heat exchanger surface
