Phase 9 2
24
A commercial systems total heat load represents the amount of heat that the system must remove in a ...... hour period
Series
A compound refrigeration system has more than one compressor connected in .....
Expansion tank
A cylinder with a pressure responsive bladder that accounts for changes in secondary loop pressure describes a .....
Compression
A multi stage system has more than one stage of .....
Precise humidity control
A primary benefit of using hot gas bypass as a method of capacity control is ......
Saturated
A substance in vapor form that is in the presence of some of its own liquid is a ..... vapor
Eutectic plate
A thin rectangular tank containing an evaporator surrounded by a solution that freezes at a desired temperature is a .....
Exhaust
Compressor efficiency will be reduced when extra pressure is generated in a reciprocating compressor cylinder because it's ...... value is stuck
Each evaporator has its own TXV
Concerning a commercial refrigeration system with multiple evaporators .......
Sublimate
Dry ice that is indoors atmospheric pressure and temperature that is comfortable to humans will most likely ......
Bends, fittings, valves
Excessive pressure drop can be caused by refrigerant line that has too many
Flash gas
Excessivepressure.com cause ..... in a liquid line
Air film
For air cooling evaporators the heat must pass through a ....... on the evaporator tubing
500 fpm and 700 fpm
For horizontal section lines the refrigerant velocity is normally between
Thickness decreases
Heat leakage into a refrigerant cabinet will increase as the cabinet wall ........
Smaller
Heat leakage into a refrigerated cabinet increases the ..... it's exterior area is
Temperature difference between inside and outside increases
Heat leakage into a refrigerated cabinet will increase as
Smaller
Heat leakage into the refrigerator cabinet increases the ...... its exterior area is
Higher pressure
In a commercial refrigeration system with two evaporators one of the evaporators must maintain a ...... In order to maintain a higher temperature than the other evaporator
Copper ACR tubing
In a secondary loop refrigeration system the primary loop is usually built with ......
Plastic piping
In a secondary loop refrigeration system the secondary loop is built with ....
An EPR Is used on the evaporator at the higher temperature
In a single commercial refrigeration system that controls two different evaporators at different temperatures .......
Dyed
Leaks in the secondary loop are easy to detect because the fluid is ......
Condenser is warmer than the compressor
Liquid refrigerant migration from the condenser to the compressor as possible during the off cycle when the ......
404A
Low temperature and medium temperature refrigeration system used in trucks and trailers typically use ......
134A
Medium temperature in high temperature refrigeration system used in trucks and trailers typically use ......
Respiration
Part of the service heat load includes removing ...... heat from fresh vegetables and meat
Installations with a large amount of ease heat
Refrigerant jet systems are mostly used on .....
Site
Refrigeration systems that are split are essentially ...... engineered
Water cooled condenser
Since there may be an adequate airflow around the outside of refrigerated intermodal shipping containers on long trips these systems often use .....
Refrigerant line material
The basic material that must be considered when sizing refrigerant lines are the following except for
1/4
The compressor discharge line should be sloped toward the condenser a minimum of ..... per 10' of run
Ambient design
The condensing temperature is the ....... temperature plus the temperature difference
Compressor
The degree of superheat is the difference between the refrigerant evaporating temperature and the temperature of the paper at the ..... inlet
Balancing valve
The fluid flowing into the condition spaces of a secondary loop system is controlled by a .....
Does not change phases
The fluid used in the secondary loop of a secondary loop refrigeration system differs from the traditional refrigerant. However the primary operational difference is that it ......
Head pressure
The greater the ...... The lower the volumetric efficiency
Clearance space
The greater the ....... The lower the volumetric efficiency
Service heat load
The heat due to air changes the temperature of articles put into the cabinet additional heat brought into the cabinet due to operation and heat generated inside the cabinet by fans lights and other electrical devices is accounted by ......
Fins per inch
The initials for FPA stands for
1 inch
The key value and see value for a material is equal when the material is exactly ..... thick
Low side pressure
The lower the ...... the lower the volumetric efficiency
U value
The measurement that takes into account the insulation value of boundary film is the
Sever burn and instant frostbite
The most common dangers of touching gray ice with bare skin are ......
The electrical grid
The most common way of driving a compressor in a refrigerated trailer when the trailer is idle is power from ....
A diesel powered generator
The most common way of driving a compressor in a refrigerated trailer when the trailer is moving in in operation is power from ....
Tank insulation
The primary factors that affect the heat transfer rate of a liquid cooling evaporator are the following except for
Desuperheat
The purpose of an inner cooler in a compound refrigeration system is to ...... refrigeration
Condenser condensate
The refrigerant line that should have a pressure drop of 0 psi and a velocity of 100 FPM or less in the ...... line
Flash gas
The refrigerant that immediately vaporizers as it passes through the metering device is referred to as ......
500 fpm and 700 fpm
The refrigerant velocity in horizontal run of the compressor discharge line is between ......
Thermal energy into mechanical energy
The sterling cycle is a close cycle that can convert ...... and vice versa
2
The suction line should be sized so the maximum pressure drop is equal to a saturation temperature drop of ........
Quench vave
The system component that opens as needed to allow sufficient liquid refrigerant flow into the suction line to cool the compressor motor is the .......
Hot gas solenoid valve
The system component that opens to allow refrigerant vapor discharge by the compressor to enter the evaporator is the ....
Subcooler
The system component that removes additional heat from refrigerant leaving the liquid receiver to help ensure that only liquid refrigerant enters the thermostatic expansion valve is the ......
Fluid flow
The temperature of a condition space in a secondary loop system is primarily controlled by ......
Refrigerant quantity
The term referring to a refrigerants amount of saturated liquid and saturated vapor is ......
Heat leakage load
The total amount of heat that leaks through the walls windows ceiling and floor of the cabinet per unit of time describes the ......
15%
To account for a refrigerant circuit that could become restricted a commercial refrigeration systems liquid receiver should be size ..... larger than the total liquid volume in the system
Keep cooler
To cool a condenser using seawater many boats use a ...... which runs the condensing tubing outside the hull to take advantage of seawater's ability to absorb heat
True
True or false? A substance that is warmer than its surrounding will lose heat until the substance calls to the ambient temperature
True
True or false? Dry ice is sometimes used as an expandable secondary refrigerant
False
True or false? Expandable liquid nitrogen refrigeration systems may not require much power to operate but they have intensive maintenance requirements
True
True or false? If the inside of a refrigerator cabinet is cooler than the air outside of the cabinet heat from the surrounding air will tend to through the materials of the cabinet to the space inside
False
True or false? Low pressure vapor nitrogen absorbs heat from the condition space as it condenses into low pressure nitrogen liquid
True
True or false? The amount of latent heat contained in vaporizing and in condensing refrigerant changes at different pressures
False
True or false? The common unit used to measure surface area and heat flow calculations is cubic inch
False
True or false? The cooling capacity of a modulating refrigeration system is adjusted merely by turning the system on or off
False
True or false? Thermal couples are energized to move heat when electric current is applied
True
True or false? When the cold air inside a refrigerated space spills out through the bottom of the door opening warmer room air moves into the refrigerated space
False
True or false? When the physical state of a material changes its specific heat remains the same
Increases the temperature and pressure
When a compressor compresses refrigerant vapor decreases the volume of the vapor which in turn ..... of the vapor
Increase the temperature and pressure
When a compressor compresses refrigerant vapor it decreases the volume of the vapor which in turn ....... of the vapor
Mildew and mold
When choosing a compressor for a commercial refrigeration system relative humidity must be considered because levels out of range can promote the growth of
Peltier
When current is passed through the junction of two dissimilar metals he is absorbed in one part of the junction and move to another part of the junction this describes the ..... effect
Reduce proper distribution of oil
When hot gas is bypassed into the suction line instead of into the evaporator inlet the system is likely to suffer from ......
All the compressors operate
When there is nearly the maximum amount of heat to move in a multiple compressor system ........
Only one compressor runs
When there is very light and steady load and only a small amount of heat to move in a multiple compressor system .....