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 .....