Chapter 117- Heat Exchangers For Refridgeration Systems Flashcards
Define medium
The medium is another term for the substance your working with, a cooling medium could be a refrigerant, or the medium Being cooled would be air
Two types of heat exchangers
Dry or direct
Advantage of a dry evaporator over a flooded evaporator
Size
What’s the advantage of a plate heat exchanger
Increased surface area
Three types of condesors
Air cooled
Water cooled
Evaporative
Condenser is used to remove three types of heat
Heat of compression
Sensible heat
Latent heat
Three types of water cooled condenser
Double tube
Shell and coil
Shell and tube
Evaporative condensers use both _______ and____ to provide cooling
Air and water
Name two types of operating classification of refrigeration units
Dry or direct expansion evaporator units
Flooded evaporator
Define a dry evaporator
A dry evaporator only has a small amount of refrigerant at any given time. The amount admitted equals the amount that leaves the evaporator
Define a flooded evaporator
A flooded evaporator is completely filled with refrigerant at any given time
Advantage of a flooded evaporator
High rate of heat transfer
Disadvantage of a flooded evaporator
Requires more refrigerant
Four different types of evaporator a
Bare tube
Plate surface
Finned tube
Shell and tube
Different name for a finned tube evaporator
Blast coil
Three different types of condensers
Air cooled
Water cooled
Evaporative
What must be done to a large air cooled condenser
Must be taken outside in order to provide proper heat transfer
Three types of water cooled condensers
Double tube
Shell and coil
Shell and tube
Define a double tube condenser
A small tube contained concentrically within a larger tube
Shell and coil condenser Define it
The shell and coil condenser consists of a horizontal or vertical steel shel which contains a coiled tube, either bare or finned through which cooling water circulates. Hot vapour enters the top, transfers its heat to the cooling medium and then collects in the bottom of the shell as a liquid
She’ll and tube condenser define it
Same idea as the shell and coil, but with straight tubes and water boxes at either end
Evaporative condensers define it
Use both air and water to provide cooling in order to condense the refrigerant vapour
The main benefit of a evaporating condenser
A saving of 80- 90 percent in water consumption may be achieved ideal fr area where water is in high demand
What protects a condenser from freezing during cold month while not operational
Louvers in the air vents close to prevent air movement
Defective condenser operation may result from
Dirty cooling water
Why must a condenser be vented periodically
To remove non condensable gasses
If cooling war contains scale forming salts
They may build up on your tubes lowering efficiency
What type of evaporator only contains a small amount of liquid at any given time
Dry or expansion
What type of evaporator can be easily cleaned and Eurostar manually without interrupting the cooling process
Plate surface
Which type of condenser uses the least amount of cooling water
Evaporative condenser
What is the purpose of the condenser
To remove heat from the refrigerant
Two disadvantages of a flooded evaporator
Requires more refrigerant
Requires more space
What types of actuated controls control a start stop compressor 3
Temperature
Humidity
Pressure
