Demystifying Refrigeration
Michael Michrowski
Vice President of Sales
Utility Refrigerator
CSNA”s 62nd Annual Conference
November 16, 2014
Sacramento, CA
Presentation Overview
• Basic System Components
• Refrigeration Cycle
• Metering Devices
• Controls
• Accessorial Components
• Proper Care of Refrigeration Equipment
• Question and Answer Session
Basic Refrigeration System
Components
• Condenser Coil
• Metering Device
• Evaporator Coil
• Compressor
Condenser Coil
• Radiator looking component which exhausts heat
into ambient air
• Located on top or on bottom of self-contained units
• Located outside typically for remote installations
• Critical that coil stays clean and has room to breathe
Metering Device
• Used to regulate the amount of refrigerant flowing
through the evaporator coil
• Maintains a balance between system capacity and
cooling demand
• When properly selected, the right metering device
will improve efficiency, decrease compressor run
time, and prolong life of system
Evaporator Coil
• Removes heat from inside of refrigerator/freezer
• Allows refrigerant to absorb heat from warm product
and transfer it outside
• Has similar construction and function to condenser
coil
• Must have unobstructed airflow to work properly
Compressor
• The heart of the refrigeration system
• Compresses heat laden gas (refrigerant) enabling
heat to be removed by condenser coil
• Life of compressor can be extended by keeping
condenser coil clean and preventing system from
operating under low pressure conditions
Refrigeration Cycle Theory
• Compressor compresses refrigerant into high pressure vapor, which
flows to condenser coil
• Air flows over condenser coil, causing vapor to condense into liquid as
heat is transferred to ambient environment
• High pressure liquid flows from condenser to metering device
• Metering device regulates liquid flow into evaporator
• Air flows over evaporator coil, causing liquid refrigerant to evaporate
and become vapor as it absorbs heat from conditioned space
• Refrigerant returns to compressor as low pressure vapor to begin cycle
again
Refrigeration Cycle
Metering Devices
• Two types of refrigerant metering devices are commonly used
in commercial refrigeration:
– Capillary Tube
– Expansion Valve
• Main difference between two types:
fixed vs. demand-based metering
– Layman’s analogy: single speed vs. multi- speed automobile
transmission
Capillary Tubes
• Capillary tubes are designed for a specific set of conditions and
work well when these conditions remain constant:
– Ambient temperature
– Box load
– Amount of refrigerant in system
– Infiltration of warm air (doors opening and closing)
• Deviation from ideal design conditions results in long pulldown
times, excessive compressor run times, and difficulty maintaining
temperature, wasting energy and compromising food safety
Drawbacks of Capillary Tubes
• Capillary tube systems depend on a critical
refrigerant charge - over or undercharged systems
will not work properly, making service difficult
• Capillary tubes cannot adjust to changing demand,
making them fixed systems
• Systems with capillary tubes function like a
transmission with one speed, unable to vary flow as
conditions change
How Expansion Valves Work
• Valve constantly monitors cooling demand and
adjusts refrigerant flow accordingly
• Maintain a balance between evaporator inlet and
outlet temperature, no matter the conditions
• Able to make adjustments and rebalance system
instantaneously
Benefits of Expansion Valve Systems
• Systems are reactive and work only as hard as
necessary-saving money and prolonging life
• Refrigeration can function efficiently both during
periods of light and heavy demand
• Run times are shorter and pulldown is faster because
valve constantly optimizes refrigerant flow
• Service friendly since charge is not critical and valve
is less sensitive to leaks
Why Are Cap Tubes Used?
• Capillary tubes are significantly less expensive than
expansion valves
• Allows predictable resource utilization under mass
production, saving time and money
• Makes sense for certain types of refrigeration where
usage is constant
– Water coolers
– Domestic-type units
A Final Note on Metering Devices
• FACT: Many manufacturers of air conditioning
systems made the switch from capillary tubes to
expansion valve to comply with the SEER 13 energy
requirements in 2007
Controls
• All refrigeration systems require some type of control to
maintain proper temperature
• Controls modulate the compressor based on either
temperature or low pressure
– Temperature controls activate cooling based on air temperature
(e.g. thermostats, digital controls)
– Pressure controls monitor refrigerant returning to compressor
from coil, activating compressor based on evaporator temperature
(actual cooling demand)
– Added benefit of pressure controls is burnout prevention
Accessorial (Optional)
Components
• Receiver
• Service Valves
• Access Ports
• Sight Glass
Refrigerant Receiver
• Receiver: a refrigerant storage tank
– Collects excess refrigerant during normal operation
– Allows pumpdown during service and diagnosis
– Pumpdown uses the suction power of the compressor
to remove all refrigerant from the system and store it
in the receiver tank
– Eliminates the need to evacuate, reclaim, and
recharge refrigerant, saving considerable time and
money
Service Valves
• Allow isolation of portions of the system
– Used during refrigerant pumpdown
– Allows testing of compressor by checking suction
– Works in conjunction with access ports
• Often referred to as “King” (high side) and “Queen”
(low side) valves
Access Ports
• Access Ports
– Also known as service ports
– Allow easy connection of gauges and addition of
refrigerant
– Eliminates the need for saddle or piercing valves
often required on sealed systems
– Preferable to have high and low side ports for
proper system diagnosis and ease of service
Sight Glass
• Window into the refrigeration system
• Allows for quick and easy diagnosis without tools or
previous knowledge
• Shows leaks and presence of moisture
• Eliminates any guesswork from recharging or adding
refrigerant
Proper Care of Refrigeration
Equipment
• Most critical item is keeping condenser coil clean
– Keeping coil clean will prolong life of system; neglecting it will
significantly reduce compressor life
• Adequate ventilation is key, both inside and outside box
• Clean interior and exterior surfaces regularly, including gaskets!
– Use warm soap and water or diluted vinegar inside
– Stainless steel cleaner ideal for outside of unit
• If something goes wrong:
– Does unit have power? Is unit not working at all or cooling poorly?
Questions and Answers
THANK YOU FOR YOUR TIME AND
PARTICIPATION!