Appendix 1 - Glossary - Daikin R-22 Refrigerant Piping Design Manual

Appendix 1 — Glossary
Accumulator (Suction): A device installed just before a
compressor in the suction line that is used to separate vapor
refrigerant from liquid refrigerant and oil. They are common in
heat pumps and industrial refrigeration applications.
Adiabatic Process: A process where energy gain to the
surroundings is zero. Enthalpy remains constant for the fluid.
An example is the refrigeration expansion process.
ASC (Auxiliary Side Connector): A fitting used in conjunction
with a distributor to introduce hot gas refrigerant into the
distributor for hot gas bypass.
Azeotropic Refrigerants: Refrigerant blends that behave as a
single substance. An example is R410A.
Carnot Cycle: The ideal, reversible heat cycle between two
infinite heat sinks.
Check Valve: A valve that only allows flow in one direction.
Used in refrigeration systems to stop refrigerant migration
when the system is OFF.
Compressor: A component in a refrigeration system that
compresses refrigerant vapor to a higher pressure and
temperature and consumes power to do so.
Condenser: A component in a refrigeration system where
refrigerant is condensed from a gas to a liquid and heat is
rejected to the surroundings.
COP (Coefficient of Performance): The measure of the
refrigeration system efficiency. Defined as refrigeration effect
per compressor power.
Critical Point: The point on a P-H Diagram where the
saturated liquid and saturated vapor lines meet. Above the
critical point, condensation cannot occur.
Density (d): The mass of a substance divided by the volume
that substance occupies. It is measured in pounds per cubic
foot (lb/ft³) or kilograms per meter cubed (kg/m³).
Desuperheater: A device that removes superheat from either
the suction or discharge gas line. This heat may be used in a
heat recovery application such as hot water heating.
Direct Expansion (DX) Evaporator: An evaporator where the
refrigerant is in the tubes. Used for either refrigerant to air coils
or chillers.
Discharge (hot gas) Line: A refrigerant line that carries
superheated, high pressure refrigerant from the compressor to
the condenser.
Discharge Muffler: Used to reduce sound and pulsations
inrefrigerant lines. They are typically installed in discharge lines
near the compressor.
Distributor: A device that feeds two phase refrigerant evenly
to each tube of a DX evaporator. It is usually part of the coil
and is directly down stream of the TX valve.
www.DaikinApplied.com
Economizer (Refrigerant): A form of two stage refrigeration
cycle where the compressor has a port that allows
refrigerant at an intermediate pressure to be injected into the
compression process.
EER (Energy Efficiency Ratio): Refrigeration effect in British
thermal units per hour per power input in watts (Btu/hr•W).
Enthalpy (h): The measure of energy content in a fluid.
Measured in British thermal units per pound (Btu/lb).
Entropy (s): The measure of molecular disorder of a
substance. A process without change in entropyis considered
ideal and reversible. Measured in British Thermal Units per
pound–degree Rankin (Btu/lb°R)
Evaporator: A component in a refrigeration system where
refrigerant is boiled from a liquid to gas and heat is absorbed
from the surroundings. It is the component that performs the
cooling effect.
Expansion Device: A component that reduces the pressure
and temperature adiabatically in a refrigeration system. There
are several types but a thermal expansion (TX) valve is most
common for air conditioning applications. The device is located
in the liquid line as close to the evaporator as possible.
Filter-Drier: A device used to filter refrigerant to remove
contaminants. It also contains a desiccant that removes
moisture from the refrigerant. Installed on liquid and/or
suction lines.
Flashing: Partial or total vaporization obtained by sudden
reduction of pressure.
Flash Tank: A component in a refrigeration system used
to separate liquid refrigerant from vapor at an intermediate
pressure. Commonly used in two stage refrigeration cycles.
Floodback: A process where liquid refrigerant forms and
moves to the lowest or coldest part of the refrigerant circuit.
When unplanned for, floodback is detrimental to the operation
of the refrigeration system.
Flooded Evaporator: For chiller evaporators, the refrigerant
is outside the tubes and all the tubes are submersed in liquid
refrigerant.
Glide: The change in volumetric composition and saturation
temperature experienced by Zeotropic refrigerants during
boiling.
Head Pressure Control Valve: A pressure regulating valve
that diverts flow around the condenser as the pressure drops.
This is used as part of liquid flood back head pressure control
system.
Hot Gas Bypass: A method of maintaining suction pressure
to the compressor during periods of light load by recirculating
discharge gas from the leaving side of the compressor back to
either the inlet of the evaporator or the suction line.
37 AG 31-011 • REFRIGERANT PIPING DESIGN