ASHRAE Terminology

refrigeration is created by evaporating a refrigerant in a heat exchanger (evaporator) with the vapor then absorbed by an absorbent medium from which it is subsequently expelled by heating at a higher partial vapor pressure (in a generator) and condensed by cooling in another heat exchanger (condenser).

air conditioner whose refrigerating system has an air-cooled condenser.

a refrigerant condenser in which heat removal is accomplished entirely by heat absorption by air flowing over condensing surfaces. See also condenser, desuperheater, double-pipe condenser (tube-in-tube condenser), evaporative condenser, shell-and-tube condenser.

exchanger that transfers heat from an exhaust airstream to a separated supply airstream. Note: fixed plate, rotary wheels, heat pipes, runaround coil loops, and shell and tube condensers are the most common types.

device in the high side of an absorption system for increasing concentration of refrigerant in the vapor entering the rectifier or condenser.

condenser in which the pipes in open air are cooled by water flowing over them.

power input to devices that are not integral to the operation of the vapor compression cycle, excluding power input to integrated pumps (if present) used for liquid in either the evaporator or the condenser. Auxiliary power includes devices such as, but not limited to, oil pumps, refrigerant pumps, control power, fans, and heaters.

apparatus in which steam is condensed at reduced pressure by direct contact with water.

pipe attached to a unit, such as a condenser, to bleed off liquid refrigerant parallel to main flow.

(1) refrigerating capillary tube is a tube of small bore used for the simultaneous purposes of metering the refrigerant and of accomplishing the expansion process between condenser and evaporator in refrigerating systems. (2) small-bore tube used for metering by controlling length and bore size. In refrigeration, a tube of small internal diameter used as a refrigerant pressure and flow control between high and low sides. (3) tube used to transmit pressure from the sensitive bulb of some temperature controls to the operating element.

one having two or more refrigerant circuits, each with a pressure-imposing element, condenser, and evaporator, where the evaporator of one circuit cools the condenser of another (lower temperature) circuit.

(1) direct-expansion chillers are complete refrigerating systems consisting of a compressor, condenser, and evaporator with all operating and safety controls. Compressor types include the following: reciprocating, centrifugal, or screw design. Compare to absorption chiller. (2) refrigerating machine used to transfer heat between fluids. Chillers are either direct expansion with a compressor or absorption type.

water-cooled condenser in which water and refrigerant flow in parallel paths but in opposite directions.

dimension of the face of the coil perpendicular to the direction of the tubes. Does not include the casing. Note: height may be substituted for width if the condenser has a vertical coil orientation.

the heat exchanger that rejects heat to (cooling) or absorbs heat from (heating) a source external to the conditioned space. In the cooling mode, the coil operates as a condenser. In the heating mode, the coil operates as an evaporator.

System in which refrigeration is affected by the vaporization at low pressure in a heat exchanger (evaporator) of a liquid refrigerant, the vapor thus formed being restored to the liquid state by mechanical compression to a higher pressure and subsequent cooling in another heat exchanger (condenser).

a unitary air conditioner, for a computer and data processing room, consisting of one or more assemblies that include a DX evaporator or chilled-water cooling coil, an air-moving device, and air-filtering devices. The air conditioner may include a compressor, condenser, humidifier, or reheating device.

a heat exchanger in which the primary heat transfer vapor changes its state to a liquid phase.

a condenser constructed of pipe or tubing exposed to air

the fluid used as the condensing media in a liquid cooled, self-contained refrigerator.

the mass flow rate of liquid through the condensing unit under the conditions specified.

for water-cooled condensers, the amount of heat added to the water removed from the load, the integrated product of the flow rate through the condenser and the temperature difference across the condenser.

a water-cooled condenser with the tubes or pipes grouped in the upper portion of the shell, leaving the lower section of the shell for use as a receiver.

number of degrees that a pressurized liquid is cooled lower than its saturated temperature at that pressure.

heat exchanger tube manufactured to special requirements such as tolerances, finish, and temper.

(1) portion of the total refrigerant heat-rejecting effect of a condenser, which is used for condensing the entering refrigerant vapor to a saturated liquid at the entering refrigerant pressure. (2) the portion of the total heat rejection of a condenser that is used for desuperheating and condensing the entering refrigerant vapor to a saturated liquid. This is the product of the mass rate of refrigerant flow and the difference between the enthalpy of the entering refrigerant vapor and that of the saturated refrigerant liquid at the leaving pressure.

the site electric energy consumption of the mechanical cooling equipment including the compressor, air-distribution fan (regardless of whether the compressor is on or off), condenser fan, and related auxiliaries.

heat exchanger, preceding the condenser or incorporated in it, for removing all or part of the superheat.

sensible heat rejection from gaseous refrigerant in a condenser. Occurs prior to the gas-to-liquid phase change.

(1) system in which the cooling effect is obtained directly from the expansion of the liquid refrigerant into a vapor. (2) common term applied to an air-conditioning or refrigeration system that utilizes the vapor-compression refrigeration cycle. In a vapor-compression refrigeration cycle, the refrigerant removes heat in the evaporator by directly expanding the entering liquid refrigerant into vapor as it leaves the evaporator. The vapor is then compressed and piped to a condenser where the heat removed by the evaporator and the heat of compression are rejected to another medium so that the gaseous refrigerant is condensed to a liquid. The liquid is then piped to a pressure reducing device/metering device to be supplied to the evaporator.

(also known as hot gas line), line through which refrigerant vapor flows from a compressor to a condenser.

(1) the pressure generated on the leaving side of a fan or pump. (2) the pressure generated on the output side of a gas compressor in a refrigeration or air-conditioning system. The discharge pressure is affected by several factors: size and speed of the condenser fan, condition and cleanliness of the condenser coil, and the size of the discharge line. An extremely high discharge pressure coupled with an extremely low suction pressure is an indicator of a refrigerant restriction. It is also called high-side pressure or head pressure. (3) operating pressure in a system measured in the discharge line at the compressor or fan outlet.

condenser that contains two separate tube bundles, allowing the option of either rejecting the heat to the cooling tower or to another building system requiring heat input.

condenser constructed of concentric tubes in which the refrigerant circulates through the annular space and the cooling medium through the inner tube.

water evaporated into the atmosphere as the condenser water is cooled, typically in a cooling tower.

condenser in which the removal of heat from the refrigerant is achieved by the evaporation of water from the exterior of the condensing surface, induced by the forced circulation of air and sensible cooling by the air.

automatic valve, located between the air-cooled condenser and the receiver, that will back up liquid in the condenser to reduce the effective area of the condenser, thus keeping the discharge pressure to a predetermined minimum value during low ambient temperatures. Used in conjunction with a pressure differential valve between the discharge line and the receiver.

thermodynamic heating/refrigerating system to transfer heat. The condenser and evaporator may change roles to transfer heat in either direction. By receiving the flow of air or other fluid, a heat pump is used to cool or heat. Heat pumps may be the air source with heat transfer between the indoor air stream to outdoor air or water source with heat transfer between the indoor air stream and a hydronic source (ground loop, evaporative cooler, cooling tower, or domestic water).

pressure-responsive device that cycles and/or stages condensers, cooling-tower fans, and pumps to control head pressure.

(also known as high side), that portion of a refrigerating system operating at approximately the condenser pressure.

found only in double-effect machines. This type of condenser is typically inside of the tubes of the second-stage generator.

tube or pipe carrying the refrigerant liquid from the condenser or receiver of a refrigerating system to a pressure-reducing device.

an encased, factory-made assembly or assemblies designed to be used as permanently installed equipment to provide conditioned air to an enclosed space(s). It normally includes multiple evaporators, compressor(s), and condenser(s). Such equipment may be provided in more than one assembly, the separated assemblies of which are intended to be used together.

(1) a plan for gathering of relevant measurement data over time to evaluate equipment or system performance. The plan defines specific M&V methods to be used, including baseline determination, performance period measurements, savings verification calculations, and acceptance criteria. The M&V methods chosen are consistent with the current facility requirements (CFR). During the implementation phase, a list is developed of specific instrumentation and data-gathering equipment that must be maintained at the site. During the hand-off phase, the type, frequency, and distribution of M&V reports to be submitted for approval is confirmed. (2) equipment to measure and record the parameters of the HVAC&R systems (i.e., temperature, humidity, pressure, electric current, kW, and volts). (3) gathering of relevant measurement data over time to evaluate equipment or system performance (e.g., chiller electric demand, inlet evaporator temperature and flow, outlet evaporator temperature, condenser inlet temperature, and ambient dry-bulb temperature and relative humidity or wet-bulb temperature, for use in developing a chiller performance map (e.g., kW/ton versus cooling load and versus condenser inlet temperature).

condenser consisting of a number of closed shell-and-tube units.

condenser in which the water passes in a film over the inner surfaces of the tubes, which are open to the atmosphere.

(1) air-cooled condenser consisting of plates between which are arranged channels for the circulation of refrigerant. (2) water-cooled condenser consisting of a coil through which the refrigerant circulates, arranged between two plates, with water circulating between coil and plates.

(1) any refrigerant-containing receptacle in a refrigerating system. This does not include evaporators where each separate evaporator section does not exceed 0.5 ft3 (0.014 m3) of refrigerant-containing volume regardless of the maximum inside dimension. This also does not include evaporator coils, compressors, condenser coils, controls, headers, pumps, and piping. (2) container for fluids at a pressure different from atmospheric pressure (vacuum to high), capable of withstanding associated stresses.

of refrigerant, withdrawal of all refrigerant from the low side of a system by pumping it to either the condenser or the liquid receiver.

an automatic, semiautomatic, or hand-operated device that collects gases from the condenser or receiver, condenses the condensable refrigerant therefrom, and releases the remainder to the atmosphere.

(1) a condition pertaining to air-cooled condensers in which a portion of the discharge air enters along with the fresh air, the amount of recirculation is determined by equipment design, placement in regard to adjoining objects, and atmospheric conditions. The effect is generally evaluated on the basis of the decrease in unit capacity. (2) condition pertaining to cooling towers and evaporative condensers in which a portion of the discharge air enters along with the fresh air, the amount of recirculation is determined by equipment design, placement in regard to adjoining objects, and atmospheric conditions. The effect is generally evaluated on the basis of the increase in entering wet-bulb temperature compared to the ambient.

(1) externally cooled heat exchanger in the high side of a refrigerating absorption system for condensing absorbent and separating it from the refrigerant before passing it to the condenser. (2) in electricity, a device for converting AC to DC current.

total useful capacity of a refrigerant condenser for removing heat from the refrigerant circulated through it.

heat exchanger, after the condenser, for subcooling the condensed refrigerant.

interconnected parts forming a closed circuit in which refrigerant is circulated and having the condenser located to transfer heat to the zone to be heated.

a system that, in operation between a heat source (evaporator) and a heat sink (condenser) at two different temperatures, absorbs heat from the heat source at the lower temperature and rejects heat to the heat sink at the higher temperature. See also refrigerating unit.

unit assembly composed of a compressor, evaporator, condenser, and expansion device, used for refrigerating and for extracting heat.

parts subjected to approximately the condenser pressure.

refrigerating equipment forming a part of the refrigerating system, including any or all of the following: compressor, condenser, generator, absorber (adsorber), liquid receiver, connecting piping, and evaporator.

valve capable of regulating the flow of water through a condenser according to changes in condensing pressure or water temperature.

defrosting an evaporator by reversing its function with that of the condenser.

the saturation temperature corresponding to the measured refrigerant pressure at the condenser inlet for single component and azeotropic refrigerants, and the arithmetic average of the refrigerant dew-point temperature and the bubblepoint temperature corresponding to the refrigerant pressure at the condenser entrance for zeotropic refrigerants.

substance added to water used in condensers, boilers, piping, and cooling towers to prevent or minimize the formation of insoluble deposits.

condenser cooled by the evaporator of a secondary system.

(1) the fluid that flows through the condenser as a coolant. (2) fluid that flows through a heat exchanger that transfers thermal energy from the primary transfer fluid to the application that uses solar energy.

condenser in which the cooling medium circulates in a coil located in a shell containing the condensing refrigerant.

condenser consisting of an outer shell containing multiple tubes.

compression from evaporator to condenser pressure by passing through one compressor stage only.

condenser comprising several heat-exchanging components operating on one or several refrigeration systems.

additional refrigeration effect made available by subcooling the refrigerant liquid in the condenser.

(submerged condenser), condenser in which the piping is submerged in a vessel containing cooling water.

total useful capacity of a refrigerant condenser for removing heat from the refrigerant circulated through it.

condenser consisting of a tube inserted in a second tube in a helical coil, serpentine coil, or parallel tubes.

(1) an assembly of cooling coils with drain pan, fan, and enclosure. (2) direct cooling, factory made encased assembly including an air-cooling coil, refrigerating compressor and condenser, fan and motor (usually), and directional outlet, including the necessary automatic controls.

one or more factory-made assemblies that normally include an evaporator or cooling coil and a compressor and condenser combination.

refrigerating cycle using an ejector to compress the refrigerant vapor from the evaporator to the condenser. The term steam jet is used when water is the refrigerant.

an automatic valve that controls the flow of cooling water through a condenser to maintain a set condensing pressure.

a heat exchanger that uses the condenser water side of the system for cooling without requiring the operation of the chiller. Also a coil on the air entering side of a heat pump or HVAC unit that uses condenser water flow to precondition the entering air when conditions are favorable. See also cooling.