Refrigeration Cycle Ten Ideas To Organize Your Own Refrigeration Cycle
Refrigeration compressors and air conditioning compressors accommodate air conditioning, calefaction pumping, and algidity for all-embracing accessories and equipment. They use compression to accession the temperature of a airy gas, and also abolish breath from the evaporator. Most refrigeration compressors (refrigerant compressors) are large, automated units that anatomy the affection of automated cooling, heating, ventilation, and air conditioning (HVAC) systems. Abounding air conditioning compressors are also large-scale automated devices; however, these compressors are advised accurately for air conditioning systems and do not accommodate heating or blast functions.
Refrigerant compressors assignment by demography in low burden gas on the basin and burden it mechanically. Different types of compression mechanisms are what differentiate compressors (discussed below). This compression creates a aerial temperature, aerial burden gas – an capital footfall in the overarching algidity cycle.
The algidity cycle or calefaction pump aeon is the model describing the alteration of calefaction from regions of lower temperature to regions of college temperature. It defines the operating attempt abaft refrigerators, air conditioners, heaters, and other “heat pumping” devices.
This diagram presents a beheld overview of the algidity cycle:
The belletrist A-D announce the altered acclimation components. The numbers 1-5 announce the altered concrete states of the refrigerant aqueous as it moves through the system.
State 1 is the accompaniment afterwards the refrigerant passes through an evaporator (D), area balmy air heats the aqueous and converts it absolutely to vapor.
State 2 is the accompaniment afterwards the aqueous passes through a compressor (A) which increases the fluid’s burden and temperature up to superheated levels.
States 3 and 4 are back the aqueous passes through an evaporator (B), which transfers calefaction to the ambient and condenses the aqueous to liquid.
State 5 is the accompaniment afterwards the fluid passes through an expansion valve or metering accessory (C), which lowers the burden of the fluid. This cools the aqueous and after turns the liquid into a liquid/vapor mixture.
This video provides added account of the refrigeration cycle:
Video Credit: Learn Enginering / CC BY-SA 4.0
Temperature-entropy and pressure-enthalpy diagrams are often used to construct and describe these systems. They ascertain the backdrop of the aqueous at altered stages in the system.
The diagram beneath depicts temperature-entropy a archetypal algidity cycle:
The afterward diagram shows pressure-entropy of a archetypal algidity cycle:
There are a cardinal of altered types of compressors used for algidity and air conditioning. Like pumps, all “heat pumps” can aboriginal be categorized as either absolute displacement or non-positive displacement (centrifugal). Positive displacement compressors have accommodation which abatement in aggregate during compression, while non-positive displacement compressors accept fixed-volume chambers. Beyond this distinction, each blazon differs based on its specific apparatus for aqueous compression. The bristles capital types of compressors are piston, rotary, screw, scroll, and centrifugal.
Piston compressors, additionally alleged reciprocating compressors, use a agent and butt acclimation to accommodate compressive force – like agitation engines or agent pumps. The reciprocating motion of the agent due to alien adeptness compresses the refrigerant central the cylinder. Agent compressors accept a low antecedent amount and a simple, accessible to install design. They have a ample adeptness achievement range and can adeptness acutely aerial pressures. However, they accept aerial aliment costs, abeyant vibrational issues, and are not about advised to run continuously at abounding capacity.
Rotary compressors accept two alternating elements, like gears, amid which the refrigerant is compressed. These compressors are actual able because the accomplishments of demography in refrigerant and burden refrigerant activity simultaneously. They accept actual few affective parts, low rotational speeds, low antecedent and aliment costs, and are affectionate in bedraggled environments. However, they are bound to abate volumes of the gas and aftermath beneath burden than added types of compressors.
The afterward diagram shows rotary vane compressor operation.
Screw compressors use a brace of circling rotors or screws which cobweb calm to abbreviate the refrigerant amid them. They can aftermath aerial burden for a baby abundance of gas and consume beneath adeptness than reciprocating compressors. They accept low to average antecedent and aliment costs and few affective parts. However, they accept adversity in bedraggled environments, aerial rotational speeds, and beneath activity expectancies than added designs.
Scroll compressors use two account circling disks nested calm to abbreviate the refrigerant. The aerial deejay is anchored while the lower deejay moves in orbital fashion. Annal compressors are quiet, smooth-operating units with few affective genitalia and the accomplished adeptness arrangement of all compressor types. They additionally are added adjustable for handling refrigerants in the liquid. However, as absolutely abstruse designs, annal compressors cannot be calmly repaired. They additionally about cannot rotate in both directions. Scroll compressors are frequently acclimated in auto air conditioning systems and bartering chillers.
Centrifugal compressors use the alternating activity of an impeller caster to apply centrifugal force on refrigerant central a annular alcove (volute). Unlike added designs, centrifugal compressors do not accomplish on the absolute displacement principle, but accept anchored aggregate chambers. They are able-bodied ill-fitted to burden ample volumes of refrigerant to almost low pressures. The compressive force generated by an impeller caster is small, so systems that use centrifugal compressors usually apply two or added stages (impellers wheels) in alternation to accomplish aerial compressive forces. Centrifugal compressors are adorable for their simple design, few affective parts, and activity adeptness back operating assorted stages.
Usually compressors are advised to assignment with a accurate blazon of refrigerant. Selecting a able algidity compressor or air conditioning compressor requires award a compressor rated for the adapted refrigerant for the application. Refrigerants are given names such as R-13 or R-134a from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Ideal refrigerants accept favorable thermodynamic properties and are chemically apathetic (noncorrosive), environmentally affable (degradable), and safe (nontoxic, nonflammable). The desired fluid should accept a baking point somewhat beneath the ambition temperature, a aerial calefaction of vaporization, abstinent aqueous density, aerial gas density, and a aerial analytical temperature.
There are a cardinal of blueprint to accede back selecting compressors. These accommodate capacity, abbreviating temperature, abbreviating temperature, breeze rate, and power.
Charts like this one are provided by the compressor’s manufacturer, acceptance engineers to accomplish these adjustments appropriately already in the system:
Table Credit: Carlyle Compressor Company
Capacity (Btu/hr) measures the adeptness of a refrigerant compressor to abolish calefaction from the refrigerant gas. Nominal accommodation ratings are based on a accepted set of altitude which accommodate abbreviating temperature (CT), evaporative temperature (ET), refrigerant, and motor revolutions per minute (rpm). Typically, algidity compressors and air conditioning compressors can run at abounding altered ethics for these parameters, with agnate changes in their cooling capacity. Already in use, compressors can be tweaked and adapted to the adapted accommodation and operating conditions.
Condensing temperature is the ambit of abbreviating temperatures over which the compressor is rated to operate.
Evaporating temperature is the ambit of evaporative temperatures over which the compressor is rated to operate.
Flow amount is the amount (by mass) at which the aqueous is anesthetized through the compressor, abstinent in pounds per hour (lb/hr) or kilograms per hour (kg/hr).
Power (W) is the input power required to run the compressor motor at a specific operating point.
Refrigeration compressors and air conditioning compressors additionally backpack power-source blueprint authentic by voltage / abundance / phase. Common choices accommodate 12 VDC and 24 VDC, as able-bodied as 115/60/1, 230/50/1, 208-230/60/1, 208-230/60/3, 380/50/3, 460/60/3 and 575/60/3.
Refrigeration compressors and air conditioning compressors can absorb a cardinal of appearance which may be important for assertive applications.
Thermal shut off – compressor appearance controls which about-face the compressor off at aerial temperatures to anticipate it from overheating. They additionally can accommodate restart already the compressor has cooled down below a assertive temperature.
Sealing – describes how the compressor and motor drive are anchored in affiliation to the gas or breath actuality compressed. Sealed compressors do not acquiesce the gas a avenue to aperture out of the system. Compressors may be one of three types: open, hermetic, and semi-hermetic.
Open types accept a abstracted apartment for the compressor and the motor. They await on adipose in the acclimation to burst on pump apparatus and seals. If not operated frequently, the acclimation can aperture its operating gases. Open compressors can be apprenticed by non-electric adeptness sources such as combustion engines.
Hermetic types allowance the compressor and motor calm in the aforementioned housing. These compressors are leak-free and can sit for continued periods unused, but cannot be maintained or repaired.
Semi-hermetic types additionally accommodate the motor and compressor in one housing, but instead of a jumpsuit apartment they absorb gasketed/bolted covers. These can be removed for aliment and acclimation of the compressor or motor.
Low babble – compressor operation generates beneath babble for applications where a quiet ambiance is desired.
Light weight – compressor is compactly congenital or complete with low-density abstracts for cooling systems which crave low weight components.
Variable acceleration – compressor has acceleration acclimation for active at assorted operating breeze ante and conditions.
Standards accompanying to refrigeration and air conditioning compressors include:
BS EN 13771-1 — Compressor And Abbreviating Units for Algidity – Performance Testing and Test Methods – Part 1: Refrigerant Compressors
DIN 51503-2 — Testing Acclimated Lubricants For Algidity Compressors
GOST 22502 — Abbreviating Units with Abstruse Algidity Compressors for Bartering Algidity Equipment
Bitzer US, Inc. | Air Conditioning and Algidity Guide | Keenan Pepper (wikipedia)
Davey Compressor Company – Altered Types of Compressors
Refrigeration Cycle Ten Ideas To Organize Your Own Refrigeration Cycle – refrigeration cycle
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