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For commercial and industrial refrigeration systems, the kilowatt (kW) is the basic unit of refrigeration, except in North America, where both ton of refrigeration and BTU/h are used. A refrigeration system's coefficient of performance (CoP) is very important in determining a system's overall efficiency. It is defined as refrigeration capacity ...
Thermodynamic heat pump cycles or refrigeration cycles are the conceptual and mathematical models for heat pump, air conditioning and refrigeration systems. [1] A heat pump is a mechanical system that transmits heat from one location (the "source") at a certain temperature to another location (the "sink" or "heat sink") at a higher temperature. [2]
A representative pressure–volume diagram for a refrigeration cycle. Vapour-compression refrigeration or vapor-compression refrigeration system (VCRS), [1] in which the refrigerant undergoes phase changes, is one of the many refrigeration cycles and is the most widely used method for air conditioning of buildings and automobiles.
HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR (as in the designation of HACR-rated circuit breakers).
Common absorption refrigerators use a refrigerant with a very low boiling point (less than −18 °C (0 °F)) just like compressor refrigerators.Compression refrigerators typically use an HCFC or HFC, while absorption refrigerators typically use ammonia or water and need at least a second fluid able to absorb the coolant, the absorbent, respectively water (for ammonia) or brine (for water).
Members of ASHRAE receive the current volume, in both print and CD-ROM form, each year as a basic membership benefit. An enhanced electronic version, known as ASHRAE Handbook Online is a web-based version updated annually that contains the four latest volumes as well as extra content such as calculations, demonstration videos, and spreadsheets.
The refrigeration process uses a mixture of two isotopes of helium: helium-3 and helium-4.When cooled below approximately 870 millikelvins, the mixture undergoes spontaneous phase separation to form a 3 He-rich phase (the concentrated phase) and a 3 He-poor phase (the dilute phase).
A basic refrigeration cycle consists of four major elements: a compressor, a condenser, a metering device and an evaporator. As a refrigerant passes through a circuit containing these four elements, air conditioning occurs. The cycle starts when refrigerant enters the compressor in a low-pressure, moderate-temperature, gaseous form.