Vapor-compression refrigeration

Vapor-compression refrigeration
Cmglee · CC BY-SA 3.0 · source
Name	Vapor-compression refrigeration
Invented	19th century
Type	Mechanical refrigeration

Vapor-compression refrigeration is a mechanical refrigeration cycle widely used for cooling and air conditioning by compressing and expanding a working fluid to absorb and reject heat. Developed in the 19th century, the technology underpins household Refrigerators, industrial Cold storage facilities, and large-scale HVAC systems, and integrates with standards and institutions such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers and regulations influenced by agreements like the Montreal Protocol and Kyoto Protocol. The cycle is central to engineering practice in firms like Carrier Global Corporation, Daikin Industries, and Johnson Controls and is studied in curricula at institutions such as the Massachusetts Institute of Technology, Imperial College London, and Tsinghua University.

Overview

Vapor-compression systems employ a circulating Refrigerant that alternately evaporates and condenses to transfer heat between environments, an approach rooted in early experiments by inventors contemporaneous with the Industrial Revolution and commercialized by companies including Frigidaire and Westinghouse Electric Corporation. The method contrasts with absorption refrigeration used by entities such as Trane Technologies and thermoelectric devices developed from work at the Bell Laboratories. Modern uptake spans commercial players like Walmart for cold-chain logistics, military logistics managed by the United States Army, and standards bodies such as the International Organization for Standardization.

Thermodynamic Principles

The cycle is described by principles from James Prescott Joule's and Rudolf Clausius's thermodynamics and analyzed using diagrams such as the pressure–enthalpy chart and the Carnot cycle as an ideal reference. Key processes—isentropic compression modeled after work by Sadi Carnot and isobaric heat transfer—invoke properties measured and tabulated in resources from institutions like the National Institute of Standards and Technology and textbooks from publishers such as Cambridge University Press. Performance metrics including the coefficient of performance (COP) are benchmarked in comparison to limits exemplified by Lord Kelvin's formulations and applied in standards set by the American National Standards Institute and the European Committee for Standardization.

Components and Operation

Typical systems comprise a compressor, condenser, expansion device, and evaporator, components manufactured by companies like Emerson Electric, Mitsubishi Electric, and Bitzer Maschinenbau. Compressors range from reciprocating types descended from machinery used in Siemens plants to rotary and scroll designs commercialized by firms such as Copeland; condensers may be air-cooled or water-cooled in configurations supplied to utilities like EDF and industrial sites managed by ArcelorMittal. Expansion devices include thermostatic expansion valves pioneered in early refrigeration patents, while evaporators are integral in applications from supermarket display cases serviced by Tesco to cryogenic precooling at research centers such as CERN.

Types and Configurations

Configurations include single-stage, multi-stage (or tandem) systems used by petrochemical companies like Royal Dutch Shell and ammonia-based industrial plants at BASF facilities, cascade systems employed in laboratories at the California Institute of Technology and cascade chillers in semiconductor fabs operated by TSMC. Heat pump variants reverse flow for space heating in buildings designed by firms like Arup and used in municipal projects by authorities such as the City of Copenhagen. Specialized designs include transcritical CO2 systems adopted by retail chains such as Carrefour and ejector-enhanced cycles developed with research from Danfoss.

Refrigerants and Environmental Impact

Refrigerant selection has evolved from early substances to chlorofluorocarbons regulated after findings by scientists like Sherwood Rowland and Mario Molina; policy responses include the Montreal Protocol phases that shifted industry players like DuPont and Honeywell toward hydrofluorocarbons and subsequently low-global-warming-potential alternatives. Natural refrigerants such as ammonia (in facilities of companies like Yara International), carbon dioxide (transcritical systems in supermarkets by Ahold Delhaize), and hydrocarbons in refrigeration by manufacturers like IKEA are alternatives promoted by environmental NGOs and evaluated under frameworks by the Intergovernmental Panel on Climate Change. Lifecycle impact assessments are conducted by organizations including the World Bank and the United Nations Environment Programme.

Applications and Industry Use

Applications span domestic refrigeration produced by conglomerates like Haier and LG Electronics, commercial refrigeration in supermarkets operated by corporations such as Kroger and Aldi, and industrial refrigeration in food processing for companies like Tyson Foods and Nestlé. HVAC and district cooling projects serve municipalities exemplified by the City of New York and campus systems at universities such as Stanford University. Cold-chain logistics for pharmaceuticals involve collaborations with logistics firms like DHL and regulatory oversight from agencies such as the Food and Drug Administration and the World Health Organization.

Performance, Efficiency, and Control

Efficiency improvements leverage variable-speed drives from suppliers such as Siemens and ABB, advanced control strategies developed in research at ETH Zurich and the University of Tokyo, and heat-recovery integration in plants by corporations like Siemens Energy and General Electric. Performance is monitored using standards from Underwriters Laboratories and energy labeling regimes administered by the European Commission and the U.S. Department of Energy. Optimization techniques draw on control theory advanced by researchers linked to Stanford University and Princeton University and on refrigerant management policies shaped by international agreements like the Paris Agreement.

Category:Refrigeration