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Topic: Refrigeration cycles

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	Design of Vapor-Compression Refrigeration Cycles
		The design is to be based upon the ideal vapor-compression refrigeration cycle, with four components: a cooler (where we reject the heat), a throttle, a heater (where we absorb the heat), and a compressor.
		The challenge in refrigeration (and air conditioning, etc.) is to remove heat from a low temperature source and dump it at a higher temperature sink.
		This is where the useful "function" of the refrigeration cycle takes place, because it is during this part of the cycle that we absorb heat from the area we are trying to cool.
	www.qrg.northwestern.edu /thermo/design-library/refrig/refrig.html (2013 words)

	Refrigerant flow rate control based on liquid level in simple vapor compression refrigeration cycles - Patent 5435145
		The refrigerant is compressed by the compressor to high temperature and pressure and then condensed by the condenser where it loses heat to the ambient.
		Refrigerant from the condenser enters the phase separator, and liquid refrigerant is discharged to an expansion device, such as an expansion valve or a capillary tube, so that it undergoes adiabatic expansion.
		The duty cycle of the valve is varied in accordance with liquid level in the phase separator to precisely control the average flow rate.
	www.freepatentsonline.com /5435145.html (3114 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal
		Power cycles are cycles which convert some heat input into a mechanical work output, while heat pump cycles transfer heat from low to high temperatures using mechanical work input.
		The absorption refrigeration cycle is an alternative that absorbs the refrigerant in a liquid solution rather than evaporating it.
		The Carnot cycle is a cycle composed of the totally reversible processes of isentropic compression and expansion and isothermal heat addition and rejection.
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=thermodynamic_cycle (1260 words)

	Refrigeration cycle patent invention
		carbon dioxide, the refrigerant pressure on the high pressure side is not lower than the critical pressure of refrigerant, and hence this cycle is called "supercritical refrigerant cycle".
		More specifically, the lubricating oil dissolves in the liquid refrigerant, and hence assuming that only the gaseous refrigerant is returned to the compressor 101 from the accumulator 105, the lubricating oil for the compressor 101 becomes short, which can cause seizure of the compressor 101, resulting in breakage of the same.
		At this time, not all of the refrigerant introduced into the evaporator 104 evaporate, and hence the refrigerant having passed through the evaporator 104 is once separated into the liquid refrigerant and the gaseous refrigerant.
	www.freshpatents.com /Refrigeration-cycle-dt20051201ptan20050262873.php (1074 words)

	Efficient Power sources has made 12
		Refrigerator performance is not affected by small variations in refrigeration charge.
		The new 134a refrigerant is not as efficient as R-12 when used in boat refrigeration.
		My boat refrigeration system would be the best one for your boat.
	www.kollmann-marine.com /trueorfalse.html (326 words)

	Refrigeration - Refrigeration
		In the refrigeration cycle, heat is removed from a low-temperature space or source and rejected to a high-temperature sink with the help of external work.
		It is possible to build a refrigeration system which does not contain a refrigerant, and therefore does not operate a refrigeration cycle — the most common form being thermoelectric cooling used in some portable coolers.
		The absorption cycle is similar to the compression cycle, except for the method of raising the pressure of the refrigerant vapour.
	www.refrigeration-qed.com (3263 words)

	Technology Review: Refrigeration Unplugged
		Refrigeration Unplugged by Guest (Kuntalkumar Pandit) 1/23/2006 12:00 AM It seems a very exciting concept opening many more application opportunities - but more concrete information is required for evaluation of the same.
		Refrigeration Unplugged by Guest (Kent Green) 12/24/2005 4:14 AM We had a device very similar to the one you describe at our no-power cottage in Ontario.
		Refrigeration Unplugged by Guest (Gerald J. Grott) 1/23/2006 12:00 AM You do not need a fire because solar energy can be stored at the solid state Phase Chenge temperature of 465* F. The Phase FChange Energy is 27 BTU/pound of contained anhydrous sodium sulfate.
	www.technologyreview.com /NanoTech-Devices/wtr_16027,303,p1.html (1289 words)

	ORNL R&D in Nontraditional Refrigeration Cycles
		In collaboration with the Air-Conditioning and Refrigeration Institute (ARI), BTC researchers have completed an assessment of more than 25 nontraditional refrigeration cycles (e.g., Brayton, Stirling, Vuilleumier, absorption), comparing their projected performance for building heating and cooling with that of conventional electric and gas systems.
		None of the electric NIK systems were shown to outperform a standard electric heat pump in this application, but several could show promise in low-temperature refrigeration applications.
		Several of the gas-fired NIK options (GAX absorption, engine-driven, Vuilleumier, duplex Stirling) all appear to be viable alternatives to conventional gas furnace technologies.
	www.ornl.gov /sci/btc/apps/ntrf.html (104 words)

	Refrigeration Software - Web-Based analysis of Vapor compression and Gas Refrigeration Systems - Examples with ...
		The refrigerant leaves the condenser as saturated liquid and is throttled to a flash chamber operating at 0.4 MPa.
		The vapor from the flash chamber is mixed with the refrigerant leaving the low-pressure compressor and the mixture is compressed by the high-pressure compressor to the condenser pressure.
		Solution Detailed analysis of cycles (steam power, gas power, and refrigeration cycles) executed by a fluid, passing through open devices connected back to back in a loop, is carried out by the open cycle daemons located in the specific branch of the open steady daemons.
	energy.sdsu.edu /testcenter/testhome/Test/intro/exOpenRefriCycleP.html (1711 words)

	Convenience Store Refrigeration: Commercial Refrigeration
		The refrigerant (acting as a heat transfer fluid) is used to transfer heat energy from a lower temperature to a higher temperature.
		This is an important efficiency improving attribute to the cycle, since it reduces the amount of refrigerant liquid that has to evaporate (it is called flashing at this stage in the cycle) to a gas in the expansion valve to reduce the pressure and temperature of the liquid entering the evaporator.
		Refrigeration cycles transfer thermal energy continually from a region of low temperature to one of higher temperature.
	www.conveniencerefrigeration.com /terms-considerations.shtml (4172 words)

	Freezer - freezer, ice, ice cream, refrigerator, cold (Site not responding. Last check: )
		The freezer in your kitchen uses a cycle that is similar to the one described in the previous section.
		Sub-Zero claims to have invented the concept of dual refrigeration which is said to provide clean air flow, and to result in fresher and longer lasting food.
		This kind of built-in refrigerator is usually wider than normal to compensate for the shallower depth in order to maintain acceptable storage volume.
	www.thehomeappliancesguide.com /Freezer.html (1334 words)

	Refrigerator (Site not responding. Last check: )
		The cycle operates at two pressures, Phigh and Plow, and the statepoints are determined by the cooling requirements and the properties of the working fluid.
		Of these, the reversed Brayton cycle, which is also known as the gas refrigeration cycle, is used to cool aircraft and to obtain very low (cryogenic) temperatures after it is modified with regeneration.
		Another form of refrigeration that becomes economically attractive when there is a source of inexpensive heat energy at a temperature of 100 to 200°C is absorption refrigeration, where the refrigerant is absorbed by a transport medium and compressed in liquid form.
	coolingdevice.net /4.html (1139 words)

	Intermittent Absorption Refrigeration ~ Select articles, abstracts, Google search results, and patents
		For the collector with steel tubes and steel plate, the refrigerator coefficient of performance obtained with optimal choices of tube size, spacing and plate emissivity is 0.073, representing an improvement of at least 30% with respect to the reference collector.
		The ISAAC Solar Icemaker is an Intermittent Solar Ammonia-water Absorption Cycle.
		Isaac' is the acronym for Intermittent Solar Ammonia Absorption Cycle.
	www.rexresearch.com /interefr/patents.htm (4311 words)

	Trade Programs: Refrigeration and Air Conditioning Mechanic \| Manitoba Competitiveness, Training and Trade
		Refrigeration and Air Conditioning Mechanics spend a large portion of their time applying highly specialized skills to heating and cooling systems in the field.
		Refrigeration and Air Conditioning Mechanics are employed in the construction, installation and service/repair fields.
		Refrigeration and Air Conditioning Mechanics must also be aware of all regulations and codes that affect the handling, recovery and storage of ozone-depleting substances.
	www.gov.mb.ca /tce/apprent/trades/refrig.html (1401 words)

	cost cutting cube ecube flexi-freeze - About the eCube (Site not responding. Last check: )
		Air cycles (on/off) typically produce a minimum of 12 cycles per hour and, in some open display cases, 20 cycles per hour.
		Refrigeration units usually monitor circulating air temperature in order to decide when to switch on and off.
		significantly reduces the frequency of the refrigeration cycles as they are now based on food temperature rather than fluctuating air temperature.
	www.cost-cutting-cube.com /about_the_ecube (380 words)

	ME204
		To provide a comprehensive study of power and refrigeration cycles and systems, gas and water vapor mixtures, psychrometrics, Thermodynamic relations for simple compressible substances, fuels and combustion processes in the field of thermal sciences as well as applications of the first and second laws of Thermodynamics to such thermal systems and processes.
		One design project on either one of the power cycles or vapor-compression refrigeration cycle is assigned to be done using the Thermodynamic software “CyclePad,” covering design calculations and parametric studies.
		Students will demonstrate a basic understanding of irreversibility and availability, power and refrigeration cycles, gas-gas and gas-water vapor mixtures and psychrometric processes, Thermodynamic relations, fuels and combustion processes and apply first and second law of Thermodynamics to SSSF equipment and processes, power and refrigeration cycles, gas-gas and gas-water vapor mixtures and fuel combustion processes.
	www.kfupm.edu.sa /ME/courses/ME204.htm (293 words)

	Amazon.de: Principles of Refrigeration: English Books: Roy J. Dossat,Thomas J. Horan (Site not responding. Last check: )
		For courses in Refrigeration and Air Conditioning, HVAC System Design, and Principles of Heating/Ventilating/Ac/Refrigeration in two-year college departments of HVAC or four-year M.E. or M.E.T. departments.This text provides a detailed, applications-oriented treatment of the mechanical refrigeration cycle, associated equipment, component design, and system operation.
		In understanding the refrigeration cycle, Roy Dossat had 25 years in the field before teaching at the University of Houston.
		Refrigerant application is in constant change as environmental demands alter our lives.
	www.amazon.de /exec/obidos/ASIN/0130272701/geometrynet01-21/ref=nosim (483 words)

	BoatUS BoatTECH Guides: Refrigeration
		The single most important fact about marine refrigeration is that it improves your quality of life aboard with such luxuries as cold drinks and fresh food.
		The compressor cycles on and off as the box warms and cools-30 minutes running time out of every hour is the norm.
		Having a dedicated battery bank for your refrigeration unit is a good idea, but remember that you still have to run your engine to recharge the battery.
	www.boatus.com /boattech/refrig.htm (643 words)

	Research
		However, direct thermally driven refrigeration cycles are receiving increasing attention for several reasons: environmentally benign refrigerants, reducing electric utility summer peak demand, silent operation, and efficient utilization of waste heat.
		The thermally activated refrigeration cycles receiving the most attention are all dual pressure cycles requiring an electric pump to move the liquid solution from low pressure to high pressure.
		Their cycle decouples the temperature lift from the generator temperature, which allows the selection of a refrigerant that matches the application temperature requirements.
	www.me.gatech.edu /energy/resmain.htm (2778 words)

	Home Page ( sEnergy Solution )
		It is like having your thermostat regulating the temperature by the temperature of the yogurt, instead of the air temperature.
		When fitted to the thermostat sensor, which controls the compressor, the eCube significantly reduces the frequency of the refrigeration cycles as they are now based on food temperature rather than fluctuating air temperature.
		By using the eCube as a cycle control mechanism, refrigeration cycles last longer but can be reduced by as much as 80%.
	senergysolution.com (160 words)

	Air-Conditioning and Refrigeration Institute
		Had he tried the stunt with the standard refrigerants of the day--ammonia, methyl chloride, and sulfur dioxide--the outcome ultimately would have included some mix of choking, fire, burns, cancer, and death.
		When he died in 1944, Midgely had no idea that CFCs already had begun wending their way into the upper atmosphere where they were initiating the destruction of stratospheric ozone molecules, which shield life from dangerous ultraviolet portions of solar radiation.
		The refrigeration value resides in their ability to undergo countless cycles of volumetric expansion into a gaseous state--during which the CFC gas draws heat from its surroundings such as a refrigerator's interior--and condensation, during which a compressor forces the refrigerant back into the liquid state ready for the next cycle.
	www.nist.gov /public_affairs/factsheet/cfc.htm (826 words)

	Vapor compression and gas refrigeration daemon
		Example: A vapor-compression cycle with steam is executed on top of a vapor-compression cycle with R-12 as the working fluid.
		Combined cycles using a phase-change (PC) fluid for one cycle and an ideal gas (IG) for another can be analyzed with this daemon.
		Example: A vapor-compression refrigeration cycle with R-12 is executed on top of a reversed Brayton cycle with nitrogen as the working fluid.
	energy.sdsu.edu /testcenter/testhome/Test/solve/systems/open/osss/specific/refricycle/refricycle.html (263 words)

	Refrigeration & Process Cooling : The Most Practical and Useful Information Resources on HVAC and Energy Systems
		It covers refrigerants that were widely used historically, that are in common use today, and selected candidates...
		A scientific consensus on the contribution of CFCs, HCFCs and other compounds to ozone depletion led to international agreements and national regulations that began impacting the air conditioning and refrigeration industries in 1989.
		Mack received a BS in chemistry from the University of Texas at Austin in 1970 and a Ph.D. in Chemical Physics from the University of Colorado in 1973.
	www.hpac.com /Technologies/Refrigeration/396 (520 words)

	CRC Press Online
		Refrigerant mixtures are increasingly used as working fluids because they demonstrate desirable thermodynamic, feasibility, and safety characteristics.
		The authors explain in detail the thermodynamics of refrigerant mixtures, which is vastly more complex than that of individual refrigerants, as well as the fundamentals of various refrigeration cycles and methods for improving their efficiency.
		They also include important discussions on heat transfer and pressure drop correlations, experimental performance measurements and examples of using refrigerants and their mixtures, and critical operational issues such as control issues, refrigerant mixing, and mass fraction shifts.
	www.crcpress.com /shopping_cart/products/product_detail.asp?sku=3489&isbn=0849334896&parent_id=499&pc= (362 words)

	Heating, Ventilating, Air Conditioning & Refrigeration Products
		Refrigeration Basics - This course discusses the theory of refrigeration, description and uses of refrigerants and major components of a system including functions and applications.
		Refrigeration Circuits - All experienced technicians know that the majority of service work they perform on refrigerators is related to the electrical system.
		Refrigeration Fundamentals and Heat Pumps - We explain the three heat pump cycles, the operation of the reversing valve, system metering device and supplemental heat systems.
	www.maintenanceresources.com /productsshowcase/productlisting/hvacproducts.htm (2349 words)

	Refrigeration Software (Site not responding. Last check: )
		Computer programmes intended for refrigeration and air conditioning.
		Refrigeration equipment: heat exchangers of different kind, compressors.
		Work characteristics of many components of refrigerating systems.
	www.unet.com.mk /refrigeration (24 words)

	Air Conditioning & Refrigeration
		Basic instruction includes the study of mechanical refrigeration cycles, refrigeration components and their functions, electrical theory, circuit wiring, and the tools of the trade.
		An apprentice license and refrigerant handling certification are obtainable through this program.
		These include: air conditioning and refrigeration parts and equipment sales, residential and light commercial heating and air conditioning system installation and/or service, domestic or commercial refrigeration service, or sheet metal duct fabrication.
	www.meridian-technology.com /full_time/air_conditioning_and_refrigeration.asp (338 words)

	Chapter 11: Refrigeration Cycles (3/25/06) (Site not responding. Last check: )
		Heat is removed in the low temperature evaporator and rejected to the ambient in the condenser.
		Unlike the situation with steam power plants, it is considered the norm to describe refrigeration (and heat pump) systems in terms of P-h diagrams, and we will use them throughout in place of T-s diagrams presented in Çengel.
		In fact, in the Fundamentals of Engineering (FE) exam you are expected to solve all refrigeration and heat pump problems using the P-h diagram provided in the FE Handbook.
	www.ent.ohiou.edu /~thermo/me328/chapter.info/Chapter11.html (316 words)

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