Articoli di riviste: "Refrigerant replacements"

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El-Sayed, A. R., M. El Morsi e N. A. Mahmoud. "A Review of the Potential Replacements of HCFC/HFCs Using Environment-Friendly Refrigerants". International Journal of Air-Conditioning and Refrigeration 26, n. 03 (settembre 2018): 1830002. http://dx.doi.org/10.1142/s2010132518300021.

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The adequate and efficient performance of HVAC systems are signs of luxury and human comfort, and the improvement of their performance has been the target of continuous researches. Choosing the suitable refrigerant is the main parameter in matching the system components, selecting the type of heat exchangers, the compressor, the expansion device and the suitable lubricant. The theoretically ideal refrigerant is the one having zero ozone depletion potential (ODP), low global warming potential (GWP), nontoxic, nonflammable, has appropriate thermodynamic and heat transfer properties and is compatible with any type of lubricating oil. Chlorinated, fluorinated refrigerants, zeotropic and azeotropic mixtures satisfy many requirements, but have high ODP and GWP and are not compatible with all types of oil. Hydrocarbons (HCs) satisfy all the requirements except being highly flammable. This work reviews previous research aiming to find substitutes for the environmentally harmful refrigerants by other environmentally friendly ones and compare their performance in various HVAC appliances.

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Hwang, Yunho, Michael Ohadi e Reinhard Radermacher. "Natural Refrigerants". Mechanical Engineering 120, n. 10 (1 ottobre 1998): 96–99. http://dx.doi.org/10.1115/1.1998-oct-7.

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This article explains that substances such as air, water, ammonia, hydrocarbons, and carbon dioxide may provide solutions to the problem of finding environmentally acceptable refrigerants. The search for new and environmentally benign refrigerants to replace the existing chlorofluorocarbons (CFC) and hydrochlorofluorocarbons (HCFC) has led to the introduction of hydrofluorocarbons (HFC). HFCs could be useful as short- and mid-term replacements, but may ultimately not be suitable, owing to their high global-warming potential (GWP). Natural refrigerants still have several technical and safety challenges to overcome, and each has its unique advantages and disadvantages. Refrigerant, carbon dioxide offers a clear advantage over CFCs and HCFCs from the environmental impact standpoint. In addition to its environmental advantages, carbon dioxide also offers certain attractive thermal characteristics that can help it provide substantial potential as a long-term replacement if energy efficiency challenges can be addressed.

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Havelský, V. "Investigation of refrigerating system with R12 refrigerant replacements". Applied Thermal Engineering 20, n. 2 (febbraio 2000): 133–40. http://dx.doi.org/10.1016/s1359-4311(99)00016-2.

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Overton, Tina, Simon Hodgson, Alan Heaton e Richard Powell. "A case study in Green chemistry: Developing replacements for CFCs". New Directions in the Teaching of Physical Sciences, n. 2 (1 dicembre 2006): 69–72. http://dx.doi.org/10.29311/ndtps.v0i2.438.

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Chlorofluorocarbons, CFCs, were developed in the late 1920s for use as safe refrigerant alternatives to sulphur dioxide and ammonia. They were welcomed by industry because of their low toxicity, chemical stability, low flammability, low cost and ease of synthesis. They found wide application as refrigerants, blowing agents, propellants and cleaning agents. Over more than 40 years, applications of CFCs expanded into a wide variety of areas, and grew into a multibillion-dollar industry. Unfortunately, CFCs are not ecologically benign. It became increasingly clear that CFCs were responsible for ozone depletion. In the early 1970s the leading manufacturers of CFCs met to discuss the possible environmental impact of their products.This case study uses a problem based learning approach to take students through the development of replacements for CFCs from the 1970s to today. They investigate the background to the CFC problem and consider data that leads to the decision to investigate possible replacements. They must select and design replacement molecules (HFCs), devise syntheses and then consider the challenge to develop the replacements in a socio-economic and political framework. They also consider the problems posed by existing CFCs, the ‘fridge mountain’ and possible disposal and containment alternatives.The case study brings the story up to date with an investigation of the problems now being associated with HFCs and the search for new alternatives. This activity successfully teaches applied and ‘green’ chemistry via a real life context. The chemistry encountered is of an applied/industrial nature and is set in a socioeconomic context. The influence of political pressures is also brought in when appropriate. Because the activity adopts a problem based approach it is also successful in developing a range of transferable skills, particularly problem solving, teamwork plus verbal and written communication.

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Bolaji, Bukola Olalekan, Olatunde Ajani Oyelaran, Israel Olutunji Abiala, Tunde Oluwatoyin Ogundana e Semiu Taiwo Amosun. "Energy and Thermal Conductivity Assessment of Dimethyl-Ether and its Azeotropic Mixtures as Alternative Low Global Warming Potential Refrigerants in a Refrigeration System". Environmental and Climate Technologies 25, n. 1 (1 gennaio 2021): 12–28. http://dx.doi.org/10.2478/rtuect-2021-0002.

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Abstract Substituting Hydrofluorocarbons with natural refrigerants in domestic refrigerators will significantly reduce the direct contributions of fluorinated gases to global warming which will be of great environmental benefit. In this study, the performances of dimethyl-ether (RE170) and its azeotropic mixtures (R510A and R511A) in a refrigeration system were assessed theoretically and compare with that of conventional refrigerant. The study revealed that the three investigated alternative refrigerants exhibited significantly good heat transfer characteristics, low pressure ratio, high latent heat in the liquid phase which resulted in their high thermal conductivity and Volumetric Cooling Capacity (VCC). The thermal conductivity of the refrigerants reduces while the evaporating temperature rises and the value obtained for RE170 was the highest among the four refrigerants studied. The Coefficient of Performance (COP) for RE170, R510A and R511A were higher than that of R134a by 6.20, 10.06 and 3.02 % respectively while their power consumptions per ton of refrigeration were lower than that of R134a by 6.99, 11.04 and 1.47 % respectively. In conclusion, dimethyl-ether and its azeotropic mixtures performed better than R134a in that they have higher thermal conductivity, refrigerating effect, VCC, COP, lower power consumption per ton of refrigeration and hence, they can be considered as suitable replacements for R134a in domestic refrigerator.

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Ridwan Tanaka, Imam, Berkah Fajar, Tony Suryo Utomo, Eflita Yohana e Mustaqim. "Experimental Study Performance R-22 AC Split Retrofitted With Propane". MATEC Web of Conferences 159 (2018): 02021. http://dx.doi.org/10.1051/matecconf/201815902021.

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Refrigerant 22 or called R-22 is still the most widely used for air conditioners. However, since it has a relatively high global warming properties, the use of R-22 should be stopped. Refrigerant 290 briefed as R-290 (propane) is the type of refrigerant recommended by many experts for R-22 replacements because the global warming properties of R290 are much lower than R-22. Therefore, in this study the cooling capacity, flow rate mass, power consumed and COP will be evaluated. The air conditioner engine used in this research has 1 PK capacity which is redesigned by adding separator / ducting on various main components of AC. From the result of the study, there are several conclusions revealed: on the same compressor capacity, R-22 cooling capacity is still greater than R290. Meanwhile, the flow rate of R290 is lower than R-22. For power consumption from R-290, it is smaller than R-22. For the value of COP R-290, the value shows greater ie at R-290 on the variation of Incoming Temperature In Evaporator 20°C = 6.23, 23°C = 6.36, 25°C = 6.86, 29°C = 6.20. While at R-22, it shows 20°C = 5.36, 23°C = 6.02, 25°C = 5.76, 29°C = 6.335

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Arcaklıoğlu, Erol, Abdullah Çavuşoğlu e Ali Erişen. "Thermodynamic analysis of refrigerant mixtures for possible replacements for CFCs by an algorithm compiling property data". Applied Thermal Engineering 26, n. 4 (marzo 2006): 430–39. http://dx.doi.org/10.1016/j.applthermaleng.2005.06.005.

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Siddiqui, M. U., Amro Owes, F. G. Al-Amri e Farooq Saeed. "Recent Developments in the Search for Alternative Low-Global-Warming-Potential Refrigerants: A Review". International Journal of Air-Conditioning and Refrigeration 28, n. 03 (settembre 2020): 2030004. http://dx.doi.org/10.1142/s2010132520300049.

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Conventionally, the CFC-type refrigerants were used until Montreal Protocol which stated that CFC refrigerants cause ozone depletion and should be replaced with alternative refrigerants. The alternative refrigerants are safe for ozone but they have comparatively high flammability, toxicity and global warming potential. Thus they need careful handling. In Kyoto Protocol, it was stated that the currently used refrigerants with high global warming potential need to be replaced with yet other alternative refrigerants with low global warming potential. This paper comprehensively reviews those recent studies that focused on the possible replacement of currently in-use refrigerant with a comparatively more environmental-friendly alternative refrigerant. Initially, the progression of refrigerants through different generations has been described and discussed. A list of currently in-use refrigerants has been presented. Then, the scientific developments for the replacement of listed refrigerants are thoroughly reviewed and critically analyzed. From the comprehensive review, it was found that R1234yf has the most potential to be a suitable low-flammable replacement for R134a for domestic refrigeration and automotive air-conditioning systems. Also, R32 has the most potential to be a suitable alternative of R410A.

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Abdulqadir, Ibrahim F., Badran M. Salim e Omar Shamdeen. "Performance Investigation of refrigerant R-407C as a Replacement to refrigerant R22 in Window Air Conditioner Unit". Journal of Civil Engineering Frontiers 1, n. 2 (31 dicembre 2020): 37–43. http://dx.doi.org/10.38094/jocef1218.

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The present work deal with the experimental study to retrofit the refrigerant R407c with the refrigerant R22 in the air conditioning unit at an ambient temperature range between 30-45°C. The main component of the experimental rig includes a window air conditioner with a refrigeration capacity of 2 Ton refrigeration that used refrigerant R22 as a working fluid in the experimental work. The refrigerant R22 is replaced with refrigerant R407C due to similar operation properties for the two refrigerants. The experimental results displayed the refrigeration effect and coefficient of performance COP of the R22 system are high as with those of the R407C system. The falls in the evaporator and condenser for the R407C system is lower than that of the R22 system. The temperature of discharge in the compressor for the system of refrigerant R22 is greater than that of the R407C system. Moreover, condensation temperature along the tube of the condenser is decreased with the increase of the distance for both refrigerants. The refrigerant R407C may be selected as a good alternate for R22 with an agreement difference in the two refrigerants’ performance. The system did not require replacement for any part of the AC unit.

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Morales-Espejel, Guillermo E., Hans H. Wallin, Rudolf Hauleitner e Magnus Arvidsson. "Progress in rolling bearing technology for refrigerant compressors". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, n. 16 (21 agosto 2017): 2948–61. http://dx.doi.org/10.1177/0954406217725772.

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The paper describes the latest technological solutions in rolling bearings (ball and roller) used in refrigerant compressors. First, the numerous tribological challenges faced by rolling contacts in a lubricant environment made of oil and refrigerant mixture are discussed. It is followed by a description of the even tougher conditions derived by the replacement of the more chemically stable pre-Montreal and pre-Kyoto Protocol refrigerants by the new generation of more environmental friendly refrigerants. In these conditions, rolling bearings are expected to suffer from surface distress and sometimes corrosion fatigue. Thus, attempts to model these conditions by using advanced tribological models are described. Finally, descriptions of different solutions in rolling bearings in refrigerant compressors facing challenges in lubrication and bearing life are described, all the way from traditional oil–refrigerant mixture lubrication up to the latest innovation related to oil-free lubrication, namely the pure refrigerant lubrication.

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Nguyen, Bao The, Tuan Huy Dao e Tue Duy Nguyen. "Feasibility study of the replacement of refrigerants R22 & R12 by using environmentally friendly refrigerants R404A, R290 & R600A". Science and Technology Development Journal 16, n. 4 (31 dicembre 2013): 60–67. http://dx.doi.org/10.32508/stdj.v16i4.1585.

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Refrigerant system is broadly applied in several areas currently. Their importances we can’t deny. However, beside it’s convenience, there are a lot of problems appearing impact on our living environment such as: Ozon depletion, global warming that create a lot of disaster for our life. To contribute for solving those problems, we researched theories, also to conduct experiments for R22, R12 replacement by using friendly environment refrigerant as: R404A, R290, R600A. Our research purpose comparing different refrigerants to find out the one that has compatible thermodynamic property to apply in Viet nam’s condition. Among those, the refrigerant that we can produce ourselves is R290 having same thermodynamic property with R22, R12, and also achieve a good result for R22, R12 replacement.

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Simmonds, Peter G., Matthew Rigby, Archie McCulloch, Simon O'Doherty, Dickon Young, Jens Mühle, Paul B. Krummel et al. "Changing trends and emissions of hydrochlorofluorocarbons (HCFCs) and their hydrofluorocarbon (HFCs) replacements". Atmospheric Chemistry and Physics 17, n. 7 (10 aprile 2017): 4641–55. http://dx.doi.org/10.5194/acp-17-4641-2017.

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Abstract. High-frequency, in situ global observations of HCFC-22 (CHClF2), HCFC-141b (CH3CCl2F), HCFC-142b (CH3CClF2) and HCFC-124 (CHClFCF3) and their main HFC replacements, HFC-134a (CH2FCF3), HFC-125 (CHF2CF3), HFC-143a (CH3CF3) and HFC-32 (CH2F2), have been used to determine their changing global growth rates and emissions in response to the Montreal Protocol and its recent amendments. Global mean mole fractions of HCFC-22, -141b, and -142b have increased throughout the observation period, reaching 234, 24.3 and 22.4 pmol mol−1, respectively, in 2015. HCFC-124 reached a maximum global mean mole fraction of 1.48 pmol mol−1 in 2007 and has since declined by 23 % to 1.14 pmol mol−1 in 2015. The HFCs all show increasing global mean mole fractions. In 2015 the global mean mole fractions (pmol mol−1) were 83.3 (HFC-134a), 18.4 (HFC-125), 17.7 (HFC-143a) and 10.5 (HFC-32). The 2007 adjustment to the Montreal Protocol required the accelerated phase-out of emissive uses of HCFCs with global production and consumption capped in 2013 to mitigate their environmental impact as both ozone-depleting substances and important greenhouse gases. We find that this change has coincided with a stabilisation, or moderate reduction, in global emissions of the four HCFCs with aggregated global emissions in 2015 of 449 ± 75 Gg yr−1, in CO2 equivalent units (CO2 eq.) 0.76 ± 0.1 Gt yr−1, compared with 483 ± 70 Gg yr−1 (0.82 ± 0.1 Gt yr−1 CO2 eq.) in 2010 (uncertainties are 1σ throughout this paper). About 79 % of the total HCFC atmospheric burden in 2015 is HCFC-22, where global emissions appear to have been relatively similar since 2011, in spite of the 2013 cap on emissive uses. We attribute this to a probable increase in production and consumption of HCFC-22 in Montreal Protocol Article 5 (developing) countries and the continuing release of HCFC-22 from the large banks which dominate HCFC global emissions. Conversely, the four HFCs all show increasing mole fraction growth rates with aggregated global HFC emissions of 327 ± 70 Gg yr−1 (0.65 ± 0.12 Gt yr−1 CO2 eq.) in 2015 compared to 240 ± 50 Gg yr−1 (0.47 ± 0.08 Gt yr−1 CO2 eq.) in 2010. We also note that emissions of HFC-125 and HFC-32 appear to have increased more rapidly averaged over the 5-year period 2011–2015, compared to 2006–2010. As noted by Lunt et al. (2015) this may reflect a change to refrigerant blends, such as R-410A, which contain HFC-32 and -125 as a 50 : 50 blend.

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PASEK, ARI D., e ARYADI SUWONO. "APPLICATION OF HYDROCARBON BASED REFRIGERANTS FOR AIR CONDITIONING IN INDONESIA". International Journal of Air-Conditioning and Refrigeration 19, n. 04 (dicembre 2011): 303–9. http://dx.doi.org/10.1142/s201013251100065x.

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Electrical energy consumption in air conditioning systems reaches 60% to 70% of the total electric energy consumption in buildings. Therefore, saving electrical energy consumption in air conditioning systems would have a significant impact on the national electrical energy consumption. Currently, the air conditioning sectors were having a dilemma on finding the alternative substitutes for CFC and HCFC refrigerants which are proven to cause destruction of the ozone layer and contribute to the effects of global warming. This paper will discuss the problems faced by an Article 5 country similar to Indonesia in phasing-out HCFC especially in air conditioning and refrigeration sectors. This paper will also discuss the possibility to use hydrocarbon-based refrigerants, which have zero ozone depletion potential (ODP) and low global warming potential (GWP), in air conditioning sectors. Some results of field applications of this refrigerant will be reported, and in general it can be concluded that the air conditioning retrofitted with hydrocarbon refrigerant consumes 10%–20% less electrical energy. Mixture of R-290 and R-134a was also investigated. R-134a is used to reduce the flammability of R-290 and to make the saturation pressure close to R-22. The results show that at composition of 0.6 R-290/0.4 R-134a mole fractions, the mixture behave as an azeotrope refrigerant mixture and can be used for R-22 replacement. At this composition, lower flammability limit (LEL) is 3693%, which is higher than pure R-290. Hence, the refrigerant mixture can be classified as less flammable A2 class refrigerant. The performance test shows that the refrigerant mixture can be used as a drop-in refrigerant in the R-22 machine. The measurement of refrigeration capacity and compressor input work at the same chilled water temperature shows that the calculated COP of the refrigerant mixture is better than R-22's but lower than R-290's.

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Muhammad, Nuriyadi. "Analisis Numerik Simulasi Kinerja Sistem Tata Udara Unitary Menggunakan Liquid-Suction Heat Exchanger dengan Refrigeran Hidrokarbon". Jurnal Engine: Energi, Manufaktur, dan Material 2, n. 2 (19 novembre 2018): 11. http://dx.doi.org/10.30588/jeemm.v2i2.419.

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<p><em>One of the environmental issues to be addressed, particularly in the field of refrigeration and air conditioning, is the destruction of the ozone layer and the effects of global warming due to the use of environmentally inefficient refrigerants. In the field of Refrigeration and Air Conditioning, refrigerant as a cooling medium, plays an important role, and until now there is still the use of refrigerant materials that are not environmentally friendly, generally synthetic refrigerant. One alternative refrigerant replacement against the synthetic refrigerant is hydrocarbon refrigerant (HC). On the other hand, several ways can improve the performance of refrigeration system by lowering the temperature of liquid line using liquid to suction heat exchanger. In this study, a numerical simulation was conducted to examine the effect of using liquid to suction heat exchanger on the performance of a unitary air-conditioning system using hydrocarbon refrigerant as a coolant fluid. The results are, liquid to suction heat exchanger increase refrigeration effect by raising heat exchanger effectivity, the highest increase is about 7%. But the use of LSHX also rises up the compression work by increasing heat exchanger effectivity by 19%. So the Coefficient of performance (COP) and relative capacity index decrease by 5%. Decreasing performance is higher in the unit that operates at higher temperatures.</em></p>

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Gill, Jatinder, e Jagdev Singh. "Experimental Analysis of R134a/LPG as Replacement of R134a in a Vapor-Compression Refrigeration System". International Journal of Air-Conditioning and Refrigeration 25, n. 02 (4 aprile 2017): 1750015. http://dx.doi.org/10.1142/s2010132517500158.

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This paper presents an experimental analysis of a vapor compression refrigeration system (VCRS) using the mixture of R134a and LPG with mass fractions of 28:72 as an alternative to R134a. In this work, we compare the energy performance of both refrigerants, R134a/LPG (28:72) and R134a, in a monitored vapor compression refrigeration system under a wide range of experimental conditions. So, the System with R134a/LPG (28:72) was tested by varying the capillary tube length and refrigerant charge under experimental conditions. Performance comparisons of both the systems are made taking refrigerant R134a as baseline, and the results show that the compressor power consumption, compressor discharge temperature and pull down time obtained with R134a/LPG (28:72) of 118[Formula: see text]g and capillary tube length of 5.1 m in vapor compression refrigeration system are about 4.4% 2.4% and 5.3%, respectively, lower than that obtained with R134a in the studied range. Also, when using R134a/LPG (28:72), the system shows values of refrigeration capacity and COP are about 10.6% and 15.2% respectively, higher than those obtained using R134a, In conclusion, the mixing refrigerant R134a/LPG proposed in this study seems to be an appropriate long-term candidate to replace R134a as a new generation refrigerant of VCRS, because of its well environmentally acceptable properties and its favorable refrigeration performances.

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Hussain, Rafah, e Issam Mohammed Ali. "The Experimental Assessment of R134a and Its Lower GWP Alternative R1234yf in an Automobile Air Conditioning System". Journal of Engineering 25, n. 12 (26 novembre 2019): 1–14. http://dx.doi.org/10.31026/j.eng.2019.12.1.

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Reducing global warming potential (GWP) of refrigerants is needed to the decrease of ozone-depleting of refrigeration systems leakages. Refrigerant R1234yf is now used to substitute R134a inside mobile air conditioning systems. Thermodynamic properties of R1234yf are similar to R134a. Also, it has a very low GWP of 4, compared to 1430 for R134a, making it a proper choice for future automobile refrigerants. The purpose of this research is to represent the main operating and performance differences between R1234yf and R134a. Experimental analysis was carried out on the automotive air conditioning system (AACS) with 3 kW nominal capacity, to test and compare the performance of R134a with R1234yf. Experiments were accomplished for both refrigerants in almost the same working conditions and procedure with a range of ambient temperature varied from 26oC to 50oC. Parameters studied were ambient temperature, type of refrigerant in the system at compressor speed 1450 rpm, and internal thermal loads of passenger room. The performance characteristics of the system, including COP and cooling capacity, were studied by changing different parameters. The results show that COP of R134a is higher than R1234yf by 12.6%, while the refrigeration effect of R134a is higher than R1234yf by 25%. This shows that R1234yf is a suitable and good candidate for drop-in replacement of R134a in AACS.

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Abrams, Michael. "The Rebirth of Cool". Mechanical Engineering 129, n. 01 (1 gennaio 2007): 34–37. http://dx.doi.org/10.1115/1.2007-jan-3.

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This article discusses design and developments in the refrigeration and compressor fields to deal with Montreal Protocol’s announcement of expiration of R-22 as refrigerant. The Montreal Protocol dictates that by 2010 no new refrigerators or air conditioners will use R-22, a hydrochlorofluorocarbons (HCFC), as a refrigerant. The replacement, known as R-410A, is an HFC (hydrofluorocarbon) rather than an HCFC. Jim Crawford, director of regulatory affairs at The Trane Co., a heating and air conditioning company in Tyler, Texas, said that industry is adopting R-410A primarily in air conditioning. Companies like Trane have used the time allotted by the Montreal Protocol to design, test, and build R-410A equipment for 2010. Compressors have had to be optimized both for the refrigerant and the application. Since the heat characteristics are different between the two refrigerants, heat exchangers must be made larger or smaller. Many new air conditioners, like Trane’s XL16i, already use R-41OA, which contains no chlorine.

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Kim, Nae-Hyun. "Application of the Natural Refrigerant Mixture R-290/DME to a Soft Ice Cream Refrigerator". International Journal of Air-Conditioning and Refrigeration 24, n. 04 (dicembre 2016): 1650027. http://dx.doi.org/10.1142/s2010132516500279.

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Due to the ozone depletion issue, R-502, which had long been used as the refrigerant of an ice cream refrigerator, has been replaced by R-404A. However, global warming potential (GWP) of R-404A is high, and thus, a replacement refrigerant is necessary in the long term. Natural refrigerants, such as R-290 or DME (dimethylether), could be a choice. In this study, an ice cream refrigerator cycle was optimized using R-290/DME mixture (mass fraction 65/35). The optimization was accomplished through a search for the proper refrigerant charge amount and the opening of the expansion valve. For the present ice cream refrigerator having 2.8[Formula: see text]L freezer volume, the optimum charge amount was 900[Formula: see text]g, and the optimum valve opening was [Formula: see text]120[Formula: see text]. At this configuration, the ice cream formation time was 3[Formula: see text] 6[Formula: see text] and COP was 2.0. The ice cream formation time was much shorter than when R-404A was used, and the COP was increased by more than 100%. For actual usage of the refrigerant, however, the flammability issue of the R-290/DME mixture should be cleared.

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YANG, Y., M. W. TONG, G. YANG e X. P. WANG. "APPLICATION OF CASCADE REFRIGERATION SYSTEM WITH MIXING REFRIGERANT IN COLD AIR CUTTING". International Journal of Modern Physics B 19, n. 01n03 (30 gennaio 2005): 521–23. http://dx.doi.org/10.1142/s0217979205028955.

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In the mechanical cutting process, the replacement of traditional cutting solution with cold air can avoid the pollution of environment. In order to high efficient the refrigerating device and flexible adjust the temperature of cold air, it is necessary to use cascade refrigeration system to supply cool quantity for the compressed air. The introduction of a two-component non-azeotropic mixing refrigerant into the cryogenic part of the cascade system, can effectively solve the problems of the system working at too high pressure and the volume expanding of refrigerant in case of the cascade refrigeration sets closed down. However, the filling ratio of mixing refrigerants impact on the relationships among the closing down pressure, refrigerating output and refrigerating efficiency. On the basis of computing and experiment, the optimal mixing ratio of refrigerant R22/R13 and a low temperature of -60° were obtained in this study. A cold air injecting device possessing high efficiency in energy saving has also been designed and manufactured. The cold air, generated from this cascade system and employed in a cutting process, takes good comprehensive effects on machining and cutting.

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Shen, Bo, e Moonis R. Ally. "Energy and Exergy Analysis of Low-Global Warming Potential Refrigerants as Replacement for R410A in Two-Speed Heat Pumps for Cold Climates". Energies 13, n. 21 (29 ottobre 2020): 5666. http://dx.doi.org/10.3390/en13215666.

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Heat pumps (HPs) are being developed with a new emphasis on cold climates. To lower the environmental impact of greenhouse gas (GHG) emissions, alternate low global warming potential (GWP) refrigerants must also replace the exclusive use of the refrigerant R410A, preferably without re-engineering the mechanical hardware. In this paper, we analyze the performance of four low-GWP alternative refrigerants (R32, R452B, R454B, and R466A) relative to the conventional R410A and draw conclusions on the relative performances for providing heating in cold climates based on the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) 210/240 standard for two-speed heat pumps. The simulations are carried using the Department of Energy, Oak Ridge National Laboratory (DOE/ORNL) Heat Pump Design Model (HPDM), a well-known heating, ventilation, and air conditioning (HVAC) modeling and design tool in the public domain and the HVAC research and development community. The results of the simulation are further scrutinized using exergy analysis to identify sources of systemic inefficiency, the root cause of lost work. This rigorous approach provides an exhaustive analysis of alternate low-GWP refrigerants to replace R410A using available compressors and system components, without compromising performance.

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Groza, Doru, e Dan Mihai Dogariu. "Investigation on the Intake Process for a Theoretical Twin Opposite Piston Compressor Using R744 Refrigerant". Applied Mechanics and Materials 823 (gennaio 2016): 75–78. http://dx.doi.org/10.4028/www.scientific.net/amm.823.75.

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This study aims to validate the use of R744 for a resonant twin piston compressor for domestic applications. The vapor-compression refrigeration is the most commonly approached method for cooling household appliances such as refrigerators and air conditioning systems. The R134a refrigerant is one of the most suitable refrigerants from an energetic point of view. R744 (CO2) compressors are less efficient, but the fact that the R134a raises serious environmental issues pushes commercial trend towards the usage of R744 [1]-[3]. Use of R744 in household appliances is currently an open topic and no company has switched yet to the environmental-friendly alternative. In this paper the fill efficiency will be simulated in order to validate if a conventional compressor such as the opposite twin piston compressor is capable of filling with refrigerant when operating at a 50Hz frequency. Such a validation can enable further investigations regarding the replacement of R134a with R744.

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Zhao, Yu, Zhaogang Qi, Jiangping Chen, Baixing Xu e Bin He. "Experimental analysis of the low-GWP refrigerant R1234yf as a drop-in replacement for R134a in a typical mobile air conditioning system". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, n. 11 (16 gennaio 2012): 2713–25. http://dx.doi.org/10.1177/0954406211435583.

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This study investigated the performance of a typical mobile air conditioning system using R134a and R1234yf as the working fluids under different working conditions. The system is composed of a microchannel parallel flow condenser, a laminated plate evaporator, a variable displacement compressor, and a thermal expansion valve. The different working cycles of each refrigerant were comprehensively compared. The optimum refrigerant charge amount of the R1234yf system was approximately 95% of the R134a system during drop-in tests. The performance of the R134a system was a little higher than that of the R1234yf system. The cooling capacity and system coefficient of performance of the R134a system were 12.4% and 9% larger, respectively. This result is mainly because of the thermophysical property differences between the two refrigerants and the improper expansion valve opening of R1234yf. Analysis on the whole cycle revealed that the R1234yf system could obtain a higher evaporating pressure and a larger superheat and subcooling. Redesigning the expansion valve for R1234yf could improve performance of the system.

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23

KOH, J. H., e Z. ZAKARIA. "Hydrocarbons as Refrigerants―A Review". ASEAN Journal on Science and Technology for Development 34, n. 1 (14 agosto 2017): 35. http://dx.doi.org/10.29037/ajstd.73.

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Abstract (sommario):

Refrigerants used in air conditioning and refrigeration (AC&R) indusries have come full circle since the beginning of the industrialrevolution. With concern on issues relating to the environment such as the global warming and climate change issues, we should finda better alternative than to continue using these refrigerants that cause global warming and ozone depletion. AC&R industryplayers have blended in by introducing some new equipment and components that are specificallydesigned for hydrocarbon (HC) use. Mostnew refrigerators sold in Malaysia are already equipped with isobutane [a hydrocarbon designated as R-600a by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards]as refrigerants. Malaysia has ratifiedthe Montreal Protocol and targetted a 10% reduction in hydrochlorofluorocarbon(HCFC) consumption, beginning 2016 with the banning of 2.5 horsepower (hp) and below in air-conditioning (AC) equipment to be used. Instead,hydrofluorocarbon(HFC) R-410a was introduced as a replacement for HCFC- 22, whereas in other countries this HFC has been phased down. This article was initiated because of the difficultin findinga replacement for HCFC. Also, the possibilities of using HC as an alternative to replace HCFC insteadof using HFC as a transitional refrigerant in place of HCFC is reviewed in this article. The performance of HC is very similar to HCFC and flmmability issues could be easily overcome with the use of an effectivedesign. Their use could be facilitated with the adaptation of specific standards and properly enacted legislatio

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24

Pendyala, Srinivas, Ravi Prattipati e A. V. Sita Rama Raju. "Optimization Process of a Visi-Cooler Using Ternary Mixtures of R134a and Hydrocarbons". International Journal of Air-Conditioning and Refrigeration 25, n. 02 (20 aprile 2017): 1750019. http://dx.doi.org/10.1142/s2010132517500195.

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Abstract (sommario):

Ozone depletion and global warming phenomenon necessitates the replacement of widely used refrigerants which consist of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) in refrigeration and air-conditioning systems. In this paper, experimental analysis on the performance of hydrofluorocarbon/hydrocarbon (HFC/HC) mixture as a possible drop-in replacement for R134a refrigerant is presented. The influence of capillary length, composition of the mixture and refrigerant charge at various evaporator temperatures on coefficient of performance (COP) are investigated. The optimum operating conditions are obtained by applying Taguchi technique for the acquired experimental results. The results of analysis of variance indicated that for a given evaporator temperature, HFC/HC mixture charge amount is the most influencing parameter. At the optimum condition, the simulation showed that the amount of charge required for HFC/HC mixture in visi-cooler is 120[Formula: see text]g which is 50% lower than required quantity of R134a for the same system. The HC mixture quantity amounted to 90[Formula: see text]g in the HFC/HC mixture which is lower than the safe limit of 150[Formula: see text]g. This eliminates the risk of flammability of HC in the proposed mixture while reducing the quantity of R134a by 87.5%.

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25

Lee, Byungmoo, e Nae-Hyun Kim. "Drop-In Tests of R-404A Alternative Refrigerants R-455A and R-454C in a Small Ice Maker". International Journal of Air-Conditioning and Refrigeration 27, n. 02 (giugno 2019): 1950017. http://dx.doi.org/10.1142/s2010132519500172.

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Abstract (sommario):

R-404A, which had long been used as the refrigerant of a unitary ice maker, has to be replaced due to global warming. In the present study, drop-in tests were conducted for long-term alternative refrigerants R-455A and R-454C on the ice maker of 100[Formula: see text]kg/day capacity. Five samples were made having different combinations of refrigerant, condenser and compressor. Tests were conducted changing the outdoor and the supply water temperature. At the standard outdoor condition (21∘C, 65 RH and 10∘C water temperature), change of refrigerant from R-404A to R-455A for the same ice maker extended the ice ball formation time by 13% and reduced the amount of ice production per day by 6%. Larger vapor density and smaller temperature glide of R-404A may have resulted in a better performance. Furthermore, adoption of a larger (from 1/3 HP to 3/8 HP) compressor reduced the ice ball formation time by 12% and increased the amount of ice production per day by 8%. In addition, change of the fin-tube condenser to the microchannel condenser reduced the ice ball formation time by 9% and increased the amount of ice production per day by 4%. The refrigerant charge was also significantly reduced from 440[Formula: see text]g to 316[Formula: see text]g. Thermal performance of R-454C was poorer than that of R-455A. Replacement to R-454C increased the ice ball formation time by 14% and decreased the amount of ice production per day by 8%. The reason may be attributed to a larger pressure lift, which leads to smaller refrigerant mass flow rate. Ice production was possible even at the harsh environment (35∘C, 65 RH and 21∘C water temperature), although the production amount decreased.

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26

Mancuhan, Ebru. "Comparative evaluation of a two-stage refrigeration system with flash intercooling using different refrigerants". Thermal Science 24, n. 2 Part A (2020): 815–30. http://dx.doi.org/10.2298/tsci180921011m.

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Abstract (sommario):

The aim of this study is to investigate the effect of low global warming potential refrigerants on the optimum intermediate pressure (POPT,int) and performance (COP) values of a refrigeration system with flash intercooling. For realize, the optimum operating parameters of system were determined in low temperature applications through a theoretical analysis according to the different refrigerants (R290, R404A, R407C, R507A, and R22). The theoretical modelling of system is done by optimizing the intermediate pressure at given evaporation (TE) and condensation (TC) temperatures for selected refrigerants. After optimization, the maximized values of COP and Second law efficiency are computed from the predicted values of POPT,int . The linear regression method is then used to derive three correlations of POPT,int , maximum values of COP and Second law efficiency according to TE and TC. Hence, the POPT,int values maximizing the system performance are found from various TE and TC values for each refrigerant. Due to calculations, increasing TE and TC cause the increase in POPT,int in low temperature applications. The R507A system has the highest POPT,int values and R22 system has the lowest POPT?int values. Although R22 system has slightly more efficient than R290 system, it is being phased out world?wide because of the risk of ozone depletion potential and global warming potential considerations. Therefore, it is important to evaluate the R22 replacement options. The R290 was discovered to have better performance than the R404A, R407C and R507A systems in terms of COPmax (1.81), global warming potential (11), and ozone depletion potential (0) when TE and TC are -35?C and 40?C.

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27

Antonijevic, Dragi. "Carbon dioxide as the replacement for synthetic refrigerants in mobile air conditioning". Thermal Science 12, n. 3 (2008): 55–64. http://dx.doi.org/10.2298/tsci0803055a.

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Abstract (sommario):

Based on Kyoto Protocol and the decisions of European Commission R134a refrigerant, currently dominantly used in mobile air conditioning systems, needs to be phased-out. At present automotive industry looks at carbon dioxide (CO2; R744) as the refrigerant of the future. Apart from the environmental benefits discussed are the technical characteristics of carbon dioxide refrigeration cycle and mobile air-conditioning systems in comparison to R134a refrigerant. Analyzed are challenges emerged from the use of CO2 as refrigerant and improvement opportunities in regards to increase of the system performance and efficiency. Particular attention is dedicated to the advantages of CO2 utilization in prospective automotive heat pump systems.

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28

Gil, Bartosz, e Jacek Kasperski. "Efficiency Evaluation of the Ejector Cooling Cycle using a New Generation of HFO/HCFO Refrigerant as a R134a Replacement". Energies 11, n. 8 (16 agosto 2018): 2136. http://dx.doi.org/10.3390/en11082136.

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Abstract (sommario):

Theoretical investigations of the ejector refrigeration system using hydrofluoroolefins (HFOs) and hydrochlorofluoroolefin (HCFO) refrigerants are presented and discussed. A comparative study for eight olefins and R134a as the reference fluid was made on the basis of a one-dimensional model. To facilitate and extend the possibility of comparing our results, three different levels of evaporation and condensation temperature were adopted. The generator temperature for each refrigerant was changed in the range from 60 °C to the critical temperature for a given substance. The performed analysis shown that hydrofluoroolefins obtain a high efficiency of the ejector system at low primary vapor temperatures. For the three analyzed sets of evaporation and condensation temperatures (te and tc equal to 0 °C/25 °C, 6 °C/30 °C, and 9 °C/40 °C) the maximum Coefficient of Performance (COP) was 0.35, 0.365, and 0.22, respectively. The best performance was received for HFO-1243zf and HFO-1234ze(E). However, they do not allow operation in a wide range of generator temperatures, and, therefore, it is necessary to correctly select and control the operating parameters of the ejector.

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29

SPATZ, MARK, SAMUEL YANA MOTTA, CHRISTOPHER SEETON e YONGMING NIU. "LOW GLOBAL WARMING REFRIGERANTS FOR RESIDENTIAL AIR CONDITIONING APPLICATIONS". International Journal of Air-Conditioning and Refrigeration 22, n. 02 (29 aprile 2014): 1440005. http://dx.doi.org/10.1142/s2010132514400057.

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Abstract (sommario):

Due to the growing global concerns around the use of refrigerants with relatively high global warming potential, new refrigerants with the positive attributes of both high thermal performance and low environmental impact are currently in development by Honeywell. These new refrigerants exhibit promising performance when compared with refrigerants currently used in stationary AC systems such as those that use R-410A, R-407C, and R-134a, for example. These new refrigerants also show significantly lower flammability characteristics than the much more flammable hydrocarbons. Replacements of common HFC refrigerants such as R-410A and R-407C are discussed for residential air conditioning applications. Thermal properties as well as experimental results in representative air conditioning systems are presented, showing the benefits of using these new refrigerants.

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30

Yen, Nguyen Hai, Nguyen Hoang Ha, Pham Thi Thanh, Nguyen Huy Ngoc, Tran Dang Thanh e Nguyen Huy Dan. "Influence of Co-Doping on Magnetic Properties and Magnetocaloric Effect of Fe–Co–Zr–Cu–B Melt-Spun Ribbons". Journal of Nanoscience and Nanotechnology 21, n. 4 (1 aprile 2021): 2552–57. http://dx.doi.org/10.1166/jnn.2021.19099.

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Abstract (sommario):

In this work, we investigated magnetic properties and magnetocaloric effect in Fe90−xCoxZr7Cu1B2 (x = 0, 1, 2, 3 and 4) melt-spun ribbons. The ribbons were prepared by using a melt-spinning method with a tangential velocity of a copper wheel of 40 m·s-1. The obtained ribbons are almost amorphous. The alloys exhibit typical soft magnetic behavior with low coercivity at room temperature. A minor replacement of Fe by Co gives an increment in Curie temperature (TC) of the alloys to higher temperatures. The TC of the alloys increases from 242 to 342 K with an increase of x from 0 to 4. Maximum magnetic entropy change, ΔSm max, of the alloys, was found to be larger than 0.7 J·kg-1·K-1 in a magnetic field change ΔH of 12 kOe for all the concentrations of Co. High refrigerant capacitys (RC >100 J ·kg-1 with ΔH = 12 kOe) at room temperature region have been obtained for the alloys. The large magnetocaloric effect near room temperature suggests that the alloys can be considered as magnetic refrigerants in the range of 250–350 K.

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31

Mani, Kolandavel, e Velappan Selladurai. "Energy savings with the effect of magnetic field using R290/600a mixture as substitute for CFC12 and HFC134a". Thermal Science 12, n. 3 (2008): 111–20. http://dx.doi.org/10.2298/tsci0803111m.

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Abstract (sommario):

This paper presents an experimental study on the replacement of CFC12 and HFC134a by the new R290/R600a refrigerant mixture as drop-in replacement refrigerant with and without the effect of magnetic field. Without any modification to the system components drop-in experimental tests were performed on a vapour compression refrigeration system with a reciprocating compressor, which was originally designed to operate with CFC12.The test results with no magnets showed that the refrigerant R290/R600a had 19.9-50.1% higher refrigerating capacity than R12 and 28.6-87.2% than R134a. The mixture R290/R600a consumed 6.8- -17.4% more energy than R12. The coefficient of performance of R290/R600a mixture increases from 3.9-25.1% than R12 at lower evaporating temperatures and 11.8-17.6% at higher evaporating temperatures. The effect of magnetic field force reduced the compressor energy consumption by 1.5-2.5% than with no magnets. The coefficient of performance of the system was higher in the range 1.5-2.4% with the effect of magnetic field force. The R290/600a (68/32 by wt.%) mixture can be considered as an excellent alternative refrigerant for CFC12 and HFC134a systems.

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32

Meng, Zhaofeng, Yin Liu, Dingbiao Wang, Long Gao e Junhai Yan. "Refrigerating fluid with a low global warming potential for automotive air conditioning systems in summer". Thermal Science 25, n. 2 Part B (2021): 1443–51. http://dx.doi.org/10.2298/tsci200308045m.

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Abstract (sommario):

Refrigerants with low global warming potential (GWP) are much needed in automotive air conditioning systems. This paper compares two refrigerants, R134a (GWP=1300) and R513A (GWP = 573) experimentally. The results show that the latter has lower cooling capacity, lower COP and lower discharge temperature than the former, revealing that R513A is a promising replacement of its high GWP partner.

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33

Arias, J., e P. Lundqvist. "Modelling and experimental validation of advanced refrigeration systems in supermarkets". Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 219, n. 2 (1 maggio 2005): 149–56. http://dx.doi.org/10.1243/095440805x8593.

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Abstract (sommario):

The effective use of energy and the replacement of CFC and HCFC refrigerants are two factors that have influenced the design and operation of refrigeration systems in supermarkets during recent years. The potential for increasing energy efficiency in refrigeration systems, indoor climate and refrigerated cabinets is large. Since the energy systems of a supermarket are relatively complex, improvements in one subsystem affect other systems, thus making analysis of potential improvements non-additive. A computer model, CyberMart, that predicts building heating and cooling loads, HVAC (heating, ventilation, and air conditioning), and refrigeration system performances of a supermarket, has been developed. The focus of the model is on energy use, environmental impact (TEWI), and life cycle cost (LCC) of the refngeration system. The refrigeration system solutions included in the model are: direct system, completely indirect system, partially indirect system, cascade system, parallel system with mechanical sub-cooling (where the refrigerant in the low-temperature system is sub-cooled with the brine of the intermediate temperature level), and district cooling (that cools the condenser of the refrigeration machines). Measurements of different parameters such as outdoor and indoor temperatures, relative humidity, and compressor power have been carried out in several stores to validate the model. A theoretical description of the model and results from the model and measurements are presented in this paper.

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34

Nunes, R. O., L. F. N. Castro, L. Machado e R. N. N. Koury. "Distributed and Nonsteady-State Model of an Air Cooler Working with R22 and R410A". International Journal of Air-Conditioning and Refrigeration 24, n. 02 (giugno 2016): 1650008. http://dx.doi.org/10.1142/s2010132516500085.

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Abstract (sommario):

The restrictions imposed by Montreal Protocol for use of CFCs fluids and Kyoto Protocol to HCFCs have motivated researchers and the industry to seek new alternatives. Within this context, R410A has emerged as one of the most likely replacement of R22. The purpose of this work is to develop a numerical model of an air cooler to simulate its behavior operating under dynamic conditions loaded with R22 or R410A refrigerant. The model divides the air cooler in volumes control in which mass, energy, and momentum balance equations are applied and solved. Theoretical data obtained by model simulations repeated tendencies observed in experimental data taken from literature. Model simulations have also shown that for a step change in the inlet refrigerant mass flow, the superheating response of air cooler is almost the same when it is working with R22 or R410A refrigerant.

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35

Perang, Mohd Rozi Mohd, Henry Nasution, Abdul Latiff Zulkarnain, Azhar Abdul Aziz e Afiq Aiman Dahlan. "Experimental Study on the Replacement of HFC-R134a by Hydrocarbons in Automotive Air Conditioning System". Applied Mechanics and Materials 388 (agosto 2013): 111–15. http://dx.doi.org/10.4028/www.scientific.net/amm.388.111.

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Abstract (sommario):

The HFC-R134a and hydrocarbon refrigerant (HCR) will be evaluated on the automotive air conditioning (AAC) experimental test rig which completed with the AAC system including the blower, evaporator, condenser, radiator, electric motor, compressor, alternator and equipped with the simulation room acting (equipped with internal heat load) as the passenger compartment. The electric motor operated as a car’s engine and will drive the compressor simultaneously to the alternator to recharge the battery. The tests have been performed by varying the motor speed; 1000, 2000 and 3000 rpm, temperature set-point; 21 and 230C, and internal heat loads; 0, 500, 700 and 1000 W. The results of the performance characteristics of the HCR indicate the encouraging enhancement of the AAC system compared to Hydrofluorocarbon refrigerant (HFC-R134a).

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36

Tsvetkov, Oleg B., Igor V. Baranov, Yuriy A. Laptev, Alexander V. Sharkov, Vladimir V. Mitropov e Alexey V. Fedorov. "Third Generation of Working Fluids for Advanced Refrigeration Heating and Power Generation Technologies". Key Engineering Materials 839 (aprile 2020): 51–56. http://dx.doi.org/10.4028/www.scientific.net/kem.839.51.

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Abstract (sommario):

Since the 1987 Montreal Protocol, chlorinated refrigerants (CFCs and HCFCs) have been pointed out as responsible for the destruction of the ozone layer. The chemical industry has realized suitable replacement for CFC-12 and for HCFC-22 e.g. HFC-134a, HFC-404A, HFC-410A, HFC-507. This generation of refrigerants developed by the chemical industry can be characterized by the no ozone depleting potential and long atmospheric lifetime resulting in global warming potential. The contribution of the HFCs to the global warming brings up to discussion whether the HFCs should be considered as a transitional substance. Historically the use of natural and ecologically safe refrigerants was a strategy to eliminate environmental problems and avoid uncertainties with synthetic replacement fluids. Since ammonia is toxic, carbon dioxide provide high pressure, and the hydrocarbons are flammable, the general conclusion is often drawn that natural fluids gave safety problems. This paper will describe the possibilities of application as working fluids in low-temperature engineering refrigeration, heat pumping and organic Rankine cycles of the hydrofluoroolefins (HFOs) as third generation of synthetic working fluids.

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Karthick, M., e K. Senthil Kumar. "Performance Investigation of an Eco-Friendly Refrigerant Mixture as an Alternative to R290/R600a". Applied Mechanics and Materials 787 (agosto 2015): 202–6. http://dx.doi.org/10.4028/www.scientific.net/amm.787.202.

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Abstract (sommario):

R134a is the most widely used refrigerant in domestic refrigerators. It must be phased out soon according to Kyoto protocol due to its high global warming potential (GWP) of 1300. It has been proposed that by previous experimental investigations, R290/R600a is the best alternate ozone friendly refrigerant mixture for R134a. But due to its high flammability this mixture is not completely substituted as an alternate working fluid in our country. In the present work, performance investigation has been made with eco-friendly refrigerant mixture (composed of R123 and R290 in the ratio of 70:30 by weight) in a refrigerator. This mixture has a very low ozone depletion potential (ODP) and has zero GWP value. Also this mixture has low flammability index when compared with R290/R600a. Continuous running tests were performed under different ambient temperatures (23°C, 28°C, 32°C and 36°C).The ON OFF and DOOR OPEN test results showed that ON TIME percentage of the compressor for the mixture (HCFC123/HC290) is less than that for HCM (R290/R600a). Also the power consumed by mixture (HCFC123/HC290) is lesser by 15% than that of R290/R600a and due to its low flammability property it can be a valuable replacement for the R290/R600a refrigerant mixture.

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38

OHUCHIDA, Satoshi, e Tatsuya HASEGAWA. "C212 Cycle Simulation of Air-Conditioning System Considering Refrigerant Replacement". Proceedings of the Thermal Engineering Conference 2006 (2006): 287–88. http://dx.doi.org/10.1299/jsmeted.2006.287.

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39

Ghanbarpour, Morteza, Adrián Mota-Babiloni, Bassam E. Badran e Rahmatollah Khodabandeh. "Theoretical Global Warming Impact Evaluation of Medium and High Temperature Heat Pumps Using Low GWP Refrigerants". Applied Sciences 11, n. 15 (1 agosto 2021): 7123. http://dx.doi.org/10.3390/app11157123.

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Abstract (sommario):

This study provides a global warming impact analysis of environmentally friendly refrigerants used as replacements for R134a and R245fa. R290, R1234yf, R1234ze(E), R513A and R450A are considered as refrigerants to replace R134a in medium temperature applications. For R245fa, there are five alternative refrigerants, R1224yd(Z), R600, R1336mzz(Z), R1233zd(E) and R1234ze(Z), which are selected for high-temperature applications. The analysis is done considering the emission factors in Brazil, Sweden, Canada and Poland. In Sweden and Brazil, the total equivalent warming impact per heating capacity of R134a is higher than its alternative refrigerants in medium temperature application, although R134a exhibits a higher coefficient of performance than its alternatives. In high-temperature applications, R1336mzz(Z) has the lowest total equivalent warming impact per heating capacity due to its higher coefficient of performance than other tested refrigerants. The highest total equivalent warming impact per heating capacity belongs to R245fa in all countries except in Poland, where R600 exhibits a higher value due to its lower coefficient of performance and the relatively higher emission factor in Poland compared to other selected countries. These results revealed that in addition to the global warming potential, the emission factor associated with the sources of electricity generation has a crucial impact on indirect emissions.

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40

Aisbett, Emma K., e Q. Tuan Pham. "Natural replacements for ozone-depleting refrigerants in eastern and southern Asia". International Journal of Refrigeration 21, n. 1 (gennaio 1998): 18–28. http://dx.doi.org/10.1016/s0140-7007(97)00080-7.

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41

Roy, Zunipa, e Gopinath Halder. "Replacement of halogenated refrigerants towards sustainable cooling system: A review". Chemical Engineering Journal Advances 3 (novembre 2020): 100027. http://dx.doi.org/10.1016/j.ceja.2020.100027.

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42

Direk, Mehmet, Cuneyt Tunckal e Fikret Yuksel. "Comparative performance analysis of experimental frigorific air conditioning system using R-134a and HFO-1234yf as a refrigerant". Thermal Science 20, n. 6 (2016): 2065–72. http://dx.doi.org/10.2298/tsci140715130d.

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Abstract (sommario):

In this study, to evaluate the comparative experimental performances, a frigorific air conditioning system using HFO1234yf and R134a was developed and refrigerated air was introduced into a conditioned room. The experiment was carried out at different condenser inlet temperatures and using the refrigerants at different charges, 1250 g, 1500g, and 1750g. Experiments were conducted for a standard frigorific air conditioning system using the HFO1234yf and R-134a system. Air flow was introduced to the conditioned room for 60 minutes for each performance test. The results revealed that the temperature gradient in time was comparable for both refrigerants. The results of this investigation propose utilising HFO1234yf as a replacement for the currently favoured R134a in a frigorific air conditioning system.

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43

Feller, Michael, Karin Lux, Christian Hohenstein e Andreas Kornath. "Structure and Properties of 2,3,3,3-Tetrafluoropropene (HFO-1234yf)". Zeitschrift für Naturforschung B 69, n. 4 (1 aprile 2014): 379–87. http://dx.doi.org/10.5560/znb.2014-4017.

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Abstract (sommario):

The novel refrigerant 2,3,3,3-tetrafluoropropene (HFO-1234yf) is discussed as a replacement for 1,1,1,2-tetrafluoroethane (R-134a) due to its low global warming potential. Although it may therefore have great potential for use on a large scale, no structural data and only a fewvibrational data of the compound are known.We describe low-temperature X-ray structure analysis, vibrational spectra and combustion properties of 2,3,3,3-tetrafluoropropene. The experimental data are compared with the results of theoretical calculations. Furthermore the basic combustion properties have been investigated.

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44

Rusowicz, Artur, e Andrzej Grzebielec. "Legal and technical aspects of replacement refrigerants in refrigeration and air conditioning". Journal of Civil Engineering, Environment and Architecture XXXII, n. 1/2015 (marzo 2015): 359–67. http://dx.doi.org/10.7862/rb.2015.25.

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45

Fang, Yu, Sergio Croquer, Sébastien Poncet, Zine Aidoun e Yann Bartosiewicz. "Drop-in replacement in a R134 ejector refrigeration cycle by HFO refrigerants". International Journal of Refrigeration 77 (maggio 2017): 87–98. http://dx.doi.org/10.1016/j.ijrefrig.2017.02.028.

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46

Stuart, David G., Daniel Ghidoni e Dennis Eagleson. "Helium as a Replacement for Dichlorodifluoromethane in Class II Biological Safety Cabinet Integrity Testing". Journal of the American Biological Safety Association 2, n. 2 (giugno 1997): 22–29. http://dx.doi.org/10.1177/109135059700200207.

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Abstract (sommario):

Dichlorodifluoromethane was commonly used for many years as a tracer gas for leak testing biological safety cabinets. International agreement to ban release of chlorofluorocarbons into the atmosphere led the United States Environmental Protection Agency to regulate the discharge limit to zero when adequate substitutes are available. Hence the need arose to develop a leak test using an alternative tracer gas that is environmentally friendly. Helium was compared to refrigerant 12 and found to be an adequate substitute in this testing of Class II Type A biological safety cabinets. A waiver was obtained from NSF International to permit the use of the proposed helium leak test as an alternative to the Halogen Leak Test.

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47

Shen, Bo, e Moonis R. Ally. "Comparative Performance of Low Global Warming Potential (GWP) Refrigerants as Replacement for R-410A in a Regular 2-Speed Heat Pump for Sustainable Cooling". Sustainability 13, n. 15 (22 luglio 2021): 8199. http://dx.doi.org/10.3390/su13158199.

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Abstract (sommario):

Heat pumps are currently being developed to reduce the energy footprint for residential and commercial building space conditioning and water heating loads in cold climates. To mitigate the nocuous impact of greenhouse gas emissions on the environment, and to create a carbon-neutral building stock, alternate lower-GWP refrigerants must also replace the predominant use of R-410A, without re-engineering the mechanical hardware. In this paper, we analyze the performance of lower-GWP alternative refrigerants (R-32, R-452B, R-454B, and R-466A) relative to the conventional R-410A and draw conclusions on the relative performances to meet cooling loads. The simulations are accomplished using the heat pump design model, a well-known, public-domain design tool with a free web interface and downloadable desktop version to support public use and the HVAC R&D community. The contributions contain detailed, hardware-based heat exchanger and system analyses to provide a comprehensive assessment. The results of the simulation are scrutinized from the first (capacity and energy efficiency) and second laws (exergy analysis) to identify sources of systemic inefficiency, the root cause of lost work. This rigorous approach provides an exhaustive analysis of alternate lower-GWP refrigerants to replace R-410A using the same hardware. The results have practical value in engineering heat pumps in an economy that is compelled to alter by the consequences and uncertainties of climate change, to reduce its anthropogenic carbon footprint.

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48

Brown, J. Steven. "Preliminary Selection of R-114 Replacement Refrigerants Using Fundamental Thermodynamic Parameters (RP-1308)". HVAC&R Research 13, n. 5 (1 settembre 2007): 697–709. http://dx.doi.org/10.1080/10789669.2007.10390981.

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49

Hasheer, Sk Mohammad, e Kolla Srinivas. "Thermodynamic Analysis of Low GWP Refrigerant Mixtures in a Refrigerator as Replacement to R-134A". Strojnícky časopis - Journal of Mechanical Engineering 69, n. 4 (1 dicembre 2019): 147–58. http://dx.doi.org/10.2478/scjme-2019-0049.

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Abstract (sommario):

AbstractChlorofluorocarbons and hydro chlorofluorocarbons (HCFCs) are replaced by hydroflourocarbons (HFCs) which is not harmful to the ozone layer. However, few of HFCs have a relatively high global warming potential (GWP) and are subject to further examination due to growing concerns about global climate change. The goal now is to find the next generation of environmentally sustainable work fluids with an insignificant direct environmental impact in terms of ozone depletion and global warming potential. This document introduces the mixture of low-GWP refrigerants like R440A, R430A, R1234ze (E)/152a (50:50 by mass), R290/600a (40/60), R290/600(60/40), R290/600(50/50), ARM 42,ARM 42a and AC5 are used to replace R-134a in a domestic refrigeration system without doing any modifications to the system. The performance of the refrigerator was observed in terms of volumetric cooling capacity, blower discharge temperature, and coefficient of performance, refrigeration effect and energy consumption of a blower.

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50

Wang, Yabo, Shengchun Liu, Victor Nian, Xueqiang Li e Jun Yuan. "Life cycle cost-benefit analysis of refrigerant replacement based on experience from a supermarket project". Energy 187 (novembre 2019): 115918. http://dx.doi.org/10.1016/j.energy.2019.115918.

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