Relevant bibliographies by topics / Refrigerant replacements

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Refrigerant replacements'

Author: Grafiati
Published: 4 June 2021
Last updated: 19 February 2022

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Journal articles on the topic "Refrigerant replacements"

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El-Sayed, A. R., M. El Morsi, and N. A. Mahmoud. "A Review of the Potential Replacements of HCFC/HFCs Using Environment-Friendly Refrigerants." International Journal of Air-Conditioning and Refrigeration 26, no. 03 (September 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, and Reinhard Radermacher. "Natural Refrigerants." Mechanical Engineering 120, no. 10 (October 1, 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, no. 2 (February 2000): 133–40. http://dx.doi.org/10.1016/s1359-4311(99)00016-2.

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Overton, Tina, Simon Hodgson, Alan Heaton, and Richard Powell. "A case study in Green chemistry: Developing replacements for CFCs." New Directions in the Teaching of Physical Sciences, no. 2 (December 1, 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, and 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, no. 1 (January 1, 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, and 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, and Ali Erişen. "Thermodynamic analysis of refrigerant mixtures for possible replacements for CFCs by an algorithm compiling property data." Applied Thermal Engineering 26, no. 4 (March 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, and Farooq Saeed. "Recent Developments in the Search for Alternative Low-Global-Warming-Potential Refrigerants: A Review." International Journal of Air-Conditioning and Refrigeration 28, no. 03 (September 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, and 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, no. 2 (December 31, 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, and 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, no. 16 (August 21, 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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Dissertations / Theses on the topic "Refrigerant replacements"

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Neilson, Martin M. "The bulk and surface properties of HFC replacement refrigerants." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312801.

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Ciantar, Christopher. "Sustainable development of refrigerator systems using replacement environmentally acceptable refrigerants." Thesis, Bournemouth University, 2000. http://eprints.bournemouth.ac.uk/374/.

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Environmental considerations have led to the phase out of chlorofluorocarbon (CFC) refrigerants from the domestic refrigeration industry. One intriguing aspect is that the chlorine in CFCs is a good lubricating agent and any deterioration of system performance may adversely influence other environmental considerations. Based on the above, the aim of this research is to address the sustainable development of domestic refrigeration systems using the replacement refrigerant HFC-134a. The work focuses on the emissions that may arise if the electrical consumption of the product deteriorates or its durability is curtailed. Tribological characteristics on compressor components influence both of these product attributes and therefore a thorough system analysis was carried out. An in-house built experimental test rig, which monitored slight variations in the electrical power drawn by a reciprocating hermetic compressor, was used under different experimental conditions. Furthermore, a detailed life cycle assessment on a domestic refrigerator was performed to help quantify the ensuing environmental burdens. In this way, a relation between tribological characteristics, power consumption and environmental impact was studied. Results have shown that the CFC substitute will increase friction and wear characteristics on the aluminium alloy connecting rod and the steel gudgeon pin. These characteristics led to an increase in the electrical energy consumption of the compressor such that the indirect global warming implications are set to rise with HFC-134a. If the sustainable development of this product is to be ascertained then a change in refrigerants alone will not suffice. New design considerations, primarily aimed at servicing and extending the life of the hermetic compressor itself, are considered. This work helps stimulate new ideas to address environmental issues influenced by traditional engineering disciplines. For this reason additional future research work, which will help determine these implications further, is outlined.
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Mirza-Tolouee, Changiz M., and n/a. "Experimental study of zeotropic refrigerant mixture HFC-407C as a replacement for HCFC-22 in refrigeration and air-conditioning systems." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20070416.141307.

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HCFC-22 is the world�s most widely used refrigerant. It serves in both residential and commercial applications, from small window units to large water chillers, and everything in between. Its particular combination of efficiency, capacity and pressure has made it a popular choice for equipment designers. Nevertheless, it does have some ODP, so international law set forth in the Montreal Protocol and its Copenhagen and Vienna amendments have put HCFC-22 on a phase out schedule. In developed countries, production of HCFC-22 will end no later than the year 2030. Zeotropic blend HFC-407C has been established as a drop-in alternative for HCFC-22 in the industry due to their zero Ozone Depletion Potential (ODP) and similarities in thermodynamic properties and performance. However, when a system is charged with a zeotropic mixture, it raises concerns about temperature glide at two-phase state, differential oil solubility and internal composition shift. Not enough research has been done to cover all aspects of alternative refrigerants applications in the systems. This research intended to explore behavior of this alternative refrigerants compare to HCFC-22 and challenges facing the industry in design, operation service and maintenance of these equipments. The purpose of this research is to investigate behavior of R407C refrigerant in chiller systems. This includes performance and efficiency variations when it replaces R22 in an existing system as well as challenges involved maintaining the system charged with R407C. It is a common practice in the industry these days to evacuate and completely recharge when part of the new refrigerant blend was leaked from the system. This has proved to be extremely costly exercise with grave environmental ramifications. This research is intended to address challenges faced in the real world and practical terms. Theoretical and experimental approaches used as a methodology in this work. The system mathematically modeled to predict detailed system performance and effect of the leak at various conditions. To make this feasible and accurate enough, two separate approaches made, first system performance for pure R22 and R407C, and second system subjected to range of leak fractions. The earlier model was relatively straight forward when compared to the latter. Modeling a system charged with R407C ternary mixture and subjected to range of leaks posed enormous challenges. A sophisticated experimental test apparatus was also designed and built. Comprehensive and detailed tests at various conditions were conducted with special attention on instrumental accuracy and correct methodology. The first part has been successfully modeled and predicted all the factors and performance with excellent accuracy when compared to the test results. In these approaches pure refrigerants R22 and R407C were used and simulated the system behavior at range of conditions. However, the second part was the most challenging ever. Comprehensive leak process simulations produced trends of R32/R125/R134a composition change as function of rate of leak. Starting from this point, equations have been created to represent the composition change as function of percentage of the leak. The system thermodynamic cycle was also modeled to calculate capacity, power input and COP at the range of the conditions. Despite many affecting parameters and complexity of the model, the mathematical model successfully predicted the test outcome with a very reasonable accuracy, averaging around 3% with some times reaching to 5 to 6%. On the experimental stage the system charged with the new HFC-407C was deliberately subjected to refrigerant leak at various leak stages. The aim was to objectively determine to what extend the gas leak can be still acceptable without going through the expensive complete gas charge. The effect of leak was tested and verified at 10% steps, from 10% up to 50% mass fraction for the total charge. It has been observed that at the leaks beyond 30%, the adverse effect on the capacity becomes more significant, from 8 to about 15% decrease. While the power input decreased at slower pace, from 3% up to about 8% depending on the test conditions. This translated to COP decrease ranging from 4 to about 7%. This capacity loss and efficiency decrease are significant figures which suggests that the system, here chiller, can not be allowed to degrade the performance to that extend and still continue operating.
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Mirza-Tolouee, Changiz M. "Experimental study of zeotropic refrigerant mixture HFC-407C as a replacement for HCFC-22 in refrigeration and air-conditioning systems." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070416.141307/index.html.

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Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, 2006.
A thesis submitted for the degree of Doctor of Philosophy, School of Engineering and Science, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 123-127).
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Fiorelli, Flávio Augusto Sanzovo. "Análise do escoamento de fluidos refrigerantes alternativos ao HCFC22 em tubos capilares adiabáticos." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/3/3132/tde-24102001-160408/.

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Este trabalho apresenta os resultados da pesquisa "Análise do Escoamento de Fluidos Refrigerantes Alternativos ao HCFC 22 em Tubos Capilares Adiabáticos", desenvolvida para obtenção do título de Doutor em Engenharia no Departamento de Engenharia Mecânica da EPUSP. Essa pesquisa foi motivada pelas resoluções do Protocolo de Montreal, que prevêem a eliminação gradativa do HCFC 22 e, conseqüentemente, impõem a necessidade da realização de estudos sobre o comportamento de fluidos alternativos ecologicamente aceitáveis nos sistemas de refrigeração e seus componentes. Até o momento, as pesquisas e as referências bibliográficas indicam a utilização de misturas zeotrópicas e quase-azeotrópicas como a melhor alternativa para substituição do HCFC 22. Desta forma, foi realizado um extenso levantamento experimental do escoamento do R-407C (uma mistura zeotrópica) e do R-410A (uma mistura quase-azeotrópica) através de tubos capilares, em uma unidade laboratorial construída para essa finalidade. Esse levantamento, realizado para condições de entrada subresfriada e saturada, caracterizou a influência destes fluidos refrigerantes e dos diversos parâmetros operacionais e geométricos no comportamento do tubo capilar em sistemas de refrigeração. Foram desenvolvidos dois modelos (fases separadas e homogêneo) para a modelagem matemática do escoamento de fluidos refrigerantes através de tubos capilares, a fim de verificar o efeito do tipo de escoamento adotado nessa modelagem. A validação dos programas de simulação desenvolvidos, tanto para os dados experimentais obtidos no presente trabalho quanto para dados de literatura, mostra que os dois modelos podem ser utilizados para essa modelagem, apresentando desvios semelhantes em relação aos dados experimentais. A fim de aprimorar os modelos, é necessária a realização de estudos mais aprofundados sobre o atraso de vaporização e a ocorrência de blocagem na saída do tubo capilar. Por fim, foi realizado um estudo numérico comparativo do desempenho do HCFC 22 e dos alternativos R-407C e R-410A, que indicou que o primeiro é adequado tanto para o "retrofit" de equipamentos existentes quanto para utilização em novos equipamentos, enquanto que o segundo deve ser utilizado apenas em novos equipamentos.
This work presents the results of the research activities on the "Analysis of HCFC 22 Alternatives Flow Through Adiabatic Capillary Tubes", developed at the Mechanical Engineering Department of Escola Politécnica da Universidade de São Paulo. Such research was motivated by the resolutions of Montreal Protocol, which imposes gradational elimination of several refrigerants, among them HCFC 22. This leads to the necessity of carrying out studies on the behaviour of ecologically acceptable refrigerants in refrigeration systems and components. So far, researches and literature indicate the usage of zeotropic and near azeotropic refrigerant mixtures as the best alternative to HCFC 22. Therefore, it was performed an extensive experimental survey on R-407C (a zeotropic mixture) and R-410A (a near azeotropic mixture) flow through capillary tubes. Such survey, which was carried out for both subcooled and two-phase inlet conditions, characterised the influence of these refrigerants, as well as the several operating and geometric parameters on the behaviour of capillary tubes used in refrigeration systems. In order to analyse the effect of different approaches for two-phase flow, it was developed two models (separated flow model and homogeneous model) for mathematical simulation of refrigerant flow through adiabatic capillary tubes. Models validation using both experimental and literature data shows that the two models are suitable for such simulation, with the same error level in relation to experimental data. It was also noticed that it is necessary to perform more comprehensive studies on the delay of vaporisation and capillary tube outlet shocking flow phenomena. Finally, it was performed a comparative study on the performance of HCFC 22, R-407C and R-410A, which indicates that R-407C is suitable both for retrofitting actual equipment and for new ones, while R-410A is suitable only for new equipment.
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Tadros, Amir The University of New South Wales School of Mechanical &amp Manufacturing Engineering UNSW. "Performance and safety of centrifugal chillers using hydrocarbons." 2008. http://handle.unsw.edu.au/1959.4/41242.

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The high ozone depletion and global warming potentials of fluorocarbon refrigerants have resulted in prohibitions and restrictions in many markets. Hydrocarbon refrigerants have low environmental impacts and are successfully used in domestic refrigerators and car air conditioners but replacing fluorocarbons in centrifugal chillers for air conditioning applications is unknown. Hydrocarbon replacements need a heat transfer correlation for refrigerant in flooded evaporators and predictions for operating conditions, capacity and performance. Safety precautions for large quantities of hydrocarbon refrigerants are needed and control of overpressure in plantrooms requires accurate prediction. Reliable correlations exist for forced convection in a single phase flow, condensation outside tubes and evaporation off sprayed tubes. For flooded evaporators this thesis proposes a new correlation for forced convection boiling of any refrigerant. An enhancement factor is combined with a modified Chen coefficient using recent pool boiling and forced convection correlations outside tubes. This correlates within typically a factor of two to known boiling literature measurements for CFC-113, CFC-11, HCFC-123, HFC-134a and HC-601. The operating conditions, capacity and performance of replacement hydrocarbons in centrifugal chillers were predicted using fluorocarbon performance as a model. With the new heat transfer correlation hydrocarbon predictions for flooded evaporators were made. For any fluorocarbon refrigerant there exists a replacement mixture of hydrocarbons which with a rotor speed increase about 40% gives the same cooling capacity in the same centrifugal chiller under the same operating conditions. For example replacing HCFC-123 in a flooded evaporator with HC-601/602 [90.4/9.6] and increasing the rotor speed by 43% will increase the coefficient of performance by 4.5% at the same cooling capacity. The maximum plantroom overpressure considered was from leakage and ignition of a uniform air/refrigerant mixture with maximum laminar burning velocity. Flow was modelled using a turbulence viscosity due to Launder and Spalding and turbulent deflagration using a reaction progress variable after Zimont. These partial differential equations were solved approximately for two and three dimensional geometries using finite volume methods from the Fluent program suite. Simple overpressure predictions from maximum flame area approximations agreed with Fluent results within 13.7% promising safe plantroom design without months of computer calculation.
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Books on the topic "Refrigerant replacements"

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Ciantar, Christopher. Sustainable development of refrigerator systems using replacement environmentally acceptable refrigerants. Poole: Bournemouth University, 2000.

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An experimental evaluation of medium and high pressure HFC replacements for R-22. [Washington, D.C.?: U.S. Environmental Protection Agency, 1996.

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S, Bayoglu Evren, Delafield Francis R, and United States. Environmental Protection Agency, eds. Performance of environmentally friendly CFC-12 replacements for refrigerator/freezers. [Washington, D.C.?: U.S. Environmental Protection Agency, 1996.

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United States. Environmental Protection Agency. Office of Research and Development, National Risk Management Research Laboratory (U.S.), and United States. Environmental Protection Agency. Air Pollution Prevention and Control Division, eds. Stratospheric ozone: Research on replacement chemicals to protect the earth's fragile ozone layer. Washington, DC: U.S. Environmental Protection Agency, Office of Research and Development, 1995.

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United States. Environmental Protection Agency. Office of Research and Development., National Risk Management Research Laboratory (U.S.), and United States. Environmental Protection Agency. Air Pollution Prevention and Control Division., eds. Stratospheric ozone: Research on replacement chemicals to protect the earth's fragile ozone layer. Washington, DC: U.S. Environmental Protection Agency, Office of Research and Development, 1995.

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Book chapters on the topic "Refrigerant replacements"

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Pendyala, Srinivas, and R. Prattipati. "Criteria for Drop-in Replacement of Existing Refrigerant with an Alternative Refrigerant." In Learning and Analytics in Intelligent Systems, 424–31. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-24314-2_51.

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Ajayi, Oluseyi O., Teddy I. Okolo, Enesi Y. Salawu, F. T. Owoeye, D. K. Akinlabu, E. T. Akinlabi, S. T. Akinlabi, and S. A. Afolalu. "Performance and Energy Consumption Analyses of R290/Bio-Based Nanolubricant as a Replacement for R22 Refrigerant in Air-Conditioning System." In Energy Technology 2019, 103–12. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-06209-5_10.

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"New and replacement refrigerants." In Refrigeration Equipment, 188–203. Routledge, 2007. http://dx.doi.org/10.4324/9780080515984-26.

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Bryant, A. C. "New and replacement refrigerants." In Refrigeration Equipment, 178–93. Elsevier, 1998. http://dx.doi.org/10.1016/b978-075063688-9/50019-8.

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Cremaschi, L., X. Wu, A. Biswas, and P. Deokar. "Experimental study of compressor operating characteristics and performance when using refrigerants R32, R1234yf, and two new low GWP developmental refrigerants as drop-in replacements for R410A." In 8th International Conference on Compressors and their Systems, 57–66. Elsevier, 2013. http://dx.doi.org/10.1533/9781782421702.2.57.

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Manke, Charles W., and Esin Gulari. "Rheological Properties of Polymers Modified with Carbon Dioxide." In Green Chemistry Using Liquid and Supercritical Carbon Dioxide. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195154832.003.0016.

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Use of supercritical fluids (SCFs), particularly supercritical carbon dioxide, as alternative solvents in polymer synthesis and processing is a rapidly growing research area with successful industrial applications (McCoy, 1999). In some cases, the need for alternative solvents is based on environmental concerns, with regulations mandating replacement solvents. An environmentally mandated example is the 1995 ban of the use of chlorofluorocarbons (CFCs) as physical blowing agents in the manufacture of polymeric foams after CFCs were classified as class-I-ozone-depleting substances (ODPs). Among the alternative blowing agents are gases like CO2 and N2 and refrigerants such as 1,1-difluoroethane (R152a) and 1,1,1,2-tetrafluoroethane (R134a). Under the foaming conditions, at temperatures above the glass transition temperature of a polymer, and at pressures required for flow of highly viscous polymer melts, these alternative blowing agents are frequently supercritical. When polymers are formed into final products by various melt-processing techniques, such as extrusion, injection molding, blow molding, foaming, and spin-coating, extremely high melt viscosity presents a major difficulty. A common method to moderate the processing conditions is to add a liquid solvent or plasticizer to the melt. Solvents and plasticizers lower the glass transition temperature, Tg, of the polymer so that the polymer can be made to flow at lower pressures and temperatures. Replacing liquid solvents with SCFs presents unique processing advantages. Higher diffusivity and lower viscosity of SCFs, compared with liquid solvents, increase rates of dissolution and mixing. The properties of polymer–SCF solutions are tunable via pressure or temperature changes, thus allowing efficient downstream separations. Most importantly, dissolution of an SCF produces very large reductions in melt viscosity compared with a liquid solvent dissolved in the melt. Whether the interest in using SCFs in polymer synthesis and processing is driven by environmental concerns or processing advantages, it is important to understand the rheological behavior of polymer–SCF mixtures. In this chapter, we describe rheological measurements of polymer melts containing dissolved gases for two polymers, polydimethylsiloxane (PDMS) swollen with CO2 at 50 °C and 80 °C and polystyrene (PS) swollen with CO2, R152a, and R134a at 150 °C and 175 °C.
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Conference papers on the topic "Refrigerant replacements"

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Shaligram, Avinash, and Sandip Kumar Saha. "Application of Dynamic Bubble Departure Model for New, Low-GWP Refrigerants on Enhanced, Structured Surfaces." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71324.

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Structured surfaces consisting of sub-surface tunnels and openings in the form of pores or gaps are used to enhance boiling heat transfer resulting into compact heat exchangers. One of the applications of enhanced surface tubes is in flooded evaporators in water chillers. The fundamental mechanisms in nucleate boiling on structured surfaces are not still well understood, especially for new, low-GWP refrigerants. In this study, the focus is on bubble departure models. Most of the nucleate boiling models consider the static force model for calculating bubble diameter at the departure. However as per flow visualization studies in published literatures, the process of bubble growth and departure is dynamic and hence three more forces (in addition to buoyancy and surface tension) need to be accounted for while calculating the instantaneous bubble departure diameter. In this study, numerical results are presented for bubble departure diameter for four refrigerants, viz. R134a (the currently used, high GWP refrigerant) and its targeted low-GWP replacements, viz. R1234ze (E), R513A and R450A on enhanced, structured surfaces. Results from the dynamic force model show the bubble departure diameter in the range of 0.78 mm to 0.85 mm for all the four refrigerants. The unsteady growth force ranges from 4.8 × 10−6 N to 1.35 × 10−5 N while the surface tension force ranges from 2.49 × 10−6 N to 1.975 × 10−6 N. Similar results are provided for other forces as a function of wall superheat.
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Kornhauser, Alan A. "Aqua-Ammonia as an Environmentally Acceptable Low Temperature Brine." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62684.

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In many industrial processes, cooling with brines is preferable to cooling with an evaporating refrigerant. For medium and high temperatures (above about −35°C/−30°F), aqueous solutions of calcium chloride, sodium chloride, ethylene glycol, propylene glycol, and methanol have typically been used. For very low temperatures (down to about −80°C/-110°F) halocarbon refrigerants methylene chloride and trichloroethylene have generally been used. In recent years, both methylene chloride and trichloroethylene have come under increasingly strict regulation because of their toxicity. While many plants continue to use these brines, most are searching for alternates. This study was begun in response to the needs of a plant that was replacing methylene chloride with aqueous calcium chloride. The high viscosity of the calcium chloride brine caused design and operational problems. The above-mentioned brines, as well as aqua-ammonia, polydimethylsiloxane, and d-limonene, were compared for cost, toxicity, flammability, environmental safety, and energy efficiency. The energy efficiency comparison included comparisons of heat transfer coefficient, mass flow rate, volume flow rate, frictional pressure drop, inertial pressure drop, and pumping power. The comparisons indicated that aqua-ammonia was the best choice as a replacement for methylene chloride and trichloroethylene in some temperature ranges.
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Pramudantoro, Triaji P., Edi Sukamto, K. Sumeru, Ade Suryatman Margana, and M. F. Sukri. "Effect of refrigerant charge variation of R32 as drop-in replacement for R22 in air conditioning system." In ADVANCED MATERIALS: Proceedings of the International Workshop on Advanced Materials (IWAM-2017). Author(s), 2018. http://dx.doi.org/10.1063/1.5049969.

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4

El-Morsi, Mohamed, and Karim Hamza. "Multi-Objective Optimization of Gas Blend Alternative Refrigerants for Vapor-Compression Refrigeration Systems." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-46472.

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This paper presents a theoretical study on optimizing the mixing ratios of hydrocarbon blends to be used as refrigerants in existing refrigeration equipment. The primary objective is to maximize the coefficient of performance. The gas blending optimization problem is posed in a multi-objective framework, where the optimization seeks to generate Pareto optimal solutions that span the trade-off frontier between coefficient of performance versus deviation from a desired volumetric refrigeration capacity, while adhering to a maximum compression ratio. Design variables in the optimization are the mass fractions of hydrocarbon gases in the blend. A domain reduction scheme is introduced, which allows for efficient conduction of exhaustive search, with up to three hydrocarbon gases in the blend. While exhaustive search guarantees that the obtained solutions are global optima, the computational resources it requires scale poorly as the number of design variables increase. Two alternative approaches, (multi-start SQP) and (NSGA-II) are also tested for solving the optimization problem. Numerical simulation case studies for replacement of R12, R22 and R134a with hydrocarbon blends of isobutane, propane and propylene show agreement between solution methods that good compromises are possible to achieve, but a small loss in coefficient of performance is inevitable.
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Vyas, Mayank I., Salim A. Channiwala, and Mitesh N. Prajapati. "Proposed Correlation for Forced Convection Boiling Heat Transfer in Mini and Micro Channels With CO2 as a Fluid." In ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icnmm2014-21567.

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After reviewing the available literature on flow boiling heat transfer in mini/micro tubes and channels, it is felt that there is need for predictive correlations which is applicable over wide range of parameters. In present work a new correlation for two-phase flow boiling heat transfer coefficient is developed, which has considered nucleate boiling and convective boiling heat transfer effect. To develop this correlation we have considered total 651 data points, which have been collected from the open available literature covering different operational conditions and different dimensions of channels. We have selected CO2 as a working fluid because it does not contain chlorine, hence an efficient and environmentally safe refrigerant and would be potential replacement for R-22. CO2 has unusual heat transfer and two-phase flow characteristics, and is very different from those of conventional refrigerant. Also a comparison of present correlation with the best published correlation for CO2 is done. The results of this comparison indicate that the new developed correlation is superior to published best correlation for CO2. Present correlation is also compared with best published correlation for all fluids and with the correlation developed by using CO2 data. The results of these both case, indicate that the present correlation is superior.
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Feenstra, Paul, Teguewinde Sawadogo, Bruce Smith, Victor Janzen, Anne McLellan, Helen Cothron, and Sean Kil. "Investigations of In-Plane Fluidelastic Instability in a Multi-Span U-Bend Test Rig: Tests in Two-Phase Flow." In ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93729.

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Abstract Tests to study FluidElastic Instability (FEI) in an array of U-bend tubes were recently completed in the Multi-Span U-Bend (MSUB) test rig at Canadian Nuclear Laboratories (CNL). These tests were sponsored by the Electric Power Research Institute (EPRI) and were designed to study In-Plane (IP or streamwise) FEI of steam generator tubes in two-phase cross flow. This instability mechanism was first observed in previous research tests by Atomic Energy of Canada Limited (AECL). Although AECL planned additional research into IP FEI, this mechanism was not thought to be a serious practical concern until it recently caused severe damage to tubes in a new replacement steam-generator. The MSUB tests were conducted both with flows of air and two-phase liquid/vapour Refrigerant 134a. With 22 flexible U-bend tubes supported by a configurable flat-bar arrangement, the tests were focused on the effects of support geometry and tube-to-support interaction. Data was recorded from 33 dynamic signals from accelerometers, displacement probes, force transducers, and void-fraction probes. The paper describes the experimental test setup and reviews some of the initial test results and their implications for steam-generator users and researchers. Tests with two-phase Freon refrigerant (R-134a) are presented here.
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7

Shaligram, Avinash G. "Solar Thermal Power for Large Chillers: A Feasibility Study." In ASME 2007 Energy Sustainability Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/es2007-36037.

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Centrifugal chillers using CFC’s were made in India in the capacity range from 150 TR to approximately 700 TR. Currently, there are around 500 units operating in India ranging in age from 10 to 30 years. All of these units will have to be replaced eventually since CFC’s are to be phased out by 2010 in Article 5 countries as per Montreal Protocol. The World Bank has made a detailed study of the issue and proposed a Global Chiller Replacement Project whereby the old units will be replaced by the current generation of energy-efficient chillers using non-CFC refrigerants. This paper deals with a novel, alternate proposal in which solar thermal power is used to power an electric-driven compression chiller and a heat-driven absorption chiller; as a pair of units, which would replace 2 Centrifugal chillers. The concept is found to be economically viable as a CDM project. The simple payback period works out to be 2 1/2 years. The investments required are large which can be brought down if the cost of solar concentrator is reduced.
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