| 1. |
- Belman-Flores, J. M., et al.
(författare)
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Using ANNs to approach to the energy performance for a small refrigeration system working with R134a and two alternative lower GWP mixtures
- 2017
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Ingår i: Applied Thermal Engineering. - : Elsevier Ltd. - 1359-4311 .- 1873-5606. ; 127, s. 996-1004
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, an artificial neural network application to model a small refrigeration system is presented. The main objective of this study is an energy comparison of three refrigerants: R134a, R450A and R513A. The application of the artificial neural network was designed to model individually three typical energy parameters: the cooling capacity, the power consumption and the coefficient of performance, as a function of the evaporating temperature and the condensing temperature. Each model was validated using a technique called cross-validation, producing minimum relative errors of 0.15 for the cooling capacity and the coefficient of performance, while 0.05 for the power consumption. Based on the appropriate validation results, computer simulations were performed to build 3D color surfaces. After inspecting these 3D color surfaces, it was concluded that R450A presented a slightly lower cooling capacity than R134a, actually a 10% reduction in the cooling capacity was estimated. Similar results were observed for the power consumption, that is, R450A had about 10% less power consumption than the other two refrigerants. On the other hand, it was observed that R134a and R513A presented very similar energy behaviors. With respect the COP, it was concluded that all three refrigerants showed a very similar behavior. After the analysis performed with the artificial neural networks and the use of 3D surface color, it was concluded that R450A and R513A are appropriate refrigerants to replace R134a in the short term in applications at medium evaporating temperature.
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| 2. |
- Ghanbarpour, Morteza, et al.
(författare)
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ANN Modeling to Analyze the R404A Replacement with the Low GWP Alternative R449A in an Indirect Supermarket Refrigeration System
- 2021
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 11:23
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Tidskriftsartikel (refereegranskat)abstract
- Artificial neural networks (ANNs) have been considered for assessing the potential of low GWP refrigerants in experimental setups. In this study, the capability of using R449A as a lower GWP replacement of R404A in different temperature levels of a supermarket refrigeration system is investigated through an ANN model trained using field measurements as input. The supermarket refrigeration was composed of two indirect expansion circuits operated at low and medium temperatures and external subcooling. The results predicted that R449A provides, on average, a higher 10% and 5% COP than R404A at low and medium temperatures, respectively. Moreover, the cooling capacity was almost similar with both refrigerants in both circuits. This study also revealed that the ANN model could be employed to accurately predict the energy performance of a commercial refrigeration system and provide a reasonable judgment about the capability of the alternative refrigerant to be retrofitted in the system. This is very important, especially when the measurement data comes from field measurements, in which values are obtained under variable operating conditions. Finally, the ANN results were used to compare the carbon footprint for both refrigerants. It was confirmed that this refrigerant replacement could reduce the emissions of supermarket refrigeration systems.
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| 3. |
- Makhnatch, Pavel, et al.
(författare)
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An experimental investigation of refrigerant R449A as replacement for R404A in supermarket refrigeration systems
- 2016
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Ingår i: 4TH IIR INTERNATIONAL CONFERENCE ON SUSTAINABILITY AND THE COLD CHAIN. - : International Institute of Refrigeration. - 9782362150142 ; , s. 324-331
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Konferensbidrag (refereegranskat)abstract
- In a global effort to mitigate global warming refrigerants with a high Global Warming Potential (GWP) will be banned in certain applications. The current European legislation prohibits a refrigerant R404A, which is commonly used in retail food refrigeration systems, from placing on the European market from the 1st of January 2020. Similarly, R404A will be soon unacceptable in retrofit and new supermarket systems in the USA. A refrigerant R449A is a potential replacement for R404A but with the GWP that is significantly lower than R404A's. In this study experimental investigations are conducted during the conversion of a supermarket refrigeration system from R404A to R449A. The performance data is presented and environmental benefits of the conversion are discussed.
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| 4. |
- Makhnatch, Pavel, et al.
(författare)
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Applicability of global temperature change potential (GTP) metric to replace GWP in TEWI environmental analysis of heat pump systems
- 2015
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Ingår i: Refrigeration Science and Technology. - : International Institute of Refrigeration. - 9782362150128 ; , s. 324-329
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Konferensbidrag (refereegranskat)abstract
- Recent legislative measures promote use of environmentally friendly refrigerants to mitigate global warming. Different environmental metrics are used to facilitate decision-making process of selection of refrigerant with low environmental impact. Total equivalent warming impact (TEWI) methodology is able to reflect the effect of heat pump or refrigeration system to global warming by accounting for both direct and indirect emissions associated with the refrigeration system. This paper extends TEWI methodology by using Global Temperature change Potential (GTP) metric instead of Global Warming Potential (GWP) one, which conventionally used to put different emissions on single CO2 scale. The analysis is done for the simple vapour compression heat pump system, where a number of refrigerants are compared. The study concludes with the analysis of applicability of modified TEWI analysis for further refrigerating system environmental assessment studies.
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| 5. |
- Makhnatch, Pavel, et al.
(författare)
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Characteristics of R454C and R455A as R404A alternatives in commercial refrigeration
- 2018
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Ingår i: Refrigeration Science and Technology. - : International Institute of Refrigeration. - 9782362150241 ; , s. 547-553
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Konferensbidrag (refereegranskat)abstract
- R404A will be soon restricted from usage in commercial refrigeration in the European Union (EU) due to the requirements of the EU Regulation on fluorinated gases. Therefore, new refrigerant HFO/HFC mixtures are being developed to replace it. This paper explores the R454C and R455A as R404A alternatives and compares the characteristics that can lead their imposition in the refrigeration market. The characteristics studied are components and composition, current penetration in the market, security issues, global warming potential, energetic performance, material and lubricant compatibility and, finally, most likely applications.
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| 6. |
- Makhnatch, Pavel, et al.
(författare)
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Energy evaluation of drop-in replacements for R134a in cascade CO2/R134a refrigeration units
- 2018
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Ingår i: Refrigeration Science and Technology. - : International Institute of Refrigeration. - 9782362150265 ; , s. 1147-1153
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Konferensbidrag (refereegranskat)abstract
- The energy performance of CO2 standard booster systems is limited in countries with high ambient temperatures to replace R404A direct expansion architectures. Therefore, cascade refrigeration systems with CO2 in the low-pressure stage can be considered. Most of the conventional cascade refrigeration systems rely on using R134a, a high global warming potential (GWP) refrigerant, in the high pressure stage. However, R134a needs to be replaced by lower GWP refrigerants to meet the targets of current environmental agreements. This study investigates R450A and R513A refrigerants as drop-in replacements to R134a in R134a/CO2 cascade refrigeration units. The experimental energy performance results suggest that both R450A and R513A can substitute R134a in cascade systems. R513A provides comparable COP and cooling capacity values to R134a, whereas the cooling capacity and COP of R450A are lower than that of the baseline R134a.
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| 7. |
- Makhnatch, Pavel, et al.
(författare)
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Evaluation of Cycle performance of R448A and R449A as R404A replacements in supermarket refrigeration systems
- 2015
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Ingår i: Refrigeration Science and Technology. - : International Institute of Refrigeration. - 9782362150128 - 9781479954421 ; , s. 437-444
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Konferensbidrag (refereegranskat)abstract
- According to the requirements of the European regulation on fluorinated greenhouse gases, refrigeration equipment that contain high Global Warming Potential (GWP) refrigerants that have GWP equal or greater than 2500, with some exceptions, will be prohibited from placing on the European market from 1st January 2020. Moreover, the use of such fluorinated greenhouse gases to service or maintain refrigeration equipment with a charge size of 40 tonnes of CO2 equivalent or more will be prohibited as well. The greatest impact of the Regulation in the nearest time will be therefore on users of R404A refrigerant, which is the most popular refrigerant for supermarket refrigeration systems. Equipment users and manufacturers are therefore looking for the alternative refrigerants to replace R404A in new and existing equipment. R448A and R449A are potential R404A replacements. Both are non-toxic and non-flammable refrigerant blends that closely match the properties of R404A and have GWPs significantly lower than R404A. Cycle performance of a supermarket refrigeration system, operated with R448A, R449A and R404A is modelled in this study.
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| 8. |
- Makhnatch, Pavel, et al.
(författare)
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Experimental study of R450A drop-in performance in an R134a small capacity refrigeration unit
- 2017
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Ingår i: International journal of refrigeration. - : Elsevier. - 0140-7007 .- 1879-2081. ; 84, s. 26-35
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Tidskriftsartikel (refereegranskat)abstract
- The Kigali's amendment to the Montreal Protocol has highlighted the hydrofluorocarbons (HFCs) phase out as a priority to reduce the future global Earth's mean temperature increase. R134a is the most abundant HFC in the atmosphere and therefore it must be substituted using environmentally benign alternatives. In the short term, blends of HFCs and hydrofluoroolefins can replace R134a. This paper experimentally evaluates R450A (GWP of 547), a non-flammable mixture of R1234ze(E) and R134a, in an R134a small capacity refrigeration system. The controlled experimental conditions cover evaporating temperatures from -15 to 12.5 °C and condensing temperature of 25, 30 and 35 °C (36 tests in total for each refrigerant). The experimental results showed that with only a thermostatic expansion valve adjustment the average R450A cooling capacity and COP are 9.9 and 2.9% lower than those measured using R134a. Besides, the observed compressor discharge temperature values of R450A are not greater than that of R134a.
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| 9. |
- Makhnatch, Pavel, et al.
(författare)
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Field measurements of AR404A low-temperature supermarket refrigeration system retrofitted with R449A
- 2018
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Ingår i: Refrigeration Science and Technology. - : International Institute of Refrigeration. - 9782362150241 ; , s. 468-474
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Konferensbidrag (refereegranskat)abstract
- Current international regulations set incentives to replace refrigerants with high global warming potential (GWP) values using environmentally friendly alternatives. This study presents the field measurements of an indirect commercial refrigeration system retrofitted with R449A, an alternative to R404A with a GWP value of 1282 (67% lower than that of R404A). The system has been operated at low evaporation temperature conditions(secondary refrigerant temperatures from -34 to -25°C). The results indicate that the cooling capacity of the retrofitted system was 1.3% lower than that of the reference R404A system on average, while the COP values are higher when using R449A (8.1% increase on average). The compressor discharge temperature increase is approximately 18.5 K. As a conclusion, R449A can be used as a replacement to R404A in indirect low-temperature supermarket refrigeration systems given that implications of its higher compressor discharge temperature, lower mass flow and difference in transport properties are taken into consideration.
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| 10. |
- Makhnatch, Pavel, et al.
(författare)
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Future refrigerant mix estimates as a result of the European Union regulation on fluorinated gases
- 2019
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Ingår i: Refrigeration Science and Technology. - : International Institute of Refrigeration. - 9782362150357 ; , s. 2318-2325
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Konferensbidrag (refereegranskat)abstract
- The requirements of the European Union (EU) regulation on fluorinated greenhouse gases has created an incentive to reduce their amount that can be placed on the EU market (including many commonly used refrigerants) to 21% of the baseline level. This study attempts to develop a methodology to predict the future refrigerant mix in refrigeration, air conditioning, and heat pumps that will be available to the EU customers by 2021 and 2030 years. The work is based on the relevant current statistical data, refrigerant distribution, and future technology acceptance and trends in refrigerants. The study presents a refrigerant demand grow scenario and provides a basis for closer market follow up in order to facilitate decision making for refrigeration industry stakeholders. The results of the study indicate that by 2021 will be difficult to accomplish the fluorinated gas quota but by 2030 the transition is possible. By that time, the natural refrigerants will dominate the market, and a small share of lower GWP refrigerants will be necessary for specific applications.
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