Papers by Pavel Makhnatch
Proceedings of the 25<sup>th</sup> IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019., Aug 24, 2019
Universitetsservice US-AB, 2019
Given the global commitment to reduce the impact of fluorinated gases on climate and the regulati... more Given the global commitment to reduce the impact of fluorinated gases on climate and the regulations controlling their use in the European Union (EU), this thesis investigates new refrigerants that have been recently proposed to meet the demands of the refrigeration industry in the EU, which must satisfy the legislative requirements of the F-gas Regulation and facilitate meeting the goals of the Paris Agreement. The legislative requirements of the EU have intensified refrigerant development with reduced GWP. New refrigerants have been identified in the form of six new substances and 40 new refrigerant mixtures that have been added to the ANSI/ASHRAE 34 standard during a period following the proposal for the F-gas Regulation. New refrigerants have been theoretically analysed in comparison with the commonly used fluorinated refrigerants R134a, R404A and R410A. While new refrigerants provide a variation in operating parameters when used in a refrigeration, air conditioning or heat pump (RACHP) system, none of the new refrigerants can be considered being fully design compatible with R134a, R404A or R410A. Several commercially available refrigerants have been further evaluated in experimental studies to analyse their suitability for replacing R134a and R404A in existing systems with regards to their thermal properties, requirements for component safety and energy efficiency. R450A and R513A have been analysed as alternatives to R134a in a small capacity refrigeration system, and an R449A was studied in a retrofit of an R404A supermarket indirect system. It was shown that the analysed refrigerants can replace baseline HFCs in the analysed systems, but the variation in energetic performance and main operation parameters should be taken into account when considering such replacement. LCCP metric has been used to analyse the overall climate impact of a heat pump system using refrigerants with various GWP values. It was shown that most climate impact from an RACHP system is due to indirect emissions relating to energy use. Thus, addressing the overall climate impact of RACHP systems is necessary to facilitate meeting the goals of the Paris Agreement. It is possible to facilitate a comparative LCCP analysis by addressing the uncertainties of the input data.Med tanke på det globala åtagandet att minska effekterna av fluorerade gaser på klimatet och regler som styr deras användning i Europeiska unionen (EU), undersöker denna avhandling nya köldmedier som nyligen har föreslagits för att möta kraven från kylindustrin i EU, och som måste uppfylla lagstiftningskraven i F-gas förordningen och underlätta att Parisavtalets mål uppfylls. Lagkraven i EU har intensifierat utvecklingen av köldmedier med reducerad GWP. Nya köldmedier har identifierats i form av sex nya ämnen och 40 nya köldmedieblandningar som har lagts till ANSI/ASHRAE 34-standarden efter det att förslaget till F-gasförordningen publicerats. Nya köldmedier har analyserats i teoretisk jämförelse med de ofta använda fluorerade köldmedierna R134a, R404A och R410A. Medan nya köldmedier ger en variation i driftsparametrar när de används i ett kyl-, luftkonditionerings- eller värmepumpssystem, kan inget av de nya köldmedierna anses vara helt designkompatibelt med R134a, R404A eller R410A. Flera kommersiellt tillgängliga köldmedier har utvärderats vidare i experimentella studier för att analysera deras lämplighet för att ersätta R134a och R404A i befintliga system med avseende på deras termiska egenskaper, krav på komponenternas säkerhet och energieffektivitet. R450A och R513A har analyserats som alternativ till R134a i ett kylsystem med liten kapacitet, och R449A studerades i en retrofit av ett indirekt R404A system i en livsmedelsbutik. Det visades att de analyserade köldmedierna kan ersätta befintliga HFC:er i de analyserade systemen, men variationen i energiprestanda och huvuddriftparametrar bör beaktas när man överväger en sådan ersättning. LCCP-analys har använts för att analysera den totala klimatpåverkan av ett värmepumpsystem med köldmedier med olika GWP-värden. Det visades att den största klimatpåverkan från ett RACHP-system beror på indirekta utsläpp relaterade till energianvändning. Således är det nödvändigt att redovisa och ta hänsyn till den totala klimatpåverkan av RACHP-system för att uppfylla målen i Parisavtalet. Det är möjligt att underlätta en jämförande LCCP-analys genom att ta itu med osäkerheterna i inmatningsdata
Applied Sciences, 2021
Artificial neural networks (ANNs) have been considered for assessing the potential of low GWP ref... more 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. Th...
International Journal of Refrigeration
Applied Thermal Engineering
The paper studies the effect of different climate conditions (average, cold and warm European cli... more The paper studies the effect of different climate conditions (average, cold and warm European climate) on total lifetime global warming gas emissions of 30 kW capacity air/water heat pump systems designed for retrofitting of heating systems in European building sector applications. The analysis is performed for low GWP refrigerant selection with GWP values not greater than 150 (including R152a, R1234yf, R290, R1270 and others). The results are compared with R410A which is used as a reference refrigerant. Indirect emissions are shown to dominate the total lifetime emissions of the heat pump system. The amount of indirect emissions is dependent on a number of parameters, including the heat pump system performance under various climate conditions. That affects the total lifetime emission of air/water heat pump systems at different locations.
International Journal of Refrigeration
Life cycle climate performance (LCCP) is environmental metrics that aim to indicate total environ... more Life cycle climate performance (LCCP) is environmental metrics that aim to indicate total environmental impact caused by a refrigeration or heat pump system. It often used to justify the choice of some refrigerant in favor of another when considering its effect on entire environmental impact from a system. Calculation of LCCP relies on a number of inputs that are often uncertain. This work introduces the cumulative uncertainty of LCCP metrics and analyses effect of the uncertainty on the comparative LCCP analyses. The results suggest that the uncertainties of LCCP analysis inputs should not be neglected. Moreover, when the uncertainties are taken into account, it can be speed up the analysis by focusing on refining the uncertainties of the inputs that have the greatest contribution to the uncertainty of the entire LCCP analysis.
Journal of Civil and Environmental Engineering, 2014
The ice rink floor is the largest heat exchanger in an ice rink. The important part of the floor ... more The ice rink floor is the largest heat exchanger in an ice rink. The important part of the floor consists of concrete, and the thermophysical properties of this concrete have strong influence on the energy usage of the ice rink. The thermal conductivity of concrete can be increased by using iron ore as ballast. In this study, the Transient Plane Source (TPS) method showed an increase up to 58.2% of thermal conductivity comparing the improved concrete to standard concrete. Moreover, two alternative ice rink floor designs are suggested to incorporate the improved concrete. A 2D simulation was developed to investigate the temperature distribution in the conventional and the suggested designs. The results show that the suggested designs reduce the temperature difference between the ice surface and the brine by 1-4 ̊C, when comparing with convectional designs at equal heat flux. This primarily leads to an increased coefficient of performance (COP) in the primary refrigeration cycle and s...
Many currently used refrigerants are potent greenhouse gases and therefore need to be replaced wi... more Many currently used refrigerants are potent greenhouse gases and therefore need to be replaced with lower global warming potential (GWP) fluids. The list of the proposed replacements includes a sig ...
In a global effort to mitigate global warming refrigerants with a high Global Warming Potential (... more 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.
With the growing concern over global warming and increasing contribution of refrigeration and hea... more With the growing concern over global warming and increasing contribution of refrigeration and heat pump systems to climate change, it is necessary to mitigate the greenhouse gases emissions from re ...
Currently 341 ice rinks are in operation in Sweden with an estimated total energy consumption of ... more Currently 341 ice rinks are in operation in Sweden with an estimated total energy consumption of 384 GWh/year. As it has been revealed in previous studies, most of the ice arenas are constructed an ...
According to the requirements of the European regulation on fluorinated greenhouse gases, refrige... more 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 o ...
International Journal of Engineering Education, 2018
Lower global warming potential (GWP) refrigerants must be used in refrigeration education to inte... more Lower global warming potential (GWP) refrigerants must be used in refrigeration education to integrate the environmen-tally responsible engineering principles in class. However, most of the refrigeration educational laboratories are still usinghydrofluorocarbons (HFCs) as working fluids, which are considered as greenhouse gases. This paper shows the procedureto adapt the new refrigerant R513A in a refrigeration system used for a cooling capacity educational laboratory. First, thepaper describes the organization of the laboratory session, and the characteristics of the different methods of coolingcapacity calculation taught to the master’s degree students. Then, the benefits of including new sensors in the experimentalsetup to obtain more accurate results are explained. Later, accurate new graphics and an equation to calculate the R513Acooling capacity are provided. Finally, the educational aspects worked with the students in this session, and each coolingcapacity method are assessed...
R404A will be soon restricted from usage in commercial refrigeration in the European Union (EU) d... more 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 ...
Recent legislative measures promote use of environmentally friendly refrigerants to mitigate glob... more Recent legislative measures promote use of environmentally friendly refrigerants to mitigate global warming. Different environmental metrics are used to facilitate decision-making process of select ...
Life cycle climate performance (LCCP) is environmental metrics that aim to indicate total environ... more Life cycle climate performance (LCCP) is environmental metrics that aim to indicate total environmental impact caused by a heat pump or refrigeration system. Calculation of LCCP relies on a number of inputs that are often uncertain or, sometimes, unknown. This work introduces the methodology of simplifying the comparative LCCP analysis of a heat pump system based on example of a fictitious domestic hot water heat pump system using different refrigerants.
The energy performance of CO2 standard booster systems is limited in countries with high ambient ... more 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 syste ...
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Papers by Pavel Makhnatch