Refrigerant R134a Research Articles

Selection of refrigerant for use in chillers

BACKGROUND: Chillers (chillers) are essential components in various industrial processes. They are primarily used when direct cooling through direct heat exchange between the boiling coolant and the cooled medium is not feasible. This could be attributed to the cost of the refrigerant, especially when a large amount of expensive substances for long refrigerant lines is needed, or the risks associated with using toxic and flammable refrigerants, which could be hazardous in case of leaks. Chillers are typically classified into three types based on their temperature applications: high-temperature chillers for uses like plastic manufacturing and data centers, medium-temperature chillers for air conditioning systems, etc.) and low-temperature chillers for applications like ice fields and food storage. Given their widespread use and high production volume, designing efficient chillers is an important task. AIMS: Substantiating refrigerant use in terms of efficiency and service life of refrigeration equipment. MATERIALS AND METHODS: Chillers are designed for various industrial applications, with specific inlet and outlet temperatures for the evaporator: +26°С / + 20°С (ВТ); +12°С / +7°С (ST); −10°С / −13°С (НТ)). These chillers operate using refrigerants R134a, R410A, R404A, and R1270, evaluated through an entropy-statistical method of thermodynamic analysis [1]. R1270 is highlighted as a promising refrigerant for monoblock chillers, since there are no filling restrictions for these chillers when installed in open space [2]. RESULTS: Among the refrigerant reviewed, R1270 demonstrates the highest thermodynamic efficiency in BT mode, outperforming R404A by 11.97%, R134a by 2.15%, and R410A by 5.48%. In CT mode, R1270 also leads,–with a 14.13% advantage over R404A, 3.04% over R134a, and 3.41% over R410A. Similarly, in HT mode, R1270 shows superior thermodynamic performance, being 21.95% more efficient than R404A, 29.73% more than R134a, and 11.44% more than R410A. The use of R410A and R134a in NT mode is limited owing to high discharge temperatures during compression, namely 116.94°C for R410A and 114.63°C for R134a, potentially reducing equipment lifespan. The lowest discharge temperature during actual compression, 84.63°C, is achieved using R404A coolant. However, despite its efficiency, this refrigerant results in a relatively high discharge temperature of 96.84°C. CONCLUSIONS: The analysis highlights specific applications for various refrigerants in chillers and underscores the potential of natural refrigerant R1270, which is produced in the Russian Federation.

Analyze the effect of external conditions of the cooling cycle on precooled linde systeme

This study investigates the influence of critical operating variables on the efficiency of the precooled Linde cycle, with a focus on refrigerant mass flow rates, condensation temperatures, and cooling power. The study explored condensation temperatures ranging from 2°C to 45°C and refrigerant mass flow rates between 0.1 and 0.9 g/s to understand their impact on system performance. Three refrigerant mixtures R229, R134a, and R410a were analyzed to evaluate their effect on key performance metrics, including the figure of merit and the proportion of gas liquefied. Nitrogen was utilized as the standard permanent gas to benchmark the system's overall effectiveness. The results demonstrate that lowering condensation temperatures enhances the system's efficiency, resulting in increased liquid yield, especially at higher refrigerant mass flow rates. The characteristics of the refrigerant used in the cold circuit emerged as a crucial factor influencing the efficiency of Linde’s precooling cycle. This research offers valuable insights into optimizing operating parameters, contributing to the development of more efficient precooled Linde systems. By improving system performance, this study advances the understanding of cryogenic refrigeration cycles, providing a pathway for future enhancements in design and application.

Performance of R134a vapour compression refrigeration system by using Gr and Al2o3 hybrid nano lubricants

Nowadays, in many developing countries like India they are facing the shortage of energy. The Refrigeration system has become the major consumer of energy for many industrial as well as household applications. So, it is the need to enhance the energy efficiency of the refrigeration systems. Performance of the refrigeration system can be improved either by increasing the rate of heat absorption in evaporator or by reducing the compressor power. Use of efficient lubricant oil can help to remove the heat generated in the compression process which leads to less power consumption. Development in Nanotechnology makes it possible to develop a new class of lubricant called nanolubricant, in which nanoparticles are added in base lubricant oil to enhance the thermal properties. The two step technique with ultrasonic agitation force is used tosynthesise stable nanolubricant. The present study investigates the performance of an R-134a refrigerant vapour compression refrigeration system using nanolubricant with different volume concentrations (0.05%, 0.075%, 0.1% and 0.2%) of Graphene/Aluminium nanoparticles to mineral oil (MO) experimentally. The result shows maximum enhancement in COP approximately as 85% for 0.075 % volume fraction Nano lubricant as compared to base fluid. Use of nanolubricant saves approximately 27% compressor power.

Experimental study on electricity generation performance of T‐type direct‐expansion solar PVT heat pump system

AbstractFocusing on the electricity generation performance of a direct expansion solar PVT heat pump system, a novel T‐type optimized collector/evaporator was designed. The experiment used refrigerant R410a as the working medium and was conducted under the average winter ambient temperature of 16°C in Fuzhou. Through experimental comparison, the differences in panel temperature, electricity generation, and efficiency under different radiation intensities were tested against traditional PV panels and honeycomb PVT panels. The experimental results showed that the T‐type PVT system exhibited significant advantages under various weather conditions. The back panel temperature was reduced by 12.74, 8.52, and 13.06°C compared to traditional PV panels and honeycomb PVT panels, respectively, and it maintained a stable increase in electricity generation. The maximum instantaneous electricity output increased by 56.6% relatively, and the total electricity generation increased by 9.3% to 14.5% compared to traditional PV panels. The photoelectric efficiency reached 21.54% and 22.6%, surpassing traditional PV panels and honeycomb PVT panels, with measured values relatively increased by 1.7%, 2.38%, and 2.76%, respectively. Economic evaluation indicated that the T‐type PVT system could save on self‐generated electricity costs, achieving savings of up to 386.50 and 210.81 yuan/year compared to traditional PV panels and honeycomb PVT panels. The T‐type PVT system demonstrated clear advantages in self‐generated electricity costs, significantly reducing costs for application scenarios and providing strong support for the practical application of renewable energy technologies.

Experimental study on hydraulic performance and cavitation characteristics of a R134a refrigerant self-lubricating centrifugal pump

As the primary power equipment in pump flooding cooling systems, the efficiency and performance of mechanical pumps play a crucial role in two-phase cooling systems. A high-speed centrifugal pump with self-lubricating working fluid was designed with a speed of 7500 rpm and a flow coefficient of 0.0506. The hydraulic and cavitation performance of the pump were tested with R134a as the working fluid. The results show that the working fluid pump is capable of efficiently pumping R134a with an efficiency of 40.3% and a head coefficient of 0.988 under the design condition. Within the tested range of inlet temperature from 5°C to 15°C, the flow coefficient from 0.01 to 0.105, and the height of the refrigerant tank from 1.4 m to 5 m, lower net positive suction heads available at the same flow rate will reduce the pump head, increase power consumption, and decrease efficiency. Increasing the pump speed from 3000 rpm to 7500 rpm can improve the pump's performance. At 6000 rpm, the critical cavitation number of the working fluid pump increases with the increase in flow coefficient. At 7500 rpm, the critical cavitation number has a minimum value when the flow coefficient φ = 0.0434. At the design speed and flow rate, both the critical cavitation coefficient and fracture cavitation number increase as the inlet temperature decreases. The inducer can significantly reduce the critical cavitation number of the pump. Finally, an empirical correlation considering the thermodynamic effects is proposed to predict the increase in the critical cavitation number.

REFRIGERANT CHARGING UNIT FOR THE RESIDENTIAL AIR CONDITIONERS: AN EXPERIMENT

In the present work, an automatic R410A refrigerant charger for residential air conditioners is fabricated and tested. The charger operates on the throttling principle and uses the suction pressure of the compressor to estimate the refrigerant charge level. This helps to reduce the risk of compressor damage and ensures the correct composition ratio of R410A refrigerant when charged into the machine. The charging process is controlled by the LabVIEW platform, which provides adequate control and visualization of the charging process. The developed charger meets expectations in solving the technical problems encountered when charging R410A refrigerant for residential air conditioners. It is compact, portable and can be directly controlled through the LabVIEW interface, allowing real-time visualization of the charging process. The present work is expected to make a significant practical contribution, serving as a useful reference for the future manufacturing of compact portable equipment in the residential air conditioning field.

Using froude and weber numbers to represent the changes in the flow pattern from stratified to stratified-wavy or plug for wire-on-tube condenser

According to manufacturing data, a theoretical study of condensation inside a heat exchanger with wires on tubes.examined flow patterns with variable refrigerant mass flow rates. Wire-on-tube condensers are adopted with tubes, which have multiple diameters (3.25, 4.83 and 6.29 mm). In addition to the use of two refrigerants (R-134a, R-600a) working at condensing temperatures of (54.4, 45, and 35 °C). The Equal Equation Solver software (EES) was used to obtain the results for the mass velocity range from 8 to 167 kg s−1m−2. Using the non-dimensionless numbers, the model determines the refrigerant flow pattern. Weber number (We) and Froude number (Fr) were used for mass velocity in a range below 100 kg s−1 m−2, which is recommended flow inside the wire-on-tube condenser. The initial transition of the two-phase flow pattern from stratified to stratified-wavy occurred at beginning of condensation for the quality range (0.78-0.42) was Fr (2.7-2.0) and We (6.1-4.0) for R-134a, while the quality range (0.85-0.39) was Fr (5.0-2.4) and We (7.0-4) for R-600a. Second, as the quality range approached, the stratified-wavy flow was replaced by a plug at quality (0.23-0.06) were Fr (1.5-0.4) and We (3.8-2.1) for R-134a and for R-600a the quality range (0.22-0.05) were Fr (1.7-0.55) and We (3.7-2.2).

Investigation of the insoluble impurities' impact on flow boiling heat transfer in aluminum microchannel heat exchangers

Microchannel flat-tube heat exchangers are known for their high heat transfer efficiency and compact size. In practical applications, the predominantly adverse influence of insoluble impurities on the condensation process necessitates further exploration into the underlying mechanisms affecting the flow boiling process. The effect of common insoluble impurities on the flow boiling of R410A refrigerant in a microchannel flat-tube heat exchanger has been investigated, and variation of the impurity volume fraction on heat transfer, mass transfer, pressure drop, and bubble formation are analyzed. Additionally, an adaptive modification method for the mass transfer factor is proposed. The numerical model of flow boiling heat transfer in a microchannel is validated through experimental data and empirical correlations. Thermo-hydraulic performance evaluation incorporates efficiency index and area goodness ratio metrics. Results reveal that the presence of insoluble impurities complicates the boiling heat transfer mechanism by influencing bubble evolution and multiphase flow patterns. Air impurities at a volume fraction not exceeding 5% prove beneficial for enhancing flow boiling efficiency in microchannels; however, a 38.5% decrease in efficiency index is observed with 1% oil impurities present. Optimal thermo-hydraulic performance is achieved with approximately 2%–3% water impurities.

Ionic liquids based azeotropic separation of refrigerants R410A (R32+R125) and R508B (R23+R116) through hybrid extractive distillation

ABSTRACT The increment in GreenHouse Gases (GHGs) promotes high Global Warming Potential (GWP) due to the production and consumption of hydrofluorocarbons (HFCs) that diverts the aim toward the recycling and reclaiming of refrigerant gases. However, the presence of azeotrope in refrigerant mixtures restricts the recycling process. Therefore, in this work, the refrigerant R410A and R508B have been separated through the hybrid extractive distillation method by using [HMIM][TF2N] and [BMIM][BF4] as a solvent in ASPEN Plus. UNIFAC model has been used for the correlation of ionic liquid in ASPEN Plus. For thermodynamic properties, Cosmotherm has been used with the collaboration of TurbromoleX. The Vapor-liquid Equilibrium (VLE) data has been predicted by using the UNIFAC group contribution method. The Total Annual Cost (TAC) analysis with optimization has been performed. Besides that, the energy analysis has also been performed. In the overall separation process and (TAC) analysis, [BMIM][BF4] proves to be more efficient with high separation efficiency and minimal TAC requirements. Whereas, [HMIM][TF2N]/R508B provides less CO2 emission.

Assessing PEM fuel cell performance in a geothermal Cogeneration system for peak-time energy storage

In this investigation, a novel geothermal power plant was designed, combining absorption chiller units, PEMFC, EPEM, and ORC. We conducted a comprehensive case study across four continents—Asia, Oceania, Europe, and America—leveraging weather data from various cities to evaluate the system's efficacy. Our modeling utilized EES (Engineering Equation Solver) software, optimizing the setup via the RSM with three key objective functions: exergy efficiency, hydrogen production, and cost rate. The primary focus was on delivering electricity to residential properties during peak demand periods. Exploring six scenarios for organic fluids in organic Rankine cycles, we gauged energy, exergy, and overall system performance. The TOPSIS method led us to select scenario 3, employing R123 and R134a refrigerants, as the optimal choice. The results of the optimization showcased impressive figures: an exergy efficiency of 81.816%, a hydrogen production rate of 25.119 kg/h, and a cost rate of 15.967 $/h for the system's most efficient configuration. Economic analysis highlighted the organic Rankine cycle units 1 and 2 as the components with the highest costs. Our evaluation extended to various cities—Aomori, Grosseto, Lhasa, Wellington, and San Diego—assessing the electricity, heating, and cooling needs of residential complexes based on the system's performance.

Exploring novel approaches on impact of micro-fin tubes on flow boiling heat transfer using R134a refrigerant: A parametric case study

This paper experimentally investigates the factors influencing the flow boiling heat transfer of R134a refrigerant within smooth and micro-fin tubes having an outer diameter of 9.52 mm. The tube has a peculiar micro-fin shape with a 46° apex angle and 22° helix angle, producing a surface area 1.62 times bigger than a smooth tube of identical diameter. The main goal of the study is to understand the influences of mass flux, heat flux, saturation temperature, and average vapor quality on heat transfer characteristics. The findings are initially compared with known flow boiling correlations; moreover, performance index, penalty factor, and enhancement factor considerations are also made. The heat transfer coefficient (HTC) relies on mass flux, with significant improvements at G = 200 kg m−2 s−1, despite dry-out difficulties at high vapor quality. Intensified flow velocity from higher mass flux causes a rise in frictional pressure drop (FPD), with micro-fin tubes demonstrating superior heat transfer, owing to their larger surface area and improved swirl formation. Compared to smooth tubes, FPD is significantly influenced by vapor quality for micro-fin tubes. The study analyses the importance of micro-fin tubes to improve heat transfer in industrial applications, as well as the effects of saturation temperature and vapor quality on HTC.

How to cool a warming world? – The potential of photovoltaic green cooling with natural refrigerants in sunbelt countries

The study investigates the economic feasibility of photovoltaic-powered air-conditioning (AC) systems in thirteen different sunbelt countries. Two different technical solutions have been analysed: (i) hybrid (partially PV powered, grid-connected) and (ii) off-grid (fully PV powered, no grid connection). These two solutions have been studied for three different locations in each country, namely minimum, average and maximum annual global solar irradiation on the horizontal. Lastly, each solution and location has been examined for application in the residential and commercial sector. All solar-based air-conditioning scenarios use high efficiency AC appliances with R290 as refrigerant (Global Warming Potential – GWP of 1) and have been compared against a base-case scenario using AC units with moderate efficiency AC appliances with conventional R410a refrigerant (GWP of 2088) and 100 % grid electricity supply. The scope of the study is to identify the economic potential of solar PV cooling technologies. Levelized Cost of Electricity (LCOE) and Net Present Value (NPV) have been calculated for each scenario as part of the comparative analysis. It was found that hybrid photovoltaic-based air-conditioning for a residential house has a financial advantage over grid-based air-conditioning in eleven out of thirteen countries investigated. Exceptions are Ghana and Vietnam. Off-grid photovoltaic-based air-conditioning for residential houses is only economically feasible in five out of thirteen countries, namely Costa Rica, Iran, Grenada, Philippines and Thailand. Hybrid photovoltaic-based air-conditioning for a small commercial building has a financial advantage over grid-based air-conditioning in ten of thirteen countries, except in Colombia, Ghana and Iran. Off-grid photovoltaic-based air-conditioning for a small commercial building is only feasible in China, Grenada, Kenya and Philippines.

Experimental comparison of flow boiling heat transfer in smooth and microfin tubes using R134a, R1234yf, and R513A

Addressing the urgent need for environmentally sustainable and efficient refrigeration systems, this study investigates the performance of low-GWP refrigerants R1234yf and R513A in comparison to the high-GWP refrigerant R134a, focusing on the heat transfer coefficient (HTC) and pressure drop during flow boiling in smooth and microfin tubes. The experimental setup involves tubes with a 6.14 mm internal diameter and 500 mm length. Data were collected across a broad range of operating conditions, including mass fluxes from 170 to 495 kg/m² s, heat fluxes from 10 to 40 kW/m², saturation temperatures of 15 °C and 25 °C, and vapor qualities from 0.15 to 1.0. In a specific case with a mass flux of 170 kg/m² s, heat flux of 23 kW/m², and a saturation temperature of 15 °C, the results indicate that the microfin tube achieves an HTC enhancement of up to 64 % compared to smooth tubes. However, R134a exhibits a higher HTC than R1234yf and R513A, approximately 5 % and 3 % higher, respectively. In contrast, R134a presents a higher pressure drop than R1234yf by about 8 %. While the pressure drop for R134a is slightly higher than R513A in the smooth tube, the microfin tube shows similar trends but more pronounced differences. This study comprehensively explores microfin tube performance with these refrigerants, offering critical insights for designing advanced refrigeration systems that balance environmental responsibility with energy efficiency. These findings were validated against predicted correlations, showing good agreement.

Identifying effective parameters on capillary tube performance with HCFCs, HFCs blends, and hydrocarbon refrigerants: Numerical assessment

This work offers a comprehensive numerical evaluation of the performance of capillary tube utilizing different refrigerants, including HCFCs, HFCs blends (Zeotropic, Azeotropic), and hydrocarbon, such as such as R22, R404A, R407C, R410A, R507A, and R290 refrigerants to predict the critical length of the adiabatic capillary tube. Utilizing a comprehensive thermodynamic model is applied to simulate the behavior of different refrigerants. Moreover, the effective design parameters based on the internal diameter for the adiabatic capillary tube (ACT), inside surface tube roughness, degree of subcooled, metastable region, condenser diameter, design of evaporator pressure (at critical length), condenser operating pressure, and refrigeration capacity are considered. The numerical model is developed based on the governing equations for mass, momentum, and energy, while a specified empirical equations are employed to represent each of the friction factor for single-and-two phase flow and metastable region. The results showed that the longest length of the ACT of 10.5 m revealed with R410A at mass flow rate of 8 g/s compared with 0.25 m at mass flow rate of 16 g/s for R290. Also, the results showed that the minimum value of friction factor of 0.0189 for R410A compared with maximum value of 0.0208 for R407C. The developed model is validated with available experimental results and models under different operation conditions and is found expectable with a good agreement. Where the standard error for different refrigerant with range value between (2.774% to 3.677%). However, the model represents accurate prediction the flow behavior and the thermal performance of the ACT.

Micro-fin tubes for improved flow boiling heat transfer in refrigeration systems: a performance comparison with R134a and R407c refrigerants

Micro-fin tubes for improved flow boiling heat transfer in refrigeration systems: a performance comparison with R134a and R407c refrigerants

Design considerations of a new freezer construction in the tubular ice machine by experimental study

The need to improve the structure of components to create a new system compacter and cheaper, but still ensuring the system's consistent operation is always necessary and urgent. This study found the consistent of a new integrated freezer construction in the tubular ice machine by experimental study. The measuring instruments were been set for this air-cooled experimental model to validate the system stability when integrating the freezer, accumulator and heat exchanger into an integrated freezer. At a typical experiment 50 Hz inverter control, the R404a refrigerant used to evaporate at −15 °C, achieved the duration of total ice production cycle is around 29.5 min whereas the duration of ice production process takes around 24.5 min (rated 2.88 min/°C) and the defrost takes 5 min. The experimental coefficient of performance decreases from 1.77 to 1.51 and gets averagely 1.55 in the ice production process. From three others experimental results, coefficient of performance, the duration of ice production process, and saturation temperature of refrigerant in freezer change corresponding to the supplied power by inverter control for compressor.

Two phase flow analysis of micro channel evaporator to investigate effect of geometry on pressure and heat transfer coefficient with respect to volume of fraction

Abstract Pressure and heat transfer coefficient (HTC) are parameters used to measure the performance of microchannel evaporators (MCE). By keeping the same overall dimensions, optimised hydraulic diameters of three different port shapes, square, rectangle and trapezoid, are analysed using CFD software to study the effect of geometry on the performance characteristics of MCE. The number of square, rectangle, and trapezoid channels is 580, 986, and 812, respectively. CFD analysis of the evaporator using R134a refrigerant is performed using the Volume of Fluid (VOF) with the SST k-ω model and Lee model for interphase mass transfer trace. Variation of pressure and HTC concerning volume of fraction liquid refrigerant (α) is compared for these three port structures. The trapezoid port microchannel evaporator (MCE) exhibits the highest pressure drop compared to square and rectangular port MCEs. The rectangular port MCE demonstrates the highest heat transfer coefficient among the configurations studied. The rectangular port MCE outperforms both square and trapezoid port MCEs in overall performance.

Exploring the potential of biomass-derived carbons for the separation of fluorinated gases with high global warming potential

The development of advanced and innovative biomaterials with porous structural characteristics for the capture of fluorinated gases (F-gases) is important to contribute to the reduction of emissions of these gases with very high global warming potential. In this work, four biocarbons (CC-1:3H3PO4, CC-1:1H3PO4, CC-K2CO3 and CC-CO2) were produced by chemical and physical activation of corn cob biomass (CC). The adsorption equilibria of difluoromethane (R-32), pentafluoroethane (R-125), 1,1,1-tetrafluoroethane (R-125), 1,1,2-tetrafluoroethane (R-134a), sulphur hexafluoride (SF6), and nitrogen (N2) on these biocarbons were determined at 303.15 K. The highest adsorption capacities were obtained for CC-K2CO3 and CC-CO2 and a full characterization was also performed for these biomaterials at 283.15 and 323.15 K. On the other hand, the selectivities of SF6/N2 and the commercial refrigerants R-410A, R-407C, and R-407F were estimated using the Ideal Adsorption Solution theory (IAST). The results obtained for SF6/N2 show that the biocarbon CC-K2CO3 stands out from the other materials. In addition, the CC-CO2 shows a preference for R-32 over R-125 for the separation of the R-410A. Finally, CC-K2CO3 has a greater preference for R-134a over R-32 and R-125 in the R-407C and R-407F blends. Overall, these novel biocarbons improve the separation and purification of the F-gases under study, facilitating their application on a pilot scale.

Measurement of local boiling heat transfer coefficient (HTC) within a brazed plate heat exchanger (BPHE) and heat transfer assessment of low-GWP R134a replacements

This article shows the local boiling HTCs of R134a and three low-GWP replacements, R1234yf, R1234ze(E) and R152a within a (BPHE). The experimentation was performed in a test-section specially set up for the measurement of the local two-phase HTC at a saturation temperature of 10 °C, with a refrigerant mass velocity from 9.5 to 35.2 kg m−2 s−1, incoming vapour quality between 0.2 and 0.3 and almost complete vaporisation. Both nucleate boiling and forced-convection boiling play an important role in these tests, depending, mainly, on the location along the plate. The comparison with theoretical models shows that both Longo et al. (2015) and Amalfi et al. (2016) models reproduce very well the experimental HTCs. The measurement of local temperature profiles within the BPHE allows to couple the evaluation of thermal and hydraulic performances of refrigerants into a single parameter named Total Temperature Penalty (TTP). The TTP analysis highlights similar boiling performance for R134a, R1234yf and R152a refrigerants, while R1234ze(E) displays worse performance.

Numerical Study with CFD of the Refrigeration in a Vehicle Cabin with two Refrigerants R32 and R600a

Numerical Study with CFD of the Refrigeration in a Vehicle Cabin with two Refrigerants R32 and R600a