Refrigerants R22 Research Articles

Comparative Analysis of the Environmental Load of Natural Refrigerant (R290)

Due to the detrimental environmental consequences of synthetic refrigerants, natural refrigerants have gained renewed interest as alternative refrigerants for a variety of applications due to their minimal ozone depletion potential (ODP) and insignificant global warming potential (GWP). This study compares the performance characteristics of R32-based Air Source Heat Pump (ASHP) to those of R290 and R410A refrigerants. In this study, analyses of the cooling effect, heat output, compressor work input, and coefficient of performance (COP) for various refrigerants will be undertaken. Additionally, the environmental consequences of R32, R410A, and R290 are discussed. The results indicate that R290 is the most efficient refrigerant in terms of performance coefficient, followed by R410A and R32. Considering environmental protection aspects, R290 is a favorable substitute medium.

Experimental investigation of a capillary tube for 2 TR water chiller with R22 & R407C refrigerant

Capillary tube is most widely used expansion device in the refrigeration system having small applications. It is made up of copper tube having small diameter (0.5–5 mm) & very long length (0.5–5 m). The main aim of this research is to study the effect of different dimensions of capillary tube on COP, R.E. & Power input of water chiller and to find the optimum dimensions of capillary tube for which COP of the system is maximum using experimental results. For this, standard experimental test rig having 2 TR refrigeration capacity was developed in order to perform experimentation on different sets of capillary tubes. The result obtained through this experimentation is used to study the effect of changing dimensions of capillary tube on various performance parameters & to find out the optimum dimensions of capillary tube for 2TR water chiller having R22 & R407C as refrigerants. Also, comparative study between results obtained for R22 & R407C is done. The result obtained through this study is useful to design a capillary tube for 2 TR water chiller (having R22 & R407C as refrigerants) for which performance of chiller is maximum for a given application. As R407C refrigerant is direct substitute for R22, so comparative study will be useful to select and modify the dimensions of capillary tube while replacing the refrigerant with substitute one.

Evaluation and quantification of compressor model predictive capabilities under modulation and extrapolation scenarios

Testing and evaluation of select semi-empirical and black-box compressor models is carried out to quantify performance in modulation (variable speed), extrapolation, and additionally, variable superheat scenarios. Three representative literature models and an artificial neural network (ANN) model are benchmarked against the industry standard AHRI model. A methodology quantifying model performance, compared against experimental data, in said scenarios is presented. High-fidelity test data taken from either a hot-gas bypass load stand or compressor calorimeter. Scroll, screw, reciprocating, and spool compressor technologies were collected with R410A, R1234ze(E), R134a, and R32 refrigerants totaling 434 experimental points. Data is divided into training, extrapolation, variable speed, and variable superheat data splits to examine model performance. Mean Absolute Percentage Error (MAPE) is computed for mass flow rate and power after training models with training data and evaluating them against the other data splits. Two literature models are true semi-empirical formulations while the other, the ANN, and AHRI model are more empirical in nature. Neither semi-empirical model predicted all compressors. When the compressor type is predicted, the semi-empirical models yield MAPE’s less than 8%, 5%, and 4% for mass flow rate and power prediction in extrapolation, modulation, and variable superheat scenarios, respectively. The exception is the Popovic and Shapiro model performing at 21% MAPE in variable superheat power prediction for the spool compressor with R1234ze(E). The ANN showed highest errors of 9.3%, 12%, and 17% in extrapolation, modulation, and variable superheat scenarios, respectively. All models outperformed the AHRI model by several orders of magnitude in these scenarios.

Optimization of compressor work, power and heat on efficiency refrigerant r290 on split ac

The vapor compression cycle refrigeration machine is the type of refrigeration machine that is most widely used today, generally the medium used as a working fluid that transfers heat from the product being cooled to its environment is a synthetic refrigerant. The working fluid is called refrigerant. Refrigerant is the main working fluid used in air conditioning systems to absorb heat and convert it in the refrigeration system. This then encourages countries in the world including Indonesia to then jointly carry out prevention and improvement by making agreements. Then this agreement was known as the Vienna Convention in 1985 followed by the Montreal agreement in 1987. In order to reduce the impact of ODS (Ozone Depleting Substances), in 1992 Indonesia signed the Montreal protocol. At that time, Indonesia also launched the "Indonesian Country for the phase Out of Ozone Depleting Substances (ODS) under the Montreal Protocol". This study aims to compare the work of compression, heat absorbed, and the electric power used by the split type refrigeration machine between refrigerant R-22 and refrigerant R-290. These results and analysis show that R-290 has a higher value than R-22 in compression performance. R22 power consumption is 0.30 kw and R290 is 0.26. R290 this is influenced by the light work of the compressor so that it will have an impact on electric power consumption. The power consumption of R290 is 42% less than R22. The heat absorbed by R 22 is smaller than that using hydrocarbons. The results of the optimization of compressor work, power and heat variables show an effect on efficiency.

Experimental investigation on the inhibition of flame retardants on the flammability of R1234ze(E)

Owing to environmental friendliness, R1234ze(E) is considered as an alternative refrigerant, but the flammability restricts its use and promotion. To reduce the combustible risk, nonflammable refrigerants can be blended, while there is a lack of research on mixture flammability. In this paper, the inhibition effects of three typical refrigerants R744, R1336mzz(E) and R1233zd(E) on the flammability of R1234ze(E) were experimentally investigated under the condition of 23 °C and 50% relative humidity. The flammable limits at different concentrations were measured and the critical suppression concentrations of the three retardants were determined as 0.41, 0.2 and 0.4 respectively, by which the parameters of fitting equations to their flammable limits were obtained. The inhibition mechanisms were briefly analyzed in terms of both physical and chemical effects, and typical flame propagation phenomena were compared with further analyses. A model for estimating critical suppression concentrations of ternary blends was established. The critical suppression lines of ternary blends R744/R1234ze(E)/R1336mzz(E) and R744/R1234ze(E)/R1233zd(E) were obtained, by which the nonflammable zones of the two ternary blends were preliminarily determined. The results have provided complements for previous studies using R744/R1234ze(E) at flammable concentrations and will contribute to utilize R1234ze(E) and its blends in safety for both scientific researches and industrial applications.

Experimental test on the performance of a −80 °C cascade refrigeration unit using refrigerants R290-R170 for COVID-19 vaccines storage

With the urgent demand for ultralow-temperature refrigerators worldwide, the operation reliability and stability of the refrigeration system becomes greatly crucial. In this study, a -80 oC ultralow-temperature cascade refrigeration system (CRS) is developed. From aspects of global warming potential (GWP) and ozone depletion potential (ODP), the environmentally friendly refrigerants R290 and R170 are utilized in the high-temperature cycle and low-temperature cycle of CRS. The experimental measurement is conducted in a Type-laboratory with a dry bulb temperature of 25.0 °C and a wet bulb temperature of 20.2 °C. The pull-down and stable operation performance of the CRS freezer are experimentally investigated. Both the inlet and outlet temperature and pressure of two compressors are monitored, and the operation characteristic of the CRS is analyzed. With some temperature test points arranged in the freezer, the temperature drop and temperature fluctuation variation of air are assessed. The operation power consumption of the CRS is also measured during the whole process. It shows that the −80 °C temperature can be generated and realized by the developed ultralow-temperature freezer.

Comparison of the performance of propane ([formula omitted]) and propene ([formula omitted]) as alternative refrigerants for cooling during expansion in a helical capillary tube: A CFD-based insight investigation

The current research compared the efficiency of the new generation refrigerants, propane (R290) and propene (R1270), for cooling applications. The refrigerants’ flow and phase change properties in a helical capillary tube are simulated using ANSYS Fluent 2021 R2 CFD software. For this virtual experiment, a helical capillary tube with an inner diameter of 1.2 mm and a total length of 2100 mm is used. The flashing phenomenon, in which the refrigerants undergo a phase change, is simulated using a finite volume-based mixture model. The Zwart–Gerber–Belamri model is utilized to estimate mass transfer during flashing, which adheres to a homogeneous equilibrium strategy. A set of user-defined functions (UDF) are created to access the refrigerant properties and implement the cavitation model. Bilinear interpolation is used to calculate the fluid’s characteristics at a particular cell pressure and temperature. Available numerical and experimental results are used to verify the constructed numerical model. The investigation shows that under the same operating conditions, R290 refrigerant maintains a higher mass flow through the helical capillary tube than R1270. R1270 produces a lower temperature vapour-liquid mixture at the exit of the capillary tube in comparison to R290. CFD simulations have generated information and data that are helpful in choosing proper refrigerants for different purposes.

Energy and exergy analysis of a novel ejector-assisted compression–absorption–resorption refrigeration system

We propose two novel configurations of an ejector-assisted compression–absorption–resorption refrigeration system. In these configurations, an absorption–resorption sub-cycle is cascaded to a compression sub-cycle to deliver two simultaneous refrigerating effects to the end-users. The absorption–resorption sub-cycle utilises waste heat and delivers the refrigerating effect at -5°C, while the compression sub-cycle delivers the refrigerating effect at 7°C. The two novel configurations are categorised as the first configuration (C1) and the second configuration (C2), based on the cascading of the compression sub-cycle. The first and second law coefficients of performance (COP) of the proposed configurations are computed and compared at different compression ratios, generator and absorber temperatures, and ejector pressure ratios. The results indicate that the configuration C2 achieves the highest COP of 0.98 at 25°C absorber temperature and the COP changes from 0.98 to 0.79 as the absorber temperature increases from 25°C to 55°C. For the same refrigerating capacity, the proposed configurations C1 and C2 save electricity consumption by 36 % and 23 %, respectively, as compared with the electricity consumption by the conventional compression refrigeration system. The performance of the cascaded compression sub-cycle using R717, R600, and R290 refrigerants is assessed and compared with the widely used R134a and R410A refrigerants.

Experimental Analysis of Different Refrigerants’ Thermal Behavior and Predicting Their Performance Parameters

This study experimentally compares thermodynamic performance of R290 and R404A refrigerants in a refrigeration system. In the first part of the paper, energy analysis of the refrigeration system was performed at various evaporator and condenser temperatures. Results revealed that R404A refrigerant caused an 18.6% increase in compressor power consumption. The highest coefficient of performance values in the system for R290 and R404A were 3.99 and 3.21, respectively. The second part of the paper includes artificial intelligence prediction studies. The pace and elastic net regression models were used to predict performance parameters. A single equation that can predict the cooling capacity and compressor power consumption of R290 and R404A simultaneously was derived. For the cooling capacity, pace regression showed mean absolute error of 0.0252 and root-mean-squared error of 0.0334, while elastic net regression indicated mean absolute error of 0.1103 and root-mean-squared error of 0.1262. It was concluded that R290 had better thermodynamic performance than R404A and the equations obtained with artificial intelligence were applicable to predict the experimental findings, regardless of which refrigerant gas was used.

Condensation heat transfer of pure refrigerants R1234yf and R32 inside multiple circular minichannels

This study experimentally investigated condensation heat transfer coefficients inside horizontal multiple circular minichannels with inner diameters of 0.81 and 0.49 mm, using pure refrigerants R1234yf and R32. The effects of mass flux, vapor quality, channel size, heat flux, and refrigerant properties on condensation flow characteristics within a mass flux range of 50–400 kgm−2s−1 were clarified. Annular, churn, slug–annular, and plug (intermittent) flows were visualized inside multiple circular minichannels. It was determined that the heat transfer coefficients of R1234yf and R32 were affected by mass flux, vapor quality, and heat flux. At lower mass fluxes, the contribution of surface tension to heat transfer was dominant relative to that of forced convection. The heat transfer coefficient increased with decreasing channel size, and R32 exhibited higher values of the heat transfer coefficient compared to those exhibited by R1234yf. The proposed heat transfer correlation, accounting for the effects of forced convection and surface tension, predicted heat transfer coefficients for circular minichannels with a mean absolute deviation of 15.2%.

A study on performance characteristics of vapor injection heat pump cycle with indirect heat recovery

This paper proposes a vapor injection heat pump cycle with indirect heat recovery, which adds a sub-cooler and an evaporator on the basis of conventional vapor injection heat pump cycle. In the added first sub-cooler, refrigerant exchanges heat with outdoor fresh air entrancing into indoor for improving the indoor air quality, which increases the temperature of the outdoor fresh air and the subcooling of refrigerant. In the added high-temperature evaporator, refrigerant absorbs the heat from indoor exhaust air through heat exchange, which can improve the heating capacity and the cycle performance. The refrigerant R32 is selected as the working fluid to analyze the performance of the cycle. The results show that under the same operating conditions, the volumetric heating capacity of the cycle is increased by 33%–72% and the coefficient of performance is improved by 20.5%–33.5% compared with the conventional sub-cooler vapor injection heat pump cycle. When the outdoor ambient temperature is lower, the improvement ratios of volumetric heating capacity and coefficient of performance is larger. Therefore, this novel cycle is suitable to be used at the lower ambient temperatures. In addition, the larger fresh air ratio can bring better cycle performance.

Refrigeration system development with limited charge of flammable Refrigerant, R-290

Recently, natural refrigerants have gained a significant attention as a future alternative because of their performance and environmentally friendly characteristics; No Ozone Depleting Potential and near zero Global Warming Potential. The present paper reports an experimental study performed with refrigeration systems developed using one of natural refrigerants, R-290 (Propane & GWP = 3), particularly with the limited charge amount to meet the most stringent regulatory requirement, IATA - Dangerous Goods Regulation. Under IATA regulation, refrigerating machines and components containing flammable gas are forbidden for international air freight unless the flammable charge shall be less than 100 g. Two types of standalone system were developed, so called Liquid Circulating Chiller and Air-Air Cooler. Both were with air-cooled condensers. Liquid Circulating Chiller consisted of a liquid cooled evaporator (liquid to liquid heat exchanger) while Air-Air Cooler came with an air-cooled evaporator (air to liquid heat exchanger). All component selections were made to achieve the minimum refrigerant charge and as a result, the total system charge was kept around 100 g or less. During the system development, several combinations of the components were considered (e.g., compressors and heat exchangers), and system developed was tested under various test conditions as a part of the system optimization. From the study, the maximum cooling capacity achieved was around 3 kW with less than 100 g of R-290 refrigerant charge.

Analysis of a novel combined cooling and power system by integrating of supercritical CO2 Brayton cycle and transcritical ejector refrigeration cycle

This paper presents a novel combined cooling and power (CCP) system that integrates a supercritical CO2 Brayton (sCO2) cycle and a transcritical ejector refrigeration cycle. The two cycles are combined by a heat exchanger wherein heat is exchanged between CO2 and the refrigerant at supercritical pressures to reduce exergy destruction and improve system performance. A thermodynamic model was established to simulate the CCP system based on energy and exergy balance equations. The transcritical ejector model was validated with experimental and literature data. The performance of the system was studied for different CO2 mass flow rates, turbine inlet temperatures, turbine inlet pressures, turbine outlet pressures, and pump outlet pressures. The thermal, exergy, and effective efficiencies of the CCP system were compared with those of a combined cooling and power system (CCP_ab) that uses a single-effect absorption refrigeration cycle. The CCP system maximum thermal efficiencies of four refrigerants—R32, R134a, R1234yf, and R1234ze—were obtained using a genetic algorithm. The results show that the major components that contribute in exergy destruction are internal heat exchanger, ejector, compressor and turbine, and the heat exchanger has small exergy destruction because of a good variable-temperature match between the supercritical pressure refrigerant and supercritical pressure CO2. The effective efficiency of the CCP system reaches 0.42 at turbine inlet temperature of 873.15 K. The CCP system is more stable and efficient than the CCP_ab system in varying conditions. The CCP system with R32 has the highest thermal efficiency. R1234ze with relatively high thermal efficiency and low Global Warming Potential is a good choice in the future as it is environmentally friendly.

Experimental study of R290 replacement R134a in cold storage air conditioning system

R290 refrigerant offers good environmental protection and thermodynamic characteristics. The feasibility of R290 replacing R134a was summarized through theoretical analysis and experimental tests in this paper. A coiled ice storage experimental test platform was built, and the performance of R290 and R134a cool storage air conditioning systems was analyzed. The experimental analysis confirmed that the R290 system has a higher volumetric refrigerating capacity, and the system COP (coefficient of performance) is comparable to the R134a system. At the same evaporation temperature, the pressure ratio and exhaust temperature of the R290 system are lower than those of the R134a system. In addition, the charge amount of the refrigerant can have an impact on cold storage performance. It was found that the optimal charge range of R134a is 1300–1400 g, and that of R290 ranges from 500 to 600 g. The optimal charge amount for R290 is only 43–46% of R134a. A lower charge amount is beneficial to reduce the explosion risk of the R290 cool storage air conditioner. Under the optimal charge, the R290 system has a fast cooling rate and shorter cooling storage time, and the average specific refrigerating effect is increased by approximately 52% compared with R134a.

Numerical investigation of flashing of propane (R-290) in a helical capillary tube

The present study addresses the expansion of pressurized liquid R-290 through a diameter capillary tube and its subsequent motion through a metastable condition entailing a change of phase through flashing phenomenon. The expansion of R-290 through a helical capillary tube is numerically simulated using a finite volume-based mixture model. For the simulation of the flashing phenomena, a homogeneous equilibrium approach is used. The Zwart–Gerber–Belamri model is deployed to represent mass transfer during flashing. ANSYS Fluent 2021 R2 software has been used for the numerical simulations. A series of UDF (user defined functions) are developed to read the recorded database of R-290 and perform the cavitation modeling. Bilinear interpolation is performed for determining the fluid properties at the corresponding pressure and temperature. The developed numerical model has been validated against the available numerical and experimental results. For the simulations, tubes with lengths of and have been considered, and the impacts of increasing length on the flow characteristics at the outlet have been determined. In this investigation, the R-290 refrigerant expands from three different condenser pressures of 16, 14, and 12 bar. Evaporator pressure is adjusted from 2 bar to 8 bar to investigate its influence on flow characteristics. The fall in evaporator pressure brings about a flow transition from subsonic to supersonic. The effects of tube length, condenser, and evaporator pressures on mass transfer rate, evaporator entry temperature, mixture quality at the evaporator entrance, and available refrigeration effects have been analyzed.

Experimental Investigation of an Air-Conditioner Performance and Chemical Compositions of Differently Sourced R410A and R22 Refrigerants

Experimental Investigation of an Air-Conditioner Performance and Chemical Compositions of Differently Sourced R410A and R22 Refrigerants

Thermodynamic analysis and multi-objective optimization of a modified solar trigeneration system for cooling, heating and power using photovoltaic-thermal and flat plate collectors

Most solar polygeneration systems use a single solar source to power the system. Despite their importance, dual-source systems received less attention. To address this gap, this study aims to analyze a new polygeneration arrangement that combines photovoltaic thermal (PVT) and flat plate collector (FPC). A detailed thermodynamic and economic analysis is conducted for a newly designed cooling, heating, and power (CCHP) system powered by solar energy for domestic applications. PVT and FPC collectors, with an ejector-vapor-compression refrigeration cycle that is equipped with a booster compressor, are used in the proposed system. The key goal of using a PVT with FPC panel in a series configuration is to achieve maximum electrical and thermal efficiencies. The effects of various factors on the system performance, including booster pressure ratio, R600a, and R290 refrigerants, PVT-FPC cycle water flow rate, and solar irradiation, are investigated. The multi-objective optimization results show that energy and exergy efficiency, payback period, and internal rate of return are 90.15%, 12.46%, 4.025years, and 26.67%, respectively. The results showed that using a booster compressor significantly increases the system performance by 96.34% in coefficient of performance (COP), 55.1% in exergy efficiency, and 121.9% in net output power. This optimum system also prevents the release of 2504 kg of carbon dioxide into the environment.

Design and analysis of a novel solar compression-ejector cooling system with eco-friendly refrigerants using hybrid photovoltaic thermal (PVT) collector

• A novel solar cooling system is designed and analyzed. • The solar cooling efficiency increased by 33.1 %. • The COP of the refrigeration cycle is improved by 8.23 %. • R290 has the best performance in the system. World faces cold crunch and solar energy exploitation plays a vital role in facing this problem. This study aims at improving the performance of combined solar ejector vapor compression refrigeration cycles ( EVRC ) with two evaporators using a photovoltaic thermal ( PVT ) collector. The PVT collector supplies the system's required power, such as compressor and water circulator pump. The outgoing water is further used to cool the condenser and subcool the condenser outlet refrigerant to improve the system efficiency. This work also investigates the utilization of the environmentally friendly refrigerants of R1234yf, R600a, and R290 to reduce the global warming issue by replacing the typical R134a refrigerant. The results showed that the optimal water flow rate for the highest system efficiency and the lowest exergy destruction is 0.05 kg/s. With the passage of water (with optimal flow rate), the collector's electrical efficiency, total solar cooling efficiency, and refrigeration cycle performance coefficient ( COP ) can be increased by 11%, 33.1%, and 8.23%, respectively, compared to the non-cooling state. The R290 refrigerant also performs best in terms of maximum efficiency and lowest system exergy destruction, among other refrigerants, with COP and solar cooling efficiency of 3 and 0.52, respectively, which is 4.8% and 4.6% higher in comparison with the R134a.

Investigation and Analysis of R438A as an Alternative Refrigerant to R22 with Lower Global Warming Potential

This research presents the R438A refrigerant that non-flammable refrigerant and develop for retrofit to R404A. The hydrofluorocarbons/hydrocarbon (HFCs/HCs) R463A (GWP=2,265) was zeotropic mixture of R125 (45%), R134a (44.2%), R32 (8.5%), R600 (1.7%) and R600a (0.6%). The R463A refrigerants is no frame propagation class A1 and lower toxicity and used polyol ester oil (POE). The results will investigation and analysis of the environmentally friendly refrigerant for R22 replacement. All refrigerant properties in this research were based on results from the REFPROP and CYCLE_D-HX software of NIST under CAN/ANSI/AHRI540. The results of this work show that HCs R170, R290, R600, R600a, R601, R601a, R1150 and R1270 can be mixed in HFCs R417A, R417B, R422A, R422B, R422C, R422D, R424A, R437A, R438A and R453A and able to be further developed in the future. All refrigerants are non-flammable refrigerants, non-toxic and zero ODP. The R438A mixed with HCs R600 (1.7%) and R601a (0.6%) and is the refrigerant cooling coefficient of performance close to that of R22 refrigerant. In conclusion, it can be used as an environmentally friendly and energy efficiency replacement for R22. The result of R438A normal boiling was lower than R404A 4% that high cooling capacity and zero ODP. All refrigerants are also refrigerants that are matched with the 4th generation refrigerants with the use of natural refrigerants.

An optimization approach in the development of a new correlation for two-phase heat transfer coefficient of R744 in a microchannel

To date, no single method has been found to satisfactorily predict the two-phase heat transfer coefficient of R744 refrigerant in small channels. Studies are continuously being done to obtain a coefficient with acceptable mean absolute error (MAE) which measures the difference between the predicted and experimentally determined coefficient values. It is important to have available accurate heat transfer coefficient correlation for the two-phase heat transfer coefficient so that a compact heat exchanger that maximizes device performance while reducing cost and energy needs can be designed. In this study, genetic algorithm (GA) is used as an optimization tool to achieve a more accurate correlation for R744 in a microchannel by minimizing the MAE. Over 536 sets of experimental data from previous studies were utilized, optimizing the six constants appearing in the force convective factor, F, and nucleate boiling suppression factor, S, of the selected superposition correlation. The results showed that the MAE between the newly optimized correlation and selected experimental data at all ranges of vapor quality has been successfully reduced from 38.39 to 34.40%. With more available data, the suggested method can be utilized to achieve a more accurate empirical prediction that matches well with the experimental data.