Hydrofluorocarbons Research Articles

US Senate approves HFC treaty

The Senate voted 69–27 on Sept. 21 to allow the US to join an international treaty to curb the production and use of hydrofluorocarbons (HFCs). The chemicals are industrial gases used in a slew of applications, including as refrigerants in air conditioners and freezers. They are potent greenhouse gases. In late 2020, Congress passed a law authorizing the federal government to meet the terms of the pact , the 2016 Kigali amendment to the Montreal Protocol. Using that law, the Environmental Protection Agency issued a regulation last year to reduce allowable US production and use of HFCs to 15% of 2011–13 average levels by 2036. Such reduction will meet the terms of the Kigali amendment. But because the Senate had not ratified the Kigali deal, the US could not participate as a full treaty partner in international talks related to it. Almost a year ago, President Joe Biden asked the

SIMULATION OF THE IMPACT OF HYDROFLUOROCARBON (HFC) EMISSIONS IN TOGO ON GLOBAL AVERAGE TEMPERATURE

Background:Several IPCC scenarios have predicted a global temperature increase of 1.5°C by 2030 attributable to greenhouse gases (GHGs) including hydrofluorocarbons (HFCs) controlled by the Kigali Amendment. Objectives:Thus, this study aims to simulate the increase in global temperature by 2030 attributed only to HFC emissions in Togo, given that the country is a party to the Kigali amendment and the Paris agreement. Methods:The methodology applied in this study is based on the projection to 2030 of HFC emissions in 2018 in order to simulate their impact on global average temperature using the LEAP-IBC tool. Results:HFCs emissions in Togo will reach 2598.13 GgCO2-e and will contribute to the increase in global average temperature by representing 18/100000 of the 0.5°C over the period 2018 to 2030 predicted by the IPCC scenarios. This increase attributed to the HFCs sector alone in Togo once again shows the impact of GHG on global average temperature.These results should therefore alert political decision-makers to redouble their efforts in the implementation of mitigation measures.

Viscosity prediction of pure refrigerants applying the residual entropy scaling theory coupled with a “Generalized Chart” parametrization method for the Statistical Associating Fluid Theory

The residual entropy scaling (RES) theory integrated with different thermodynamic Equation of States (EoS) have obtained several accurate and simple viscosity models of working fluids, which is crucial for designing and optimizing of the energy utilization system. However, the influence of parameterization methods on RES’s viscosity calculations is rarely mentioned in a systematic way. Hence, a robust parameterization method based on generalized relation between the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) EoS’s input parameters of 11 pure refrigerants (including hydrocarbons (HCs), CO2, hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs)) and their critical properties is introduced and coupled with a robust formulation of the reduced viscosity term in RES theory recently proposed by Dehlouz et al. Accurate vapor pressure calculations and near-constant difference between calculated liquid densities and high-accuracy correlation model in saturated state could be obtained with this parameterization method. Viscosities in vapor and liquid phases are exactly reproduced with an overall error of 3.14% applying the model proposed in this work, which is comparable to those from three RES models in literature and the extended corresponding states (ECS) model with overall errors of 3.36%, 3.22%, 3.41% and 1.77%, respectively. In addition, the divergence behavior in dilute region and the component-specific curves of dimensionless reduced viscosity and entropy variables are improved than other RES models under study to a certain extent. Meanwhile, as a supplement, the limitation of the above RES models on predicting viscosities in the near critical region is also discussed in detail.

Separation of Azeotropic Hydrofluorocarbon Refrigerant Mixtures: Thermodynamic and Kinetic Modeling for Binary Adsorption of HFC-32 and HFC-125 on Zeolite 5A.

Hydrofluorocarbons (HFCs) have been used extensively as refrigerants over the past four decades; however, HFCs are currently being phased out due to large global warming potentials. As the next generation of hydrofluoroolefin refrigerants are phased in, action must be taken to responsibly and sustainably deal with the HFCs currently in circulation. Ideally, unused HFCs can be reclaimed and recycled; however, many HFCs in circulation are azeotropic or near-azeotropic mixtures and must be separated before recycling. Previously, pure gas isotherm data were presented for both HFC-125 (pentafluoroethane) and HFC-32 (difluoromethane) with zeolite 5A, and it was concluded that this zeolite could separate refrigerant R-410A (50/50 wt % HFC-125/HFC-32). To further investigate the separation capabilities of zeolite 5A, binary adsorption was measured for the same system using the Integral Mass Balance method. Zeolite 5A showed a selectivity of 9.6-10.9 for HFC-32 over the composition range of 25-75 mol % HFC-125. Adsorbed phase activity coefficients were calculated from binary adsorption data. The Spreading Pressure Dependent, modified nonrandom two-liquid, and modified Wilson activity coefficient models were fit to experimental data, and the resulting activity coefficient models were used in Real Adsorbed Solution Theory (RAST). RAST binary adsorption model predictions were compared with Ideal Adsorbed Solution Theory (IAST) predictions made using the Dual-Site Langmuir, Tóth, and Jensen and Seaton pure gas isotherm models. Both IAST and RAST yielded qualitatively accurate predictions; however, quantitative accuracy was greatly improved using RAST models. Diffusion behavior of HFC-125 and HFC-32 was also investigated by fitting the isothermal Fickian diffusion model to kinetic data. Molecular-level phenomena were investigated to understand both thermodynamic and kinetic behaviors.

Deep near-term mitigation of short-lived climate forcers in Oman: grand challenges and prospects.

Over time, short-lived climate forcers (SLCFs) have gradually gained prominence as a rationale in the international global mitigation strategy to preserve temperature below 1.5 °C by the end of this century. Scientists cite the short-term gains in air quality and health co-benefits associated with reducing SLCFs as grounds for raising the pressure on governments to eliminate SLCFs rapidly and aggressively. There is little research on whether deep SLCF mitigation during the next decade is feasible in low- and middle-income nations, particularly the hydrocarbon-based economy. This study estimates current and future emissions of potent SLCFs as methane (CH4) hydrofluorocarbons (HFCs) in Oman using the basic tier 1 approach of the Intergovernmental Panel on Climate Change (IPCC) greenhouse gases (GHG) inventory Guidelines of 2006. Current and future emission of black carbon (BC) was also quantified using specific emission factors. A total of 38,268 Gg of SLFCs were released into the atmosphere in Oman in 2015, accounting for 38.8% of the country’s total GHG emissions, and is expected to rise significantly over the next decade to reach 67,777 Gg by 2030. The analysis reveals that the source of Oman’s highly potent SLCF emissions is associated with key and critical economic sectors such as the oil and gas industry, heavy road transportation, residential air conditioning (RAC), and industrial refrigeration. These vital economic sectors impose a “Grand Challenge” on the immediate reduction of SLCFs in Oman and the Gulf Cooperation Council (GCC). Accomplishing a rapid, significant reduction in highly potent SLCFs from the three challenging sectors over a 5- to 10-year time period does not appear feasible or realistic in the context of international market mechanisms, socioeconomic factors, and mitigation targets. Achieving a significant reduction in SLCFs for a hydrocarbon-based economy requires a profound economic shift. Creating an effective long-term vision for a post-oil economy over the next two decades provides a sound foundation for implementing economic and societal transformation policies incorporating near-zero-emission measures for the potent SLCFs.

In Vitro and In Silico Vibrational-Rotational Spectroscopic Characterization of the Next-Generation Refrigerant HFO-1123.

Very short-lived substances have recently been proposed as replacements for hydrofluorocarbons (HFCs), in turn being used in place of ozone-depleting substances, in refrigerant applications. In this respect, hydro-fluoro-olefins (HFOs) are attracting particular interest because, due to their reduced global warming potential, they are supposed to be environmentally friendlier. Notwithstanding this feature, they represent a new class of compounds whose spectroscopic properties and reactivity need to be characterized to allow their atmospheric monitoring and to understand their environmental fate. In the present work, the structural, vibrational, and ro-vibrational properties of trifluorothene (HFO-1123, F2C = CHF) are studied by state-of-the-art quantum chemical calculations. The equilibrium molecular structure has an expected error within 2 mÅ and 0.2° for bond lengths and angles, respectively. This represents the first step toward the computation of highly accurate rotational constants for both the ground and first excited fundamental vibrational levels, which reproduce the available experimental data well within 0.1%. Centrifugal distortion parameters and vibrational–rotational coupling terms are computed as well and used to solve some conflicting experimental results. Simulation of the vibrational transition frequencies and intensities beyond the double harmonic approximation and up to three quanta of vibrational excitation provides insights into the couplings ruling the vibrational dynamics and guides the characterization of the gas-phase infrared spectrum experimentally recorded in the range of 200–5000 cm–1. The full characterization of the IR features is completed with the experimental determination of the absorption cross sections over the 400–5000 cm–1 region from which the radiative forcing and global warming potential of HFO-1123 are derived.

CASCADE REFRIGERATION SYSTEM FOR LOW TEMPERATURES USING NATURAL FLUIDS

Cascade refrigeration systems work with two or more serial disposed cycles and can obtain internal temperatures below -60°C, which is necessary for several activities in medicine and scientific research. This paper presents a thermodynamic analysis of cascade system refrigeration using natural refrigerant fluids for ultra low temperatures. These fluids areenvironmentally friendly refrigerant and are an alternative to hydro chlorofluorocarbons (HCFCs) and to hydrofluorocarbons (HFCs). Energy and exergy analyses were performed using a thermodynamic model based on the law of conservation of massand also on the first and second laws of thermodynamics. A simulator was developed to assess the technical practicability of this system, considering it running as a real refrigeration cycle.

Global warming awareness among the Islamia university of Bahawalpur students (In the light of Seerah)

According to the environmental protection agency (EPA), global warming is defined as the recent and ongoing rise in earth surface temperature. The greenhouse gases are the most contributors to climate pattern change. The greenhouse gases (GHGs) include water vapor (H2O), carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and fluorinated gases including hydro fluorocarbons (HFCs), per fluorocarbons (PFCs) and sulfur hexafluoride (SF6). The hazard of global warming is one of the most important and critical problems of the world.
 Purpose of the Study: The main purpose of the study is to find out awareness among the university students.
 Methodology: Survey research method will be adopted, employing the questionnaire as an instrument of data collection. Population of this study will be youth of the Islamia 
 University of Pakistan and for this purpose researcher will use convenient sampling technique. The sample size will be selected by using proportional allocation method. Statistical analysis of the data will be done on SPSS.
 Applications of the study: This study can be helpful in better understanding of awareness among university students about climate change.

Scenarios for future Indian HFC demand compared to the Kigali Amendment

Demand for hydrofluorocarbon (HFC) refrigerants used as substitutes for ozone-depleting substances is growing in India and is estimated to continue growing at a high rate through the middle of this century. HFCs, although not directly ozone-depleting, are highly potent greenhouse gases subject to a global phasedown under the 2016 Kigali Amendment to the Montreal Protocol on Substances that Deplete the Ozone Layer. As of 20 January 2022, 130 Parties have ratified the Kigali Amendment, including India. This analysis evaluates scenarios for India’s HFC demand trajectory compared to likely control obligations under the Kigali Amendment. It is based on current and projected markets for HFC-using equipment and types of refrigerants utilized now and likely to be used in the future. Sectors considered in this work include mobile air conditioning, stationary air conditioning, refrigeration, and foam blowing agents. Results suggest that India’s annual HFC demand under current market trends could reach 76 MMT CO2-equivalent (CO2e) in 2030 and 197 MMT CO2e in 2050, from 23 MMT CO2e in 2020, making no changes to the current mix of HFCs in use. The Kigali Amendment requires for compliance that India freeze its HFC consumption in 2028 at a projected level of 59–65 MMT CO2e and phase down progressively over the following 29 years; in that case, annual Indian HFC demand would peak in 2030 at a projected 57 MMT CO2e and fall to 8 MMT CO2e by 2050. This trajectory would avoid cumulative HFC use of 2.2 GT CO2e through 2050 versus the current market trends. If actions are taken to accelerate the refrigerant transition in stationary air conditioning by five years, India could peak its annual HFC demand by 2028 at 40 MMT CO2e and avoid additional cumulative HFC demand of 337 MMT CO2e between 2025 and 2050, exceeding its obligations under the Kigali Amendment.

Opportunities to tackle short-lived climate pollutants and other greenhouse gases for China

To limit the global temperature increase to below 1.5 °C, it is critical to reduce not only carbon dioxide (CO2), but also specific non-CO2 greenhouse gases (GHGs) and precursors, including some short-lived climate pollutants (SLCPs). These include emissions of black carbon, methane (CH4), tropospheric ozone, and fluorinated gases such as hydrofluorocarbons (HFCs). As the largest CH4 emitter and second-largest HFCs emitter, China plays a critical role in global efforts to reduce SLCPs and has acknowledged the need to reduce non-CO2 GHGs in its 2060 carbon neutrality goal. This study reviewed leading international experiences with SLCP reduction to identify global best practices to inform target development and policy actions in China and elsewhere. We used bottom-up modeling and scenario analysis to evaluate pathways of non-CO2 emission mitigation in China to 2050, drawing on mitigation measures developed through updated 2030 and 2050 cost curves. We identified a cost-effective reduction potential of 35 % for methane, 30 % for fluorinated gases, and 40 % for nitrous oxides—another potent GHG—in 2030 relative to 2015 levels for China under a Deep Non-CO2 Mitigation scenario. Annual total reduction potential of 1080 million metric tons of CO2 equivalent is also possible by 2030. For long-term targets, progress made on reducing SLCPs could help China reach its carbon neutrality target by 2060. While some uncertainties regarding the long-term mitigation potential of SLCPs remain, our analyses suggest that the fast adoption of available cost-effective technologies could allow China to reduce its non-CO2 GHGs by 56 % by 2050.

Estimating the solubility of HFC/HFO in ionic liquids from molecular structure using machine learning method

Hydrofluorocarbon (HFC) + ionic liquid (IL) and hydrofluoroolefin (HFO) + IL are two new types of working pairs developed for absorption refrigeration system. In this paper, aiming to provide a guide for screening the optimal one from many candidates, a model based on group contribution (GC) method and artificial neuron network (ANN) is presented to estimating the solubility of HFC/HFO in ILs from molecular structure. The input variables of the ANN-GC model are temperature, pressure, and the number of various groups. A dataset containing 1693 solubility data for 18 HFC/HFO in ILs consisting of 10 cations and 17 anions at temperature from 273.13 K to 413.30 K and pressure from 0.99 kPa to 41,000 kPa were established to train the model. The ANN-GC model has great regression ability indicated by the average relative deviation of 8.8 % from experimental data. Besides, the case study on predicting [HMIM][BF4] - R134a working pairs solubility shows that our model has great prediction ability on new substances. The sensitivity analysis points out the groups influence on the solubility and give a guideline for designing high solubility working pairs. We also used Leverage approach to find the outlier data and high leverage data.

Drop-in Replacement of Conventional Automotive Refrigeration System to Hybrid-Ejector System with Environment-Friendly Refrigerants

Ejector refrigeration system (ERS) is a propitious cooling skill for automobiles with a reduced fuel consumption along with structural simplicity, low cost, and driven by engine waste heat. Conversely, the lower coefficient of performance (COP) of standalone ERS is the major drawback for automotive applications, which can be overcome by hybridizing with a conventional compression system. Therefore, an indigenously designed hybrid cooling system is proposed to switch in three different cooling modes based on required thermal comfort— compressor, ejector, and hybrid. A real gas property-based theoretical model of this hybrid system is established under critical and sub-critical modes with a variable area ejector for a better entrainment ratio. In parallel, the performance of the proposed system is explored with two environment-friendly hydrofluorocarbon (HFC) refrigerants R152a, R440a and four extremely low global warming potential (GWP) hydrofluoroolefin (HFO) refrigerants R1234yf, R1243zf, R1234ze(E) and R513a, as an immediate replacement of commonly used R134a. The thermodynamic performance variation is compared for an extensive choice of the evaporator, generator, and condenser temperatures. Due to the conversion of waste heat into work in the hybrid mode, the compression ratio reduces maximum by 54% and cooling capacity increases by almost 22% more than in the conventional compressor mode. Moreover, compared with the standalone ejector system, the hybrid system improves the cooling capacity and COP by up to 4 times. Irrespective of the circumstances, the maximum entrainment ratio and COP are achieved with refrigerant R1234yf in hybrid mode, claiming ideal replacement of R134a for automotive air conditioning applications.

Pore-Nanospace Engineering of Mixed-Ligand Metal–Organic Frameworks for High Adsorption of Hydrofluorocarbons and Hydrochlorofluorocarbons

The isostructural mixed-ligand metal–organic frameworks (MOFs), LIFM-66, 66/67-mix, and 67, have been constructed via organic-linker modification and variation to introduce different portions of functional groups into the pore-nanospaces with tunable surface areas. Adsorption measurements of hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC) with these MOFs reveal a record high uptake of R134a (1.09–1.14 g g–1) and an ultrahigh uptake of R22 (0.85–0.96 g g–1) under ordinary conditions of room temperature and atmospheric pressure. Noteworthily, the adsorption performance of greenhouse gases CO2, R134a, and R22 can be finely regulated by introduced methyl groups, which has been elucidated by molecular modeling and transient breakthrough simulations/experiments, demonstrating an effective protocol of pore-nanospace engineering through rational design of mixed-ligand MOFs for HFC and HCFC capture, sequestration, and reclamation.

Effect of dilutant concentration on the performance of environment-friendly mixed refrigerants used in domestic refrigerators.

This paper presents the environment-friendly mixture compositions of hydrocarbons (HC)- and hydrofluorocarbon (HFC)-based ternary mixtures that can be better alternatives for R134a in domestic refrigeration units. Combustible refrigerant HCs (R290, R600, R600a) and HFCs (R152a and R161) are used along with the dilutants R13I1, R245fa, R134a, R227ea, and R125 and their flammability studies were carried out theoretically. Minimum inerting concentration (MIC) is used to classify the flammable and non-flammable zones of the ternary mixtures. MIC points estimated with modified thermal balance method (MTBM) are compared with 62 experimental data points available in the literature. It was calculated that MTBM predicted the MIC values with in ±9%, for most of the working fluids selected in this study. R13I1 is used along with all the refrigerant (HC and HFC) combinations (as the first dilutant) while the effect of other dilutants on the system performance is carried out theoretically. It is predicted from the flammability diagram (developed in this study) that the inert effect of R227ea is higher than of R245fa, R134a, and R125. It is also observed that the drop in coefficient of performance (COP) is significant with R290/R13I1/R245fa (with increase in R245fa) mixture when compared to other combinations. Finally, mixtures R600a/R13I1/R245fa, R600a/R13I1/R227ea, R600a/R13I1/R134a, R600a/R13I1/R125, R161/R13I1/R134a, R290/R13I1/R125, R161/R13I1/R227ea, and R161/R13I1/R125 are identified as the best environment-friendly mixture compositions as alternatives to R134a. It is also calculated that the mixture R600a/R13I1/R125 possesses COP greater than 10% to R134a at the same working conditions.

Five-step plasma-enhanced atomic layer etching of silicon nitride with a stable etched amount per cycle

Atomic layer etching is an advanced plasma etching technique that enables the atomic-precision control. In this study, the effects of surface conditions on the stability of the etched amount per cycle (EPC) in silicon nitride (SiN) plasma-enhanced atomic layer etching (PE-ALE) were examined. A single cycle of SiN PE-ALE consisted of two steps: hydrofluorocarbon (HFC) absorption step and argon-ion (Ar+) desorption step. After a few cycles, an etch-stop of SiN occurred due to the HFC deposition. An oxygen-plasma ashing step was introduced after desorption step, which made three-step SiN PE-ALE. The etch-stop was avoided but the EPC was low due to the surface oxidation of SiN. By combining this three-step SiN PE-ALE with subsequent two-step SiO2 PE-ALE, which consists of fluorocarbon adsorption step and Ar+ desorption step, SiN PE-ALE was achieved with a stable and large EPC. This five-step SiN PE-ALE allows the precise control of SiN etched depth.

Modeling thermal conductivity of liquid hydrofluorocarbon, hydrofluoroolefin and hydrochlorofluoroolefin refrigerants

• A model was proposed to represent thermal conductivities of liquid HFC/HFO/HCFO refrigerants. • This model shows reasonable performance for representing liquid thermal conductivity of refrigerants. • The present model outperforms the conventional models, with respect to the accuracy. A simple and accurate thermal conductivity model is of importance for the development of hydrofluorocarbon (HFC), hydrofluoroolefin (HFO) and hydrochlorofluoroolefin (HCFO) refrigerants. In this work, a semi-empirical model for representing the thermal conductivity of HFC/HFO/HCFO refrigerants in liquid phase was established. The proposed thermal conductivity model was based on Modified Enskog Theory (MET) model, combining with Peng-Robinson Equation of State (PR equation), with the empirical modification made in the cross contribution term of MET model to improve its accuracy. The newly derived equation was then used to calculate liquid thermal conductivities of 14 HFC/HFO/HCFO refrigerants to check its accuracy. The thermal conductivity correlation for 14 refrigerants is estimated to have an uncertainty of about 3.0% at 95% confidence level. In addition, the performance of the present method was compared with that of previously reported models in the literature and the results indicate that the present model is generally superior to the conventional models with regard to accuracy.

Projections of hydrofluorocarbon (HFC) emissions and the resulting global warming based on recent trends in observed abundances and current policies

Abstract. The emissions of hydrofluorocarbons (HFCs) have increased significantly in the past 2 decades, primarily as a result of the phaseout of ozone-depleting substances under the Montreal Protocol and the use of HFCs as their replacements. In 2015, large increases were projected in HFC use and emissions in this century in the absence of regulations, contributing up to 0.5 ∘C to global surface warming by 2100. In 2019, the Kigali Amendment to the Montreal Protocol came into force with the goal of limiting the use of HFCs globally, and currently, regulations to limit the use of HFCs are in effect in several countries. Here, we analyze trends in HFC emissions inferred from observations of atmospheric abundances and compare them with previous projections. Total CO2 eq. inferred HFC emissions continue to increase through 2019 (to about 0.8 GtCO2eq.yr-1) but are about 20 % lower than previously projected for 2017–2019, mainly because of the lower global emissions of HFC-143a. This indicates that HFCs are used much less in industrial and commercial refrigeration (ICR) applications than previously projected. This is supported by data reported by the developed countries and the lower reported consumption of HFC-143a in China. Because this time period preceded the beginning of the Kigali provisions, this reduction cannot be linked directly to the provisions of the Kigali Amendment. However, it could indicate that companies transitioned away from the HFC-143a with its high global warming potential (GWP) for ICR applications in anticipation of national or global mandates. There are two new HFC scenarios developed based (1) on current trends in HFC use and Kigali-independent (K-I) control policies currently existing in several countries and (2) current HFC trends and compliance with the Kigali Amendment (KA-2022). These current policies reduce projected emissions in 2050 from the previously calculated 4.0–5.3 GtCO2eq.yr-1 to 1.9–3.6 GtCO2eq.yr-1. The added provisions of the Kigali Amendment are projected to reduce the emissions further to 0.9–1.0 GtCO2eq.yr-1 in 2050. Without any controls, projections suggest a HFC contribution of 0.28–0.44 ∘C to global surface warming by 2100, compared to a temperature contribution of 0.14–0.31 ∘C that is projected considering the national K-I policies current in place. Warming from HFCs is additionally limited by the Kigali Amendment controls to a contribution of about 0.04 ∘C by 2100.

A DIRECT CONTRIBUTION OF MARINE REFRIGERATION TO ANTHROPOGENIC GREENHOUSE GASES EMISSION - A SHORT REVIEW

The problem of reducing greenhouse gas (GHG) emissions in the maritime sector are currently important. The share of shipping emissions in global anthropogenic emissions was 2.89% in 2018 [1]. The main contribution to GHG emissions (indirect emission) on the marine fleet generates the main and auxiliary engines, and boilers during fuel combustion as well as incinerators [1, 2]. However, marine merchant and passenger ships have another significant source of direct GHG emissions, which is currently not directly regulated and considered as not mandatory inventory – hydrofluorocarbons (HFCs) refrigerants emissions from refrigeration and air conditioning systems. It should be highlighted, that reduction of the direct GHG emissions for marine refrigeration systems is the most difficult among all types of refrigeration systems.

Energy performance evaluation of variable-speed milk refrigerator using propane (R290)

Hydrofluorocarbons (HFCs) such as R134a, R410A, and R407C may not be the long-term solution for the HVAC & R industry due to their higher potential for global warming. People’s interest is now shifting toward alternate refrigerants like hydrocarbons (HCs). In this research paper, an experimental energy performance evaluation of a variable-speed milk refrigerator was conducted using propane (R290). R290 has good environmental and thermodynamic properties, and it is known as a fourth-generation refrigerant. Various performance parameters, such as Cooling Capacity, COP, and Compressor Energy Consumption, are analyzed using different speeds of DC compressor. The DC compressor has four different types of fixed speed along with one variable speed operation. The results achieved from the performance tests are presented and discussed.

Assessment and development of the viscosity prediction capabilities of entropy scaling method coupled with a modified binary interaction parameter estimation model for refrigerant blends

Low global warming potential (GWP) refrigerant blends have been identified that may play a role according to the gradually reduction of the baseline amount of hydrofluorocarbons (HFCs) that can be replaced on the future market. Entropy scaling theory is a potential way to describing viscosity behavior of refrigerant mixtures, which is crucial for designing and optimizing of refrigeration system. However, an important prerequisite to apply entropy scaling model to mixture is reliable binary interaction parameters (kij). To promote intensive industrialization of entropy scaling theory and avoid expensive and time-consuming experiments for kij regression simultaneously, a modified Quantitative Structure Property Relationship (QSPR) theory is proposed in this work to provide reasonable estimated kij values with an additional dispersion term. To evaluate the performance of the proposed theory systematically, five different estimation methods are considered when predicting phase behavior and viscosity. Such model shows better performances: for the non-associating mixtures including HFCs, hydrofluoroolefins (HFOs), R744 and hydrocarbons (HCS), vapor liquid equilibrium data are predicted with the deviation of 1.47%, liquid mixture viscosities are exactly reproduced with an error of 3.49%. Besides that, the modified QSPR associated with the PC-SAFT equation of state (EoS) has superior performance of kij estimation than the London’s dispersive theory and the original QSPR, especially in describing some highly nonideal systems. As a supplement, the residual entropy scaling model for viscosity by Yang et al. and the commonly used extended corresponding states model are also applied to verify the modified method.