Refrigerant HFO-1234yf Research Articles

Exploring the Impact of HFO-1234YF Refrigerant on the Tribological Properties of Advanced Polymeric Coatings

Abstract The global focus has shifted toward mitigating the impact of global warming, particularly in the air-conditioning and refrigeration sectors, where there is a strong emphasis on the use of environmentally friendly refrigerants. One such refrigerant that has gained increased usage is HFO-1234yf. The increasing use of HFO-1234yf as a refrigerant in automobile air-conditioning compressors presents new challenges in terms of material compatibility. In this research, we investigate the impact of HFO-1234yf in automobile compressor applications by comparing the tribological results of the same materials in air. We conducted tribological experiments under starved lubrication conditions using polyetheretherketone (PEEK)/polytetrafluoroethylene (PTFE) and aromatic thermosetting co-polyesters (ATSP)/PTFE-coated aluminum alloy samples. We found that the ATSP/PTFE coatings perform exceptionally well irrespective of the atmosphere, while the presence of HFO-1234yf refrigerant adversely affects the tribological performance of the PEEK/PTFE coatings, citing the lack of a stable tribofilm formation. These findings offer valuable insights for the development of materials and lubricants that are compatible with HFO-1234yf refrigerant applications.

Evaluation of adsorption characteristics of HFO-1234yf refrigerant with different adsorbents

The adsorption refrigerator system with HFO-1234yf refrigerant (2,3,3,3-tetrafluoropropene) has a global warming potential of less than 4 and activated carbons (MaxsorbIII, MH-00), mesoporous silica (TMPS-2), and metal organic frameworks (MOF-177). We measured the adsorption isotherm under diverse temperature and pressure conditions experimentally, and evaluated the adsorption characteristics of these adsorbents. In this study, we designed an experimental apparatus using a volumetric method and measured the adsorption equilibrium uptake. The MaxsorbIII/HFO-1234yf pair has an adsorption uptake as high as 1.30 g-HFO-1234yf/g-ads at 40 °C and 300 kPa. The adsorption uptake is approximately equivalent to that of the MaxsorbsIII/HFC-134a pair. The experimental data of the adsorption/desorption isotherms show that there is no hysteresis for the studied pair. The experimental results were reproduced using the Dubinin–Astakhov model (D–A model). The D–A model fits the experimental results precisely within 7%. A diagram of the relationship between HFO-1234yf and MaxsorbsIII also generated the D–A model, and the adsorption uptake capacity between the adsorption and desorption steps was obtained as 0.07 kg-HFO-1234yf/kg-ads at 40 and 80 °C. The adsorption capacities of MOF-177, MaxsorbIII, TMPS-2, and MH-00 were evaluated under similar operating conditions to be 0.19, 0.08, 0.11, and −0.03 kg/kg respectively.

Polymeric Coatings With Superior Tribological Performance for Lightweight Materials in HFO-1234yf Refrigerant

As global warming concerns continue to rise, research has shifted toward developing more climate-friendly refrigerants for air-conditioning and refrigeration compressors, with HFO-1234yf being a prominent candidate. In line with the need for lightweight engineering in electric vehicles, advanced composite coatings are necessary to improve the surface properties of parts and system components made from light metals such as magnesium and aluminum, which typically have poor tribological performance. This study investigates the tribological performance of advanced polymeric coatings (aromatic thermosetting copolyester [ATSP]-, polytetrafluoroethylene [PTFE]-, and polyether ether ketone [PEEK]-based) on lightweight aluminum alloy substrates in the presence of HFO-1234yf refrigerant and polyalkylene glycol (PAG) lubricant under starved lubrication conditions. Using a high-pressure tribometer, scuffing pressure, friction, and wear experiments were conducted, with all three coatings exhibiting excellent tribological performance compared to the bare substrate. Notably, PEEK and ATSP coatings demonstrated superior performance with high load-to-failure, low coefficient of friction, and negligible wear. Results also showed ATSP to have superior durability against a broad range of stress levels, while PEEK coating partially wears out at higher stress levels. These findings provide valuable insights for developing robust coatings on lightweight materials for high-stress applications.

Design and Development of R32a and HFO-1234yf Refrigeration blend in Air conditioning System

Abstract: Refrigeration and air-conditioning systems become an integral part of modern society. Electricity-driven vapour compression systems have been dominating the heating, ventilation, air conditioning and refrigeration (HVAC&R) industry. The working fluids of these systems often contribute to the environmental issues in the forms of direct and indirection emissions. Pure refrigerants are often limited inmeeting criteria such as efficiency, flammability, toxicity, and compatibility. Meanwhile, refrigerant mixtures offer flexibilities to tune these criteria, This paper will review the status worldwide on technical and policy search for next-generation refrigerants with both low Global Warming Potential (LGWP) and low Life Cycle Climate Performance (LCCP) with particular focus on R410A replacement for unitary A/C & H/P. R32 and the HFO blends offer potential solutionsbut all involve tradeoffs among Global Warming Potential (GWP), efficiency, safety, and cost. With the U.S. mandating new higher regional efficiency standard taking effect January 2015, there is even more pressure in finding a LowGWP refrigerant solution that is affordable and can sustain efficiency and reduce charge requirement. This paper focuses more on R32 as the available data for HFO blends is limited. And Mixing of both R32a and HFO-1234yf in Ac To Study the performance two different next generation refrigerants R32 and Hfo-1234yf.To determine most promising refrigerant blend for air conditioning system test observe, anaylize and compare result obtained with conventional refrigerant. To determine impact of R32 and HFO-1234yf refrigerant as a replacement of R410A

Flow Boiling Heat Transfer of Refrigerants HFO-1234yf and HFC-134a in an Extruded Aluminum Tube with Multi-Port microchannels

Extruded flat aluminium tubes with multi-parallel ports microchannel heat exchangers are popularly used in automotive air-condition systems. The automotive air-condition is one of the earliest systems that is being banned for using a working fluid with a GWP value higher than 150. HFO-1234yf is one of the most possible candidates to replace the current refrigerant HFC-134a used in it but very few studies have been conducted for flow boiling of HFO-1234yf in rectangular microchannels. This study provides an experimental investigation and comparison on the flow boiling heat transfer of refrigerants HFO-1234yf and HFC-134a in a microchannel heat exchanger with a channel size of 0.5 mm. The test results show that the heat transfer coefficients of HFC-134a are from 0 to 22% higher than those of HFO-1234yf depending on mass velocity and vapor quality. Kandlikar and Balasubramanian (2004) correlation provides the best predictions for the present test results. The major controlling properties for flow boiling heat transfer coefficients in rectangular microchannels is similar to those for flow in larger circular tubes. They are strongly depending on the two-phase flow pattern at various flow conditions.

Experimental investigation on flow boiling characteristics of HFO-1234yf in a 0.5 mm microchannel

The flow boiling heat transfer of environmentally friendly refrigerant HFO-1234yf in a horizontal circular microchannel is experimentally investigated. The inner diameter and heating length of the test channel are 0.5 mm and 300 mm, respectively. Experiments are conducted at relatively high mass flux ranging from 750 to 1500 kg m−2s−1, heat flux from 25 to 85 kW m−2 and inlet pressure between 0.604 and 0.634 MPa. The heat flux is stepwise imposed to the test channel until dryout occurs. The flow boiling heat transfer characteristics are analyzed in detail. In the pre-dryout region, the heat transfer coefficient (HTC) is found to be mainly determined by the heat flux, while the effect of mass flux is weak. Two different HTC behaviors are observed at low and high mass fluxes, which can be attributed to the prominent effect of thin liquid film evaporation on heat transfer and the occurrence of partial dryout. Moreover, the oscillation of mass fluxes and wall temperatures are observed at high mass flux conditions, resulting in heat transfer deterioration. In the post-dryout region, the critical heat flux (CHF) is found to increase with mass flux, while the critical vapor quality would decrease. Finally, the experimental data of HTC and CHF are compared with correlations from the literature and good agreements are presented.

Evaporation Heat Transfer and Pressure Drop of Low-Global Warming Potential Refrigerant HFO-1234yf in 6.95-mm Horizontal Smooth Tube

This study investigated the evaporative heat transfer coefficient and pressure drop characteristics of R-1234yf in a horizontal tube with an inner diameter of 6.95 mm under various experimental conditions. The heat transfer coefficient increased with an increase in quality but showed a sharp decrease in the high-quality area. In addition, the heat transfer coefficient increased as the mass flux, heat flux, and saturation temperature increased. Although R-1234yf and R-134a presented similar heat transfer coefficients, that of R-134a was higher. The pressure drop increased with an increase in the quality and mass flux but decreased with an increase in the saturation temperature. The pressure drop of R-134a was larger than that of R-1234yf. In light of the flow pattern diagram by Taitel and Dukler, most of the experiments were included in the annular flow region, and some regions showed intermittent and stratified corrugated flow regions. Kandlikar’s heat transfer coefficient correlation provided the best prediction for the experimental database, with approximately 84% of the predicted data within ±30%. Moreno Quibén and Thome’s equation for pressure drop predicted approximately 88.71% of the data within ±30%.

Basic study of adsorption refrigerator with HFO-1234yf refrigerant

HFO-1234yf(2,3,3,3-Tetrafluoropropene) refrigerant has a global warming potential (GWP) of less than 4, compared to 1430 for HFC-134a. We suggested the adsorption refrigerator system with HFO-1234yf refrigerant for improvement of thermal efficiency in industrial process. In this study, we have designed experimental apparatus in volumetric method, and measured the adsorption equilibrium uptake. We evaluated the characteristic of adsorption cycle in static analysis based on experimental results. We measured the adsorbed amount at equilibrium with MaxsorbIII (KANSAI Kagaku ltd.). The experimental results were reproduced using Dubinin- Astakhov model (D-A model). A Duhring diagram in relationship of HFO-1234yf and Maxsorb3 was also generated the D-A model, and the adsorption uptake capacity between adsorption and desorption step was obtained 0.19 kg-HFO-1234yf/kg-ads.

Experimental Research on Flow and Heat Transfer in Microchannel with Refrigerant HFO1234yf

An experiment was carried out to study the effect of refrigerant mass flow rate, heat flux density, and saturation temperature on boiling heat transfer coefficient and frictional pressure drop in microchannel. Flow patterns are captured by a high-speed camera. HFO1234yf was used in rectangular microchannels with a hydraulic diameter of 0.5 mm. The results showed that there were eight flow patterns in the experiment, and the change of flow pattern is closely related to the change of heat flux and mass flow rate. The higher the heat flux and mass flow rate, the more the flow patterns appear. Different flow patterns have different heat transfer mechanisms. The heat transfer mechanism is mostly nuclear boiling at the region of bubble flow, slug flow, elongated slug flow, and agitated flow; the heat transfer mechanism is film convection boiling at the region of annular flow, and it is vapor convection at the region of dryout flow. When the dryness is about 0.4, the heat transfer mechanism changes from nuclear boiling to film boiling. The friction resistance decreases with the increase of dryness and saturation temperature.

Effect of channel size and shape on condensation heat transfer of refrigerants HFO-1234yf and HFC-134a in rectangular microchannels

Refrigerant HFO-1234yf has similar properties to HFC-134a but much lower GWP value. It is possible to replace HFC-134a by directly drop into the air-condition systems and expected to be an appropriate replacement for these systems. Microchannel heat exchangers have been commonly used in the vehicle air-condition systems attributed to their less weight and low air side pressure drops. However, there is no experimental study on condensation heat transfer performance of HFO-1234yf in microchannel with hydraulic diameter lower than 1 mm. This study provides an experimental comparison on condensation heat transfer and pressure drops of refrigerants HFO-1234yf and HFC-134a in multiport microchannels. The experimental results show that the effect of surface tension drainage force is important on condensation heat transfer in square channels especially for very small channels. The surface tension drainage force pulled the condensate to the corner of the square microchannels. This caused a very thin liquid film left on the tube wall and liquid conductivity became the major controlling property on the condensation heat transfer. Since the liquid conductivity of HFO-1234yf is 27% less than that of HFC-134a, the condensation heat transfer coefficients of HFO-1234yf are 15% to 23% lower than those of HFC-134a at various mass velocities and vapor qualities. The surface tension drainage force is in the direction of normal to the liquid and vapor flow. The experimental two-phase pressure drops are not affected by surface tension force and can be predicted reasonably well by using conventional correlations.

Heat transfer and pressure drop of film condensation in a horizontal minitube for HFO1234yf refrigerant

This paper applies the computational fluid dynamics (CFD) simulation to study the condensate two-phase thermofluid characteristics of refrigerant HFO-1234yf flowing through horizontal straight and convergent passages for guiding the design of minitube heat exchangers. The theoretical analysis employs the volume-of-fluid (VOF) method to model the progression of film condensation process for determining the distributions of velocity, pressure, temperature, vapor volume fraction and film thickness for liquid-vapor interfacial flows. The Lee model is formulated as a user defined function to treat the phase change effect at the interface. The predictions of heat transfer coefficients and pressure drops agree reasonably well with the measured data from the referencing literature at the mass and heat fluxes of 200–800 kg/m2 s and 9.9–24.3 kW/m2 for validation of the computational model. The simulated results are presented to capture the complex two-phase flow behaviors during the film condensation progression, including the formation of interfacial ripples of annular films, wave-shaped films with elongated necking regions, shedding of liquid ligaments and breakup of these ligaments entrained into the vapor core. The VOF calculations also estimate the average heat transfer coefficient and pressure drop up to 11.3 kW/m2 K and 55.1 kPa at a mass flux of 800 kg/m2 s for the straight tube, showing similar thermal performance to refrigerant HFC-134a reported by open literature. The convergent passage essentially raises the average heat transfer coefficient and pressure drop because of more severe shear stresses over the film surface. The correlations of heat transfer coefficient and pressure drop are compared with CFD predictions for straight and convergent tubes. The performance assessment is thus conducted using the validated correlations to guide the redesign of minitube heat exchangers with HFO1234yf as an alternative refrigerant in various energy systems. Two design changes are presented using HFO1234yf refrigerant to enlarge the total surface area up to 13.49% in straight tubes or broaden the cooling surface area of only 6.4% in convergent tubes for matching the performance of R134a.

Effects of Convergent Angle on Subcooled Boiling Phenomena in Two-phase Flow Nozzle Applied to HFO-1234yf Refrigerant.

Effects of Convergent Angle on Subcooled Boiling Phenomena in Two-phase Flow Nozzle Applied to HFO-1234yf Refrigerant.

Experimental analysis of condensation heat transfer and frictional pressure drop in a horizontal circular mini channel

The present study aims to investigate the effect of working fluid, mass flux, vapour quality and saturation temperature on local condensation Heat Transfer Coefficient (HTC) and local Frictional Pressure Drop (FPD) in a horizontal circular mini-channel. The refrigerants HFO-1234yf and HFC-R134a have been used as a working fluids. The mass flux was varied from 200 to 800 kg/m2 s whereas two distinct saturation temperatures were used: 35 °C and 40 °C. The experimental analysis was carried out using horizontal circular single port mini-channel of hydraulic diameter 1 mm. During experiment, inlet condition of refrigerant was maintained to be saturated vapour. The results show that HTC and FPD increases with increase in vapour quality and mass flux whereas decreases with increase in saturation temperature. The experiment results of present study and previously published results are compared with various predictive models. Models which show minimum deviation from experimental results were used to develop new modified model to predict HTC with MARD of ± 15 % and FPD with MARD of ± 10 %.

C-H and C-F Bond Activation Reactions of Fluorinated Propenes at Rhodium: Distinctive Reactivity of the Refrigerant HFO-1234yf.

The reaction of [Rh(H)(PEt3 )3 ] (1) with the refrigerant HFO-1234yf (2,3,3,3-tetrafluoropropene) affords an efficient route to obtain [Rh(F)(PEt3 )3 ] (3) by C-F bond activation. Catalytic hydrodefluorinations were achieved in the presence of the silane HSiPh3 . In the presence of a fluorosilane, 3 provides a C-H bond activation followed by a 1,2-fluorine shift to produce [Rh{(E)-C(CF3 )=CHF}(PEt3 )3 ] (4). Similar rearrangements of HFO-1234yf were observed at [Rh(E)(PEt3 )3 ] [E=Bpin (6), C7 D7 (8), Me (9)]. The ability to favor C-H bond activation using 3 and fluorosilane is also demonstrated with 3,3,3-trifluoropropene. Studies are supported by DFT calculations.

Condensation heat transfer and pressure drop of refrigerants HFO-1234yf and HFC-134a in small circular tube

HFO-1234yf has similar thermodynamic properties to HFC-134a but much lower GWP value. It is expected as a good candidate to replace the refrigerant HFC-134a in the near future. However, only very few papers have been published in the past years regarding to the flow condensation heat transfer performance of this new refrigerant. This study provides an experimental analysis of flow condensation heat transfer and pressure drops of refrigerants HFO-1234yf and HFC-134a in a small circular tube. The test results show that both pressure drop and condensation heat transfer performance depend on the fluid properties, flow conditions and flow patterns. The major controlling properties on pressure drops and heat transfer coefficients is strongly depending on their two-phase flow pattern at various flow conditions. At the lowest mass velocity, gravity is the major force that dominates the heat transfer mechanism and the flow pattern is slug. Higher liquid viscosity retarded the condensate flow but higher liquid conductivity provided better heat transfer through the liquid film. Both liquid viscosity and conductivity are the important controlling properties. While mass velocity and vapor quality increased, the effect of shear force increased and the flow pattern transferred to annular. Liquid thermal conductivity became the major controlling property at high vapor qualities. But at low vapor qualities, gravity is still important and therefore liquid viscosity is one the major controlling parameter. At the highest mass velocity conditions, gravity effect is negligible even though at very low vapor quality condition. Shear force dominated the condensation heat transfer mechanism and liquid conductivity is the most important controlling property. It can be concluded that the flow condensation heat transfer performance is strongly depending on the two-phase flow patterns at various flow conditions.

Flow boiling heat transfer and pressure drop of refrigerants HFO-1234yf and HFC-134a in small circular tube

HFO-1234yf has similar thermodynamic properties to HFC-134a but much lower GWP value. It is expected as a good candidate to replace the refrigerant HFC-134a in the near future. However, only very few papers have been published in the past years regarding to the flow boiling heat transfer performance of this new refrigerant, but some of their results are still not in consistent with each other. This study provides an experimental measurement of flow boiling heat transfer and pressure drops of refrigerants HFO-1234yf and HFC-134a in a small circular tube. The test results show that both pressure drop and flow boiling heat transfer performance depend on the fluid properties, flow conditions and flow patterns. The major controlling properties on pressure drops and heat transfer coefficients of flow boiling is strongly depending on their two-phase flow pattern at various flow conditions. The flow pattern analysis is able to explain the inconsistency between the test results in the previous published literatures on flow boiling heat transfer and pressure of refrigerants HFC-134a and HFO-1234yf adequately.

Combustion and flammability chemistry for the refrigerant HFO-1234yf (2,3,3,3-tetrafluroropropene)

A comprehensive chemical mechanism has been developed to describe combustion of the refrigerant HFO-1234yf (2,3,3,3-tetrafluroropropene, YF), revealing the dominant pathways for its stoichiometric combustion with O2. This novel mechanism is a quantum-chemistry-based extension to a previous mechanism developed at NIST for small fluorinated hydrocarbons. The new reactions were proposed by analyzing the YF molecule for potential unimolecular and bimolecular destruction routes, including chemical-activation channels. Kinetic parameters and thermochemistry were calculated using computational quantum chemistry or were developed by analogy to similar reactions or species. The new mechanism was compared favorably to experimental adiabatic-flame-speed data for stoichiometric YF/(35% O2/65% N2) flames at different initial temperatures. Analyses of these predictions revealed the key YF-destruction step at this H-starved condition to be F addition, producing CH2CF2+CF3 via chemically activated (•CH2CF2CF3)*.

Second law analysis of an automotive air conditioning system using HFO-1234yf, an environmentally friendly refrigerant

In this paper, a comparative study of the second law of thermodynamics is presented to determine the possibility of using HFO-1234yf, an environmentally friendly refrigerant, as a drop-in replacement of HFC-134a in automotive air conditioning system. For the thermodynamic analysis, a computer program is written to simulate the operating conditions of automobile air conditioning system. The thermodynamic properties of the refrigerants are extracted from the REFPROP 8.0 software. For calculating the coefficient of performance (COP), exergy destruction, exergy efficiency and entropy generation, computational models are used to evaluate the effects of different parameters on their changes. It is found that using HFO-1234yf as the air conditioning refrigerant leads to higher exergy efficiency compared to HFC-134a. Also, maximum entropy generation and exergy destruction occur in the compressor. The exergy destruction and entropy generation of the cycle components are less in the case of using HFO-1234yf refrigerant instead of HFC-134a.

A comprehensive modeling of choked two-phase flow through short-tube orifices with application to alternative refrigerants HFO-1234yf and HFO-1234ze

Due to the evaporating two-phase flow and the choked-flow condition, numerical analysis of flow through short-tube orifices is a complicated procedure. A comprehensive method for analyzing such flows is the two-fluid model, which does not assume equilibrium between phases. However, in all previous applications of this model, two-phase flow calculations at the entrance and vena contracta regions were eliminated. In this investigation, two additional steps were introduced to improve the accuracy of computations: (1) applying a comprehensive two-fluid model, including the effect of various two-phase flow patterns and the metastability of liquid phase; and (2) performing a two-phase analysis of the evaporating flow through the entrance and vena contracta, which involves simulation of this region as a contraction from the up-stream to the throat, and an expansion from the throat to downstream. Results showed more compatibility with experimental data in comparison with those of previous investigations for predicting the critical flow condition of common refrigerants HFC-134a, HCFC-22, and HFC-410a through short-tube orifices. In addition, the developed numerical scheme was utilized in order to develop selection charts for short-tube orifices based on the common refrigerant HFC-134a and the alternative newly released hydrofluoroolefin refrigerants HFO-1234yf and HFO-1234ze.

Effect of Condenser Fouling on Performance of Vapor Compression Refrigeration System

Effect of condenser fouling is evaluated on the performance of a vapour compression system with refrigerants HFO1234yf and HFO1234ze as an alternative to HFC134a. The condenser coolant temperature has been varied between 35 and 40°C to evaluate the effect of fouling at different condenser temperatures. A simulation model is developed in EES for computing the results. The results have been computed by varying condenser conductance. The same has been validated with literature available before calculating the results. It is observed that the condenser fouling has larger effect on compressor power (Wcp%) as it increases up to 9.12 for R1234yf and 7.41 for R1234ze, whereas for R134a its value increases up to 7.38. The cooling capacity (Qevap%) decreases up to 13.25 for R1234yf and 8.62 for R1234ze, whereas for R134a its value decreases up to 8.76. The maximum percentage of decrease in value of COP is up to 19.29 for R1234yf and 14.47 for R1234ze, whereas for R134a its value decreases up to 14.49. The second-law efficiency is also observed to decrease with decrease in the condenser conductance. The performance of HFO1234ze is found to be better under fouled conditions in comparison to R134a and R1234yf.