Replacement For R134a Research Articles

Experimental comparison of an air-to-water refrigeration system working with R134a and R1234yf

In this work, the use of R1234yf as a drop-in replacement for R134a in an air to water refrigeration system used to produce cool water at 7 °C is studied. This equipment was constructed in our laboratory with a minichannel heat exchanger working as condenser and a plate heat exchanger working as evaporator resulting in a 2.5 kW water chiller, which initially was working with R134a as refrigerant. A brief description of the refrigeration system and the installation used to test its behaviour as well as the uncertainty analysis is presented.Then, the test matrix defined in order to evaluate the effect of the different variables of interest on the performance of the refrigeration cycle is also presented. Air inlet temperature in the condenser was varied in order to analyse the influence of a variation in the ambient temperature. Other variables were varied in order to analyse the influence of different operating conditions as a variation in the compressor frequency or in the condenser fan velocity (by varying air inlet velocity). Finally, the subcooling degree was varied in order to compare a system with refrigerant receiver (no subcooling) and a system without refrigerant receiver and different refrigerant charge (different subcooling).According to the results obtained, R1234yf performs worse than R134a, presenting lower cooling capacity and higher compressor consumption in all tests, with a global efficiency around 25% lower. This can be explained by its lower isentropic and volumetric efficiency, which could be related to the type of lubricant used.

Experimental study on R1234yf/R134a mixture (R513A) as R134a replacement in a domestic refrigerator

In this paper, a comparative experimental study between R134a and its low GWP alternative R1234yf/R134a (called R513A, 44/56% weight) in a domestic refrigerator was presented. Three kinds of tests were carried out under the same ambient condition. The optimal charge for R513A is 80 g, which is 5.9% lower than that of R134a (85 g). The pull down time of R513A is reduced by 21% compared to R134a. The 24-h energy consumption of R513A is 3.5% lower than that of R134a. During the freezing test, R513A saved 43.2 min compared to the baseline test, which indicates that the freezing capacity of R513A is better than R134a. In addition, R513A shows a similar behavior to the baseline test with the discharge temperature and compressor pressure ratio of R513A lower than those of R134a.

R-152a as an alternative refrigerant to R-134a in domestic refrigerators: An experimental analysis

Among all sectors of refrigeration, one of the most affected by the latest international regulations is the domestic refrigeration. Although for it has been suggested some solutions, such as the construction of household refrigerator operating with the hydrocarbons, there remains the need to find a substitute for R-134a. With the aim of finding a simple implementation solution, in the present work, it is reported an experimental investigation carried out on a domestic no-frost refrigerator designed and built to operate with R-134a and for which a drop-in with R-152a has been realised. Different tests have been performed with the aim to identify the right charge of R-152a too. In line with the standard ISO 15502:2005 (2005), pull-down and 24 h energy consumption experiments have been run to evaluate the performance of R-152a as the drop-in replacement of R-134a in a domestic refrigerator. Also, a theoretical model has been proposed with the aim to give support to the observed energy change.

Thermodynamic analysis of a novel Ejector Enhanced Vapor Compression Refrigeration (EEVCR) cycle

This paper presents a theoretical thermodynamic analysis of a novel Ejector Enhanced Vapor Compression Refrigeration (EEVCR) cycle using zeotropic mixture of propane and isobutane (R290/R600a) as a refrigerant to replace R134a in domestic refrigerators/freezers. 1 D thermodynamic model for a constant area mixing ejector is used to estimate the cycle performance under the condition of optimal operating regime. The Coefficient of Performance (COP), the Volumetric Cooling Capacity (VCC), Qv and the compressor pressure ratio are studied for the novel EEVCR cycle and the results are compared to the conventional cycle using pure fluid R134a and zeotropic mixture R290/R600a. A comparative study was carried out to determine the propane mass fraction, z in the zeotropic mixture that would be a suitable replacement for R134a. The results indicated that the cycle COP and Qv could be improved by 23% and 62.71%, respectively. In addition, the cycle COP and Qv for the proposed EEVCR cycle were higher by 70% than those for a modified ejector expansion cycle. Finally, the propane mass fraction of 60% in the zeotropic R290/R600a mixture was found to have similar saturation pressure as R134a and the cycle COP and Qv were found similar to those of R134a.

Exergy analysis of vapor compression refrigeration system using R450A as a replacement of R134a

This paper experimentally investigated exergetic performance analysis of vapor compression refrigeration system using R450a as a replacement for R134a at different evaporator and condenser temperatures within controlled environmental conditions. The exergetic performance analysis of the vapor compression refrigeration system with test parameters including efficiency defects in the components, total irreversibility, and exergy efficiency of the refrigeration system was performed. Findings showed that the total irreversibility and exergy efficiency of the vapor compression refrigeration system using R450A refrigerant were lower and higher than R134a by about 15.25–27.32% and 10.07–130.93%, respectively. However, the efficiency defect in the condenser, compressor, and evaporator of the R450A refrigeration system was lower than R134a by about 16.99–26.08%, 5.03–20.11%, and 1.85–15.85%, respectively. Conversely, efficiency defect in the capillary tube of the R450A refrigeration system was higher than R134a by about 14.66–78.97% under similar operating conditions. Overall, it was found that the most efficient component was the evaporator, and the least efficient component was the compressor for both refrigerants.

Pool Boiling of Low-GWP Replacements for R134a on a Reentrant Cavity Surface.

This paper quantifies the pool boiling performance of R134a, R1234yf, R513A, and R450A on a flattened, horizontal reentrant cavity surface. The study showed that the boiling performance of R134a on the Turbo-ESP exceeded that of the replacement refrigerants for heat fluxes greater than 20 kWm-2. On average, the heat flux for R1234yf and R513A was 16 % and 19 % less than that for R134a, respectively, for R134a heat fluxes between 20 kWm-2 and 110 kWm-2. The heat flux for R450A was on average 57 % less than that of R134a for heat fluxes between 30 kWm-2 and 110 kWm-2. A model was developed to predict both single-component and multi-component pool boiling of the test refrigerants on the Turbo-ESP surface. The model accounts for viscosity effects on bubble population and uses the Fritz (1935) equation to account for increased vapor production with increasing superheat. Both loss of available superheat and mass transfer resistance effects were modeled for the refrigerant mixtures. For most heat fluxes, the model predicted the measured superheat to within ± 0.31 K.

Efficiency Evaluation of the Ejector Cooling Cycle using a New Generation of HFO/HCFO Refrigerant as a R134a Replacement

Theoretical investigations of the ejector refrigeration system using hydrofluoroolefins (HFOs) and hydrochlorofluoroolefin (HCFO) refrigerants are presented and discussed. A comparative study for eight olefins and R134a as the reference fluid was made on the basis of a one-dimensional model. To facilitate and extend the possibility of comparing our results, three different levels of evaporation and condensation temperature were adopted. The generator temperature for each refrigerant was changed in the range from 60 °C to the critical temperature for a given substance. The performed analysis shown that hydrofluoroolefins obtain a high efficiency of the ejector system at low primary vapor temperatures. For the three analyzed sets of evaporation and condensation temperatures (te and tc equal to 0 °C/25 °C, 6 °C/30 °C, and 9 °C/40 °C) the maximum Coefficient of Performance (COP) was 0.35, 0.365, and 0.22, respectively. The best performance was received for HFO-1243zf and HFO-1234ze(E). However, they do not allow operation in a wide range of generator temperatures, and, therefore, it is necessary to correctly select and control the operating parameters of the ejector.

ANN approach for irreversibility analysis of vapor compression refrigeration system using R134a/LPG blend as replacement of R134a

This paper experimentally evaluated the irreversibility in the components (compressor, condenser, capillary tube, and evaporator) of the vapor compression refrigeration system (VCRS) using R134a/LPG refrigerant as a replacement for R134a. For this aim, different tests were conducted for various evaporator and condenser temperatures under controlled surrounding conditions. The results reported that the irreversibilities in the components of VCRS using R134a/LPG blend were found lesser than irreversibilities in the components of VCRS using R134a under similar experimental conditions. Artificial neural network (ANN) models were developed to predict the second law of efficiency and total irreversibility of the refrigeration system. ANN and ANFIS model predictions were also compared with experimental results and an absolute fraction of variance in range of 0.980–0.994 and 0.951–0.977, root-mean-square error in the range of 0.1636–0.2387 and 0.2501–0.4542 and mean absolute percentage error in the range of 0.159–0.572 and 0.308–0.931%, respectively, were estimated. The outcomes suggested that ANN model shows better statistical prediction than ANFIS model.

Experimental analysis of R1234yf as a drop-in replacement for R134a in a small power refrigerating system

This paper presents an experimental study of the R1234yf drop-in performance in an R134a small power vapor-compression refrigeration system. Experiments were performed for two compressor supply frequency values of 40 and 60 Hz, evaporation temperatures from −5 to +5 °C and condensation temperatures of 45, 50 and 55 °C. From the experimental measurements, parameters such as the cooling power, compressor electric power or the energy efficiency ratio (EER) of the system are obtained and compared between the two refrigerants. Results show that R1234yf may be an adequate drop-in refrigerant for R134a as it closely matches its cooling capacity at the expense of lower EER values.

Comparison of transient response of an evaporator model for water refrigeration system working with R1234yf as a drop-in replacement for R134a

This study is developed to evaluate the possibility of R1234yf to be a drop-in replacement for a pre-designed system with R134a, including the characterization of control system in a vapor compression system. The control algorithms are required for regulating the refrigerant flow rate into the evaporator and their control parameters depend intrinsically on refrigerant fluid. This paper presents a comparison of the effects of R134a and R1234yf refrigerants on the transient response of an evaporator operating with water as secondary fluid (counter-flow). The dynamic heat exchanger distributed model combines principles of thermodynamics, heat and mass transfer with empirical correlations, which are proposed in the literature, in order to compute the void fraction, pressure drop and heat transfer in two-phase flow. Experimental tests are carried out on a fixed refrigeration system for cooling capacity less than 3 kW, with constant condensation conditions, variable evaporating temperature and compressor speed to validate the model. The results demonstrated that a good agreement between simulation results and experimental data was achieved. The evaporation temperature data were within ± 1 °C error band. Furthermore, comparative simulations between the refrigerants R-134a and R-1234yf exhibited a similar dynamic behavior during a step at the inlet mass flow rate, and the gain and time constant for superheat control were not considerably modified. Therefore, the refrigerant changing does not demand many changes in the expansion device control strategy.

Energy analysis of a domestic refrigerator system with ANN using LPG/TiO2–lubricant as replacement for R134a

This paper experimentally investigated and also modeled using artificial neural networks (ANN) approach the energy analysis of a domestic refrigerator using selected charges of LPG refrigerants (40, 50, 60 and 70 g) and different concentrations (0, 0.2, 0.4 and 0.6 gL−1) of TiO2-based nanolubricants as replacement for R134a refrigerant. The parameters for energy analysis include: compressor power consumption, cooling capacity, COP, compressor discharge temperature and pressure ratio. The findings showed that cooling capacity and COP of the domestic refrigerator using LPG refrigerant with TiO2 nanoparticles dispersed in a mineral oil lubricant was found to be higher than that of R134a by around 18.74–32.72 and 10.15–61.49%, respectively. Furthermore, compressor power consumption and pressure ratio of the domestic refrigerator using LPG refrigerant with TiO2–mineral oil lubricant were also found to be lower than that of R134a by about 3.20–18.1 and 2.33–8.45%, respectively, under similar conditions. The compressor discharge temperature was also found to be lower using LPG refrigerant with lubricant TiO2–mineral oil than R134a. The results further suggested that the best energetic performance of the domestic refrigerator was obtained using 40 g charge of LPG refrigerant with TiO2–mineral oil lubricant at 0.4 gL−1 of TiO2 concentration under similar operating conditions. The predictions from ANN models had excellent alignment with experimental results giving a range of values for R2 from 0.914 to 0.970, RMSE from 0.111 to 2.317, and MAPE from 0.865 to 3.148%.

Thermodynamic modeling of VLE and VLLE for the ternary system of 2,3,3,3-tetrafluoroprop-1-ene(R1234yf) + propane (R290) + 1,1,1,2-tetrafluoroethane(R134a) at 253.15 K-313.15 K

The excess Gibbs free energy-equation of state (GEEoS) models is presented based on the Peng-Robinson (PR) EoS combined with the Wong-Sandler (WS) mixing rule and the modified UNIFAC group contribution method (PR-WS-MUNIFAC). The average absolute deviation (AAD) of vapor phase mass fraction and the absolute average relative deviation (AARD) of pressure are 0.0047 and 0.53%, respectively, for R152a + R1234yf; 0.0064、0.0050 and 1.59%, respectively, for R32 + R125 + R134a. The VLE properties of the ternary mixture R1234yf + R290 + R134a as a drop-in replacement for R134a were predicted over the temperature range of (253.15–313.15 K) at 10 K intervals. The vapor–liquid-liquid equilibrium (VLLE) was qualitatively analyzed in theory, and the relevant phase equilibrium diagrams were constructed. The R290 + R134a system has clear characteristics of VLLE near the azeotropic point; the pressure of the upper critical end point (UCEP) is approximately 1.627 MPa. Liquid phase separation also exists in the ternary system of R1234yf + R290 + R134a.

Artificial neural network approach for irreversibility performance analysis of domestic refrigerator by utilizing LPG with TiO2–lubricant as replacement of R134a

This paper experimentally investigated irreversibility performance analysis of domestic refrigerator using 40 g, 50 g, 60 g and 70 g of LPG refrigerant with varying concentration of TiO2 nanoparticles dispersed in a mineral oil lubricant as replacement of R134a. The irreversibility performance analysis of the domestic refrigerator investigated with test parameters including irreversibility in the components, total irreversibility, and second law efficiency. Findings showed that under similar operating conditions irreversibilities in condenser, capillary tube, evaporator and compressor of the domestic refrigerator using LPG refrigerant with lubricant TiO2–mineral oil found lower than R134a by 6.05–48.10%, 17.83–46.98%, 2.51–33.17% and 2.21–23.29% respectively. Additionally, total irreversibility and second law efficiency in the domestic refrigerator using LPG refrigerant with TiO2, nanoparticles dispersed in a mineral oil lubricant found lower and higher than R134a by around 0.65–35.97% and 6.23–54.74% respectively. All in all 0.4 g L−1 of TiO2 and 40 g of LPG charge were the attained optimal values of nanoparticle concentration and LPG charge respectively in the domestic refrigerator utilizing LPG as replacement of R134a. Artificial Neural Networks (ANN) approach to delineate total irreversibility and second law efficiency of the domestic refrigerator was additionally applied to develop the models. It found that ANN models predictions concurred well with experimental results and brought out an absolute fraction of variance of (0.989–0.990), root mean square error of (0.831–1.061) and mean absolute percentage error of (1.734–2.056%) respectively with experimental results.

Horizontal convective boiling of R1234yf, R134a, and R450A within a micro-fin tube

This paper presents local convective boiling heat transfer and Fanning friction factor measurements in a micro-fin tube for R134a and two possible low global warming potential (GWP) refrigerant replacements for R134a, namely R1234yf and R450A. Test section heating was achieved with water in either counterflow or in parallel flow with the test refrigerant to provide for a range of heat fluxes for each thermodynamic quality. An existing correlation from the literature for single and multi-component mixtures was shown to not satisfactorily predict the convective boiling measurements for flow qualities greater than 40%. Accordingly, a new correlation was developed specifically for the test fluids of this study so that a fair comparison of the heat transfer performance of the low GWP refrigerants to that of R134a could be made. The new correlation was used to compare the heat transfer coefficient of the three test fluids at the same heat flux, saturated refrigerant temperature, and refrigerant mass flux. The resulting example comparison, for the same operating conditions, showed that the heat transfer coefficient of the multi-component R450A and the single-component R1234yf were, on average, 15% less and 5% less, respectively, than that of the single-component R134a. Friction factor measurements were also compared to predictions from an existing correlation. A new correlation for the friction factor was developed to provide a more accurate prediction. The measurements and the new models are important for the evaluation of potential low-GWP refrigerants replacements for R134a.

Isobaric Heat Capacity Measurements of Supercritical R1234yf

R1234yf (2,3,3,3-tetrafluoropropene) is a low global warming potential (GWP) replacement for R134a, a fluid commonly used as a refrigerant in domestic and automotive air conditioning systems and as a working fluid in organic Rankine cycles. The use of R1234yf in energy conversion cycles requires an accurate determination of its thermophysical properties, including the isobaric heat capacity (cP). Using a custom-made flow calorimeter, experimental cP measurements of supercritical R1234yf were made at temperatures T = 373.15 to 413.5 K and absolute pressures P = 3.5 to 10 MPa. The experimental apparatus was calibrated using R134a to increase the measurement accuracy. The heat capacity measurements of R1234yf were compared to available published experimental data and to values obtained from a multiparameter equation of state (EOS). The measured cP values agreed well with the EOS, providing an average absolute deviation (AAD) of 1.6%.

Systematic Optimization-Based Integrated Chemical Product–Process Design Framework

An integrated optimization-based framework for product and process design is proposed. The framework uses a set of methods and tools to obtain the optimal product–process design solution given a set of economic and environmental sustainability targets. The methods and tools required are property prediction through group contributions, unless supported with a database, computer-aided molecular and mixture/blend design for generation of novel as well as existing products and mathematical programming for formulating and solving multiscale integrated process–product design problems. The application of the framework is demonstrated through three case studies: (i) refrigeration cycle unit for R134a replacement, (ii) a mixed working fluid design problem for R134a replacement, and (iii) pure solvent design for water-acetic acid LLE extraction. Through the application of the framework it is demonstrated that all solutions satisfy product, process, economic, and environmental targets simultaneously. The solution is...

A study on the use of propane (R-290) in vending machines as a substitute for R-134a to minimise the global warming potential

The refrigerant R-134a is widely used in vending machines, and it is a greenhouse gas with high global warming potential. The United States Environmental Protection Agency has mandated that R-134a be replaced with an environmentally friendly refrigerant. In this study, we compared the performance and safety of R-290 as a substitute for R-134a in vending machines. We compared the two refrigerants in a vending machine equipped with a single-stage compressor, four thermocouples, and a data log recorder. Our results demonstrate that R-290 performs as well as R-134a; in addition, it uses 31.4% less energy and 60% less refrigerant. The evaporator and condenser temperatures for R-290 were comparable to those for R-134a. Therefore, we conclude that R-290 is an excellent replacement for R-134a. In addition, R-134a's global warming potential is 1300, while R-290's global warming potential is 3, and its ozone depletion potential is zero. Finally, R-290 can be used safely and complies with Underwriter Laboratory® safety standards.

A study on the use of propane (R-290) in vending machines as a substitute for R-134a to minimise the global warming potential

The refrigerant R-134a is widely used in vending machines, and it is a greenhouse gas with high global warming potential. The United States Environmental Protection Agency has mandated that R-134a be replaced with an environmentally friendly refrigerant. In this study, we compared the performance and safety of R-290 as a substitute for R-134a in vending machines. We compared the two refrigerants in a vending machine equipped with a single-stage compressor, four thermocouples, and a data log recorder. Our results demonstrate that R-290 performs as well as R-134a; in addition, it uses 31.4% less energy and 60% less refrigerant. The evaporator and condenser temperatures for R-290 were comparable to those for R-134a. Therefore, we conclude that R-290 is an excellent replacement for R-134a. In addition, R-134a's global warming potential is 1300, while R-290's global warming potential is 3, and its ozone depletion potential is zero. Finally, R-290 can be used safely and complies with Underwriter Laboratory® safety standards.

Component-wise exergy and energy analysis of vapor compression refrigeration system using mixture of R134a and LPG as refrigerant

In this work, the experimental examination was carried out using a mixture of R134a and LPG refrigerant (consisting of R134a and LPG in a proportion of 28:72 by weight) as a replacement for R134a in a vapor compression refrigeration system. Exergy and energy tests were carried out at different evaporator and condenser temperatures with controlled environmental conditions. The results showed that the exergy destruction in the compressor, condenser, evaporator, and a capillary tube of the R134a / LPG refrigeration system was found lower by approximately 11.13–3.41%, 2.24–3.43%, 12.02–13.47% and 1.54–5.61% respectively. The compressor exhibits the highest level of destruction, accompanied by a condenser, an evaporator and a capillary tube in refrigeration systems. The refrigeration capacity, COP and power consumption of the compressor of the R134a /LPG refrigeration system were detected higher and lower compared to the R134a refrigeration system by about 7.04–11.41%, 15.1–17.82%, and 3.83–8.08% respectively. Also, the miscibility of R134a and LPG blend with mineral oil discovered good. The R134a and LPG refrigerant mixture proposed in this study perform superior to R134a from component-wise exergy and energy analyses under similar experimental conditions.

Low GWP refrigerants condensation inside a 2.4 mm ID microfin tube

This paper explores the possible use of R1234yf and R1234ze(E) during condensation inside a microfin tube with an inner diameter at the fin tip of 2.4 mm as replacement of R134a. Having thermodynamic properties close to those of R134a, R1234yf and R1234ze(E) are some of its possible replacements for air conditioning and refrigeration systems. Experimental tests were carried out for mass velocities from 300 to 1000 kg m−2 s−1, vapor qualities from 0.95 to 0.2, at saturation temperatures of 30 °C and 40 °C. From the experimental measurements, it has been possible to calculate the heat transfer coefficient and to measure the frictional pressure drop. Globally speaking, R1234ze(E) shows heat transfer coefficients similar to those of R134a, whereas R1234yf shows slightly lower values. R1234ze(E) frictional pressure drops are some 30% higher than those of R134a, whereas R1234yf shows values similar to R134a. The experimental results of heat transfer coefficient and frictional pressure drop were also compared against values predicted by empirical correlations.