Artykuły w czasopismach: „REFPROP”

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Gao, Lei, Takuro Shibasaki, Tomohiro Honda i Hiroyuki Asou. "Measurement of the Speed of Sound in 2,3,3,3-Tetrafluoropropylene (R-1234yf) Liquid Phase with an Ultrasonic Sensor". Advanced Materials Research 875-877 (luty 2014): 588–92. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.588.

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The speeds of sound in near saturated and subcooled liquid phases of R-1234yf have been measured using a ultrasonic sensor. The measurements were conducted at the temperature range from 0 to 80 °C, and the pressure range from 0.316 to 2.52 MPa. In order to validate the ultrasonic sensor, the measurement in pure water at the temperature range from 0 to 80 °C was also performed. The measurement result of water was compared with those calculated from REFPROP (based on IAPWS-95) and PROPATH (based on IAPWS-IF97). The result of water agrees well with that calculated from REFPROP within a maximum deviation of 0.28%, except for that at temperature of 80 °C. And it agrees well also with that calculated from PROPATH within a maximum deviation of ±0.2%. The measurement results for near saturated and subcooled liquid phases of R-1234yf were compared with those calculated from REFPROP and JSRAE thermodynamic table.

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Odabaee, Mostafa, Emilie Sauret i Kamel Hooman. "CFD Simulation of a Supercritical Carbon Dioxide Radial-Inflow Turbine, Comparing the Results of Using Real Gas Equation of Estate and Real Gas Property File". Applied Mechanics and Materials 846 (lipiec 2016): 85–90. http://dx.doi.org/10.4028/www.scientific.net/amm.846.85.

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The present study explores CFD analysis of a supercritical carbon dioxide (SCO2) radial-inflow turbine generating 100kW from a concentrated solar resource of 560oC with a pressure ratio of 2.2. Two methods of real gas property estimations including real gas equation of estate and real gas property (RGP) file - generating a required table from NIST REFPROP - were used. Comparing the numerical results and time consumption of both methods, it was shown that equation of states could insert a significant error in thermodynamic property prediction. Implementing the RGP table method indicated a very good agreement with NIST REFPROP while it had slightly more computational cost compared to the RGP table method.

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Ekundayo, Jamiu M., i Reza Rezaee. "Volumetric Measurements of Methane-Coal Adsorption and Desorption Isotherms—Effects of Equations of State and Implication for Initial Gas Reserves". Energies 12, nr 10 (27.05.2019): 2022. http://dx.doi.org/10.3390/en12102022.

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This study presents the effects of equations of state (EOSs) on methane adsorption capacity, sorption hysteresis and initial gas reserves of a medium volatile bituminous coal. The sorption experiments were performed, at temperatures of 25 °C and 40 °C and up to 7MPa pressure, using a high-pressure volumetric analyzer (HPVA-II). The measured isotherms were parameterized with the modified (three-parameter) Langmuir model. Gas compressibility factors were calculated using six popular equations of state and the results were compared with those obtained using gas compressibility factors from NIST-Refprop® (which implies McCarty and Arp’s EOS for Z-factor of helium and Setzmann and Wagner’s EOS for that of methane). Significant variations were observed in the resulting isotherms and associated model parameters with EOS. Negligible hysteresis was observed with NIST-refprop at both experimental temperatures, with the desorption isotherm being slightly lower than the adsorption isotherm at 25 °C. Compared to NIST-refprop, it was observed that equations of state that gave lower values of Z-factor for methane resulted in “positive hysteresis”, (one in which the desorption isotherm is above the corresponding adsorption curve) and the more negatively deviated the Z-factors are, the bigger the observed hysteresis loop. Conversely, equations of state that gave positively deviated Z-factors of methane relatively produced “negative hysteresis” loops where the desorption isotherms are lower than the corresponding adsorption isotherms. Adsorbed gas accounted for over 90% of the calculated original gas in place (OGIP) and the larger the Langmuir volume, the larger the proportion of OGIP that was adsorbed.

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Xu, Zhangliang, Hongbo Tan i Hao Wu. "Determination of Hydrogen’s Thermophysical Properties Using a Statistical Thermodynamic Method". Applied Sciences 13, nr 13 (24.06.2023): 7466. http://dx.doi.org/10.3390/app13137466.

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Accurate determination of the thermophysical properties of hydrogen is a crucial issue in hydrogen system design. By developing computational programs, a statistical thermodynamic model based on fundamental equations of state was implemented to determine hydrogen’s thermophysical properties, including the ortho-hydrogen fraction in equilibrium hydrogen, para-ortho hydrogen conversion heat, isobaric heat capacities and enthalpies. The deviations of calculated para-hydrogen enthalpies from REFPROP data were within 2.22%, ranging from 20 K to 300 K at 0.1 MPa, and within 2.32% between 100 K and 1500 K at pressures from 0.1 MPa to 20 MPa. To quantitatively assess the convenience of the statistical thermodynamic method, the running speeds of programs with different methods for determining hydrogen’s thermophysical properties were compared. The time required for statistical thermodynamic calculation was 7.95% that required for treading REFPROP data when the performance of the variable density multilayer insulation combined with a one vapor-cooled shield and para-ortho hydrogen conversion was calculated. The programs developed based on the statistical thermodynamic method can be used to determine the thermophysical properties of hydrogen or other fluids.

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Mocanu, Gabriel, Ion V. Ion i Cristian Iosifescu. "Energy and economic analysis of an ORC combined to steam boiler". E3S Web of Conferences 327 (2021): 01002. http://dx.doi.org/10.1051/e3sconf/202132701002.

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Energy and economic performance of an organic Rankine cycle (ORC) system designed to recycle waste heat of a steam boiler was analysed. Optimisation of ORC system was performed by using the Cycle-Tempo software and the REFPROP program. The selected working fluid was R245fa. For the exhaust gases temperature of 163°C and mass flow rate of 11.83 kg/s, cooling water temperature of 20°C resulted a gross efficiency of 21.02% and a cost of 2987 €/kW, an electricity levelised cost of 102 €/kWh and a payback period of 5.5 years.

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Mulero, A., i I. Cachadiña. "Recommended Correlations for the Surface Tension of Several Fluids Included in the REFPROP Program". Journal of Physical and Chemical Reference Data 43, nr 2 (czerwiec 2014): 023104. http://dx.doi.org/10.1063/1.4878755.

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Komarov, S. G., i S. V. Stankus. "Density and speed of sound in refrigerant vapor R-125 (31 wt. %) + R-134A (69 wt. %)". Journal of Physics: Conference Series 2057, nr 1 (1.10.2021): 012105. http://dx.doi.org/10.1088/1742-6596/2057/1/012105.

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Abstract Using a constant volume piezometer and ultrasonic interferometer methods, the density and speed of sound in gaseous mixture R-125 (31 wt. %) + R-134a (69 wt. %) were measured within the temperature range from 293 to 393 K and at pressure from 0.18…0.47 to 2.5 MPa. The errors in the measuring temperature, pressure, density and speed of sound were ±20 mK, ±4 kPa, ± (0.15–0.3) %, ± (0.1–0.2) %, respectively. It was shown that the speed of sound values increase with temperature and decrease with pressure. The obtained results were compared with the calculations using the REFPROP software.

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MALIK, F. ELMZUGHI, M. MJANI ABDULHAFED, S. LAGHA SAJI i A. ELHAJ MOHAMED. "OPTIMIZATION AND ENERGY PERFORMANCE OF 400MW STEAM POWER PLANT BASED ON MINI REFPROP SOFTWARE PACKAGES". i-manager's Journal on Mechanical Engineering 11, nr 4 (2021): 9. http://dx.doi.org/10.26634/jme.11.4.18078.

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Galashov, Nikolay, Svyatoslav Tsibulskiy i Tatiana Serova. "Analysis of the Properties of Working Substances for the Organic Rankine Cycle based Database “REFPROP”". EPJ Web of Conferences 110 (2016): 01068. http://dx.doi.org/10.1051/epjconf/201611001068.

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Zakirova, G. S., i E. I. Krapivsky. "Application of REFPROP software package for examinations automation of phase states of multicomponent hydrocarbon systems". Journal of Physics: Conference Series 1118 (grudzień 2018): 012052. http://dx.doi.org/10.1088/1742-6596/1118/1/012052.

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Zhang, Cuihua, Huili Yi i Jianxiang Tian. "Lielmezs–Herrick correlation for the temperature-dependent surface tension of hydrocarbons". International Journal of Modern Physics B 30, nr 23 (15.09.2016): 1650154. http://dx.doi.org/10.1142/s021797921650154x.

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In this paper, we analyzed the ability of Lielmezs–Herrick (LH) correlation for the temperature-dependent surface tension of 28 hydrocarbons. We found that compared with other published correlations, the original LH correlation stands well only for four fluids. By using new data in REFPROP database, we refitted the two parameters of LH correlation. Two sets values are obtained. One is the updated corresponding state LH correlation, which is fluid independent. The other is the two-parameter LH correlation, which is fluid dependent. We found that the former clearly improves the accuracy of the original LH correlation and the latter is the best among all of the correlations we know.

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Zakirova, G. S., i E. I. Krapivsky. "Thermophysical properties control during transportation of the liquefied hydrocarbon mixtures by means of REFPROP software package". Journal of Physics: Conference Series 1728 (styczeń 2021): 012026. http://dx.doi.org/10.1088/1742-6596/1728/1/012026.

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Malik, F. Elmzughi, i I. Dekam Elhadi. "Exergoeconomic and sensitivity analyses of a gas turbine power plant using MINI-REFPROP and MATLAB simulink". i-manager's Journal on Power Systems Engineering 10, nr 4 (2023): 1. http://dx.doi.org/10.26634/jps.10.4.19203.

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In this paper, exergy, exergoeconomic, and exergoenvironmental analysis of a gas turbine cycle and its optimization have been carried out by MINI-Reference Fluid Properties (MINI-REFPROP) and Matrix Laboratory (MATLAB) SIMULINK. The parametric study was carried out based on the Specific Exergy Costing approach. The mathematical models were developed and presented regarding mass, energy, and economy. The Excel and MATLAB LIBRARY TOOLS BOX are used to perform thermodynamic properties and research analyses. The analyses lead to valuable economic status benchmarks. The exergoeconomic factor, relative cost, total cost of energy loss, and energy destruction for the combustion chamber and work output were determined. The parametric study was conducted, considering the effects of the gas turbine inlet temperature, air compressor inlet temperature, and compressor pressure ratio. For the considered case study status, the combustion chamber in the plant revealed the highest amount of energy destruction (85%), leading to the recommendation that more attention be paid to boilers in terms of design, selection, operation, and maintenance, while the combustion chamber has a high improvement potential (91%).

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Liang, Hong, Xing Liu, Hong Guang Zhang, Bin Liu, Yan Chen, Yu Ting Wu i Wei Wang. "Pure Working Fluid Selection for the Organic Rankine Cycle in Waste Heat Recovery of Diesel Engine". Advanced Materials Research 383-390 (listopad 2011): 6110–15. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.6110.

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According to the analysis of heat balance, about 1/3 of the fuel combustion heat is taken away into the ambience by exhaust gas of diesel engine. Depending on the characteristics of the diesel, this paper uses a special system to recover this waste heat, in which the organic Rankine cycle is combined with a single screw expander. The economy should be improved by using this system in the diesel. The model of this system is designed in Matlab combined with REFPROP. Using this way, the thermodynamic parameters should be calculated and the thermodynamic properties of this system with different working fluids should be analyzed. At last, R245fa, R245ca, R123 and R141b are selected as the alternative refrigerants used in this system.

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Nasruddin, Septian Khairul Masdi i Arief Surachman. "Exergy Analysis and Exergoeconomic Optimization with Multiobjective Method of Unit 4 Kamojang Geothermal Power Plant". Applied Mechanics and Materials 819 (styczeń 2016): 523–29. http://dx.doi.org/10.4028/www.scientific.net/amm.819.523.

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This study presents four analysis at unit 4 Kamojang geothermal power plant are exergy analysis at current condition, exergy efficiency optimization, economic optimization, and exergoeconomic optimization with wellhead valve pressure as a variable. Calculations are conducted by using the MATLAB. Thermodynamics characteristic of geothermal fluid assumed as water characteristic which get from REFPROP. Wellhead pressure operational condition 10 bar has exergy efficiency 31.91%. Exergy efficiency optimization has wellhead valve pressure 5.06 bar, exergy efficiency 47.3%, and system cost US$ 3,957,100. Economic optimization has well pressure 11 bar, exergy efficiency 22.13%, and system cost US$ 2,242,200. Exergoeconomic optimization has 15 optimum condition. Exergoeconomic optimization aims to analyze the optimum wellhead valve pressure for maximum exergy efficiency and minimum cost of power plant system.

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Alawadhi, Khaled, Yousef Alhouli, Ali Ashour i Abdullah Alfalah. "Design and Optimization of a Radial Turbine to Be Used in a Rankine Cycle Operating with an OTEC System". Journal of Marine Science and Engineering 8, nr 11 (29.10.2020): 855. http://dx.doi.org/10.3390/jmse8110855.

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Design and optimization of a radial turbine for a Rankine cycle were accomplished ensuring higher thermal efficiency of the system despite the low turbine inlet temperature. A turbine design code (TDC) based on the meanline design methodology was developed to construct the base design of the turbine rotor. Best design practices for the base design were discussed and adopted to initiate a robust optimization procedure. The baseline design was optimized using the response surface methodology and by coupling it with the genetic algorithm. The design variables considered for the study are rotational speed, total to static speed ratio, hub radius ratio, shroud radius ration, and number of blades. Various designs of the turbine were constructed based on the Central Composite Design (CCD) while performance variables were computed using the in-house turbine design code (TDC) in the MATLAB environment. The TDC can access the properties of the working fluid through a subroutine that links NIST’s REFPROP to the design code through a subroutine. The finalization of the geometry was made through an iterative process between 3D-Reynolds-Averaged Navier-Stokes (RANS) simulations and the one-dimensional optimization procedure. 3D RANS simulations were also conducted to analyze the optimized geometry of the turbine rotor for off-design conditions. For computational fluid dynamics (CFD) simulation, a commercial code ANSYS-CFX was employed. 3D geometry was constructed using ASYS Bladegen while structured mesh was generated using ANSYS Turbogrid. Fluid properties were supplied to the CFD solver through a real gas property (RGP) file that was constructed in MATLAB by linking it to REFPROP. Computed results show that an initial good design can reduce the time and computational efforts necessary to reach an optimal design successfully. Furthermore, it can be inferred from the CFD calculation that Response Surface Methodology (RSM) employing CFD as a model evaluation tool can be highly effective for the design and optimization of turbomachinery.

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Sucahyo, Lilis. "PERFORMANCE ANALYSIS OF WORKING FLUIDS ON ORGANIC RANKIE CYCLE (ORC) MODEL WITH BIOMASS ENERGY AS A HEAT SOURCES". Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) 8, nr 3 (30.09.2019): 175. http://dx.doi.org/10.23960/jtep-l.v8i3.175-186.

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Organic Rankine Cycle (ORC) is an electricity power technology particularly suitable for medium-low temperature heat sources and/or for small available termal power. This paper presents the simulation and performance analysis of working fluids R-134a, R-414B, R-404A and R-407C on ORC with biomass energy as a heat source. Simulation of the ORC system using Cycle Tempo software. The property of working fluids is obtained by using Reference Fluid Properties (Refprop). The best result performance of ORC was shown by working fluid R-404A with thermal efficiency 7.54 % and electric power output ranges between 0.075 kW. This condition operated on turbine inlet temperature at 60 oC, difference turbine working temperature of 15 oC, condensing temperature 25 oC and water boiler mass flow rate 3 lpm.

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Widodo, TK Berkah Fajar, MSK Tony Suryo i SH Winoto. "Simulation of Mixing Synthetic with hydrocarbons Refrigerant to Reduce the Value of Global Warming Potential with Refprop Software". Journal of Physics: Conference Series 1764, nr 1 (1.02.2021): 012158. http://dx.doi.org/10.1088/1742-6596/1764/1/012158.

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Yusibani, Elin, Nursabila Al Hazmi i Evi Yufita. "Pengukuran Viskositas beberapa Produk Minyak Goreng Kelapa Sawit setelah Pemanasan". Jurnal Teknologi dan Industri Pertanian Indonesia 9, nr 1 (1.04.2017): 28–32. http://dx.doi.org/10.17969/jtipi.v9i1.6108.

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Measurement of palm oil viscosity after heat treatment has been done. The sample is palm oil packaging and bulk ones Falling body method is used as an instrument to determine the coefficient of viscosity which had previously been calibrated using water and REFPROP. The measurement results showed that the coefficient of viscosity of palm cooking oil that has been used 10 times for 30 minuted will rise by 76% for oil packs A and about 45% for a sample of bulk, respectively. For palm oil used once but its has been using for one hour, the viscosity will be comparable to 6 times the use of the cooking oil used for 30 minutes. Thus based on the masurement of viscosity value, the palm oil will have a viscosity values are relatively small when used often, but in a short time than is used only once, but in a relatively longer.

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Chen, Qiuju, Jianxiang Tian i Hua Jiang. "A new one-parameter correlation for the surface tension of saturated liquids". International Journal of Modern Physics B 33, nr 25 (10.10.2019): 1950294. http://dx.doi.org/10.1142/s0217979219502941.

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In this paper, we proposed a new one-parameter correlation for the surface tension of saturated fluids. This new correlation requires only the critical temperature as inputs and is tested by using the REFPROP data for 72 saturated fluids including refrigerants, alkanes and some other simple fluids such as argon, carbon dioxide, etc. It is found that this correlation well stands in the whole temperature range from the triple point to the critical point with high accuracy for 59 liquids with average absolute deviations (AADs) less than 5%, 50 liquids with AADs less than 3%, and 13 liquids with AADs less than 1%. These results are clearly better than those of the other available correlations. This correlation can be used to estimate the value of the surface tension of the corresponding liquids at any temperature point from the triple point to the critical point.

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Shreenaath, K. G. Sai, Jigar Golecha, L. Bruno Augustin i M. Suresh. "Numerical Studies on R22 Refrigerant Compressor Using Environment Friendly Working Fluids". Applied Mechanics and Materials 493 (styczeń 2014): 21–26. http://dx.doi.org/10.4028/www.scientific.net/amm.493.21.

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Vapour compression refrigeration is the most widely used method in domestic and commercial air conditioning and refrigeration systems. R22 (difluoromonochloromethane) is the most widely used HCFC (hydro chlorofluorocarbon) refrigerant in residential, commercial, industrial and transport cooling systems. Montreal protocol in 1987 banned the use of CFCs (chlorofluorocarbon) due to their adverse impact on the environment causing ozone depletion and global warming. HCFCs are also being phased out, though they are less destructive than CFCs. The present work explores compressor performance using alternate environment friendly working fluids so that R22 can be replaced in future. The refrigerants used for the studies are R134a (tetrafluoroethane), R290 (propane) and R600a (isobutane). Compressor performance is analysed by varying refrigerant mass flow rate, evaporator and condenser temperatures and studying their effect on compressor size, power and discharge temperature. A numerical simulation code has been developed in MATLAB using refrigerant properties taken from REFPROP.

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Sabir, S. M., K. Chun, L. Petriw, M. Saifullah, A. Vashi, A. Zvorykin, S. Clark i I. L. Pioro. "COMPARISON OF THERMOPHYSICAL PROPERTIES (NIST REFPROP VER. 10) AND HEAT TRANSFER TO HEAVY AND LIGHT WATER AT SUBCRITICAL PRESSURES". Proceedings of the International Conference on Nuclear Engineering (ICONE) 2019.27 (2019): 2017. http://dx.doi.org/10.1299/jsmeicone.2019.27.2017.

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Zhang, Hong Guang, Hong Liang, Xing Liu, Bin Liu, Yan Chen, Yu Ting Wu, Wei Wang i Kai Yang. "Research of Two Stage Single Screw Expander Organic Rankine Cycle System Scheme Based on the Waste Heat Recovery of Diesel Engine’s Exhaust Gas". Advanced Materials Research 201-203 (luty 2011): 600–605. http://dx.doi.org/10.4028/www.scientific.net/amr.201-203.600.

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According to the analysis of heat balance, about 1/3 of the fuel combustion heat is taken away into the ambience by exhaust gas of diesel engine. In this article, to improve the using level of the fuel’s combustion heat, a two stage single screw expander organic Rankine cycle (ORC) system has been used to recover the waste heat from exhaust gas of a certain turbine diesel engine. In this article, physical model of the recovery system was built at first, then the T-S curve was drawn, at last, REFPROP was used to calculate thermodynamics parameter in different state point of this system, and analyze the whole system’s thermodynamics character. By analyzing, the evaporation temperature of this system should be optimized to get the relatively evaporation press; by calculating, it could be seen that the middle heater in this system should be taken away to improve the economy of this scheme. This scheme should supply a direction for the exhaust heat recovery of diesel engine.

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Najib, Joelle, Maroun Nemer i Chakib Bouallou. "Study of a Gas Turbine Cycle to Boost the Autonomy of Electric Cars". Energies 15, nr 9 (4.05.2022): 3348. http://dx.doi.org/10.3390/en15093348.

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The greenhouse gas emissions from the transportation sector are the primary cause of climate change. As a result, many studies have developed new powertrains with reduced CO2 emissions for the automotive industry. The gas turbine cycle coupled to an alternator is an autonomy booster for series hybrid electric vehicles. Many gas turbine configurations are proposed in the literature to obtain the highest cycle efficiency. This paper suggests a new architecture offering higher efficiency than all the previous cycles. The two-step methodology consists at first of a sensibility analysis using VBA and Refprop to determine the optimal operating conditions in terms of higher efficiency. The selected cycle consists of two compression stages with an intercooler, a combustion chamber, a cooled hot pressure turbine, an uncooled low-pressure turbine, and a recuperator. The efficiency of this design reaches 51.39%, which approximately matches the designs compared in the literature, but is more compact because it does not require a second combustion chamber.

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Redjeb, Youcef, i Khatima Kaabeche-Djerafi. "Thermodynamic Optimization of an Air bottoming Cycle for Waste Heat Recovery from Preheater Tower in a Cement Industry". Algerian Journal of Renewable Energy and Sustainable Development 03, nr 01 (15.06.2021): 97–103. http://dx.doi.org/10.46657/ajresd.2021.3.1.10.

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This work evaluated the air bottoming cycles(ABC) as a technology for waste heat recovery (WHR) at the level of the preheater tower in a cement industry. An optimization code has been developed in MATLAB environment and linked with REFPROP database as a way to design and calculate the different parameters and points of the cycle. The theory of power maximization is adopted and the genetic algorithm is employedasa way to maximize the net power output of the cycle, while a case study of a real cement plant has been taken into consideration for the examination purpose. Results showed that the integration of the ABC cycle for energy valorization contributes to covering around 8.5% of the industry need for electrical energy, by generating an amount of power that can achieve 1.07 MW.In addition, although the cycle has shown a low efficiency, it can be a practical WHR solution especially in case of water deficiency.

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Ramu, Neerathalingam Suguna, Palanisamy Senthilkumar i Murugesan Mohanraj. "Exergy Performance Assessment of a Residential Air Conditioner Working with R22 and R32/R125/R600a Mixture as an Alternative". Advanced Materials Research 984-985 (lipiec 2014): 1108–14. http://dx.doi.org/10.4028/www.scientific.net/amr.984-985.1108.

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The main aim of this article is to evaluate the performance of an air conditioner working with R22 and the new ternary mixture which comprises R32/R125/ R600a (0.4:0.4:0.2, by mass). The energy performance assessment of the air conditioner is made for four different condensing temperatures such as 30, 35, 40 and 45 °C with evaporator temperatures 22 and 25 °C respectively. The experimental tests are performed with secondary fluids like water and air in the condenser and in the evaporator respectively. The experimental tests are performed and comparative exergy analysis has been presented. REFPROP is utilized to find the thermodynamic properties of the mixture. The overall exergetic performance of R22 is comparatively better than that of the mixture. The performances of the individual components are also examined. The exergy destruction of compressor is larger for the mixture, followed by condenser then evaporator and ended with expansion valve. Thus to improve the performance of the system the compressor design has to be reformed.

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Ouelhazi, I., Y. Ezzaalouni i L. Kairouani. "Parametric analysis of a combined ejector-vapor compression refrigeration cycle". International Journal of Low-Carbon Technologies 15, nr 3 (15.06.2020): 398–408. http://dx.doi.org/10.1093/ijlct/ctaa011.

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Abstract From the last few years, the use of efficient ejector in refrigeration systems has been paid a lot of attention. In this article a description of a refrigeration system that combines a basic vapor compression refrigeration cycle with an ejector cooling cycle is presented. A one-dimensional mathematical model is developed using the flow governing thermodynamic equations based on a constant area ejector flow model. The model includes effects of friction at the constant-area mixing chamber. The current model is based on the NIST-REFPROP database for refrigerant property calculations. The model has basically been used to determine the effect of the ejector geometry and operating conditions on the performance of the whole refrigeration system. The results show that the proposed model predicts ejector performance, entrainment ratio and the coefficient of performance of the system and their sensitivity to evaporating and generating temperature of the cascade refrigeration cycle. The simulated performance has been then compared with the available experimental data from the literature for validation.

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Cardona Palacio, Luis Fernando, i Viviana Gómez Ceballos. "Modelamiento de la viscosidad dinámica de refrigerantes utilizando la teoría de reacción absoluta de Eyring". INVENTUM 17, nr 32 (21.07.2022): 3–12. http://dx.doi.org/10.26620/uniminuto.inventum.17.32.2022.3-12.

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En este trabajo se evalúa la capacidad de un modelo basado en la teoría de la reacción absoluta de Eyring en describir la viscosidad líquida saturada de refrigerantes y sus mezclas. Para la estimación de las propiedades termodinámicas asociadas al modelo de viscosidad se utiliza una versión modificada de la ecuación de estado de Peng-Robinson. El modelo tiene tres parámetros que son determinados utilizando datos pseudo-experimentales a partir de la base de datos de la NIST-REFPROP 8. En total, 660 datos pseudo-experimentales en un intervalo de temperatura entre 121.00 K y 479.98 K y de presión entre 2.18 kPa y 5782.6 kPa son utilizados en el proceso de ajuste. Las desviaciones absolutas promedio en la viscosidad son de 0.52 %. Posteriormente, el modelo es comparado con otros desarrollados en la literatura y este proporciona la menor desviación. Finalmente, el modelo es extendido a mezclas utilizando una regla de mezcla simple y las desviaciones promedio son de 2.01 %. En general, los resultados muestran que el modelo representa una alternativa apropiada para modelar la viscosidad saturada de líquidos de refrigerantes.

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Chen, Qiuju, Jianxiang Tian i Hua Jiang. "Three-parameter correlation for the surface tension of saturated liquids". Modern Physics Letters B 34, nr 11 (3.02.2020): 2050107. http://dx.doi.org/10.1142/s0217984920501079.

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In this paper, we study the multiple-parameter correlations for the surface tension of saturated liquids. The proposed three-parameter correlation requires only the critical temperature as inputs and is tested by using the NIST REFPROP data for 72 saturated liquids including refrigerants, alkanes and some other simple liquids such as argon, carbon dioxide, etc. It is found that this correlation well stands in the whole temperature range from the triple point to the critical point with high accuracy for 71 liquids with average absolute deviations (AADs) less than 5% and for 66 liquids with AADs less than 1%. These results are clearly better than the ones of other available correlations. This correlation can be directly used to estimate the value of the surface tension of the corresponding liquids at any temperature point from the triple point to the critical point. The accuracy of the predictions would clearly have economic benefits since it would allow improvement of process operating conditions, the development of new processes, the reduction of oversizing in the design of new equipment and even reduction of energy requirements.

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Sakina, Fara Nabilah, Habibatu Nihayah, Teguh Hady Ariwibowo i Lohdy Diana. "THERMODYNAMIC ANALYSIS OF RECUPERATIVE AND REHEAT BASED ON ORGANIC RANKINE CYCLE FOR HIGH-TEMPERATURE WASTE HEAT RECOVERY". Jurnal Rekayasa Mesin 14, nr 1 (29.05.2023): 331–42. http://dx.doi.org/10.21776/jrm.v14i1.1310.

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Heat recovery from available waste heat is an essential method in renewable energy processes due to the ability to generate electricity by using Organic Rankine Cycles (ORC). The process model is developed with the Cycle Tempo software. Fluid properties were analyzed with Reference Fluid Properties (REFPROP) software. This research presents a thermodynamic comparison of the Basic Organic Rankine Cycle (BORC) and Recuperative Organic Rankine Cycle (RORC) for waste heat recovery applications using pure refrigerants R-141b, R-245fa, R-123, and R-21. By performing simulations for heat source high-temperatures ranging from 160 to 200 °C. The comparison between BORC and RORC performance parameters and refrigerant properties was evaluated on the heat source temperature. Research shows that RORC produces higher thermal efficiency but has lower irreversibility than BORC. RORC has a maximum thermal efficiency of 12.67%, and BORC has a thermal efficiency of 11.49% for refrigerant R-141b at a flue gas temperature of 160 °C. The thermal efficiency of the ORC increases as the temperature of the heat source increases.

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Piyanut Saengsikhiao i Chayapat Prapaipornlert. "Low GWP Refrigerant R1234yf, R1234ze(z), R13I1 as an Alternative to New Zeotropic Refrigerant". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 98, nr 2 (29.09.2022): 80–89. http://dx.doi.org/10.37934/arfmts.98.2.8089.

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This study will present R13I1 or trifluoroiodomethane as a CFCs refrigerant, the chemical formula is CF3I. R13I1 is a halocarbon agent used in fire extinguishing agents same as R227ea. R13I1 has a GWP of 1, a boiling point of -21.9, a critical temperature of 123.3 °C and a critical pressure of 3950kPa. It can be seen that it is a refrigerant with properties similar to R134a. R1234yf and R1234ze(z) therefore can be mixed with HFCs. The result the national institute of standards and technology (NIST) reference fluid thermodynamic and transport properties database (REFPROP) software and NIST vapor compression cycle model accounting for refrigerant thermodynamic and transport properties (CYCLE_D-HX) software as CAN/ANSI/AHRI540 standards of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI) show that R13I1 has cooling coefficient of performance of 1.49, 2.43 and 2.79 kJ/kg which are lower than of R13I1 10.33% 8.13% and 9.40% for LT, MT and HT conditions as a result of low evaporator pressure, condenser pressure and refrigerant work .R13I1 which is a refrigerant that is mixed in low-GWP and low-GWP HFCs, as well as providing good energy efficiency zeotropic blends.

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Smith, William R., Magda Francová, Marian Kowalski i Ivo Nezbeda. "Refrigeration cycle design for refrigerant mixtures by molecular simulation". Collection of Czechoslovak Chemical Communications 75, nr 4 (2010): 383–91. http://dx.doi.org/10.1135/cccc2009544.

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We describe a molecular simulation methodology to calculate the properties of a vapor-compression refrigeration cycle and its Coefficient of Performance, in the case when the refrigerant is a mixture. The methodology requires only a molecular force-field model for each refrigerant pure component and, for improved accuracy, an expression for the vapor pressure of each pure component as a function of temperature. Both may be constructed by means of theoretical approaches in combination with minimal amounts of experimental data, and the latter may also be estimated by empirical formulae with reasonable accuracy. The approach involves a combination of several available molecular-level computer simulation techniques for the individual processes of the cycle. This work extends our earlier study to cases when the refrigerant is a pure fluid. The mixture refrigerant simulations entail the calculation of bubble- and dew-point curves for the refrigerant mixtures, and we propose a new approach for dew-point calculations via molecular simulation. We compare results for a test case with those obtained from the Equation-of-State model used in the standard REFPROP software and with experimental data for a commercially available refrigerant mixture of R32 (CH2F2) and R143a (CH2FCF3).

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Nowak, Bernard, Piotr Życzkowski i Rafał Łuczak. "Functional Dependence of Thermodynamic and Thermokinetic Parameters of Refrigerants Used in Mine Air Refrigerators. Part 1 – Refrigerant R407C". Archives of Mining Sciences 62, nr 1 (1.03.2017): 55–72. http://dx.doi.org/10.1515/amsc-2017-0005.

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Abstract The authors of this article dealt with the issue of modeling the thermodynamic and thermokinetic properties (parameters) of refrigerants. The knowledge of these parameters is essential to design refrigeration equipment, to perform their energy efficiency analysis, or to compare the efficiency of air refrigerators using different refrigerants. One of the refrigerants used in mine air compression refrigerators is R407C. For this refrigerant, 23 dependencies were developed, determining its thermodynamic and thermokinetic parameters in the states of saturated liquid, dry saturated vapour, superheated vapor, subcooled liquid, and in the two-phase region. The created formulas have been presented in Tables 2, 5, 8, 10 and 12, respectively. It should be noted that the scope of application of these formulas is wider than the range of changes of that refrigerant during the normal operation of mine refrigeration equipment. The article ends with the statistical verification of the developed dependencies. For this purpose, for each model correlation coefficients and coefficients of determination were calculated, as well as absolute and relative deviations between the given values from the program REFPROP 7 (Lemmon et al., 2002) and the calculated ones. The results of these calculations have been contained in Tables 14 and 15.

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Pan, Yachao, Fubin Yang, Hongguang Zhang, Yinlian Yan, Anren Yang, Jia Liang i Mingzhe Yu. "Performance Prediction and Working Fluid Active Design of Organic Rankine Cycle Based on Molecular Structure". Energies 15, nr 21 (1.11.2022): 8160. http://dx.doi.org/10.3390/en15218160.

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Working fluid selection is crucial for organic Rankine cycles (ORC). In this study, the relationship between molecular structure and ORC performance was established based on the quantitative structure–property relationship (QSPR) and working fluid parameterized model (WFPM), from which an ORC working fluid was actively designed. First, the QSPR model with four properties, namely, critical temperature (Tc), boiling point (Tb), critical pressure (pc), and isobaric heat capacity (cp0), was built. Second, the evaporation enthalpy (hvap), evaporation entropy (svap), and thermal efficiency (η) were estimated by WFPM, and the results were compared with those using REFPROP to verify the calculation accuracy of the “QSPR+WFPM” coupling model. The average absolute relative deviations of evaporation enthalpy and entropy are below 8.44%. The maximum relative error of thermal efficiency is 6%. Then, the thermodynamic performance limit of ORC and corresponding thermophysical properties of the ideal working fluid were calculated at typical geothermal source conditions. Finally, the active design of the working fluid was conducted with the ideal working fluid Tc and pc as the target. The research shows that C3H4F2 and C4H3F5 are optimal working fluids at 473.15 and 523.15 K heat sources, respectively.

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Di Nicola, G., S. Tomassetti, M. Pierantozzi i P. F. Muciaccia. "Semi-empirical correlations and an artificial neural network for liquid dynamic viscosity of low GWP refrigerants". IOP Conference Series: Earth and Environmental Science 1106, nr 1 (1.11.2022): 012018. http://dx.doi.org/10.1088/1755-1315/1106/1/012018.

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Abstract In this work, simple semi-empirical correlations to describe the temperature and the pressure dependence of the dynamic viscosity of low GWP refrigerants, namely HydroFluoroOlefins (HFOs) and HydroChloroFluoroOlefins (HCFOs), in the liquid phase are presented. Firstly, the experimental liquid dynamic viscosity data available in scientific literature and databases were collected and statistically analyzed. From the data collected for low pressures, the Latini et al. (2002, 1990) correlation for the dynamic viscosity of liquid refrigerants in saturated conditions was re-fitted and constants expressly dedicated to the studied low GWP refrigerants were obtained. Then, the proposed temperature-dependent correlation was modified to represent liquid dynamic viscosity dependence on pressure. In addition, an artificial neural network was developed to predict the dependence of the liquid viscosity of the studied refrigerants on temperature and pressure. This model was trained, validated, and tested for the selected dataset. The results of the proposed correlations and the multi-layer perceptron neural network were compared with the liquid viscosity calculations provided by some of the most well-known literature correlations and REFPROP 10.0, proving the accuracy of the proposed models for engineering applications.

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Zhang, Xinxin, Yin Zhang, Zhenlei Li, Jingfu Wang, Yuting Wu i Chongfang Ma. "Zeotropic Mixture Selection for an Organic Rankine Cycle Using a Single Screw Expander". Energies 13, nr 5 (25.02.2020): 1022. http://dx.doi.org/10.3390/en13051022.

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The organic Rankine cycle (ORC) is a popular and promising technology that has been widely studied and adopted in renewable and sustainable energy utilization and low-grade waste heat recovery. The use of zeotropic mixtures in ORC has been attracting more and more attention because of the possibility to match the temperature profile of the heat source by non-isothermal phase change, which reduces the irreversibility in the evaporator and the condenser. The selection of working fluid and expander is strongly interconnected. As a novel expander, a single screw expander was selected and used in this paper for efficient utilization of the wet zeotropic mixtures listed in REFPROP 9.1 in a low-temperature subcritical ORC system. Five indicators, namely net work, thermal efficiency, heat exchange load of condenser, temperature glide in evaporator, and temperature glide in condenser, were used to analyze the performance of an ORC system with wet and isentropic zeotropic mixtures as working fluids. The calculation and analysis results indicate that R441A with an expander outlet temperature of 320 K may be the suitable zeotropic mixture used for both open and close type heat source. R436B may be selected with an expander outlet temperature of 315 K. R432A may be selected with an expander outlet temperature from 295 K to 310 K.

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Shamoushaki, Moein, Giampaolo Manfrida, Lorenzo Talluri, Pouriya H. Niknam i Daniele Fiaschi. "Different Geothermal Power Cycle Configurations Cost Estimation Models". Sustainability 13, nr 20 (9.10.2021): 11133. http://dx.doi.org/10.3390/su132011133.

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An economic assessment of different geothermal power cycle configurations to generate cost models is conducted in this study. The thermodynamic and exergoeconomic modeling of the cycles is performed in MATLAB coupled to Refprop. The models were derived based on robust multivariable regression to minimize the residuals by using the genetic algorithm. The cross-validation approach is applied to determine a dataset to examine the model in the training phase for validation and reduce the overfitting problem. The generated cost models are the total cost rate, the plant’s total cost, and power generation cost. The cost models and the relevant coefficients are generated based on the most compatibilities and lower error. The results showed that one of the most influential factors on the ORC cycle is the working fluid type, which significantly affects the final economic results. Other parameters that considerably impact economic models results, of all configurations, are geothermal fluid pressure and temperature and inlet pressure of turbine. Rising the geothermal fluid mass flow rate has a remarkable impact on cost models as the capacity and size of equipment increases. The generated cost models in this study can estimate the mentioned cost parameters with an acceptable deviation and provide a fast way to predict the total cost of the power plants.

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Tashtoush, Bourhan, Karima Megdouli, Mouna Elakhdar, Ezzedine Nehdi i Lakdar Kairouani. "A Comprehensive Energy and Exergoeconomic Analysis of a Novel Transcritical Refrigeration Cycle". Processes 8, nr 7 (29.06.2020): 758. http://dx.doi.org/10.3390/pr8070758.

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A comprehensive energy and exergoeconomic analysis of a novel transcritical refrigeration cycle (NTRC) is presented. A second ejector is introduced into the conventional refrigeration system for the utilization of the gas-cooler waste heat. The thermodynamic properties of the working fluid are estimated by the database of REFPROP 9, and a FORTRAN program is used to solve the system governing equations. Exergy, energy, and exergoeconomic analyses of the two cycles are carried out to predict the exergetic destruction rate and efficiency of the systems. The optimum gas cooler working pressure will be determined for both cycles. A comprehensive comparison is made between the obtained results of the conventional and the new cycles. An enhancement of approximately 30% in the coefficient of performance (COP) of the new cycle was found in comparison to the value of the conventional cycle. In addition, the results of the analysis indicated a reduction in the overall exergy destruction rate and the total cost of the final product by 22.25% and 6%, respectively. The final product cost of the proposed NTRC was found to be 6% less than that of the conventional ejector refrigeration cycle (CERC), whereas the optimum value of the gas cooler pressure was 10.8 MPa, and 11.4 MPa for the NTRC and CERC, respectively.

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Almeida, I. M. G., C. R. F. Barbosa i F. A. O. Fontes. "THERMODYNAMIC AND THERMOPHYSICAL ASSESSMENT OF HYDROCARBONS APPLICATION IN HOUSEHOULD REFRIGERATOR". Revista de Engenharia Térmica 9, nr 1-2 (31.12.2010): 19. http://dx.doi.org/10.5380/reterm.v9i1-2.61926.

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The research efforts and development in the refrigeration and air conditioning sector applied to the use of natural refrigeration fluids is not associated only with the need to preserve the environment alone, but has great importance with regard to the latent need for energy efficient equipment. With this perspective, the present study deals with the thermodynamic evaluation of the use of hydrocarbons refrigerants in household refrigeration systems that utilize HFC134a as a working fluid. A theoretical-computational analysis was developed for R134a, propane (R290) and the selected mixtures (R290/R600a 60%/40%, R290/R600a/R134a 40%/30%/30% and R600a/R290 50%/50%) in the standard refrigeration cycle ASHRAE, using the thermodynamic and thermophysical properties provided by the REFPROP 6.0 software. The results of computational simulations between the fluids were compared to find the evidence of the best alternative to HFC134a. In this sense, it was observed that the hydrocarbons reduced the levels of pressure on the condenser and evaporator, along with smaller compression tasks necessary in the system, owing to the thermo-physical properties privileged in these fluids. The use of these fluids is also proportionate to lower temperatures of compressor discharge, increasing the life of this highly valuable component of the system.

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Silva, Jucélio Gomes da, Maria Luiza Ramos da Silva, Igor Marcel Gomes Almeida i Cleiton Rubens Formiga Barbosa. "ESTUDO TERMODINÂMICO DA APLICAÇÃO DE HIDROCARBONETOS EM SISTEMA DE REFRIGERAÇÃO". HOLOS 4 (28.11.2010): 99. http://dx.doi.org/10.15628/holos.2010.469.

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Os esforços de pesquisa e desenvolvimento na área de Refrigeração e Ar-Condicionado aplicados ao uso de fluidos refrigerantes naturais não esta associada somente à necessidade de preservação do meio-ambiente em si, mas também apresenta grande importância na necessidade latente do aumento da eficiência energética dos equipamentos. Neste sentido, o presente trabalho trata da avaliação termodinâmica da aplicação de fluidos refrigerantes hidrocarbonetos em um sistema de refrigeração residencial que utiliza o HFC134a como fluido de trabalho. Uma análise teórico-computacional foi desenvolvida para o R134a, propano (R290) e as misturas selecionadas (R290/R600a 60%/40%, R290/R600a/R134a 40%/30%/30% e R600a/R290-GLP 70%/30%) no ciclo de refrigeração padrão ASHRAE, utilizando as propriedades termodinâmicas e termofísicas fornecidas pelo software REFPROP 6.0. Os resultados das simulações computacionais foram comparados entre os fluidos para indicação da melhor alternativa ao HFC134a. Neste sentido, pôde-se observar que os hidrocarbonetos reduzem os níveis de pressão no condensador e evaporador, além de menores trabalhos de compressão serem necessários no sistema devido às propriedades termofísicas privilegiadas destes fluidos. A utilização destes fluidos também proporciona uma menor temperatura de descarga do compressor, incrementando a vida útil deste componente de alto valor do sistema.

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Jemni, Nourheine, Mouna Elakhdar, Ezzedine Nehdi i Lakdar Kairouani. "Performance Investigation of Cascade Refrigeration System Using CO2 and Mixtures". International Journal of Air-Conditioning and Refrigeration 23, nr 03 (wrzesień 2015): 1550022. http://dx.doi.org/10.1142/s2010132515500224.

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This paper presents reports on simulation and comparative analysis of single stage vapor compression refrigeration system and cascade systems using carbon dioxide, hydrocarbons (HCs) and CO2/HCs mixture. Thermodynamic parameters of fluids are given using the software REFPROP 9.0. To select the most suitable HCs, three criteria have been fixed: Tc, Tt and Tb. It is found that the HCs chosen in low-stage are propane, propylene and ethane and those for the high-stage are propane, propylene and isobutane. The fraction mixture in the two loops has been varied and results are compared with single stage and cascade systems using CO2 and R22. The fraction x[Formula: see text] is varied in the two loops. Results are compared for single and cascade systems using CO2 and R22. For the single stage system, we find for xCO2 = 0.5, an improvement of COP of 14% for CO2/propane mixture and 36% for the CO2/propylene mixture. It is found that for xCO2 = 0.3, cascade system using propane/CO2 mixtures presents a COP lower than that of cascade system using pure CO2. About of 70% of unfriendly fluids like CFCs and HCFCs can be replaced with CO2, without affecting the performance of cascade refrigeration systems.

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Lu, Kun-Hsien, Hsiao-Wei D. Chiang i Pei-Jen Wang. "Sensitivity Analysis of Transcritical CO2 Cycle Performance Regarding Isentropic Efficiencies of Turbomachinery for Low Temperature Heat Sources". Energies 15, nr 23 (24.11.2022): 8868. http://dx.doi.org/10.3390/en15238868.

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The transcritical CO2 (T-CO2) power cycle using low temperature waste heat is a promising technique for energy saving and environmental protection. However, according to the literature, there is no commercialized unit in service yet. This study provides developers a reference to shorten the design phase of the T-CO2 cycle commercialization process. A sensitivity analysis of the system performance, i.e., thermal efficiency and net power output, regarding the isentropic efficiencies of pump (ηp) and expander (ηe) and the heat source temperature (Th,in) has been carried out using MATLAB and NIST REFPROP database. Simple and recuperative configurations are investigated based on their own optimal working pressures. The results show that the enhancement of ηe has a greater influence on improving the system performance, but the improvement will diminish as ηp, ηe, and Th,in increase. Although better system performance can be achieved with higher ηp, ηe, and Th,in, the cost of the system equipment will also increase due to the higher optimal working pressure. In addition, increasing ηp and ηe will negatively affect the effectiveness of the recuperator. Therefore, the turbomachinery efficiencies and the heat source temperature should be considered simultaneously for the most cost-effective system design.

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Kalair, Ali Raza, Mehdi Seyedmahmoudian, Muhammad Shoaib Saleem, Naeem Abas, Shoaib Rauf i Alex Stojcevski. "A Comparative Thermal Performance Assessment of Various Solar Collectors for Domestic Water Heating". International Journal of Photoenergy 2022 (16.06.2022): 1–17. http://dx.doi.org/10.1155/2022/9536772.

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Growing population, depleting fossil fuels, economic expansions, and energy intensive life style demand are resulting in higher energy prices. We use energy as of heat and electricity, which can directly be obtained from sun using thermal collectors and solar cells. Solar thermal systems are gaining attention for water and space heating applications due to green aspects of solar energy. A solar thermal collector is a vital part of solar thermal energy system to absorb radiant energy from the sun. In this study, a solar water heating (SWH) system has been designed and simulated in the TRNSYS ® software using thermal and chemical properties of heat transfer fluids using REFPROP for dwellings located on ±31° latitudes (+31 Lahore in Pakistan and -31° Perth in Australia). We present an efficiency parametric optimization-based model for water and space heating. Simulation results for four types of solar thermal collectors are presented, and performance is analyzed on the basis of output temperature ( T out ), solar fraction ( f ), and collector efficiency ( η ). This study evaluates the comparative performance of evacuated tube collector (ETC), flat-plate collector (FPC), compound parabolic concentrator (CPC), and thermosiphon-driven systems. Our findings conclude the evacuated glass tube collector achieves the highest solar fraction, i.e., 50% of demand coverage during August in Pakistan and February in Australia, with an overall average of 43% annually.

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Piyanut Saengsikhiao i Juntakan Taweekun. "Investigation and Analysis of R438A as an Alternative Refrigerant to R22 with Lower Global Warming Potential". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 95, nr 1 (18.06.2022): 164–87. http://dx.doi.org/10.37934/arfmts.95.1.164187.

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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.

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Saengsikhiao, Piyanut, i Juntakan Taweekun. "The Data Mining Technique Using RapidMiner Software for New Zeotropic Refrigerant". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 83, nr 1 (3.06.2021): 70–90. http://dx.doi.org/10.37934/arfmts.83.1.7090.

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This research presents the development of environmentally-friendly and energy efficient refrigerant for medium temperature refrigeration systems that new azeotropic refrigerant mixture of hydrofluorocarbons and hydrocarbon that can retrofit in the refrigeration system using R404A. The medium back pressure refrigeration testing standard that follow CAN/ANSI/AHRI540 standard air-conditioning, heating, and refrigeration institute (AHRI) and The properties of refrigerants and refrigeration simulation system that used national institute of standards and technology (NIST) reference fluid thermodynamic and transport properties database (REFPROP) software and NIST vapor compression cycle model accounting for refrigerant thermodynamic and transport properties (CYCLE_D-HX) software. The methodology uses decision tree function in datamining by rapid minor software that first of KDnuggets annual software poll that showed new azeotropic refrigerant mixture had cooling capacity, refrigerant effect, GWP and boiling point were lower than R404A but work and pressure for medium temperature refrigeration system of azeotropic refrigerant mixture were higher than R404A. The artificial intelligence (AI) by data mining technic can predictive environmentally-friendly and energy efficient refrigerant for medium temperature refrigeration. The result of refrigerant mixed by R134A, R32, R125 and R1270 and is consistent with the evolution of fourth-generation refrigerants that contain a mixture of HFCs and HCs which are required to produce a low-GWP, zero-ozone-depletion-potential (ODP), high-capacity, low-operating-pressure, and nontoxic refrigerant.

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Tu, Yi, i Yu Zeng. "Numerical Study on Flow and Heat Transfer Characteristics of Supercritical CO2 in Zigzag Microchannels". Energies 15, nr 6 (13.03.2022): 2099. http://dx.doi.org/10.3390/en15062099.

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The zigzag channel is the uppermost channel type of an industrial printed circuit heat exchanger (PCHE). The effect of geometric properties on the flow and heat transfer performance of the channel is significant to the PCHE design and optimization. Numerical investigations were conducted on the flow and heat transfer characteristics of supercritical CO2 (sCO2) in semicircular zigzag channels by computational fluid dynamics method. The shear stress transfer (SST) k–ω model was used as turbulence model and the National Institute of Standards and Technology (NIST) real gas model with REFPROP database was used to evaluate the thermophysical parameters of sCO2 in this numerical method. The effectiveness of the simulation method is verified by experimental data. Thermal hydraulic performance for zigzag channels with different pitch lengths, bending angles, and hydraulic diameters are studied comparatively based on this numerical method, with the boundary conditions which cover the pseudocritical point. The comparison results show that reducing the bending angle and pitch length will strengthen the effect of boundary layer separation on the leeward side of the wall and enhance the heat transfer performance, but the pressure drop of the channel will also increase, and the decrease of channel hydraulic diameter is beneficial to the heat transfer enhancement, but it is not as significant as that of the straight channel.

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Zhang, Jiangnan, i Yi Tang. "Design of Radial-Inflow Turbines for Low-Temperature Organic Rankine Cycle". Machines 11, nr 7 (9.07.2023): 725. http://dx.doi.org/10.3390/machines11070725.

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This study presents the development of a design method that has been extended to the design of radial-inflow turbines operating in organic Rankine cycles (ORC). Both the conventional design method and the circulation method available in the literature have been reviewed. The two main limitations of the current circulation method that make it not suitable for the ORC turbine design are the lack of real gas capability and 3D blades with high stresses. Using the circulation method, the flow field is decomposed into a potential part and a rotational part. The mean velocity field and the periodic velocity field are solved separately. To model the thermodynamic properties of the real gas, NIST REFPROP or CoolProp are used. The blade geometry is then solved iteratively by assuming that the velocity vector is parallel to the blade surface. The blade boundary condition is modified to force the blade camber to be radial-fibred, which is helpful to reduce the centrifugal bending stress on the blade. All the formulations are derived step by step, and the numerical treatments, including grid generation, numerical differentiation, computational scheme, and convergence, are discussed in detail. This method is validated by designing a R245fa ORC turbine rotor. The performance of the rotor design is predicted by CFD and FEA simulations, and it is compared to the results using other methodologies in the literature.

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Boumaraf, Latra, i Rachedi Khadraoui. "Investigation on the Performance of a Solar Hybrid Refrigeration System Using Environmentally Friendly Fluids". International Journal of Heat and Technology 38, nr 4 (31.12.2020): 960–66. http://dx.doi.org/10.18280/ijht.380423.

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In order to evaluate the performance of a hybrid compression / ejection refrigeration system using solar energy at low or medium temperature, a simulation model of its behavior based on those of its various components has been developed. It includes in particular for the ejector, a 1-D model of the "constant section mixing" type developed in optimal transition regime. The refrigerants tested are steam for the ejector loop and the R1234yf (replacing the R134a) for the mechanical compression loop. The behavior of the H2O vapor flowing in the ejector is considered that of the perfect gas. The properties of refrigerants are calculated using REFPROP® software, everywhere else. For a cooling capacity of 10 kW and air conditioning operating conditions, the model allows to determine the main parameters of the ejector and its entrainment ratio, the thermal and mechanical COP of the whole refrigeration system as well as the necessary surface of the solar collector. Furthermore, the influence of the temperature of the boiler, the condenser, the intercooler as well as that of the evaporator on the mechanical COP of the hybrid system and the solar collection surface in particular, were examined. The results highlight that the solar refrigeration system with hybrid cycle compression/ejection using the refrigerants H2O/R1234yf allows an increase of the mechanical COP higher than 50% compared to that of the conventional refrigeration system and thus constitutes an acceptable ecologically system that can compete with the latter.

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Daniarta, Sindu, Attila R. Imre i Piotr Kolasiński. "The efficiency of transcritical CO₂ cycle near critical point and with high temperature". MATEC Web of Conferences 345 (2021): 00005. http://dx.doi.org/10.1051/matecconf/202134500005.

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Efficiency is a key parameter used to assess the quality of operation of power generation systems and devices applied for converting one type of energy to the other. Although, in the end, an investment project is mainly evaluated by economic aspect. Furthermore, many researchers have been investigating the possible types of energy conversion systems and devices applied for power generation and utilizing different types of working fluids. This paper presents the inside into transcritical carbon dioxide (CO2) cycle and the gradients of its efficiency. Transcritical CO2 cycle (TCO2C) here refers to a CO2-based thermal power generation cycle absorbing heat from a heat source (ideally with constant pressure) till the supercritical state is reached. It is followed by an expansion to a sub-critical superheated or even two-phase (wet) state. As alternatives, trilateral flash cycle (TFC) and organic Rankine cycle (ORC) utilizing CO2 are also introduced in this paper. The calculation in this study is computed based on MATLAB integrated with thermophysical properties like CoolProp and REFPROP, the mathematical models of the system are built and calculated with the same heat sink temperature of 224.41 K, and the heat source temperature is varied between 274.41 K and 500 K. At a certain temperature, the obtained result shows that the efficiency of the TCO2C is lower than the efficiency of ORC. Another result proves that the quality of working fluid at the end of the expansion process significantly influences the efficiency of the cycle.

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Liu, Zhan, Wenguang Jia, Longhui Liang i Zhenya Duan. "Analysis of Pressure Pulsation Influence on Compressed Natural Gas (CNG) Compressor Performance for Ideal and Real Gas Models". Applied Sciences 9, nr 5 (6.03.2019): 946. http://dx.doi.org/10.3390/app9050946.

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This work investigates the effects of pressure pulsations on reciprocating natural gas compressor performance thermodynamically. A nonlinear hybrid numerical model is thus developed to consider the interaction between the compressor and the pipeline system. The suction chamber, compressor cylinder and discharge chamber are modelled integrally based on the first law of thermodynamics and mass balance, and the pipeline flow is described by using the gas dynamic model. Methane is considered as the working fluid and its properties are computed based on ideal and real gas assumptions. For the real gas model, the methane properties are obtained by means of calling the NIST REFPROP database. The validity of numerical results is confirmed by previous experimental values. Results from the examinations of pressure pulsation influence demonstrate that discharge resonance requires more specific work than suction resonance in the same harmonic; in the suction system, the first harmonic response reduces the mass flow rate but significantly increases specific work, and the second harmonic response has a strong supercharging effect but the specific work is increased slightly; in the discharge system, the mass flow rate is changed little by pressure pulsations, but the indicated power and specific work are increased significantly; for the real gas model, the in-cylinder temperature during the compression and discharge phases, mass flow rate and indicated power are higher than those for the ideal gas model, whereas the specific work is less for the real gas model than for the ideal gas model.

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