44 research outputs found
Local heat transfer coefficients during the evaporation of 1,1,1,2-tetrafluoroethane (R-134a) in a plate heat exchanger
The evaporation heat transfer coefficient of the refrigerant R-134a in a vertical plate heat exchanger was investigated experimentally. The area of the plate was divided into several segments along the vertical axis. For each of the segments, the local value of the heat transfer coefficient was calculated and presented as a function of the mean vapor quality in the segment. Owing to the thermocouples installed along the plate surface, it was possible to determine the temperature distribution and vapor quality profile inside the plate. The influences of the mass flux, heat flux, pressure of system and the flow configuration on the heat transfer coefficient were also taken into account and a comparison with literature data was performed
Gustine i viskoznosti binarnih sistema sa N,N-dimetilanilinom i tetra etilen glikolom dimetil etrom ili N-metil-2-pyrolidonom, kao potencijalni rastvaraÄi za procese odsumporavanja dimnih gasova
Sulfur oxides are emitted as one of the products in the process of combusting solid fossil fuels in thermal power plants, especially the Kolubara and Kostolac lignites in the Republic of Serbia. In order to reduce the emission level of the indirect Greenhouse gases (GHG) from stationary sources, it is inevitable to implement flue gas desulfurization (FGD) technology. In addition to the classic limestone process, technological procedures based on the physical or chemical absorption of sulfur oxides in the solvent and its thermal regeneration are becoming increasingly common. In order to properly design and optimize the process, it is significant to precisely determine the thermophysical properties of pure components and their mixtures. The paper presents the results of determining the density and viscosity of two binary mixtures, N,N-Dimethylaniline (N,N-DMA) + Tetra Ethylene Glycol Dimethyl Ether (TEGDME) and N,N-Dimethylaniline (N,N-DMA) + N-methyl-2-pyrrolidone (NMP). Measurements were made using a densitometer Anton Paar DMA 5000 and Stabinger viscometer Anton Paar SVM 3000/G2, at atmospheric pressure. The obtained experimental results are presented as a function of temperature and N,N-DMA mole fraction. N,N-DMA belongs to the group of amines, and it has been used as a sorbent for purification of flue gases in processes with thermal regeneration (CANSOLV, Sulphidine and ASARCO processes). The other two organic solvents are TEGDME and NMP. Special attention was paid to NMP due to its low cost and low viscosity, with its favorable properties, making it competitive as a solvent for FGD. TEGDME is a polar solvent, but it is not selective to SO2 and other gaseous components, so NMP has been suggested as an alternative solution. A regenerative process for SO2 removal, with TEGDME, has already found commercial application (Solinox process). NMP is already industrially used as a solvent in Lurgi's Purisol process, due to its nature for selective desulfurization of flue gases.Oksidi sumpora emituju se kao jedan od proizvoda u procesu sagorevanja Ävrstih fosilnih goriva u termoelektranama, posebno kolubarskog i kostolaÄkog lignita u Republici Srbiji. Da bi se smanjio nivo emisije indirektnih gasova staklene baÅ”te (GHG) iz stacionarnih izvora, neizbežna je primena tehnologije odsumporavanja dimnih gasova (FGD). Pored klasiÄnog kreÄnjaÄkog postupka, sve su ÄeÅ”cĢ i tehnoloÅ”ki postupci zasnovani na fiziÄkoj ili hemijskoj apsorpciji sumpornih oksida u rastvaraÄu i njegovoj termiÄkoj regeneraciji. Da bi se pravilno dizajnirao i optimizovao proces, važno je precizno odrediti termofiziÄka svojstva Äistih komponenti i njihovih smeÅ”a. U radu su prikazani rezultati odreÄivanja gustine i viskoziteta dve binarne smeÅ”e, N,N-dimetilanilin (N,N-DMA) + tetra etilen glikol dimetil etar (TEGDME) i N,N-dimetilanilin (N,N-DMA) + N-metil-2-pirolidon (NMP). Merenja su vrÅ”ena pomocĢu gustinomera Anton Paar DMA 5000 i Stabinger viskozimetra Anton Paar SVM 3000/G2, na atmosferskom pritisku. Dobijeni eksperimentalni rezultati su prikazani kao funkcija temperature i molskog udela N,N-DMA. N,N-DMA pripada grupi amina, a koriÅ”cĢ en je kao sorbent za preÄiÅ”cĢ avanje dimnih gasova u procesima sa termiÄkom regeneracijom (CANSOLV, Sulphidine i ASARCO procesi). Druga dva organska rastvaraÄa su TEGDME i NMP. Posebna pažnja je posvecĢ ena NMP-u zbog niske cene i niskog viskoziteta, sa svojim povoljnim svojstvima, Å”to ga Äini konkurentnim kao rastvaraÄ za FGD. TEGDME je polarni rastvaraÄ, ali nije selektivan ka SO2 i druge gasovite komponente, pa je NMP predložen kao alternativno reÅ”enje. Regenerativni proces za uklanjanje SO2, sa TEGDME, vecĢ je naÅ”ao komercijalnu primenu (Solinox proces). NMP se vecĢ industrijski koristi kao rastvaraÄ u Lurgi's Purisol procesu, zbog svoje prirode za selektivno odsumporavanje dimnih gasova.Procesing '24 : 37. MeÄunarodni kongres o procesnoj industriji : zbornik radova - Proceedings, 29-31. maj 2024, Beogra
Viskoznost binarne smeÅ”e DMA + 2-butanol za potencijalnu upotrebu kao rastvaraÄa za regenerativne procese odsumporavanja dimnih gasova
Sulfur dioxide (SO2) is an environmental pollutant with multiple harmful effects on biological world. One of the main emission sources are industrial activities in thermal power plants, foundries and steel mills which involve combustion of fossil fuels containing sulfur, such as coal and oil. Initial step towards removal of SO2from flue gases was the so-called limestone process, a wet non-regenerative process that even today is the mostused flue gas desulfurization method. However, wet regenerative processes with gas absorption in liquid organic solvent and thermal regeneration recently have found practical application. Processes based on n,n-dimethylaniline (DMA) have alre-ady been patented and industrially applied. This solvent has high selectivity towards SO2in compa-rison to the other components of flue gas like CO2, and excellent binding capability by the 214ā¢ 32ndINTERNATIONAL CONGRESS ON PROCESS INDUSTRYmechanisms of chemical absorption, but main disadvantage is its high toxicity. On the other hand, in more ambient friendly 2-butanol binding of sulfur-dioxide occurs by means of physical absorption. Investigations have shown that mixtures of physical and chemical solvents usually show better cha-racteristics regarding binding capacityand selectivity than traditionally used aqueous solutions of amines, due to the synergetic effect.One of the most important thermophysical properties of solvents, necessary for process and equipment design is dynamic viscosity. In this investigation viscosity of binary mixture DMA + 2-butanol is experimentally determined in temperature and concentration range and correlated afterwards using different literature models. These correlations present useful method to acquire reliable data necessary for fluid flow analysis and mass and heat transfer calculations, since experi-mental values for desired process conditions are often not available. In this study, two or three-pa-rameter Eyring-UNIQUAC, Eyring-NRTL and McAllister models were used, while model that co-uples Eyring equation, Peng-Robinson equation of state and van der Waals mixing rule, was tested for simultaneous calculation of density and viscosity. The obtained results are presented and discu-ssed regarding potential application, limitations and complexity of used approach and models.Sumpor dioksid (SO2) je zagaÄivaÄ Å¾ivotne sredine sa viÅ”estrukim Å”tetnim efektima na bioloÅ”ki svet. Jedan od glavnih izvora emisije su industrijske aktivnosti u termoelektranama, livnicama i železarama, koje ukljuÄuju sagorevanje fosilnih goriva koja sadrže sumpor, kao Å”to su ugalj i nafta. PoÄetni korak u uklanjanju SO2 iz dimnih gasova bio je takozvani kreÄnjaÄki postupak, mokri neregenerativni proces koji je i danas najÄeÅ”cĢe koriÅ”cĢen metod odsumporavanja dimnih gasova. MeÄutim, mokri regenerativni procesi sa apsorpcijom gasa u teÄnom organskom rastvaraÄu i termalnom regeneracijom nedavno su naÅ”li praktiÄnu primenu. Procesi zasnovani na n,n-dimetilanilinu (DMA) su vecĢ patentirani i industrijski primenjeni. Ovaj rastvaraÄ ima visoku selektivnost prema SO2 u poreÄenju sa drugim komponentama dimnog gasa kao Å”to je CO2, i odliÄnu sposobnost vezivanja mehanizmima hemijske apsorpcije, ali glavni nedostatak je visoka toksiÄnost. S druge strane, u, sa stanoviÅ”ta životne sredine prihvatljivijem, 2-butanolu do vezivanja sumpor-dioksida dolazi fiziÄkom apsorpcijom. Istraživanja su pokazala da smeÅ”e fiziÄkih i hemijskih rastvaraÄa obiÄno pokazuju bolje karakteristike u pogledu moguÄnosti vezivanja i selektivnosti od tradicionalno koriÅ”cĢenih vodenih rastvora amina, zbog sinergetskog efekta. Jedno od najvažnijih termofiziÄkih svojstava rastvaraÄa, neophodno za simulaciju procesa i proraÄun opreme, je dinamiÄka viskoznost. U ovom istraživanju, viskoznost binarne smeÅ”e DMA + 2-butanol eksperimentalno je odreÄena u temperaturnom i koncentracionom opsegu i nakon toga korelisana koriÅ”cĢenjem razliÄitih literaturnih modela. Ove korelacije predstavljaju korisnu metodu za dobijanje pouzdanih podataka potrebnih za analizu protoka fluida i proraÄune prenosa mase i toplote, jer eksperimentalne vrednosti za željene uslove procesa Äesto nisu dostupne. U ovom istraživanju koriÅ”cĢeni su dvo- ili troparametarski modeli Eyring-UNIQUAC, Eyring-NRTL i McAllister, dok je model koji povezuje Eyring jednaÄinu, Peng-Robinson jednaÄinu stanja i van der Waals pravilo meÅ”anja testiran za istovremeno izraÄunavanje gustine i viskoznosti. Dobijeni rezultati su prikazani i diskutovani u pogledu potencijalne primene, ograniÄenja i složenosti koriÅ”cĢenog pristupa i modela
Volumetric and Viscometric Study of 1-Hexanol-Based Binary Systems: Experimental Determination and Modeling
Density, viscosity, and refractive index of four binary mixtures with 1-hexanol are experimentally determined at seven temperatures, in the temperature range from 288.15 to 318.15 K and at atmospheric pressure. The choice of mixtures was based on their potential for applications in flue gas cleaning processes. From experimental data, excess molar volume, viscosity deviation, excess molar Gibbs free energy of activation of viscous flow, deviation in refractive index, and partial and excess partial molar volumes are calculated, correlated with the Redlich-Kister equation, and used for better understanding of molecular interactions between the mixture components. Since the mixtures were investigated both from the theoretical point of view and with the aspect for practical applications, modeling of two key properties, viscosity and excess molar volume, was performed with different models and approaches and the results are compared with experimental values
Density, Viscosity, and Refractive Index Data for a Ternary System of Wine Congeners (Ethyl Butyrate plus Diethyl Succinate plus Isobutanol) in the Temperature Range from 288.15 to 323.15 K and at Atmospheric Pressure
Density, viscosity, and refractive index data for the ternary system ethyl butyrate + diethyl succinate + isobutanol and binary system ethyl butyrate + diethyl succinate have been measured in the temperature range 288.15-323.15 K, with temperature step of 5 K, and at atmospheric pressure. The measurements were performed on an Anton Paar DMA 5000 digital vibrating tube and, Anton Paar SVM 3000 digital viscometer, an Anton Paar RXA 156 refractometer. Based on the corresponding binary data as well as ternary data, presented in this work, excess molar volumes (V-E), viscosity deviations (Delta eta), and refractive index deviations (Delta n(D)) were determined and fitted by the Redlich-Kister and Nagata-Tamura polynomial equations. The influence of mixture composition on values of excess molar volume, deviation functions, and the molecular interactions present in the mixtures was further discussed
Volumetric and viscometric study and modelling of binary systems of diethyl tartrate and alcohols
Density, viscosity, refractive index and speed of sound have been measured for the pure ester diethyl tartrate at atmospheric pressure and over the temperature range from 288.15 K to 323.15 K. Detailed investigation regarding volumetric and viscometric properties was conducted under the same conditions for three binary mixtures: diethyl tartrate +1-propanol or +1-butanol or +1-hexanol. Excess and deviation functions have been calculated from experimental data and correlated with the Redlich-Kister equation. These functions were further discussed in terms of molecular interactions existing in the mixtures as well as the temperature influence on them. Additionally, excess molar Gibbs energies of activation of viscous flow and partial and excess partial molar volumes were determined for investigated systems. Modelling was performed for viscosity and excess molar volume and the obtained results were analyzed taking into account the applied approaches and models
Organic solvents review for sulphur-dioxide absorption from flue gases for regenerative processes with physical absorption
In addition to lime / limestone process, the most common procedure for sulfur-dioxide (SO2) removal from flue gases, separation processes with physical absorption and liquid organic solvent thermal regeneration recently gained importance. Organic liquid solvent selection, ahead of other process parameters, is crucial for process separation efficiency, in terms of the amount of SO2 absorbed by the solvent. The paper presents literature review and analysis of SO2 solubility in currently used and potential liquid organic solvents, polyethylene glycols (PEG 200 and PEG 400), tetraethylene glycol dimethyl ether (TEGDME), 1-methyl-2-pyrrolidone (NMP) as well as their binary mixtures with other components. The solvents in question bind SO2 by physical absorption mechanism, with the exception of NMP which binds SO2 by two parallel mechanisms, physical and chemical absorption. Research have even shown that mixtures of physical and chemical solvents or presence of both absorption mechanisms sometimes show better characteristics regarding binding capacity and selectivity. The importance of ionic liquids, as future solvents for separation processes, is particularly highlighted, due to their favorable thermophysical properties.Pored najrasprostranjenijeg, kreÄnjaÄkog postupka, za uklanjnje sumpor-dioksida (SO2) iz dimnih gasova, u novije vreme sve veÄi znaÄaj dobijaju separacioni postupci sa fiziÄkom apsorpcijom i termiÄkom regeneracijom teÄnog organskog solventa. Izbor solventa, ispred drugih procesnih parametara, kljuÄan je za efikasnost procesa u pogledu stepena izdvajanja SO2. U radu je dat literaturni pregled i analiza rastvoljivosti SO2 u trenutno koriÅ”Äenim i potencijalnim teÄnim organskim solventima, polietilen glikolima (PEG 200 i PEG 400), tetraetilen glikol dimetil etru (TEGDME), 1-metil-2-pirolidonu (NMP) i za njihove binarne smeÅ”e sa drugim komponentama. Razmatrani solventi vezuju SO2 mehanizmom fiziÄke apsorpcije, sa izuzetkom NMP-a kod koga su prisutna dva paralelna mehanizma, fiziÄka i hemijska apsorpcija. Istraživanja su Äak pokazala da smeÅ”e fiziÄkih i hemijskih solvenata ili smeÅ”e u kojima su prisutni mehanizmi i fiziÄke i hemijska apsorpcije ponekad pokazuju bolje karaktristike u pogledu stepena izdvajanja i selektivnosti. Posebno je istaknut znaÄaj jonskih teÄnosti kao solvenata buduÄnosti za separacione proces, zbog svojih povoljnih termofiziÄkih svojstava.Power Plants 2016 : Proceeding of International Conference; November 23-26, 2016, Zlatibor, Serbi
Instrument za odreÄivanje toplotne provodljivosti teÄnih fluida na atmosferskom pritisku
Na polju toplotnog inženjerstva veliki napori su uÄinjeni u oblasti unapreÄenja konstrukcije opreme za prenos toplote, gde je visoka toplotna provodljivost teÄnosti potrebna da bi se poveÄao prenos toplote. U mnogim oblastima gde postoji zahtev za hlaÄenjem, kao Å”to je sluÄaj u automobilskoj, avio-industriji i mikroelektronici, jedan od kljuÄnih faktora je upotreba specijalnih teÄnosti sa poveÄanom toplotnom provodljivoÅ”Äu. U takvim okolnostima merenje toplotne provodljivosti teÄnosti je važno u ocenjivanju efikasnosti prenosa toplote u toplotnim i rashladnim ureÄajima. Merenje toplotne provodljivosti teÄnosti je u metroloÅ”kom smislu veÄi izazov od merenja toplotne provodljivosti supstanci u Ävrstom stanju. Merenje toplotne provodljivosti moguÄe je kada je temperaturno polje nehomogeno, jer to izaziva transport toplote. MeÄutim, usled relativno slobodnog kretanja molekula u teÄnosti i zavisnosti gustine svih supstanci (pa i teÄnosti) od temperature, u teÄnostima dolazi do spontanog strujanja teÄnosti ā tj. do prirodne konvekcije ā Å”to menja oblik temperaturnog polja i vrlo brzo otežava i na kraju praktiÄno onemoguÄava merenje. Ovaj problem se može reÅ”iti na viÅ”e naÄina tako da postoje brojne merne metode koje su prilagoÄene merenju toplotne provodljivosti supstanci u teÄnom agregatnom stanju