Search results

Filters

  • Journals
  • Authors
  • Keywords
  • Date
  • Type

Search results

Number of results: 26
items per page: 25 50 75
Sort by:
Download PDF Download RIS Download Bibtex

Abstract

In general the iconographic details recorded in the hagiographic literature are pretty meagre. Authors focus on the miraculous properties of icons. The Coptic lives of the saints may be selected as representative for the Early Christian and Byzantine hagiography. The Martyrdom and Miracles of Saint Mercurius the General and other lives contain stories about the Saint’s icons. We have some information about church decoration in the East, but, it does not look as impressive as John of Gaza’s extensive ecphraseis of St. Sergius’ and St. Stephen’s complex decorative programmes. However, we actually find a number of interesting minor descriptions in the church histories, in the theological polemic on icons, and in the hagiographies. A Syriac manuscript from the British Museum preserves a chronicle of the monastery of Qartamin, Mor Gabriel. I focus on a chapter which describes the church’s construction and its interior decoration. The essential part of the art terminology, which we know from the Coptic texts, consists of the Greek borrowings. The Syriac texts show an entirely different pattern. The Syriac description compiled by an anonymous monk from Qartamin resembles the hymn on the Edessa Cathedral. The Syriac art description in general evolved along entirely different lines from the Greek ecphrasis. Greek borrowings in the discussed Syriac texts are rare, and if they do appear, they are limited to only certain words.

Go to article

Authors and Affiliations

Tomasz Polański

Authors and Affiliations

Tomasz Polański
Download PDF Download RIS Download Bibtex

Abstract

I am going to collect dispersed items of information which clearly refer or seem to be suggestive of the Aeolic, Pergamene or Attalid school of art historians which developed in the first half of the 2nd century BC and discuss their idiosyncratic methods and original contribution to the Greek intellectual life of the Hellenistic period. Even the fragmentary history of the Attalid art collections which can be reconstructed from the archaeological data and the scarce information in the literary sources shows that the collections grew as a result of various factors: 1. wartime robbery. 2. purchases of artworks. 3. a well‑thought out programme of reproducing original Greek artworks. The Attalids must have had professional art historians at their side as consultants. We can identify two of them by name: Antigonus of Karystos and Polemon of Ilion. A number of passages testify to a lively academic debate between them. In the course of their professional polemics they discussed the problems of authorship and authenticity of artworks, they adduced biographical details in their efforts to establish the personal identities of the artists and paid tribute to their heroes with colourful anecdotes. They attributed artworks to alternative authors. They also constructed complicated genealogical trees of schools of painting and sculpture, along the principle of master/pupil relations. Their epigraphic studies must have been inspired and influenced by the editors of the Aeolic Archaic poets.

Go to article

Authors and Affiliations

Tomasz Polański
Download PDF Download RIS Download Bibtex

Abstract

In the presented work Egorov’s approach (adding a source term to the ω-equation in the k-! model, which mimics the damping of turbulence close to a solid wall) was implemented in on the subclass of shear stress transport models. Hence, turbulence damping is available for all shear stress transport type models, including hybrid models that are based on the ω-equation. It is shown that turbulence damping improves the prediction of the axial velocity profile not only for Reynolds-averaged Navier–Stokes simulation but also for detached eddy simulation and delayed detached eddy simulation models. Furthermore, it leads to a more realistic estimation of the pressure drop and, hence, to a more correct prediction of the liquid level. In this paper, simulation results for four different turbulence models are presented and validated by comparison with experimental data. Furthermore, the influence of the magnitude of the damping factor on the pressure drop in the channel is investigated for a variety of different gas-to-liquid flow rate ratios. These investigations show that higher gas-to-liquid flow rate ratios require higher damping factors to correctly predict the pressure drop. In the end, advice is formulated on how an appropriate damping factor can be determined for a specific test case.
Go to article

Bibliography

[1] Egorov Y., Boucker M., Martin A., Pigny S., Scheuerer M., Willemsen S.: Validation of CFD codes with PTS-relevant test cases. Tech. Rep. EVOL-ECORAD07, 2004.
[2] Fabre J., Masbernat L., Suzanne C.: Stratified flow. Part I: Local structure. Multiphas. Sci. Technol. 3(1987), 285–301.
[3] Höhne T., Vallée C.: Experiments and numerical simulations of horizontal twophase flow regimes using an interfacial area density model. J. Comput. Multiphas. Flow. 2(2010), 3, 131–143.
[4] Vallée C., Höhne T.: CFD validation of stratified two-phase flows in a horizontal channel. In: Annual Report 2006 (F.-P. Weiss, U. Rindelhardt, Eds.), FZR-465, Forschungszentrum Dresden Rossendorf, 2007, 33–38.
[5] Frederix E.M.A., Mathur A., Dovizio D., Geurts B.J., Komen E.M.J.: Reynolds-averaged modeling of turbulence damping near a large-scale interface in two-phase flow. Nucl. Eng. Design 333(2018), 122–130.
[6] Höhne T., Vallée C.: Modelling of stratified two phase flows using an interfacial area density model. In: Proc. Multiphase Flow 2009, 5th Int. Conf. on Computational and Experimental Methods in Multiphase and Complex Flow, New Forest, 15-17 June, 2009, 123–133.
[7] Höhne T., Mehlhoop J.-P.: Validation of closure models for interfacial drag and turbulence in numerical simulations of horizontal stratified gas–liquid flows. Int. J. Multiphas. Flow 62(2014), 1–16.
[8] Porombka P., Höhne,T.: Drag and turbulence modelling for free surface flows within the two-fluid Euler–Euler framework. Chem. Eng. Sci. 134(2015), 348–359.
[9] Ansys Fluent User’s Guide. Release 2021 R1. Ansys, Inc., Canonsburg 2021.
[10] Chinello G., Ayati A.A., McGlinchey D., Ooms G., Henkes R.: Comparison of computational fluid dynamics simulations and experiments for stratified air-water flows in pipes. J. Fluid. Eng. 141(2019), 5, 051302-1–051302-12.
[11] Gada V.H., Tandon M.P., Elias J., Vikulov R., Lo S.: A large scale interface multi-fluid model for simulating multiphase flows. Appl. Math. Model. 44(2017), 189–204.
[12] Lo S., Tomasello A.: Recent progress in CFD modelling of multiphase flow in horizontal and near-horizontal pipes. In: Proc. 7th North American Conf. on Multiphase Technology, Banff, June 2010, BHR-2010-F1.
[13] Fan W., Li H., Anglart H.: Numerical investigation of spatial and temporal structure of annular flow with disturbance waves. Int. J. Multiphas. Flow 110(2019), 256–272.
[14] Fan W., Anglart H.: Progress in phenomenological modeling of turbulence damping around a two-phase interface. Fluids 4(2019), 3, 136.
[15] Fan W., Anglart H.: varRhoTurbVOF 2: Modified OpenFOAM volume of fluid solvers with advanced turbulence modeling capability. Comput. Phys. Commun. 256(2020), 107467.
[16] Wilcox D.C.: Turbulence Modeling for CFD Vol. 2. DCW Industries, La Canada 1998.
[17] Menter F., Kuntz M., Langtry R.: Ten years of industrial experience with the SST turbulence model. In: Turbulence, Heat and Mass Transfer 4 (K. Hanjalic, Y. Nagano, M. Tummers, Eds.). Begell House, 2003.
[18] Langtry R.B., Menter F.R.: Correlation-based transition modeling for unstructured parallelized computational fluid dynamics codes. AIAA J. 47(2009), 12, 2894–2906.
[19] Egorov Y., Menter F.: Development and application of SST-SAS turbulence model in the desider project. In: Advances in Hybrid RANS-LES Modelling (S.-H. Peng, W. Haase, Eds.), Springer, Berlin Heidelberg, 2008, 261–270.
[20] Strelets M.: Detached eddy simulation of massively separated flows. In: Proc. 39th AIAA Aerospace Sciences Meet. Exhib., Reno, Jan. 8-11, 2001.
[21] Gritskevich M., Garbaruk A., Schütze J., Menter F.: Development of DDES and IDDES formulations for the k-ω shear stress transport model. Flow Turbul. Combust. 88(2012), 3, 431–449.
[22] Müller-Steinhagen H., Heck K.: A simple friction pressure drop correlation for two-phase flow in pipes. Chem. Eng. Process. 20(1986), 6, 297–308.
[23] Launder B., Spalding D.: The numerical computation of turbulent flows. Comput. Methods Appl. Mech. Eng. 3(1974), 2, 269– 289.
[24] Menter F.R.: Two-equation eddy-viscosity turbulence models for engineering applications. AIAA J. 32(1994), 8, 1598–1605.
[25] Spalart P., Deck S., Shur M., Squires K., Strelets M., Travin A.: A new version of detached-eddy simulation, resistant to ambiguous grid densities. Theor. Comput. Fluid Dyn. 20(2006), 181–195.
[26] Frank T.: Numerical simulation of slug flow regime for an air-water two-phase flow in horizontal pipes. In: Proc. 11th Int. Topical Meeting on Nuclear Reactor Thermal-Hydraulics (NURETH-11), Avignon, Oct. 2–6, 2005.
Go to article

Authors and Affiliations

Jiri Polansky
1
Sonja Schmelter
2

  1. Czech Technical University in Prague, Jugoslávských partyzánu 1580/3, 160 00 Prague 6 – Dejvice, Czech Republic
  2. Physikalisch-Technische Bundesanstalt (PTB), Abbestraße 2-12, D-10587 Berlin-Charlottenburg, Germany
Download PDF Download RIS Download Bibtex

Abstract

Energy management plays a crucial role in cabin comfort as well as enormously affects the driving range. In this paper energy balances contemplating the implementation of a heat pump and an expansion device in battery electric vehicles are elaborated, by comparing the performances of refrigerants R1234yf and R744, from –20°C to 20°C. This work calculates the coefficient of performance, energy requirements for ventilation (from 1 to 5 people in the cabin) and energy required with the implementation of a heat pump, with the employment of a code in Python with the aid of Cool- Prop library. The work ratio is also estimated if the work recovery device recuperates the work during the expansion. Comments on the feasibility of the implementation are as well explicated. The results of the analysis show that the implementation of an expansion device in an heat pump may cover the energy requirement of the compressor from 27% to more than 35% at 20°C in cycles operating with R744, and from 15% to more than 20% with refrigerant R1234yf, considering different compressor efficiencies. At –20°C, it would be possible to recuperate between around 30 and 24%. However, the risk of suction when operating with R1234yf at ambient temperatures below –10°C shows that the heat pump can only operate with R744. Thus, it is the only refrigerant that achieves the reduction of energy consumption at these temperatures.
Go to article

Bibliography

  1. Global electric car sales by key markets, 2010-2020 – Charts – Data & Statistics IEA, https://www.iea.org/data-and-statistics/charts/global-electric-car-sales-by-key- markets-2015-2020 (accessed 17 March 2021).
  2. Rietmann N., Hügler B., Lieven T.: Forecasting the trajectory  of  electric  vehicle sales and the consequences for worldwide CO2 emissions. J. Clean. Prod. 261(2020), 121038. https://doi.org/10.1016/j.jclepro.2020.121038.
  3. Greaves , Backman H., Ellison A.B.: An empirical assessment of the feasibility of battery electric vehicles for day-to-day driving. Transport. Res. A-Pol. 66(2014), 226–237. https://doi.org/10.1016/j.tra.2014.05.011.
  4. Kempton W.: Electric vehicles: Driving range. Energ. 1 (2016), 1–2. https:// doi.org/ 10.1038/nenergy.2016.131.
  5. Klamut : Attitude towards electric vehicles. Research  on the students of a tech- nical university. Zeszyty Naukowe Instytutu Gospodarki Surowcami Mineralnymi PAN 107(2018), 105–118 (in Polish). https://doi.org/10.24425/123719.
  6. Varga O., Sagoian A., Mariasiu F.: Prediction of electric vehicle range: A comprehensive review of current issues and challenges. Energies 12(2019), 946. https://doi.org/10.3390/en12050946.
  7. Lajunen , Suomela   J.:   Evaluation   of   energy   storage   system   requirements for hybrid mining loaders. IEEE T. Veh. Technol. 61(2012), 3387–3393. https:// doi.org/10.1109/TVT.2012.2208485.
  8. Garg ,  Chen  F.,  Zhang  J.: State-of-the-art of designs studies for batteries packs  of electric vehicles. In: Proc. IET Int. Conf. on Intelligent and Connected Vehicles (ICV 2016). https://doi.org/10.1049/cp.2016.1181.
  9. Hannan M.A., Hoque M.M., Hussain A., Yusof Y., Ker P.J.: State-of-the-art and energy management system of lithium-ion batteries in electric vehicle applica- tions: Issues and recommendations. IEEE Access 6(2018), 19362–19378. https://org/10.1109/ACCESS.2018.2817655.
  10. Petitjean C., Guyonvarch G., Benyahia M., Beauvis R.: TEWI analysis for different automotive air conditioning systems. In: Proc. The Future Car Congress 2000, 2000-01–1561. https://doi.org/10.4271/2000-01-1561.
  11. Guyonvarch G., Aloup C., Petitjean C., De  Monts  De  Savasse :  42  V  electric air conditioning systems (E-A/CS) for  low  emissions,  architecture,  comfort and safety of next generation vehicles. In: Proc. The Future Transportation Tech- nology Conf. & Expo. 2001, 2001-01–2500. https://doi.org/10.4271/2001-01-2500.
  12. Bashirpour-Bonab H.: Thermal behavior of lithium batteries used in electric  ve- hicles using phase change materials. Int. J. Energ. Res. 44(2020), 12583–12591. https://doi.org/10.1002/er.5425.
  13. Karimi G., Li X.: Thermal management of lithium-ion batteries for electric vehicles. Int. J. Energ. Res. 37(2013), 13–24. https://doi.org/10.1002/er.1956.
  14. Kizilel R., Lateef A., Sabbah R., Farid M., Selman J.R., Al-Hallaj S.:  Passive control of temperature excursion and uniformity in high-energy Li-ion bat- tery packs at high current and ambient temperature. J. Power Sources 183(2008), 1, 370–375. https://doi.org/10.1016/j.jpowsour.2008.04.050.
  15. Agarwal ,  Sarviya  R.M.:  Characterization  of  Commercial  Grade  Paraffin  wax as Latent Heat Storage material for Solar dryers. Materials Today 4(2017), 779–789, Proc. 5th Int. Conf. on Materials Processing and Characterization (ICMPC 2016). https://doi.org/10.1016/j.matpr.2017.01.086.
  16. Ettouney H., Alatiqi , Al-Sahali M., Al-Hajirie K.: Heat transfer enhance- ment in energy storage in spherical capsules filled with paraffin wax and metal beads. Energ. Convers. Manage. 47(2006), 211–228. https://doi.org/10.1016/j.enconman. 2005.04.003.
  17. Heath A.: Amendment to the Montreal protocol on substances that  deplete  the ozone layer (Kigali amendment). Int. Legal Mater. 56(2017), 193–205. https:// doi.org/10.1017/ilm.2016.2.
  18. Lee Y., Jung D.: A brief performance comparison  of  R1234yf  and  R134a  in  a bench tester for automobile applications. Appl. Therm. Eng. 35(2012), 240–242. https://doi.org/10.1016/j.applthermaleng.2011.09.004.
  19. Ozgur A.E., Kabul A., Kizilkan : Exergy  analysis  of  refrigeration  systems using an alternative refrigerant (hfo-1234yf) to R-134a. Int. J. Low-Carb. Technol. 9(2014), 56–62. https://doi.org/10.1093/ijlct/cts054.
  20. Vaghela K.: Comparative evaluation of an automobile air – conditioning  system using R134a and its alternative refrigerants. Energy Proced. 109(2017), 153–160, Int. Conf. on Recent Advancement in Air Conditioning and Refrigeration, RAAR 2016, 10-12 November 2016, Bhubaneswar. https://doi.org/ 10.1016/j.egypro. 2017. 03.083.
  21. Reasor P., Aute V., Radermacher R.: Refrigerant R1234yf performance com- parison investigation. Refrigeration and Air Conditioning Conference 8, 2010.
  22. Cho H., Lee H., Park : Performance characteristics of an automobile air condi- tioning system with internal heat exchanger using refrigerant R1234yf. Appl. Therm. Eng. 61(2013), 563–569. https://doi.org/10.1016/j.applthermaleng.2013.08.030.
  23. Direk M., Kelesoglu A., Akin A.: Drop-in  performance  analysis  and  effect  of IHX for an automotive air conditioning system with R1234yf as a replacement of R134a. SV-JME 63(2017), 314–319. https://doi.org/10.5545/sv-jme.2016.4247.
  24. Feng L., Hrnjak P.: Experimental Study of an Air Conditioning-Heat Pump Sys- tem for Electric Vehicles. In: Proc: SAE 2016 World Exhibit., 2016-01–0257. https://doi.org/10.4271/2016-01-0257.
  25. Wu , Zhou G., Wang M.: A comprehensive assessment of refrigerants for cabin heating and cooling on electric vehicles. Appl. Therm. Eng. 174(2020), 115258. https://doi.org/10.1016/j.applthermaleng.2020.115258.
  26. Maina P., Huan Z.: A review of carbon dioxide as a refrigerant in refrigeration technology. Afr. J. Sci. 111(2015). https://doi.org/10.17159/sajs.2015/20140258.
  27. Song X., Lu D., Lei Q., Cai Y., Wang , Shi J., Chen J.: Experimental study   on heating performance of a CO2 heat pump system for an electric bus. Appl. Therm. Eng. 190(2021), 116789. https://doi.org/10.1016/j.applthermaleng.2021.116789.
  28. Wu D., Hu B., Wang Z.: Vapor compression heat pumps with pure low-GWP refrigerants. Renew. Sust. Energ. Rev. 138(2021), 110571. https://doi.org/10.1016/ j.rser.2020.110571.
  29. Lorentzen G.: Revival of carbon dioxide as a refrigerant. International Journal of Refrigeration 17(1994), 292–301. https://doi.org/10.1016/0140-7007(94)90059-0.
  30. Großmann H.: Comparing the refrigerant R1234yf and CO2. ATZ Worldw 118(2016), 70. https://doi.org/10.1007/s38311-016-0119-0.
  31. Ma Y., Liu Z., Tian H.: A review of transcritical carbon dioxide heat pump and refrigeration cycles. Energy 55(2013), 156–172. https://doi.org/10.1016/j.energy. 03.030.
  32. Li W., Liu Y., Liu R., Wang , Shi J., Yu Z., Cheng L., Chen J.L.: Perfor- mance evaluation of secondary loop low-temperature heat pump system for frost pre- vention in electric vehicles. Appl. Therm. Eng. 182(2021), 115615. https://doi.org/ 10.1016/j.applthermaleng.2020.115615.
  33. Menken J.C., Ricke M., Weustenfeld  A.,  Koehler  J.:  Simulative  analysis of secondary loop automotive refrigeration systems operated with an HFC and carbon dioxide. SAE Int. J. Passeng. Cars-Mech. Syst. 9(2016), 434–440. https://doi.org/ 10.4271/2016-01-9107.
  34. Wang , Yu B., Hu J., Chen L., Shi J., Chen J.: Heating performance char- acteristics of CO2 heat pump system for electrical vehicle in a cold climate. Int. J.Refrig. 85(2018), 27–41. https://doi.org/10.1016/j.ijrefrig.2017.09.009.
  35. Wang , Wang D., Yu,B., Shi J., Chen J.: Experimental and numerical in- vestigation of a CO2 heat pump system for electrical vehicle with series gas coolerconfiguration. Int. J. Refrig. 100(2019), 156–166. https://doi.org/10.1016/j.ijrefrig. 2018.11.001.
  36. Bruno F., Belusko M., Halawa : CO2 refrigeration and heat pump systems – A comprehensive review. Energies 12(2019), 15, 2959. https://doi.org/10.3390/ en12152959.
  37. Baek J.S., Groll E.A., Lawless B.: Piston-cylinder work producing expansion device in a transcritical carbon dioxide cycle. Part I: experimental investigation. Int. J. Refrig. 28(2005), 141–151. https://doi.org/10.1016/j.ijrefrig.2004.08.006.
  38. Ferrara G., Ferrari L., Fiaschi , Galoppi  G.,  Karellas  S.,  Secchi  R.,  Tempesti D.: A small power recovery expander for heat pump COP improvement. Energ. Proced. 81(2015), 1151–1159, 69th Conf. Ital. Therm. Eng. Assoc., ATI 2014. https://doi.org/10.1016/j.egypro.2015.12.140.
  39. Kohsokabe H., Funakoshi S., Tojo K., Nakayama , Kohno K., Kurashige  K.: Basic operating characteristics of CO2 refrigeration cycles with expander- compressor unit 10 (2006). 
  40. Specific Heat Capacities of Air – (Updated 7/26/08). https://www.ohio.edu/mecha nical/thermo/property_tables/air/air_Cp_Cv.html (accessed 6 March 2021).
  41. Abas N., Kalair A.R., Khan  ,  Haider  A.,  Saleem  Z.,  Saleem  M.S.:  Natu-  ral and synthetic refrigerants, global warming: A review. Renew. Sust. Energ. Rev. 90(2018), 557–569. https://doi.org/10.1016/j.rser.2018.03.099.
  42. Bell H., Wronski J., Quoilin S., Lemort V.: Pure and pseudo-pure fluid thermophysical property evaluation and the open-source thermophysical property li- brary CoolProp. Ind. Eng. Chem. Res. 53(2014), 6, 2498–2508. https://doi.org/ 10.1021/ie4033999.
  43. Richter M., McLinden M.O., Lemmon E.W.: Thermodynamic Properties of 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf): Vapor Pressure and p–ρ–T Measurements and an Equation of State. ACS Publications (2011). https://doi.org/10.1021/ je200369m.
  44. Span , Wagner W.: A new equation  of  state  for  carbon  dioxide  covering  the fluid region from  the triple-point temperature  to 1100 K at pressures  up to 800 MPa.  J. Phys. Chem. Ref. Data 25(1996), 1509–1596. https://doi.org/10.1063/1.555991.
  45. Fukuda ,  Kojima  H.,  Kondou  C.,  Takata  N.,  Koyama S.:  Experimen-   tal assessment on performance of a heat pump cycle using R32/R1234yf and R744/R32/R1234yf. In; Proc. Int. Refrigeration and Air Conditioning Conf. 2016.
  46. Shin Y., Cho H.: Performance comparison of a truck refrigeration system  with R404A, R134a, R1234yf, and R744 refrigerants under frosting conditions. Int. J. Air-Cond. Ref. 24(2016), 1650005.https://doi.org/10.1142/S201013251650005X.
Go to article

Authors and Affiliations

Maria Laura Canteros
1
Jiri Polansky
2

  1. Czech Technical University in Prague, Jugoslávských partyzánu 1580/3, 160 00 Prague 6 – Dejvice, Czech Republic
  2. ESI Group, Brojova 16, 326 00 Plzen, Czech Republic
Download PDF Download RIS Download Bibtex

Abstract

The paper presents a plane model of articulated vehicles worked out for the analysis of their dynamics. The dAlambert principle was used for derivation of motion equations for this system. The forces and moments acting on wheels were formulated on the basis of the Dugoff-Uffelmann tyre model. The system consists of any number of vehicles connected by kinematic pair of the 5th class (non friction joint of pivot-bush type) and the fifth wheel (with dry fricton). Since crash calculations usually take into account the impulse of crash force only, and since it is not appropriate for articulated vehicles, a new approach to crash calculation is presented in this paper. The authors propose to calculate the force in crash point both as a function of the relative velocity of vehicles and the stiffness of their bodies. Simulation results of articulated lorry crashes and the attempt to verify the performed simulation are presented in the article.
Go to article

Authors and Affiliations

Witold Grzegożek
Piotr Świder
Andrzej Polański

This page uses 'cookies'. Learn more