Investigation of the Motive Steam Pressure Effect on Performance and Reverse Flows in Sugar Factory Thermo-compressor: Validation and Numerical Study

Document Type : Research Article

Authors

• A. Rezvanivand fanaei
• A. Hasanpour
• A. M. Nikbakht

Biosystems Engineering Department, Faculty of Agriculture, Urmia University, Urmia, Iran

https://doi.org/10.22067/jam.2021.68318.1010

Abstract

Introduction
Thermo-compressors or ejectors are used to enhance the vapor enthalpy in the process industry. The low costs of construction and maintenance, and simple structure, have increased by using this equipment in relevant fields of industry and agriculture. The thermo-compressor's inlet parameters, including the thermodynamic properties of the motive steam and suction vapor, are the foremost affecting factor of a thermo-compressor.
The steam used in processing factories loses its capability after passing through evaporators due to the reduction of pressure and temperature, gets cooled again, and returns to the boiler despite having a moderate energy level. Therefore, the use of vapor-recovery equipment can increase the efficiency of energy systems. That will lead to a significant reduction in greenhouse gas emissions and harmful environmental effects, which increase the lifetime of energy resources.
Materials and Methods
The realizable k-ε turbulence model is used to simulate turbulence within the flow. The thermo-compressor geometry has meshed in 2D and 3D modes to apply the conservation laws. For this purpose, quadratic (quad) and hexahedral (hex) types are used for two and three-dimensional meshing, respectively. Structured meshes have a high ability to obtain numerical results due to creation of structural meshes in the flow direction.
The axisymmetric structure of the thermo-compressor leads to a half simulation of geometry. The thermodynamic properties of the input flows and their variations in the output, such as pressure, velocity, Mach number, and mass ratios for different motive steam pressure are extracted and discussed.
Results and Discussion
Different levels of meshes are examined to investigate the mesh-independence test. In axisymmetric two-dimensional analysis, these levels include 33460, 51340, 78620, and 103590 cells, respectively. The relatively insignificant difference in motive flow for the third and fourth mesh levels (which proves less than 5%) clearly shows the independence of the results from the mesh size. Regarding the time considerations, the grid with 78,620 meshes was used in the simulations.
The experimental data from the article by Sriveerakul et al. (2007) are used to validate the numerical results of the present work. Validation shows that the results obtained from the simulations are in good agreement with the experimental data. Since the final results of the two-dimensional analysis are very close to the three-dimensional one, the first one is selected due to the time considerations and higher computational costs of the three-dimensional mesh analysis.
Considering the problem conditions, pressures of 10 and 15 bars are appropriate for practical application. Since the 15 bar motive stem creates a longer development length in the diffuser section, it is a better choice. At this level (15 bar), the temperature field within the thermo-compressor is well distributed in the presence of ideal temperature conditions. The ideal velocity distribution within the thermo-compressor and the uniformity of the motive and suction flows indicate the high performance of the thermo-compressor in these operating conditions. Applying the motive steam of 15 bars, the values of 0.59 and 0.41 for the motive and suction mass ratios of the diffuser output were achieved, respectively.
Conclusion
Geometrically, the study was examined in asymmetrical two-dimension and three-dimension. It was observed that there is a slight difference between the two analysis modes by comparing the velocities along the longitudinal line of the thermo-compressor. Therefore, to save computational and time costs, results are presented for the axisymmetric two-dimensional mode.
The effect of 4 levels of motive steam pressure on the thermodynamic properties within the computational domain, including pressure, temperature, velocity, Mach number, mass ratios of both motive steam, and suction vapor are evaluated. Finally, the values of the performance curve for steam with motive pressures of 3.7, 5, 10, and 15 bars are presented.

Keywords

• Entrainment ratio
• Mach number
• Suction flow
• Sugar processing

20.1001.1.22286829.1401.12.3.9.3

Main Subjects

• Modeling

Open Access

©2022 The author(s). This article is licensed under Creative Commons Attribution 4.0 International License (CC BY 4.0), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source.

References

1. Aphornratana, S., and T. Sriveerakul. 2010. Analysis of a combined Rankine–vapour–compression refrigeration cycle. Energy Conversion and Management 51 (12): 2557-2564. https://doi.org/10.1016/j.enconman.2010.04.016.
2. Ariafar, K., and A. Toorani. 2012. Effect of Nozzle Geometry on a Model Thermocompressor Performance. 20^th Annual International Conference on Mechanical Engineering 16-19.
3. Bartosiewicz, Y., Z. Aidoun, and Y. Mercadier. 2006. Numerical assessment of ejector operation for refrigeration applications based on CFD. Applied Thermal Engineering 26: 604-612. https://doi.org/10.1016/j.applthermaleng.2005.07.003.
4. Besagni, G., and F. Inzoli. 2017. Computational fluid-dynamics modeling of supersonic ejectors: Screening of turbulence modeling approaches. Applied Thermal Engineering 117: 122-144. https://doi.org/10.1016/j.applthermaleng.2017.02.011.
5. Besagni, G. 2019. Ejectors on the cutting edge: The past, the present and the perspective. Energy 170: 998-1003. https://doi.org/10.1016/j.energy.2018.12.214.
6. Bonanos, A. M. 2017. Physical modeling of thermo-compressor for desalination applications. Desalination 412: 13-19. https://doi.org/10.1016/j.desal.2017.03.004.
7. Caliskan, H. 2017. Energy, exergy, environmental, enviroeconomic, exergoenvironmental (EXEN) and exergoenviroeconomic (EXENEC) analyses of solar collectors. Renewable and Sustainable Energy Reviews 69: 488-492. https://doi.org/10.1016/j.rser.2016.11.203.
8. Chen, Q., M. K. Ja, Y. Li, and K. J. Chua. 2019. Energy, exergy and economic analysis of a hybrid spray-assisted low-temperature desalination/thermal vapor compression system. Energy 166: 871-885. https://doi.org/10.1016/j.energy.2018.10.154.
9. Dutton, J. C., and B. F. Carroll. 1986. Optimal Supersonic Ejector Designs. Journal of Fluids Engineering 108: 414-420. https://doi.org/10.1115/1.3242597.
10. Huang, B. J., J. M. Chang, C. P. Wang, V. A. and Petrenko. 1999. A 1-D analysis of ejector performance. International Journal of Refrigeration 22 (5): 354-364. https://doi.org/10.1016/S0140-7007(99)00004-3.
11. Inc. ANSYS. 2013. ANSYS FLUENT Theory Guide. Release 182 15317: 373-464.
12. Ji, M., T. Utomo, J. Woo, Y. Lee, H. Jeong, and H. Chung. 2010. CFD investigation on the flow structure inside thermo vapor compressor. Energy 35 (6): 2694-2702. https://doi.org/10.1016/j.energy.2009.12.002.
13. Keenan, J. H. 1942. A simple air ejector. Journal of Applied Mechanics 64: 75-81. https://doi.org/10.1115/1.4009187.
14. MyoungKuk, J., T. Utomo, J. Woo, Y. H. Lee, H. M. Jeong, and H. S. Chung. 2010. CFD investigation on the flow structure inside thermo vapor compressor. Energy 35 (6): 2694-2702. https://doi.org/10.1016/j.energy.2009.12.002.
15. Naimi, S., Gh. Shahgholi, A. Rezvanivand Fanaie, and V. Rotampour. 2019. Numerical Study of Wheat Conveying in Separator Cyclone Using Computational Fluid Dynamics. Journal of Agricultural Machinery 11 (2): 231-246. (In Persian). http://dx.doi.org/10.22067/jam.v11i2.79613.
16. Noori, S. M., and R. Kouhikamali. 2016. CFD-aided mathematical modeling of thermal vapor compressors in multiple effects distillation units. Applied Mathematical Modelling 40: 6850-6868. https://doi.org/10.1016/j.apm.2016.02.032.
17. Rezvanivandefanayi, A., and A. M. Nikbakht. 2015. A CFD Study of the Effects of Feed Diameter on the Pressure Drop in Acyclone Separator. International Journal of Food Engineering 11 (1): 71-77. https://doi.org/10.1515/ijfe-2014-0125.
18. Rezvanivandefanayi, A., A. Hassanpour, and A. M. Nikbakht. 2019. Study of the vapor thermos-compressor to reduce energy consumption in the sugar production line using Computational Fluid Dynamics: Journal of Agricultural Machinery 10 (2): 241-253. (In Persian). http://doi.org/10.22067/jam.v10i2.76872
19. Rezvanivand Fanaei, A., A. M. Nikbakht, and A. Hassanpour. 2021. A Computational-Experimental Investigation of Thermal Vapor Compressor as an Energy Saving Tool for the Crystallization of Sugar in a Sugar Processing Plant. Journal of Food Process Engineering 44 (7): https://doi.org/10.1111/jfpe.13727.
20. Riffat, S. B., and S. A. Omer. 2001. CFD modelling and experimental investigation of an ejector refrigeration system using methanol as the working fluid. International Journal of Energy Research 25: 115-128. https://doi.org/10.1002/er.666.
21. Sabralilou, B., A. Mohebbi, E. Akbarian, A. Rezvanicand fanaei. 2019. Aero-acoustical Study of Axial Fan using Computational Fluid Dynamics. Journal of Agricultural Machinery 10 (2): 255-264. (In Persian). http://doi.org/10.22067/jam.v10i2.74963
22. Sharifi, N., M. Boroomand, and R. Kouhikamali. 2012. Wet steam flow energy analysis within thermo-compressors. Energy 47 (1): 609-619. https://doi.org/10.1016/j.energy.2012.09.003.
23. Sharifi, N., and M. Boroomand. 2013. An investigation of thermo-compressor design by analysis and experiment : Part 2. Development of design method by using comprehensive characteristic curves. Energy Conversion and Management 69: 228-237. https://doi.org/10.1016/j.enconman.2012.12.034.
24. Sriveerakul, T., S. Aphornratana, and K. Chunnanond. 2007. Performance prediction of steam ejector using computational fluid dynamics: Part 1. Validation of the CFD results. International Journal of Thermal Sciences 46 (8): 812-822. https://doi.org/10.1016/j.ijthermalsci.2006.10.014.
25. Sun, D. W. 1997. Solar powered combined ejector-vapour compression cycle for air conditioning and refrigeration. Energy Conversion and Management 38 (5): 479-491. https://doi.org/10.1016/S0196-8904(96)00063-5.
26. Sun, D. W. 1999. Comparative study of the performance of an ejector refrigeration cycle operating with various refrigerants. Energy Conversion and Management 40: 873-884. https://doi.org/10.1016/S0196-8904(98)00151-4.
27. Zhu, J., F. Botticella, and S. Elbel. 2018. Experimental investigation and theoretical analysis of oil circulation rates in ejector cooling cycles. Energy 157: 718-733.
28. Zobeiri, M., V. Rostampour, A. Rezvanivand Fanaei, and A. M. Nikbakht. 2019. Experimental and Numerical investigation of deviation blade effect on sedimentation chamber performance in chickpea harvesting machine. Iran Biosystems Engineering 52: 329-339. (In Persian). DOI: 22059/ijbse.2020.276317.665166.