Experimental and computational investigation of gravity separation in a vertical flash tank separator

PhD Thesis


Mahmood, Raid Ahmed. 2018. Experimental and computational investigation of gravity separation in a vertical flash tank separator . PhD Thesis Doctor of Philosophy. University of Southern Queensland. https://doi.org/10.26192/5c0da776f69cf
Title

Experimental and computational investigation of gravity separation in a vertical flash tank separator

TypePhD Thesis
Authors
AuthorMahmood, Raid Ahmed
SupervisorButtsworth, David
Malpress, Ray
Sharifian, Ahmad
Institution of OriginUniversity of Southern Queensland
Qualification NameDoctor of Philosophy
Number of Pages284
Year2018
Digital Object Identifier (DOI)https://doi.org/10.26192/5c0da776f69cf
Abstract

Vapour injection through flash tank separation is an effective way to enhance the coeffcient of performance (COP) and increase the capacity of air conditioning and refrigeration systems. In refrigeration systems which use the vapour injection technique, the flash tank feeds the evaporator with refrigerant liquid and the vapour is delivered to the compressor. Hence, the vertical flash tank is an important component that can be used to improve the performance of air conditioning and refrigeration systems. Semi-empirical design methods based on settling theory can be used for flash tank design, but the approach does not offer precise sizing data or an accurate assessment of likely performance under different operation conditions. Therefore, this thesis assesses the usefulness of CFD in
flash tank design, and this is achieved through experiments and simulations on a range of relevant configurations using water as the working fluid. A new experimental facility was built and five different models of the vertical separator were used to investigate the effect of the aspect ratio (H/D) on the liquid separation efficiency for a range of mass flow rates from 2.1 to 23.4 g/s. The internal diameter of the separator in each case was 50 mm. The separation tank was fed with two-phase flow generated using an expansion device and a length of horizontal pipe of diameter 25 mm. The two-phase flow developed gradually after the expansion device, reaching the developed region at about 165 cm downstream.

For the vertical tank without enhancement options, the highest value of the liquid separation efficiency of 0.96 was achieved using the highest height separator (H=250 mm) at the maximum mass flow rate 23.4 g/s. The separation efficiency increased with increasing inlet mass flow rate. In order to improve the liquid separation efficiency of the vertical separator, four enhancement options for the design were proposed: an extractor, a change in the inlet flow direction, a change in the position of the inlet pipe and a combination of the extractor and the change of the flow direction. The highest liquid separation efficiency of 0.99 was achieved by the last option at the maximum flow rate of 23.4 g/s. Empirical correlations were developed in horizontal pipe and vertical flash tank separator cases to predict the expansion length, void fraction and liquid separation efficiency. The range of the non-dimensional two-phase flow parameters covered by this study was: Reynolds number from 450.45 to 3246, Weber number from 0.005 to 0.72, and Froude number from 0.06 to 7.86.

CFD simulations were performed to simulate the two-phase flow within the horizontal tube which formed the inlet to the vertical separator, and the vertical separator itself. The simulations adopted the pressure based solver using the Eulerian-Eulerian multiphase model. In the horizontal tube case, the numerical results underestimated the expansion length in the experimental results with the simulated expansion length being an average of 8 % lower than the experimental observations. In the vertical tank separator case, the numerical results also underestimated the liquid separation efficiency in the experimental results with an average difference of the liquid separation efficiency of between 1 % and 2 %.

Based on the assessment of the CFD against the experiments of the present work, future applications of CFD in flash tank design should achieve liquid separation efficiency results that reflect the physical reality to within a few percent for operating conditions comparable to the present work. It is concluded that CFD can reliably be used for vertical flash tank design optimisation at least for stratified inlet flow conditions.

Keywordsvertical flash tank, gravity separation, twophase flow development, stratified flow pattern
ANZSRC Field of Research 2020401706. Numerical modelling and mechanical characterisation
Byline AffiliationsSchool of Mechanical and Electrical Engineering
Permalink -

https://research.usq.edu.au/item/q4x24/experimental-and-computational-investigation-of-gravity-separation-in-a-vertical-flash-tank-separator

Download files


Published Version
Mahmood_2018_whole.pdf
File access level: Anyone

  • 812
    total views
  • 444
    total downloads
  • 18
    views this month
  • 14
    downloads this month

Export as

Related outputs

The Simulation of Biogas Combustion in Top Open Burner
Selvam, A., Noor, M.M., Norhafana, M., Ihsan, C.K., Khalid, A., Mahmood, R.A., Harikrishnan, S. and Nayak, S.. 2024. "The Simulation of Biogas Combustion in Top Open Burner." 7th International Conference on Mechanical Engineering Research 2023 (ICMER 2023). Kuantan, Malaysia 12 - 13 Sep 2023 United Kingdom . IOP Publishing. https://doi.org/10.1088/1742-6596/2688/1/012023
The application of a single slope solar still in a refinery wastewater treatment: An experimental study
Al-Manea, Ahmed, Hammoody, Idrees, Alturki, Salwan Fadhil, Al-Shamani, Ali Najah, Wadday, Ahmed, Mahmood, Raid A. and Naeem, Haider Tawfiq. 2023. "The application of a single slope solar still in a refinery wastewater treatment: An experimental study." 1st International Conference on Achieving the Sustainable Development Goals. Istanbul, Turkey 06 202 - 07 Jun 2022 United States. AIP Publishing. https://doi.org/10.1063/5.0135973
Impact of Surface Temperature of a Photovoltaic Solar Panel on Voltage Production
Al-Doori, Ghassan Fadil, Mahmood, Raid Ahmed, Al-Janabi, Abdullah, Hassan, Amer Mahmood and Chala, Girma T.. 2023. "Impact of Surface Temperature of a Photovoltaic Solar Panel on Voltage Production." Sulaiman, Shaharin Anwar (ed.) Energy and Environment in the Tropics. Singapore. Springer. pp. 81–93
CFD Simulations and Experimental Observation for Air-Water Two-phase Flow in a Vertical Pipe
Mahmood, Raid A., Saleh, Khalid, Musa, Veyan A., Massoud, Enass, Al-Lwayzy, Saddam H., Ibrahim, Ahmed Khalid, Mohammed, Ali Ghazi and Abdulkareem, Lokman A.. 2022. "CFD Simulations and Experimental Observation for Air-Water Two-phase Flow in a Vertical Pipe." Gongcheng Kexue yu Jishu. 54 (6), pp. 2363-2375.
Assessment of Densified Fuel Quality Parameters: A Case Study for Wheat Straw Pellet
Nath, Bidhan, Chen, Guangnan, Bowtell, Les and Mahmood, Raid Ahmed. 2023. "Assessment of Densified Fuel Quality Parameters: A Case Study for Wheat Straw Pellet." Journal of Bioresources and Bioproducts. 8 (1), pp. 45-58. https://doi.org/10.1016/j.jobab.2022.10.001
Experimental Investigation of Coolant Side Characteristic on the Performance of Air-Cooled Condenser Structured by Horizontal Flattened Tube
Kamil, Mohammed Gh. Mohammed, Kassim, Muna S. and Mahmood, Raid Ahmed. 2022. "Experimental Investigation of Coolant Side Characteristic on the Performance of Air-Cooled Condenser Structured by Horizontal Flattened Tube." International Journal of Heat and Technology (Calore e Tecnologia). 40 (3), pp. 828-836. https://doi.org/10.18280/ijht.400323
Modeling of Heat Transfer and Steam Condensation Inside a Horizontal Flattened Tube
Kamil, M. Gh. Mohammed, Kassim, M. S., Mahmood, R. A. and Mahdi, L. AZ. 2022. "Modeling of Heat Transfer and Steam Condensation Inside a Horizontal Flattened Tube." Fluid Dynamics & Materials Processing. 18 (4), pp. 1-14. https://doi.org/10.32604/fdmp.2022.018938
Augmentation of convection heat transfer from a horizontal cylinder in a vented square enclosure with variation of lower opening size
Ali, Omar M., Mahmood, Raid A. and Al-Brifkani, Mohammed W.. 2022. "Augmentation of convection heat transfer from a horizontal cylinder in a vented square enclosure with variation of lower opening size." Thermal Science. 26 (3), pp. 2027-2041. https://doi.org/10.2298/TSCI201119176A
Two-Phase Flow Development of R134a in a Horizontal Pipe: Computational Investigation
Mahmood, Raid A., Saleh, Khalid, Musa, Veyan A., Massoud, Enass, Sharifian-Barforoush, Ahmad and Abdulkareem, Lokman A.. 2021. "Two-Phase Flow Development of R134a in a Horizontal Pipe: Computational Investigation." International Journal of Heat and Technology (Calore e Tecnologia). 39 (5), pp. 1532-1540. https://doi.org/10.18280/ijht.390515
Review of mechanical vapour compression refrigeration system Part 2: performance challenge
Mahmood, R. A., Ali, O. M., Al-Janabi, A., Al-Doori, G. and Noor, M. M.. 2021. "Review of mechanical vapour compression refrigeration system Part 2: performance challenge." International Journal of Applied Mechanics and Engineering. 26 (3), pp. 119-130. https://doi.org/10.2478/ijame-2021-0039
Flow Patterns of Oil-Gas and Pressure Gradients in Near-Horizontal Flow Pipeline: Experimental Investigation Using Differential Pressure Transducers
Musa, Veyan A., Mahmood, Raid A., Khalifa, Shwan M. Noori, Ali, Omar M. and Abdulkareem, Lokman A.. 2021. "Flow Patterns of Oil-Gas and Pressure Gradients in Near-Horizontal Flow Pipeline: Experimental Investigation Using Differential Pressure Transducers." International Journal of Heat and Technology (Calore e Tecnologia). 39 (2), pp. 621-628. https://doi.org/10.18280/ijht.390233
Experimental comparison between wire mesh and electrical capacitance tomography sensors to predict a two-phase flow behaviour and patterns in inclined pipe
Hameed, Ali I., Abdulkareem, Lokman A. and Mahmood, Radi A.. 2021. "Experimental comparison between wire mesh and electrical capacitance tomography sensors to predict a two-phase flow behaviour and patterns in inclined pipe." Technium. 3 (5), pp. 49-63.
Effect of Radiation on Natural Convection Heat Transfer from Heated Horizontal Cylinder in Vented Enclosure
Ali, Omar Mohammed and Mahmood, Raid Ahmed. 2021. "Effect of Radiation on Natural Convection Heat Transfer from Heated Horizontal Cylinder in Vented Enclosure." 3rd International Conference on Recent Innovations in Engineering (ICRIE 2020)IOP Conference Series: Materials Science and Engineering. United Kingdom. Informa UK(IOP Books). https://doi.org/10.1088/1757-899X/978/1/012030
CFD numerical and experimental investigation of two-phase flow development after an expansion device in a horizontal pipe
Mahmood, Raid Ahmed, Buttsworth, David, Malpress, Ray and Sharifian-Barforoush, Ahmed. 2021. "CFD numerical and experimental investigation of two-phase flow development after an expansion device in a horizontal pipe." Journal of Thermal Engineering. 7 (1), pp. 307- 323. https://doi.org/10.18186/thermal.850672
Experimental and numerical investigation of two-phase flow orientation direction change on a vertical flash tank separator
Mahmood, Raid Ahmed, Buttsworth, David and Malpress, Ray. 2019. "Experimental and numerical investigation of two-phase flow orientation direction change on a vertical flash tank separator." ISER 460th International Conference on Heat Transfer and Fluid Flow (ICHTFF 2019). Brisbane, Australia 08 - 09 Jan 2019
CFD Instraction Guide to Simulate Two-Phase Flow Separation in A Vertical T-Junction Separator
Mahmood, Raid Ahmed. 2019. "CFD Instraction Guide to Simulate Two-Phase Flow Separation in A Vertical T-Junction Separator." International Journal of Advances in Science, Engineering and Technology (IJASEAT). 7 (2 (Special issue 1)), pp. 40-44.
Experimental Investigation of Two-Phase Flow Patterns in a Vertical to Horizontal Bend Pipe Using Wire-Mesh Sensor
Abdulkareem, Lokman A., Musa, Veyan A., Mahmood, Raid A. and Hasso, Ezideen A.. 2021. "Experimental Investigation of Two-Phase Flow Patterns in a Vertical to Horizontal Bend Pipe Using Wire-Mesh Sensor." Revista de Chimie. 71 (12), pp. 18-33. https://doi.org/10.37358/Rev.Chim.1949
Mechanical Vapour Compression Refrigeration System: Review Part 1: Environment Challenge
Mahmood, Raid, Ali, Omar M. and Noor, M. M.. 2020. "Mechanical Vapour Compression Refrigeration System: Review Part 1: Environment Challenge." International Journal of Applied Mechanics and Engineering. 25 (4), pp. 130-147. https://doi.org/10.2478/ijame-2020-0054
CFD Assessment and Experimental Investigation of the Liquid Separation Efficiency Enhancements in a Vertical Gravity Separator
Mahmood, Raid Ahmed. 2020. "CFD Assessment and Experimental Investigation of the Liquid Separation Efficiency Enhancements in a Vertical Gravity Separator." International Journal of Air-Conditioning and Refrigeration. 28 (3), pp. 2050021-1. https://doi.org/10.1142/S2010132520500212
Investigation study of the inlet to body diameter ratio of a vertical flash tank separator using computational fluid dynamic (CFD)
Mahmood, Raid Ahmed. 2019. "Investigation study of the inlet to body diameter ratio of a vertical flash tank separator using computational fluid dynamic (CFD)." GSRD International Conference on Science, Engineering and Technology (ICSET 2019). Amman, Jordan 20 Feb 2019 Amman, Jordan.
CFD Instraction Guide to Simulate Two-Phase Flow Separation in a Vertical T-junction Separator
Mahmood, Raid Ahmed. 2019. "CFD Instraction Guide to Simulate Two-Phase Flow Separation in a Vertical T-junction Separator." International Institute of Engineers & Researchers 576th International Conference on Recent Innovations in Engineering and Technology (ICRIET-2019). Istanbul, Turkey 06 - 07 Feb 2019 Khandagiri, India.
Computational and Experimental Investigation of the Vertical Flash Tank Separator Part 1: Effect of Parameters on Separation Efficiency
Mahmood, Raid Ahmed, Buttsworth, David and Malpress, Ray. 2019. "Computational and Experimental Investigation of the Vertical Flash Tank Separator Part 1: Effect of Parameters on Separation Efficiency." International Journal of Air-Conditioning and Refrigeration. 27 (1), pp. 1950005-1. https://doi.org/10.1142/S2010132519500056
Assessment of a Sustainable Building using Eco-Friendly Insulation Materials
Mahmood, Raid Ahmed. 2020. "Assessment of a Sustainable Building using Eco-Friendly Insulation Materials." International Journal of Advances in Mechanical and Civil Engineering (IJAMCE). 7 (2), pp. 16-20.
Case study of liquid suction heat exchanger in a mechanical refrigeration system using alternative refrigerants
Mahmood, Raid Ahmed. 2020. "Case study of liquid suction heat exchanger in a mechanical refrigeration system using alternative refrigerants." International Journal of Engineering and Technology(Uae). 9 (3), pp. 644-649. https://doi.org/10.14419/ijet.v9i3.30777
Experimental and Numerical Investigation of Two-phase Flow Orientation Direction Change on a Vertical Flash Tank Separator
Mahmood, Raid Ahmed, Buttsworth, David and Malpress, Ray. 2019. "Experimental and Numerical Investigation of Two-phase Flow Orientation Direction Change on a Vertical Flash Tank Separator ." International Journal of Management and Applied Science (IJMAS). 5 (4), pp. 25-29.
Computational and experimental investigation of using an extractor in a vertical gravitational flash tank separator
Mahmood, R. A., Buttsworth, D. and Malpress, R.. 2019. "Computational and experimental investigation of using an extractor in a vertical gravitational flash tank separator." International Journal of Automotive and Mechanical Engineering. 16 (2), pp. 6706-6722.