Draining Water from Aircraft Fuel Using Nitrogen Enriched Air
This paper concerns a computational study of the process of removing water from an aircraft’s fuel tank by pumping nitrogen enriched air (NEA) from the bottom of the tank. This is an important procedure for the smooth, efficient, and safe operation of the aircraft’s engine. Due to the low partial pr...
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| Format: | Article |
| Language: | English |
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MDPI AG
2018-04-01
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| Series: | Energies |
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| Online Access: | http://www.mdpi.com/1996-1073/11/4/908 |
| _version_ | 1798038834030575616 |
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| author | Michael Frank Dimitris Drikakis |
| author_facet | Michael Frank Dimitris Drikakis |
| author_sort | Michael Frank |
| collection | DOAJ |
| description | This paper concerns a computational study of the process of removing water from an aircraft’s fuel tank by pumping nitrogen enriched air (NEA) from the bottom of the tank. This is an important procedure for the smooth, efficient, and safe operation of the aircraft’s engine. Due to the low partial pressure of water in the pumped NEA, it absorbs water from the fuel. The water-laden bubbles enter the ullage, the empty space above the fuel, and escape into the environment. The effects of the number of NEA inlets and the NEA mass flow rate on the timescale of the NEA pumping were investigated using Computational Fluid Dynamics. The results reveal that the absorption of water by the NEA bubbles is low and is not affected by the number of the inlets used. Yet, the water content in the fuel decreases fast during the procedure, which is the desired outcome. We show that this is due to the relatively dry NEA entering the ullage and displacing the moist air, thus reducing the partial pressure of water at the fuel/ullage interface. This shift from equilibrium conditions forces water to evaporate from the fuel’s entire surface. Furthermore, the amount of water migrating from the fuel directly into the ullage is significantly greater than that absorbed by the rising bubbles. In turn, the rate of decrease of the water content in the ullage is determined by the total NEA mass flow rate and this is the dominant contributor to the draining time, with the number of NEA nozzles playing a minor role. We confirmed this by pumping NEA directly into the ullage, where we observe a significant decrease of water even when the NEA is not pumped through the fuel. We also show that doubling the mass flow rate halves the draining time. When considering the capability of most modern aircraft to pump NEA through the fuel as part of their inerting system, the proposed method for removing water is particularly attractive, requiring very little (if at all) design modification. |
| first_indexed | 2024-04-11T21:45:46Z |
| format | Article |
| id | doaj.art-34b19a3439eb426eaf65a509803d96f8 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-04-11T21:45:46Z |
| publishDate | 2018-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-34b19a3439eb426eaf65a509803d96f82022-12-22T04:01:25ZengMDPI AGEnergies1996-10732018-04-0111490810.3390/en11040908en11040908Draining Water from Aircraft Fuel Using Nitrogen Enriched AirMichael Frank0Dimitris Drikakis1Department of Mechanical Aerospace and Engineering, University of Strathclyde, 75 Montrose, Glasgow G11XJ, UKDepartment of Mechanical Aerospace and Engineering, University of Strathclyde, 75 Montrose, Glasgow G11XJ, UKThis paper concerns a computational study of the process of removing water from an aircraft’s fuel tank by pumping nitrogen enriched air (NEA) from the bottom of the tank. This is an important procedure for the smooth, efficient, and safe operation of the aircraft’s engine. Due to the low partial pressure of water in the pumped NEA, it absorbs water from the fuel. The water-laden bubbles enter the ullage, the empty space above the fuel, and escape into the environment. The effects of the number of NEA inlets and the NEA mass flow rate on the timescale of the NEA pumping were investigated using Computational Fluid Dynamics. The results reveal that the absorption of water by the NEA bubbles is low and is not affected by the number of the inlets used. Yet, the water content in the fuel decreases fast during the procedure, which is the desired outcome. We show that this is due to the relatively dry NEA entering the ullage and displacing the moist air, thus reducing the partial pressure of water at the fuel/ullage interface. This shift from equilibrium conditions forces water to evaporate from the fuel’s entire surface. Furthermore, the amount of water migrating from the fuel directly into the ullage is significantly greater than that absorbed by the rising bubbles. In turn, the rate of decrease of the water content in the ullage is determined by the total NEA mass flow rate and this is the dominant contributor to the draining time, with the number of NEA nozzles playing a minor role. We confirmed this by pumping NEA directly into the ullage, where we observe a significant decrease of water even when the NEA is not pumped through the fuel. We also show that doubling the mass flow rate halves the draining time. When considering the capability of most modern aircraft to pump NEA through the fuel as part of their inerting system, the proposed method for removing water is particularly attractive, requiring very little (if at all) design modification.http://www.mdpi.com/1996-1073/11/4/908fuel tankwaternitrogen enriched air (NEA)aircraftinerting systemdehydrate |
| spellingShingle | Michael Frank Dimitris Drikakis Draining Water from Aircraft Fuel Using Nitrogen Enriched Air Energies fuel tank water nitrogen enriched air (NEA) aircraft inerting system dehydrate |
| title | Draining Water from Aircraft Fuel Using Nitrogen Enriched Air |
| title_full | Draining Water from Aircraft Fuel Using Nitrogen Enriched Air |
| title_fullStr | Draining Water from Aircraft Fuel Using Nitrogen Enriched Air |
| title_full_unstemmed | Draining Water from Aircraft Fuel Using Nitrogen Enriched Air |
| title_short | Draining Water from Aircraft Fuel Using Nitrogen Enriched Air |
| title_sort | draining water from aircraft fuel using nitrogen enriched air |
| topic | fuel tank water nitrogen enriched air (NEA) aircraft inerting system dehydrate |
| url | http://www.mdpi.com/1996-1073/11/4/908 |
| work_keys_str_mv | AT michaelfrank drainingwaterfromaircraftfuelusingnitrogenenrichedair AT dimitrisdrikakis drainingwaterfromaircraftfuelusingnitrogenenrichedair |