Periodic Reporting for period 2 - FUEL DEOX (Optimisation of an on-board adsorbent/catalyst unit for aviation fuel thermal stability improvement)
Periodo di rendicontazione: 2017-08-01 al 2018-07-31
This project experimentally investigates the application of an optimised on-board adsorbent/catalyst unit to reduce the tendency of jet fuel to generate solid carbonaceous deposit the moderate temperature regimes which occur in engine fuels systems. The presence of dissolved oxygen is a key component in the production of these deposits and the proposed onboard conditioning system would seek to remove this dissolved gas from the fuel. Improved fuel thermal oxidative stability offers the potential for the fuel to serve as a better heat sink, absorbing more waste heat from VHBR engines, lowering the cooling load and using the heat to benefit in the engine performance cycle. This leads to a higher efficiency in comparison to adding extra cooling systems employing bleed air that is dumped overboard, and could yield around 2% SFC improvement in association with heat exchanger weight and volume savings.
The oxygen separation by adsorbent/catalysts shows promise as an alternative to the other deoxygenation methods being developed for aviation.
The application of adsorbents/catalysts requires a careful assessment of any changes in fuel chemical composition following fuel deoxygenation. This is primarily due to the fact that there is a trade-off between thermal stability enhancement via oxygen adsorptive separation and fuel lubricity decrease as a result of polar species separation.
The goal of the project is to demonstrate a TRL 5 deoxygenation unit on the Aviation Fuel Thermal Stability Test Unit at Sheffield University.
To achieve the programme goal, the following project objectives will be completed:
1) Optimise the size of the adsorbents/catalysts unit in small scale, bespoke experimental device with respect to flow regime and bulk fuel temperature.
2) Simultaneous thermal oxidative stability assessment of deoxygenated fuel using low medium scale test device namely, “High Reynold Thermal Stability (HiReTS)”.
3) Compositional analysis of deoxygenated fuels with particular focus on side reactions.
4) Fuel lubricity assessment.
5) Calculation of adsorbent longevity using available quantum chemistry methods.
6) Calculation of trade-off between thermal stability enhancement and lubricity decrease using
available quantum chemistry methods.
7) Project scale up and use of the optimised adsorbent/catalyst unit in a TRL5 scale engine representative jet fuel system simulator, namely the “Aviation Fuel Thermal Stability Test Unit (AFTSTU)”.
The oxygen separation by adsorbent/catalysts shows promise as an alternative to the other deoxygenation methods being developed for aviation.
The application of adsorbents/catalysts requires a careful assessment of any changes in fuel chemical composition following fuel deoxygenation. This is primarily due to the fact that there is a trade-off between thermal stability enhancement via oxygen adsorptive separation and fuel lubricity decrease as a result of polar species separation.
The goal of the project is to demonstrate a TRL 5 deoxygenation unit on the Aviation Fuel Thermal Stability Test Unit at Sheffield University.
To achieve the programme goal, the following project objectives will be completed:
1) Optimise the size of the adsorbents/catalysts unit in small scale, bespoke experimental device with respect to flow regime and bulk fuel temperature.
2) Simultaneous thermal oxidative stability assessment of deoxygenated fuel using low medium scale test device namely, “High Reynold Thermal Stability (HiReTS)”.
3) Compositional analysis of deoxygenated fuels with particular focus on side reactions.
4) Fuel lubricity assessment.
5) Calculation of adsorbent longevity using available quantum chemistry methods.
6) Calculation of trade-off between thermal stability enhancement and lubricity decrease using
available quantum chemistry methods.
7) Project scale up and use of the optimised adsorbent/catalyst unit in a TRL5 scale engine representative jet fuel system simulator, namely the “Aviation Fuel Thermal Stability Test Unit (AFTSTU)”.
WP1
A through literature review of the methods investigated for the removal of dissolved oxygen and on-board per-treatment of fuel was completed. Several studies were identified which utilized sparging or membrane separation techniques for the removal of oxygen on-board. No studies were identified showing the per-treatment of fuel on-board, however a limited number of studies investigated the use of sorbents as part of separation processed for the identification of trace components in fuels.
WP2 Experimental work
Significant delays have been encountered in the supply of suitable monolith catalyst and sorbent materials from the suppliers selected by the project. This has delayed the deliverable D3 as an optimisation of bed size was not possible without the material. This material was delivered to Sheffield on the 2nd August and testing work has commenced.
Whilst this work was delayed, the project, in conjunction with the topic manager, carried out work assessing the potential sorbent materials using a small scale thermal stability test methods.
Oxygen separation is delayed by the early absorbtion of Nitrogen containing species and only proceeds once this has reached a saturation absorbtion. This work was reported at the IASH (International Association for the Stability and Handling of Fuels) conference in Rome, September 2017.
WP 3 Modelling work
Computational Models have been developed to understand the interaction of specific Zeolite and Sorbant structures with dissolved oxygen and other hetroatomic species representative of those in Jet fuel.
The challenge remaining is to link the quantum chemistry results to the diffusion modelling in a macro scale which can be used for the design rules for a full scale device (this will be validated against the experimental work). A 1-D model has been developed in COMSOL and can predict the rate of oxygen and limited polar species removal from the fuel. A reaction rate term is used in the mass transport equation through a porous medium with a constant porosity to model the capture process.
A further investigation into the Si/Aluminia ratio in the zeolite is also underway using computational techniques as a result in the long lead times associated with experimental material becoming available.
WP 4 Optimisation
Based on the work in WP2, an design concept for the sorbent structure has been proposed using a monolith structure rather than a pellet based design, which was the previous best possible design. The monolith structure has a number of advantages for the application in flowing systems - it has a lower pressure drop across it and a more benign failure mode compared to other methods for carrying the active material.
WP 5 TRL5 Design work
Results of the scale up laws developed for the DEOX module in WP5 suggest that the developed design will be suitable for use in the TRL 5 rig, with a reactor bed volume of around 10L. However, the full scale system will be prohibitively large for use onboard an aircraft and may be an option for use as a ground handling process as part of the fuel handling and quality control, or at the skin of the aircraft. A TRL5 system has been designed using the pellet option due to the lack of availability of monolith structure within the project. This resulted in a large pressure drop, which had to be overcome by high inlet pump pressures on the TRL5 test rig.
WP 6 TRL 5 testing
Progress was achieved within this WP and the experimental facility was shown to be capable of adaptation to include the DEOX module. Nevertheless, due to several delays and technical constraints, the TRL5 testing for the project was not successfully completed.
A through literature review of the methods investigated for the removal of dissolved oxygen and on-board per-treatment of fuel was completed. Several studies were identified which utilized sparging or membrane separation techniques for the removal of oxygen on-board. No studies were identified showing the per-treatment of fuel on-board, however a limited number of studies investigated the use of sorbents as part of separation processed for the identification of trace components in fuels.
WP2 Experimental work
Significant delays have been encountered in the supply of suitable monolith catalyst and sorbent materials from the suppliers selected by the project. This has delayed the deliverable D3 as an optimisation of bed size was not possible without the material. This material was delivered to Sheffield on the 2nd August and testing work has commenced.
Whilst this work was delayed, the project, in conjunction with the topic manager, carried out work assessing the potential sorbent materials using a small scale thermal stability test methods.
Oxygen separation is delayed by the early absorbtion of Nitrogen containing species and only proceeds once this has reached a saturation absorbtion. This work was reported at the IASH (International Association for the Stability and Handling of Fuels) conference in Rome, September 2017.
WP 3 Modelling work
Computational Models have been developed to understand the interaction of specific Zeolite and Sorbant structures with dissolved oxygen and other hetroatomic species representative of those in Jet fuel.
The challenge remaining is to link the quantum chemistry results to the diffusion modelling in a macro scale which can be used for the design rules for a full scale device (this will be validated against the experimental work). A 1-D model has been developed in COMSOL and can predict the rate of oxygen and limited polar species removal from the fuel. A reaction rate term is used in the mass transport equation through a porous medium with a constant porosity to model the capture process.
A further investigation into the Si/Aluminia ratio in the zeolite is also underway using computational techniques as a result in the long lead times associated with experimental material becoming available.
WP 4 Optimisation
Based on the work in WP2, an design concept for the sorbent structure has been proposed using a monolith structure rather than a pellet based design, which was the previous best possible design. The monolith structure has a number of advantages for the application in flowing systems - it has a lower pressure drop across it and a more benign failure mode compared to other methods for carrying the active material.
WP 5 TRL5 Design work
Results of the scale up laws developed for the DEOX module in WP5 suggest that the developed design will be suitable for use in the TRL 5 rig, with a reactor bed volume of around 10L. However, the full scale system will be prohibitively large for use onboard an aircraft and may be an option for use as a ground handling process as part of the fuel handling and quality control, or at the skin of the aircraft. A TRL5 system has been designed using the pellet option due to the lack of availability of monolith structure within the project. This resulted in a large pressure drop, which had to be overcome by high inlet pump pressures on the TRL5 test rig.
WP 6 TRL 5 testing
Progress was achieved within this WP and the experimental facility was shown to be capable of adaptation to include the DEOX module. Nevertheless, due to several delays and technical constraints, the TRL5 testing for the project was not successfully completed.
The project has demonstrated the potential advantages from a thermal stability perspective of the removal of polar species as well as oxygen using a novel technique and sorbent materials which have previously not been used within the fuels community.
The project has demonstrated the competitive absorption characteristics of this technology for the first time.
The project has used the Quantum Chemical tools to support the experimental work for the first time in the thermal stability community.
A realisable TRL5 scale system was designed, but not tested. Its application as an on board, full engine scale is unlikely due to the size and weight of the device.
The project has demonstrated the use of novel materials for the removal of polar species as part of a ground handling step, prior to the uploading of fuel to the aircraft. This has the potential to increase the range of materials on offer to the fuel handling community to treat or upgrade fuel thermal stability performance at terminals or airport fuel farms.
The project has demonstrated the competitive absorption characteristics of this technology for the first time.
The project has used the Quantum Chemical tools to support the experimental work for the first time in the thermal stability community.
A realisable TRL5 scale system was designed, but not tested. Its application as an on board, full engine scale is unlikely due to the size and weight of the device.
The project has demonstrated the use of novel materials for the removal of polar species as part of a ground handling step, prior to the uploading of fuel to the aircraft. This has the potential to increase the range of materials on offer to the fuel handling community to treat or upgrade fuel thermal stability performance at terminals or airport fuel farms.