Browsing by Author "Huete, Jon"

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    Abating CO2 and non-CO2 emissions with hydrogen propulsion
    (Cambridge University Press (CUP), 2024-04-02) Mourouzidis, Christos; Singh, G.; Sun, X.; Huete, Jon; Nalianda, Devaiah; Nikolaidis, Theoklis; Sethi, Vishal; Rolt, Andrew Martin; Goodger, E.; Pilidis, Pericles
    This contribution focuses on the abatement with hydrogen of CO2 and non-CO2 emissions. It is agenda-setting in two respects. Firstly, it challenges the globally accepted hydrocarbon sustainable aviation fuel (SAF) pathway to sustainability and recommends that our industry accelerates along the hydrogen pathway to ‘green’ aviation. Secondly, it reports a philosophical and analytical investigation of appropriate accuracy on abatement strategies for nitrogen oxides and contrails of large hydrogen airliners. For the second contribution, a comparison is made of nitrogen oxide emissions and contrail avoidance options of two hydrogen airliners and a conventional airliner of similar passenger capacity. The hydrogen aircraft are representative of the first and second innovation waves where the main difference is the weight of the hydrogen tanks. Flights of 1000, 2000, 4000 and 8000 nautical miles are explored. Cranfield’s state of the art simulators for propulsion system integration and gas turbine performance (Orion and Turbomatch) were used for this. There are two primary contributions to knowledge. The first is a new set of questions to be asked of SAF and hydrogen decarbonising features. The second is the quantification of the benefits from hydrogen on non-CO2 emissions. For the second generation of long-range hydrogen-fuelled aircraft having gas turbine propulsion, lighter tanks (needing less thrust and lower gas temperatures) are anticipated to reduce NOx emissions by over 20%; in the case of contrails, the preliminary findings indicate that regardless of the fuel, contrails could largely be avoided with fuel-burn penalties of a few per cent. Mitigating action is only needed for a small fraction of flights. For conventional aircraft this penalty results in more CO2, while for hydrogen aircraft the additional emission is water vapour. The conclusion is that our research community should continue to consider hydrogen as the key ‘greening’ option for aviation, notwithstanding the very significant costs of transition.
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    Hydrogen propulsion for civil aviation: an introduction scenario
    (ISABE, 2022-09-30) Pantelis, Isidoros; Huete, Jon; Nalianda, Devaiah; Jarzębowska, Elżbieta; Pilidis, Pericles
    Civil aircraft that fly medium and long ranges consume a large fraction of civil aviation fuel, injecting an important amount of aviation carbon into the atmosphere. Decarbonising solutions must consider this sector in a holistic manner. Hydrogen is increasingly seen as a key solution. There is a number of major issues to resolve. One of them is the provision of appropriate airport infrastructure. A philosophical-analytical scenario feasibility is proposed here based on an airliner family, previously proposed by the authors to assist in the elimination of carbon dioxide emissions from civil aviation. The family comprises six airliner models derived (not retrofits) from existing state of the art airliners. The objective of the philosophical investigation presented here is to explore the gradual implementation of airport infrastructure considering geographical and traffic characteristics. The outcome is a plausible and effective scenario where a gradual introduction of Hydrogen fuel is proposed where for a few decades Hydrogen will coexist with conventional fuels and drop-in Sustainable Aviation Fuels. This scenario proposes a first generation of six very large hydrogen hubs to cover very large traffic centres to make in the first instance deep inroads into civil aviation carbon emissions. A second generation of 16 hydrogen hubs is also proposed that would enable a global span. These two generations of hydrogen hubs could enable a very wide introduction of hydrogen in the long term by catalysing cost reductions with volume and experience, in the long-term delivering 3rd, 4th and nth generations of hydrogen hubs where reliance on carbon fuels is gradually reduced until they have been fully displaced in the long term.
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    Impact of tank gravimetric efficiency on propulsion system integration for a first-generation hydrogen civil airliner
    (Cambridge University Press, 2022-06-10) Huete, Jon; Nalianda, Devaiah; Pilidis, Pericles
    Civil aircraft that fly long ranges consume a large fraction of civil aviation fuel, injecting an important amount of aviation carbon into the atmosphere. Decarbonising solutions must consider this sector. A philosophical-analytical feasibility of an airliner family to assist in the elimination of carbon dioxide emissions from civil aviation is proposed. It comprises four models based on the integration of the body of a large two-deck airliner with the engines, wings and flight surfaces of a long-range twin widebody jet. The objective of the investigation presented here is to evaluate the impact of liquid hydrogen tank technology in terms of gravimetric efficiency. A range of hydrogen storage gravimetric efficiencies was evaluated; from a pessimistic value of 0.30 to a futuristic value of 0.85. This parameter has a profound influence on the overall fuel system weight and an impact on the integrated performance. The resulting impact is relatively small for the short-range aircraft; it increases with range and is important for the longer-range aircraft. For shorter-range aircraft variants, the tanks needed to store the hydrogen are relatively small, so the impact of tank weight is not significant. Longer range aircraft are weight constrained and the influence of tank weight is important. In the case of the longest range, the deliverable distance increases from slightly over 4,000 nautical miles, with a gravimetric efficiency of 0.3, to nearly 7,000 with a gravimetric efficiency of 0.85.
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    Parametric study on tank integration for hydrogen civil aviation propulsion
    (Elsevier, 2021-09-30) Huete, Jon; Pilidis, Pericles
    Hydrogen powered gas turbine propulsion will play a central role in the decarbonisation of civil aviation. A key challenge is the integration of large liquid hydrogen tanks into the aircraft, given the low density of liquid hydrogen. Hydrogen offers a quarter of the energy content, per unit volume and one third of the fuel weight, when compared to a conventional fuel. Optimising tank weight is seen as key to aircraft usefulness. A detailed evaluation of tanks for civil aviation is presented here, covering a very wide range of sizes and design solutions. For passenger air transport, if the choice is made not to vent, dormancy time (the time the tank can be allowed to operate without vapour or important fuel extraction) becomes a key design parameter. This paper highlights the interdependence of Maximum Allowable Operating Pressure and the amount of insulation with heating and venting, considering the influence of dormancy time. The resulting tank gravimetric efficiency is presented for cylindrical tanks with hemispheric ends (a very likely choice for tank design). Notwithstanding conservative analysis, tank gravimetric efficiencies of 65–70% can be achieved. This permits combined fuel and tank weights that are less than half of those of current aircraft. The issue that then becomes critical is the resulting large tank and aircraft volume.
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    Propulsion system integration for a first-generation hydrogen civil airliner?
    (Cambridge University Press (CUP), 2021-05-28) Huete, Jon; Nalianda, Devaiah; Pilidis, Pericles;
    An unusual philosophical approach is proposed here to decarbonise larger civil aircraft that fly long ranges and consume a large fraction of civil aviation fuel. These inject an important amount of carbon emissions into the atmosphere, and holistic decarbonising solutions must consider this sector. A philosophical–analytical investigation is reported here on the feasibility of an airliner family to fly over long ranges and assist in the elimination of carbon dioxide emissions from civil aviation. Backed by state-of-the-art correlations and engine performance integration analytical tools, a family of large airliners is proposed based on the development and integration of the body of a very large two-deck four-engine airliner with the engines, wings and flight control surfaces of a very long-range twin widebody jet. The proposal is for a derivative design and not a retrofit. This derivative design may enable a swifter entry to service. The main contribution of this study is a philosophical one: a carefully evaluated aircraft family that appears to have very good potential for first-generation hydrogen-fuelled airliners using gas turbine engines for propulsion. This family offers three variants: a 380-passenger aircraft with a range of 3,300nm, a 330-passenger aircraft with a range of 4,800nm and a 230-passenger aircraft with a range of 5,500nm. The latter range is crucially important because it permits travel from anywhere in the globe to anywhere else with only one stop. The jet engine of choice is a 450kN high-bypass turbofan
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    Thermal management challenges in hybrid-electric propulsion aircraft
    (Elsevier, 2023-12-08) Asli, Majid; König, Paul; Sharma, Dikshant; Pontika, Evangelia; Huete, Jon; Konda, Karunakar Reddy; Mathiazhagan, Akilan; Xie, Tianxiao; Höschler, Klaus; Laskaridis, Panagiotis
    The utilization of hybrid electric propulsion concept in aviation offers a viable solution to address the limitations posed by the relatively low energy density of batteries in fully electric aviation. These hybrid systems enable the aircraft to achieve a significant range while simultaneously minimizing carbon emissions. While the individual components of a Hybrid Electric Propulsion (HEP) system, such as electric motors and batteries, are designed with high efficiency, their integration presents a significant challenge in the realm of thermal management. Designing an efficient system for managing the substantial waste heat generated by heat sources and effectively transferring it to heat sinks during various flight phases is a complex task. This challenge becomes even more critical as the design must adhere to system weight limits and prioritize aviation safety considerations. In this review article, we performed a systematic review of the challenges related to the key elements in a thermal management system. These elements encompass every component or subsystem that contributes to the thermal management of a generic hybrid-electric propulsion system. This includes electric motors and generators, batteries, heat exchangers, power transmission systems, power distribution systems, storages, fuel cells, cooling fluids and pipes, control system, pumps and fans. Following the identification of the challenges, the paper provides a comprehensive summary of the existing solutions that have been offered and pursued by the community to address the challenges. Furthermore, the paper also discusses emerging technologies related to each element, highlighting their potential in overcoming these challenges.