| Summary: | <p>Nearly 10% of the global energy demand is attributed to high-temperature industrial processes such as steel, cement, and petrochemicals production. More than 90% of this thermal energy originates directly from the combustion of fossil fuels, leading to a staggering 30% of the global anthropogenic greenhouse gas emissions.</p>
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<p>In response to the urgent demand to reduce industrial CO<sub>2</sub> emissions and achieve net-zero by 2050, a new class of electrically-driven, energy-imparting turbomachines referred to as the turbo-heaters have been developed. These machines fundamentally aim to convert mechanical energy into internal energy without pressurising the gas, enabling ultra-high-enthalpy gas heating for a range of high-temperature industrial applications. This work focuses on the development of a family of turbo-heaters tailored for the particular application of steam-cracking for light-olefins production.</p>
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<p>With the elimination of pressure rise as a design criterion, an otherwise unattainable design envelope of stable, ultra-high loading turbomachinery is now unlocked. Detailed numerical simulations were conducted to characterise the nature of the flow under these conditions and to probe the emerging aerodynamic complexities. Results from turbulence-resolving simulations indicated that a stage-loading coefficient of ψ ≥ 4 can be achieved-an order of magnitude greater than that of axial compressors. Ultra-fast energy delivery is accompanied by an ultra-fast energy conversion process, exploiting a system of shockwaves and turbulent mixing. This method not only enables a 500-fold increase in power density compared to conventional approaches but also unlocks thermal cracking chemical reaction conditions currently unattainable.</p>
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<p>In the pursuit of maximising the proposed concept performance and accelerating its industrial deployment, a series of bespoke modelling and design tools were developed. A new scale-adaptive turbulence treatment was introduced into the in-house fluid solver TBLOCK. New design methodologies for the stationary and rotating blading components were formulated and tested using high-fidelity numerical simulations. Two multistage configurations, the axial and the regenerative, were analysed, and their unique potentials in the context of robustness, flexibility and process-customisability were evaluated.</p>
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<p>In conclusion, the results from the first experimental campaign of the pilot machine, conducted by Coolbrook are presented and compared with the results of numerical simulations, strengthening the validity and conclusions drawn throughout this work.</p>
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