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This paper presents the design procedure and analysis of a radial turbine design for a mid-scale supercritical CO 2 power cycle. Firstly, thermodynamic analysis of a mid-range utility-scale cycle, similar to that proposed by NET Power, is established while lowering the turbine inlet temperature to 900 ∘ C in order to remove cooling complexities within the radial turbine passages. The cycle conditions are then considered for the design of a 100 MW t h power scale turbine by using lower and higher fidelity methods. A 510 mm diameter radial turbine, running at 21,409 rpm, capable of operating within a 5% range of the required cycle conditions, is designed and presented. Results from computational fluid dynamics simulations indicate the loss mechanisms responsible for the low-end value of the turbine total-to-total efficiency which is 69.87%. Those include shock losses at stator outlet, incidence losses at rotor inlet, and various mixing zones within the passage. Mechanical stress calculations show that the current blade design flow path of the rotor experiences tolerable stress values, however a more detailed re-visitation of disc design is necessitated to ensure an adequate safety margin for given materials. A discussion of the enabling technologies needed for the adoption of a mid-size radial turbine is given based on current advancements in seals, bearings, and materials for supercritical CO 2 cycles.

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The forecasted need for diesel fuel continues to rise, and likewise the competitive biodiesel demand in the middle to long term future remains promising. Unfortunately, biodiesel production generates a significant amount of crude glycerol with the byproduct typically exceeding 10% of the biodiesel produced. The current glycerol market cannot accommodate the use of waste crude glycerol; therefore, an alternative solution is needed for the utilization of the crude glycerol and gasification is a potential pathway. In this work, the technical feasibility of gasification of crude glycerol is assessed at two levels, equilibrium modeling which was conducted under ideal conditions, and high-fidelity reactive flow modeling in a tubular reactor. Results revealed that elevated steam ratios are required for the gasification of glycerol to reach high conversion rates of 99% and an acceptable cold gasification efficiency of 40%. Although this value is far off from the conventional coal gasification that hovers around 60%, the anlysis suggests that gasification of crude glycerol can be accepted as an intermediate solution to the expected flood of glycerol generated by the biodiesel transesterification industry before becoming a waste burden.

The low cycle efficiency of simple cycle micro gas turbines is typically raised by the use of recuperators. The recuperated cycle allows for improved efficiency at low power-to-weight ratio, mainly due to the weight of the added heat exchanger. As weight is considered to be a key parameter for aeroengines, an analysis that addresses benefits and drawbacks of a more efficient, but heavier propulsion system design is required to be carried out. This paper assesses propulsion systems based on simple and recuperated cycle small gas turbine configurations, unusual in aviation, running with conventional jet fuel or hydrogen. An analytical model capable of modelling a turboshaft engine steady state design and off-design operation is developed. The specific fuel consumption of different engine arrangements is therefore calculated to evaluate the performance trade-off between the improved power plant fuel economy and its larger weight under a generic reference mission for a light helicopter. To enable a consistent mission analysis study of the hydrogen fueled rotorcraft, the weight of the tanks for liquid hydrogen storage is estimated according to a preliminary design model. The results obtained suggest that a hydrogen-fueled recuperated powerplant can shorten the flight time to reach the breakeven point, compared to a recuperated jet fuel powerplant of the same power rating.