Higher Turbine Inlet Temperature Research Articles

Thermodynamic Analysis of Marine Diesel Engine Exhaust Heat-Driven Organic and Inorganic Rankine Cycle Onboard Ships

Due to increasing emissions and global warming, in parallel with the increasing world population and energy needs, IMO has introduced severe rules for ships. Energy efficiency on ships can be achieved using the organic and inorganic Rankine cycle (RC) driven by exhaust heat from marine diesel engines. In this study, toluene, R600, isopentane, and n-hexane as dry fluids; R717 and R718 as wet fluids; and R123, R142b, R600a, R245fa, and R141b as isentropic fluids are selected as the working fluid because they are commonly used refrigerants, with favorable thermal properties, zero ODP, low GWP and are good contenders for this application. The cycle and exergy efficiencies, net power, and irreversibility of marine diesel engine exhaust-driven simple RC and RC with a recuperator are calculated. For dry fluids, the most efficient fluid at low turbine inlet temperatures is n-hexane at 39.75%, while at high turbine inlet temperatures, it is toluene at 41.20%. For isentropic fluids, the most efficient fluid at low turbine inlet temperatures is R123 with 23%, while at high turbine inlet temperatures it is R141b with 23%. As an inorganic fluid, R718 is one of the most suitable working fluids at high turbine inlet temperatures of 300 °C onboard ships with a safety group classification of A1, ODP of 0, and GWP100 of 0, with a cycle efficiency of 33%. This study contributes to significant improvements in fuel efficiency and reductions in greenhouse gas emissions, leading to more sustainable and cost-effective maritime operations.

Comprehensive analysis on suitability of alkali metals with high enthalpy characteristics for space nuclear Rankine cycle

The compatibility between working fluids and high-temperature thermal systems is essential for improving system performance, stability, and safety. This article focuses on exploring the relative adaptability of alkali metals in nuclear high-temperature Rankine systems under three operating conditions: different output powers, different core powers, and different mass flow, evaluating from three dimensions: thermal, economic, and weight. The study finds that the cesium and potassium cycles represent systems for low and high turbine inlet temperatures, respectively. At a turbine inlet temperature of 1100 K, the cesium cycle can enhance thermal efficiency by 32.14 %, while with the turbine inlet temperature increased to 1500 K, the potassium cycle can improve efficiency by 28.19 %. Under varying output power and core power conditions, the high-temperature potassium cycle demonstrates more significant performance advantages. Compared to the cesium cycle, both economic and weight performances are seen an increase of approximately 20 %. Under varying mass flow conditions, the cesium cycle has a significant weight advantage. The mass flow increases from 0.5 to 2.5 kg/s, and the proportion of specific weight for the cesium cycle compared to the potassium cycle decreases from 54.90 % to 12.93 %. However, the output power of the potassium cycle is ten times that of the cesium cycle with the same mass flow. This research offers valuable insights for selecting optimal working fluids in high-temperature thermal systems considering operating conditions and mission requirements.

Numerical Investigation of the Effect of Trailing Edge Thickness of Simulated Ceramic Matrix Composite Blades on Loss Profiles

Abstract Ceramic matrix composite (CMC) is an enabling material allowing higher turbine inlet temperatures and possibly resulting in better thermal efficiency of gas turbine engines. This is because CMC layers with environmental barrier coating have significantly higher thermal limits (∼1755 K) compared with the more conventional alloyed metallic blades. CMCs possess a complex fabrication process resulting in different geometrical characteristics than metallic blades (e.g., larger trailing edge thickness, large leading-edge curvature, etc.). It is therefore desirable to assess the aerodynamic performance of the CMC blades using experimental and numerical simulations. To investigate, three different CMC blades with varying trailing edge thicknesses were numerically simulated. Both large-eddy simulation with the dynamic subgrid closure as well a recently implemented Reynolds-averaged Navier–Stokes coupled with an intermittency function-based transition model were utilized. Two sets of experimental test points with different Reynolds numbers at a given high-freestream turbulence range (Tu = ∼10–13%) were considered. The predicted pressure loading profiles, total loss distributions, and integrated loss of the three different CMC blades were computed and comparisons against the experimental data are presented herein. It was found that the mixing loss forms a larger proportion of the overall loss as the trailing edge thickness increases.

Design and Cooling Performance of Additively Manufactured Ceramic Turbine Vanes

Abstract Ceramic materials are of significant interest in aviation and power generation gas turbine engines due to their low density and ability to withstand high temperatures. Increased cycle thermal efficiency and higher specific power output is possible by incorporating ceramic components that enable high turbine inlet temperatures and lower required cooling airflow levels. However, ceramics can be difficult and costly to form into the complex shapes used in gas turbine components, often requiring specialized multi-step processes. Furthermore, ceramic components in the hottest areas of a gas turbine, such as vanes or blade shroud seals, will still likely require cooling which is challenging to implement in conventional ceramic manufacturing approaches. Therefore, this study presents a multidisciplinary approach that investigates the design, fabrication, and overall cooling effectiveness evaluation of additively manufactured (AM), polymer derived ceramic (PDC) turbine vanes. A thermo-mechanically optimized vane design was generated, ceramic additive manufacturing of the complex cooling configuration was developed, and quantification of the increase in overall cooling effectiveness was performed in a 1X scale, high-speed facility using infrared thermography. This study produced a PDC AM process, capable of printing complex internal cooling schemes in 1X scale turbine vanes. It was found that the optimized vane more than doubled the overall cooling effectiveness observed in the baseline design, which reasonably agreed with thermomechanical optimization model predictions. Additionally, the optimized ceramic vane outperformed an identical metal vane, in terms of area averaged cooling effectiveness, suggesting that the ceramic vane could operate at reduced coolant flowrates to achieve comparable levels of cooling performance.

Thermodynamics, Environmental and Sustainability Impacts of a Turbofan Engine Under Different Design Conditions Considering Variable Needs in the Aviation Industry.

In this study, thermodynamic analysis is implementedto the kerosene-fuelled high by-pass turbofan (HBP-TF) engine to assess entropy, exergy, environmental, and sustainability metrics for different design variables such as pressure ratio of high-pressure compressor (HPC-PR) ranging from 7.5 to 8.5 and turbine inlet temperature (TIT) varying from 1400 to 1525K considering variable needs in the aviation industry. As a novelty, entropic improvement potential (EIP) index for turbomachinery components and specific irreversibility production for the whole engine are calculated. Sustainability-based parameters for different cases are compared with the baseline values of the HBP-TF engine. The combustor has the highest entropy production of 44.4425kWK-1 at the baseline. The higher TIT increases the entropy production of the combustor by 16.56%, whereas the higher HPC-PR decreases it by 5.83%. The higher TIT and HPC-PR favorably affect the sustainable efficiency factor of the engine, which is observed as 1.5482 at baseline and increases by 4.5% and 0.058% with the increment of TIT and HPC-PR, respectively. The higher TIT and higher HPC-PR results in lowering sustainability of the engine. The specific irreversibility production of the engine decreases by 3.78% and 0.1171% respectively, as TIT and HPC-PR reach the highest point considered in the study.

System design and thermo-economic analysis of a new coal power generation system based on supercritical water gasification with full CO2 capture

To achieve sustainable energy supply and carbon neutral, it is essential to enhance the efficiency and reduce carbon emissions for coal power. In this study, a coal power generation system based on supercritical water gasification (SCWG) with full CO2 capture is proposed. The system achieves autothermal gasification by partial oxidation of coal in the SCWG gasifier. Gasification water is preheated by turbine exhaust, and organic Rankine cycle (ORC) is integrated to recover the waste heat of turbine exhaust. Simulation and thermodynamic analysis models of the system are developed. Results show the energy efficiency and exergy efficiency of system with benchmark parameters reach 52.95 % and 54.11 %, respectively. The largest exergy destruction occurs in gasifier and accounts for 41.36 % of the total exergy loss. Irreversibility of heat transfer mainly occurs in water heat exchanger and ORC, accounting for 4.81 % and 5.59 % of the total loss. Effects of key operating parameters on the system performance are investigated. Results show the optimal turbine exhaust pressure is 0.1 MPa, and higher turbine inlet temperature can enhance the system efficiency. System with reheat configuration shows potential in thermodynamic and economic aspects, and the exergy efficiency of double reheat system is improved from 37.25 % to 45.08 %.

Enhancing Gas Turbine Power Plant Performance in Tropical Climates by Using Inlet Air Cooling with Desiccant Dehumidification and Evaporative Cooling

Abstract Gas turbine power plants play a crucial role in meeting the growing demand for electrical energy. However, their performance can be hindered by high ambient temperatures and humidity levels in tropical climates, leading to a drop in power output. This study investigates the potential benefits of using inlet air cooling with desiccant dehumidification and evaporative cooling to improve the performance of gas turbine power plants in tropical regions. The results show that this inlet air cooling method, integrating evaporative cooling, desiccant wheel, and Maisotsenko cooler, is a viable alternative for mitigating the performance decrease of gas turbines in hot tropical conditions. Furthermore, the compressor inlet temperature can be reduced on average by 11.5 °C by using turbine exhaust gases to heat the regeneration air utilized in the desiccant wheel for dehumidification. Additionally, the power requirement of the inlet air cooling system amounts to around 0.9 MW compared with an improvement of more than 2 MW in power output at peak temperature. Further research is needed to understand and quantify other benefits related to inlet air cooling, such as reducing emissions of harmful pollutants and operating at higher turbine inlet temperatures.

Effect of coating degradation on the hot corrosion behavior of yttria-stabilized zirconia (YSZ) and blast furnace slag (BFS) coatings

In order to provide thermal insulation thermal barrier coatings (TBCs) used in gas turbine engine components under conditions of impure fuels and high turbine inlet temperatures are expected to have hot corrosion resistance. Techniques and material combinations used in the production of TBCs are primarily effective in the progression of failure mechanisms as a result of hot corrosion. In this study, the hot corrosion damage mechanism, which is caused by the impurities of the fuels used in the industry and causes great damage to the TBC systems, was simulated and evaluated in the laboratory environment. For the creation of TBC systems, CoNiCrAlY metallic bond coating powders were deposited on Ni-based super alloy substrates by the detonation gun (D-gun) process. Commercial yttria-stabilized zirconia (YSZ) and blast furnace slag (BFS) powders were deposited on the bond coating by Atmospheric plasma spraying (APS) technique. Hot corrosion testing of TBCs was performed at 800 °C for 8, 24, 50, and 75 h in an environmental condition consisting of a 45 wt% Na2SO4 and 55 wt% V2O5 corrosive salt mixture. Blast furnace slag, which is completely cost-free and a waste product, provided excellent protection against hot corrosion damage without deteriorating its stability at high temperatures. In this way, it is open to be evaluated as a new type of coating material alternative to the traditional top coating material YSZ, which has a very high production and cost, and to be used in different areas.

Thermodynamic performance study of large-scale industrial gas turbine with methane/ammonia/hydrogen blended fuels

The fuel interchangeability range without any modifications was proposed within 5% of Wobbe index (WI) by the gas turbine manufacturers. The system modifications, especially in combustor, are needed with the out-of-range 5% of WI. In this study, the thermodynamic performances were studied with the fuels exceeding 5% of WI, the focused fuel compositions were ammonia and hydrogen for eco-friendly power generation and carbon neutrality. A performance analysis was conducted for a J-class gas turbine wherein ammonia and hydrogen were mixed with conventional liquefied natural gas (LNG) fuel. The maximum mixable ratio of ammonia is 76%, and fuels with higher mixable ratio cannot achieve a high turbine inlet temperature (1873 K). 100% hydrogen can be used with stable operation if the flame stability is guaranteed by developing a new combustor with conventional compressor and turbines. Environmental–economic analysis was also conducted to study the effect of carbon-neutral fuel on air pollution. Mixing hydrogen is a highly effective method to reduce the air pollutant tax; however, mixing ammonia is not suitable for decreasing air pollutants. As ammonia emits enormous NOx, an after-treatment system is required to use ammonia as a carbon-neutral fuel.

Heat Transfer Analysis of Damaged Shrouded High-Pressure Turbine Rotor Blades

Due to the increasingly high turbine inlet temperatures, heat transfer analysis is now, more than ever, a vital part of the design and optimization of high-pressure turbine rotor blades of a modern jet engine. The present study aimed to find out how shape deviation and in-service deterioration affect heat exchange patterns on the rotor blade. The rotor geometries used for this analysis are represented by a set of high-resolution 3D structured light scans of blades with the same number of in-service hours. An automatic meshing technique was employed to generate high-resolution meshes directly on the scanned rotor geometries, which captured all the surface features with high fidelity. Steady-state 3D RANS flow simulations with a k-ω SST turbulence model were conducted on a one-and-a-half stage computational domain of the scanned geometries. First, the distribution of the heat transfer coefficient was calculated for each blade; then, a correlation was sought between the heat transfer coefficient and parametrized shape deviation, to assess the impact of each parameter on HTC levels.

Part-load performance analysis of a dual-recuperated gas turbine combined cycle system

To undertake peak shaving tasks, gas turbine combined cycle (GTCC) units often deviate from the design operating point. In order to improve the off-design performance of GTCCs, a dual-recuperated gas turbine combined cycle (DRGTCC) system based on partial recuperation and compressor inlet air heating is proposed in this paper. The operating characteristics of the novel system using the proposed operation strategy are investigated, and the effects of pressure drop in recuperators and ambient temperature on system performance are discussed. The results indicate that, compared with the GTCC system, the DRGTCC system has higher turbine inlet temperature (TIT) and turbine expansion ratio at the same power output, and the performance has been improved especially at lower power outputs. When the inlet temperature of the compressor is increased from 0 °C to 45 °C, the air mass flowrate can be regulated between 46.0% and 100% of the design value. The combined cycle efficiency of the DRGTCC system is improved by 2.55 percentage points at 45.5% design combined cycle load. Moreover, the sensitivity analysis shows that the system performance decreases with the increase of the pressure drop in recuperators, and the ambient temperature affects the load regulation range and efficiency.

Laser powder bed fusion technique of hydrogen–fueled gas turbine: Role of advanced materials and its challenges

Aviation accounts for 1.9% of greenhouse gas emissions, decarbonization is not straightforward as electrification is not feasible, and biofuels only partially address the issue. Therefore, aero-engine manufacturers are looking towards hydrogen as a clean fuel source as the emissions would majorly be water with no lasting greenhouse gasses. The major challenge with hydrogen-firing engines would be high firing temperatures, corrosive exhaust gasses and adverse reactions with structural components. The design flexibility of additive manufacturing (AM) and advanced materials development, such as high entropy alloys (HEAs) can be combined to produce gas turbines with higher turbine inlet temperatures and power output. This paper discusses the advantages and issues with hydrogen as fuel, the role of AM and advanced materials suitable for hydrogen-firing engines.

EFFECTS OF ADDITIVELY MANUFACTURED SURFACE ROUGHNESS ON SMALL DIAMETER PLENUMS WITH MULTIPLE SIDE DISCHARGES FOR HIGH TEMPERATURE GAS TURBINE BLADE COOLING APPLICATIONS

Combined heat and power (CHP) applications have significant environmental and economic benefits that are consistent with the goals of the U.S. Department of Energy (DOE). One area that is currently being studied includes the potential benefits of CHP turbine operation at higher turbine inlet temperatures. Internal cooling concepts enabled by additive manufacturing (AM) are of primary interest. The effectiveness of internal cooling is hindered by many factors such as velocity distribution of the cooling air to the hot surface considering impingement cooling. To simulate cooling air exiting from a series of orifices for internal cooling in an airfoil, a straight smooth wall tubing with multiple side discharging orifices is used and compared to additively manufactured tubing (Ti6Al4V Grade 23) with orifice size and spacing as well as inner and outer diameters identical to the smooth wall tubing. Similar to flow discharging form perforated pipes, the flow discharged from individual orifices along the tubes in this study is found to be nonuniformly distributed, and the horizontal (axial direction) momentum can be observed from the experimental data. Discharge velocities have been measured with two-dimensional (2D) particle imaging velocimetry (PIV) and single element hot wire anemometry. Numerical analysis has also been conducted to predict the velocity distributions along the orifices in the smooth wall and additive manufacturing (AM) tubing, which are inherited with surface roughness. Numerical and measured results in this study are compared, presented, and discussed.

Thermo-economic analysis of combined transcritical CO2 power cycle based on a novel liquefied-biomethane energy storage system

The Chinese government has been encouraging to accelerate the development of energy storage systems to support the rapid growth of renewable energy power generation. For the purpose of achieving flexible and economic energy storage, in this study, a combined transcritical CO2 power cycle is added to biomethane plants to form a liquefied-biomethane energy storage system. A mathematical model that includes terms of energy, exergy, and economy is established to assess the performance of the combined transcritical CO2 power cycle. The effects of critical parameters on the thermo-economic performance are studied. A sensitivity analysis is used to evaluate the extent of the influence of critical parameters. According to the simulation results, the characteristics of the liquefied-biomethane energy storage system are calculated and evaluated. The results show that at a liquefied-biomethane mass flow rate of 1 kg/s, the maximum net power output of the combined transcritical CO2 power cycle reaches 909.81 kW by adjusting the pressure and temperature. High turbine inlet temperature, pump pressure ratio, and methane purity have positive effects on system performance. Among these, the inlet temperature of turbine 2 is the most sensitive factor. Simultaneously, the maximum energy storage density and round-trip efficiency of the liquefied-biomethane energy storage system are 106.8 Wh/L and 52.7 %, respectively. Benefiting from less upfront equipment investment, the lowest power capital cost of the liquefied-biomethane energy storage system is 885.3 $/kW. In conclusion, the liquefied-biomethane energy storage system integrated with a combined transcritical CO2 power cycle exhibits good performance in terms of power output and economy.

Influence of operating parameters on the performance of combined cycle based on exergy analysis

This paper presents the energy and exergy analysis for actual data of the triple-pressure combined cycle power plant (CCPP). This study was carried out to evaluate each component's power plant efficiency and destruction rate. Furthermore, to investigate the effect of operating parameters on a combined cycle power plant using an engineering equation solver (EES) program. The result shows that the net energy and exergy efficiency is calculated at 56%and 54%, respectively. Also, by exergy analysis, the major source of exergy destruction among components occurs in the combustion chamber with a value of 314.6 MW which is 58% of the total exergy destruction in power plants. The exergy destruction was significantly affected by the increased ambient temperature. The heat transfer rate can be reduced with the high-pressure ratio in the gas turbine, leading to an increase in the overall efficiency. Besides that, the high turbine inlet temperature increased the steam cycle's generated power and the power plant's overall efficiency. Reducing the exergy destruction rate will increase the power output and efficiency of the combined cycle power plant. Therefore, maximum efficiency could be achieved by decreasing the ambient temperature and increasing the turbine inlet temperature.

Thermodynamic analysis of subcritical/transcritical ORCs with metal–organic heat carriers for efficient power generation from low-grade thermal energy

Recovery of low-grade energy for power generation by organic Rankine cycle (ORC) can effectively alleviate energy crisis and reduce CO2 emission, but the low heat source temperature severely affects the thermal efficiency and output power of the system. Using new working fluids with enhanced thermal properties is one promising approach to improve cycle performance. Based on the concept of nanofluids with conventional refrigerants and metal–organic heat carriers (MOHCs), thermodynamic models of subcritical/transcritical basic ORC and regenerative ORC (RORC) with R134a/Cr-MIL-101 and R134a/Mg-MOF-74 nanofluids are constructed. Thermodynamic analysis results reveal that adsorption of R134a from MOFs increases pump work input and the turbine work output, while desorption increases the evaporator heat input. Also, MOHCs improve the thermal efficiency of both ORC and RORC, and the thermal efficiency improvement ratio of transcritical cycle is maximized at high evaporation pressure and low turbine inlet temperature. By adding a 0.9% mass fraction of Mg-MOF-74 to R134a, the maximum thermal efficiency of RORC is improved from 13.66% to 16.61%, and its maximum specific net work output is increased from 27.82 kJ/kg to 34.42 kJ/kg. Furthermore, both exergy efficiency and economic benefit are improved with MOHC-added systems.

Compact High Efficiency and Zero-Emission Gas-Fired Power Plant with Oxy-Combustion and Carbon Capture

Reduction of greenhouse gases emissions is a key challenge for the power generation industry, requiring the implementation of new designs and methods of electricity generation. This article presents a design solution for a novel thermodynamic cycle with two new devices—namely, a wet combustion chamber and a spray-ejector condenser. In the proposed cycle, high temperature occurs in the combustion chamber because of fuel combustion by pure oxygen. As a consequence of the chemical reaction and open water cooling, a mixture of H2O and CO2 is produced. The resulting working medium expands in one turbine that combines the advantages of gas turbines (high turbine inlet temperatures) and steam turbines (full expansion to vacuum). Moreover, the main purpose of the spray-ejector condenser is the simultaneous condensation of water vapour and compression of CO2 from condensing pressure to about 1 bar. The efficiency of the proposed cycle has been estimated at 37.78%. COM-GAS software has been used for computational flow mechanics simulations. The calculation considers the drop in efficiency due to air separation unit, carbon capture, and spray-ejector condenser processes. The advantage of the proposed cycle is its compactness that can be achieved by replacing the largest equipment in the steam unit. The authors make reference to a steam generator, a conventional steam condenser, and the steam-gas turbine. Instead of classical heat exchanger equipment, the authors propose non-standard devices, such as a wet combustion chamber and spray-ejector condenser.

Topology Optimization and Experimental Validation of an Additively Manufactured U-Bend Channel

Abstract Serpentine channels are a common feature seen in heat ex-changer geometries. For example, they are present in midchord regions of gas turbine blades to prevent material failure at high turbine inlet temperatures. Due to their serpentine nature, these channels contain 180 deg turns or U-bends. These U-bends are responsible for nearly 20% of the pressure drop in such channels (Verstraete et al., 2013, “Optimization of a U-Bend for Minimal Pressure Loss in Internal Cooling Channels-Part I: Numerical Method,” ASME J. Turbomach., 135(5), p. 051015). A topology optimization (TO) method has been used in this study to optimize the shape of a baseline U-bend for minimum pressure drop, at a Reynolds number of 17,000. TO uses a variable permeability approach to design an optimum flow-path by manipulation of solid blockage distribution in the flow-path. The pressure drop across the channel was lowered by 50% when compared to a standard U-bend channel profile from literature. Postprocessing was performed to extract the flow-path and run a forward simulation in star-ccm+ after remeshing with wall refinement. A 3D printed model of the TO shape and benchmark U-bend was created using acrylonitrile butadiene styrene as the printing material, to confirm the results of the turbulent fluid TO, which is a relatively untouched topic in current TO literature. Experimental results showed deviation from computational fluid dynamics (CFD) by about 5%. Comparison of the TO optimum was carried out with an in-house parametric shape optimization using surrogate model-based Bayesian optimization (BO) and a similar shape optimization study from literature. A higher reduction in pressure drop was seen in the case of the TO geometry when compared to the benchmark and the BO cases.

A New Experimental Approach for Heat Transfer Coefficient and Adiabatic Wall Temperature Measurements on a Nozzle Guide Vane With Inlet Temperature Distortions

AbstractModern gas turbines lean combustors allow to limit NOx pollutant emissions by controlling the flame temperature, while maintaining high turbine inlet temperatures. On the other hand, their adoption presents other challenges, especially concerning the combustor–turbine interaction. Turbine inlet conditions are generally characterized by severe temperature distortions and swirl degree, which, in turn, is responsible for very high turbulence intensities. Several past studies have focused on the description of the effects of these phenomena on the behavior of the high pressure stages of the turbine, both considering them as separated aspects, and, in very recent years, accounting for their combined impact. Nevertheless, very limited experimental results are available when it comes to evaluate the heat transfer coefficient (HTC) on the nozzle guide vane (NGV) external surface, since relevant temperature distortions present a severe challenge for the commonly adopted measurement techniques. The work presented in this paper was carried out on a non-reactive, annular, three-sector test rig, made by a combustor simulator and a NGV cascade. Making use of three real hardware burners of a Baker Hughes heavy-duty gas turbine, operated in similitude conditions, it can reproduce a representative swirling flow, with temperature distortions at the combustor–turbine interface plane. This test apparatus was exploited to develop an experimental approach to retrieve reliable HTC and adiabatic wall temperature distributions simultaneously, in order to overcome the known limitations imposed by temperature gradients on state-of-the-art methods for HTC calculation from transient tests. A non-cooled mockup of a NGV doublet, manufactured using low thermal diffusivity plastic material, was used for the tests, carried out using infra-red thermography with a transient approach. In the authors’ knowledge, this presents the first experimental attempt of measuring a NGV HTC in the presence of relevant temperature distortions and swirl.

Proof-of-Concept of a Thermal Barrier Coated Titanium Cooling Layer for an Inside-Out Ceramic Turbine

Abstract Increasing turbine inlet temperature (TIT) of recuperated gas turbines would lead to simultaneously high efficiency and power density, making them prime candidates for low-emission aeronautics applications, such as hybrid-electric aircraft. The inside-out ceramic turbine (ICT) architecture achieves high TIT by using compression-loaded monolithic ceramics. To resist inertial forces due to blade tip speed exceeding 450 m/s, the shroud of the ICT is made of carbon-polymer composite, wound around a metallic cooling ring. This paper demonstrates that it is beneficial to use a titanium alloy cooling ring with a thermal barrier coating (TBC), rather than nickel superalloys, for the interstitial cooling ring protecting the carbon-polymer from the hot combustion gases. A numerical design of experiments (DOE) analysis shows the design tradeoffs between the minimum safety factor and the required cooling power for multiple geometries. An optimized high-pressure first turbine stage of a 500 kW microturbine concept using ceramic blades and a titanium cooling ring in an ICT configuration is presented. Its structural performance (minimum safety factor of 1.4), as well as its cooling losses, (2% of turbine stage power) are evaluated. Finally, a 20 kW-scale prototype is tested at 300 m/s and a TIT of 1375 K during 4 h to demonstrate the viability of the concept. Experiments show that the polymer composite was kept below its maximum safe operating temperature and components show no early signs of degradation.