Blog Elements

Half Sized Blog Element (Single Author Style)

Half Sized Blog Element (Multi Author Style)

Paper on energy losses in radial turbines presented by City, University of London at ASME Turbo Expo, Boston (USA)

15 July, 2023/in Conference and journal papers /by jose

Fan power consumption at reduced mass flow rate for different ACC designs The researchers at City, University of London have presented their work assessing the different contributions to energy losses experienced by radial turbines working with Carbon Dioxide mixtures in supercritical power cycles. This research work also considers the effect of turbine scale on […]

Paper on off-design operation of ACCs presented by University of Seville at ASME Turbo Expo, Boston (USA)

15 July, 2023/in Conference and journal papers /by jose

Fan power consumption at reduced mass flow rate for different ACC designs The researchers at University of Seville have presented their work assessing the part-load operation of supercritical power cycles running on Carbon Dioxide mixtures. As a continuation of the work presented at the 5th European Conference on Supercritical Carbon Dioxide Energy Systems, where […]

Paper on energy losses in radial turbines presented by City, University of London at ASME Turbo Expo, Boston (USA)

15 July, 2023/in Conference and journal papers /by jose

Paper on off-design operation of ACCs presented by University of Seville at ASME Turbo Expo, Boston (USA)

15 July, 2023/in Conference and journal papers /by jose

Full Sized Blog Element (Big Preview Pic)

Paper on energy losses in radial turbines presented by City, University of London at ASME Turbo Expo, Boston (USA)

15 July, 2023/in Conference and journal papers /by jose

Fan power consumption at reduced mass flow rate for different ACC designs

The researchers at City, University of London have presented their work assessing the different contributions to energy losses experienced by radial turbines working with Carbon Dioxide mixtures in supercritical power cycles. This research work also considers the effect of turbine scale on the breakdown of energy losses, assessing this for turbines in cycles rated at 0.1 MWe, 1 MWe and 10 MWe. The work makes use of meanline design codes and CFD analysis to assess the impact of fluid composition and scale and to compare the data obtained against data from literature.

Meridional profile of radial inflow turbines working with different Carbon Dioxide mixtures and with different scales (plots are not to scale)

The paper can be downloaded free of charge from the conference website (link). Check the abstract below:

Recent studies have indicated the potential of CO₂-mixtures to lower the cost of concentrated solar power plants. Based on aerodynamic and cost considerations, radial inflow turbines (RIT) can be a suitable choice for small to medium sized sCO₂ power plants (about 100 kW to 10 MW). The aim of this paper is to quantify the effect of doping CO₂ on the design of RITs. This is achieved by comparing the 1D mean-line designs and aerodynamic losses of pure sCO₂ RITs with those of three sCO₂ mixtures containing tetrachloride (TiCl4), sulphur dioxide (SO₂), and hexaflourobenzene (C₆F₆).

Results show that the optimal turbine designs for all working fluids will have similar rotor shapes and velocity diagrams. However, factors such as the clearance-to-blade-height ratio, turbine pressure ratio, and the difference in the viscosity of the fluids cause variations in the achievable turbine efficiency. Once the effects of these factors are eliminated, differences in the total-to-static efficiency amongst the fluids may become less than 0.1%. Moreover, if rotational speed limits are imposed, then greater differences in the designs and efficiencies of the turbines emerge amongst the fluids. It was found that limiting the rotational speed reduces the total-to-static efficiency in all fluids; the maximum reduction is about 15% in 0.1 MW CO₂ compared to the 3% reduction in CO₂/TiCl₄ turbines of the same power.

Among the mixtures studied, CO₂/TiCl₄ achieved the highest performance, followed by CO2/C6F6, and then CO2/SO2. For example, 100 kW turbines for CO₂/TiCl₄, CO₂/C₆F₆, CO₂/SO₂, and CO₂ achieve total-to-static efficiencies of 80.0%, 77.4%, 78.1%, and 75.5% respectively. Whereas, the efficiencies for 10 MW turbines are 87.8%, 87.3%, 87.5%, and 87.2%, in the same order. differences in the designs and efficiencies of the turbines emerge

Paper on off-design operation of ACCs presented by University of Seville at ASME Turbo Expo, Boston (USA)

15 July, 2023/in Conference and journal papers /by jose

Fan power consumption at reduced mass flow rate for different ACC designs

The researchers at University of Seville have presented their work assessing the part-load operation of supercritical power cycles running on Carbon Dioxide mixtures. As a continuation of the work presented at the 5^th European Conference on Supercritical Carbon Dioxide Energy Systems, where the methodology to design ACCs for supercritical CO₂ power cycles developed at University of Seville was presented, this paper explores the operation of the cycle when running in off-design. Emphasis is placed on the operation of the ACC because of the strong impact that a wrong operation of this component has on overall cycle performance.

The paper can be downloaded free of charge from the conference website (link). Check the abstract below:

This manuscript, developed in the framework of SCARABEUS project, presents an assessment of the part-load performance of a transcritical Recompression cycle running on a 80%CO₂-20%SO₂ mixture under different load-control schemes.

The first part of the paper describes the computational platform of the integrated system, implemented in Thermoflex but with profuse use of in-house scripts, in order to accurately describe the off-design performance of key components when operating on CO₂ mixtures with non-ideal gas behaviour. These off-design models make use of performance maps for turbomachinery — provided by the SCARABEUS partners — whereas the Conductance Ratio Method employed to model the counter-current heat exchangers is calibrated with in-house tools. The paper is specifically focused on the Heat Rejection Unit, for which a specific design tool accounting for accurate heat transfer between working fluid and cooling medium (air) and for auxiliary power consumption — both in off-design — has been developed by the authors.

In the second part of the paper, different operating strategies of the power cycle are considered, based on keeping one of the following three parameters constant: turbine inlet temperature, turbine outlet temperature or return temperature of molten salts. Globally, plant operation is constrained by the need to keep the temperature of cold HTF returning to the storage system as close as possible to its rated (design) value and by the need to keep turbine outlet temperature below 450°C to avoid the installation of an external cooling system in the low pressure section of this equipment. Therefore, the trade-off between these two parameters and system net efficiency are assessed in the paper. Regarding the Air-Cooled Condenser, the optimal operation strategy of this component found to be based on a combination of Single-speed and Variable Frequency Driver fans.

The results show that the operation at constant turbine inlet temperature leads to the highest net efficiency of the power block, closely followed by the control scheme based on constant return temperature of the heat transfer fluid. Nevertheless, this latter option enables a perfect control on the other two figures of merit. As a consequence, the identification of the best operation strategy must be addressed in future works by means of a thorough techno-economic assessment considering the annual yield of the plant.

Half Sized Blog Element (Single Author Style)

Half Sized Blog Element (Multi Author Style)

Paper on energy losses in radial turbines presented by City, University of London at ASME Turbo Expo, Boston (USA)

Paper on off-design operation of ACCs presented by University of Seville at ASME Turbo Expo, Boston (USA)

Paper on energy losses in radial turbines presented by City, University of London at ASME Turbo Expo, Boston (USA)

Paper on off-design operation of ACCs presented by University of Seville at ASME Turbo Expo, Boston (USA)

Full Sized Blog Element (Big Preview Pic)

Paper on energy losses in radial turbines presented by City, University of London at ASME Turbo Expo, Boston (USA)

Paper on off-design operation of ACCs presented by University of Seville at ASME Turbo Expo, Boston (USA)

Research Gate

Linkedin