[home] [Personal Program] [Help]

---

Session: New applications: Solar
Session starts: Monday 07 October, 11:10
Presentation starts: 11:10
Room: Willem Burger Zaal

---

Piero Colonna (Process and Energy Dept., Delft University of Technology)
Sebastian Bahamonde (Process and Energy Dept., Delft University of Technology)

Abstract:
The presentation illustrates the plan of a project recently started at TU Delft, in partnership with a multinational company, and aimed at developing validated methodologies for the design of mini Organic Rankine Cycle (ORC) turbogenerators. The solar-powered total energy system of so-called green buildings is the envisaged application. De-localized generation of utilities for commercial and residential buildings (electricity, heating and cooling) from solar energy can have an enormous impact on the path to a renewable energy future. Constraints on cost, efficiency, energy storage, reliability, materials, scalability and complexity have so-far prevented widespread adoption of technologies for solar energy conversion, with the partial exception of photo-voltaic panels. In principle a small CSP plant based on the ORC concept features unique advantages: it can efficiently generate electricity for local utilization, and in addition it allows for thermal energy storage, together with cogeneration of heating and cooling (by integrating an absorption chiller). This total energy system boasts an extremely high electric efficiency (up to 20\%), unparalleled total conversion efficiency (up to 95\%), and a high utilization factor throughout the year, which would put it well above competing technologies. Miniaturization of ORC technology involves a number of scientific challenges. In addition, design for volume production requires a paradigmatic change in the approach and in the base technology, starting from the adoption of a new working fluid. Studies of the TU Delft group highlighted possible solutions to the problem of realizing a small ORC turbogenerator for this application. A new turbine architecture would benefit from a new cycle configuration integrating thermal storage. Siloxanes, new perfluorocarbons and their mixtures can be used as working fluids, a key optimization parameter of the system. In this project, the group wants to further study and experiment on a new type of expander, the centrifugal turbine. Preliminary assessments indicate that it is particularly suitable for mini-ORC turbogenerators for solar applications, because it can handle the highly supersonic flow and ultra-high expansion ratio. In addition the group wants to investigate new working fluids that can also be used for thermal storage, if the recently proposed flash-cycle configuration is adopted. System studies, together with simulations on the envisaged turbine will lead to the design and implementation of a test bench that can be used to experiment with mini-turbines. We will use and further develop proprietary software for system simulations, CFD design of turbomachinery, and fluid thermophysical property estimation. One of the main deliverables will therefore be a proof-of-concept turbine prototype and all the characterizing measurements.