Thermodynamic Model of a Solar Receiver for Superheating of Sulfur Trioxide and Steam at Pilot Plant Scale

Within the European research project SOL2HY2, key components for a solar hybrid sulfur cycle are being developed and demonstrated at pilot scale in a real environment. Regarding the thermal portion, a plant for solar sulfuric acid decomposition is set up and initially operated at the research platform of the DLR Solar Tower in Jülich, Germany. One major component is the directly irradiated volumetric receiver, superheating steam and SO3 coming from a tube-type evaporator to above 1000 °C. At the design flow rate of sulfuric acid (50%-wt.) of 1 l/min, a nominal solar power of 57 kW is required at the receiver. With a flat ceramic absorber made from SiC and a flat quartz glass window, the design is based on lab scale reactors successfully demonstrated at the solar furnace of the German Aerospace Centre (DLR) in Cologne, Germany. A flexible lumped thermodynamic tool representing the receiver, compiled to assess different configurations, is presented in detail. An additional raytracing model has been established to provide the irradiation boundaries and support the design of a conical secondary concentrator with an aperture diameter of 0.6 m. A comparison with first experimental data (up to 65% nominal power), obtained during initial operation, indicates the models to be viable tools for design and operational forecast of such systems. With a provisional method to account for the efficiency of the secondary concentrator, measured fluid outlet temperatures (up to 1000 °C) are predicted with deviations of ±60 °C. Respective absorber front temperatures (up to 1200 °C) are under-predicted by 100-200 °C, with lower deviations at higher mass flows. The measured window temperature (up to 700 °C) mainly depends on the absorber front temperature level, which is well predicted by the model

Modular Robotic Vehicle

A modular robotic vehicle includes a chassis, driver input devices, an energy storage system (ESS), a power electronics module (PEM), modular electronic assemblies (eModules) connected to the ESS via the PEM, one or more master controllers, and various embedded controllers. Each eModule includes a drive wheel containing a propulsion-braking module, and a housing containing propulsion and braking control assemblies with respective embedded propulsion and brake controllers, and a mounting bracket covering a steering control assembly with embedded steering controllers. The master controller, which is in communication with each eModule and with the driver input devices, communicates with and independently controls each eModule, by-wire, via the embedded controllers to establish a desired operating mode. Modes may include a two-wheel, four-wheel, diamond, and omni-directional steering modes as well as a park mode. A bumper may enable docking with another vehicle, with shared control over the eModules of the vehicles

Using Solar Energy Continuously Through Day and Night for Methane Reforming – An Experimental Demonstration

A new concept of solar receiver/reactor is developed which combines catalytic methane reforming and air heating for solar energy storage in a single volumetric absorbing monolith. A 5 kW scale prototype has been developed and tested. The design includes a silicon carbide volumetric absorber with separate channels for heating air and for the endothermic methane reforming reaction. The energy transferred to the air stream can potentially be stored and used to provide heat for methane reforming reaction during nighttime operation. The flow rate of the air stream can also be adjusted to match variations in the solar input, such as during cloud passing, so that a constant stream of fuel products are produced even with variable solar input. Preliminary testing of the prototype has been performed using simulated solar energy provided by Xenon-arc lamps. An example test result is presented showing conversion of methane, steam, and carbon dioxide to products of hydrogen and carbon monoxide in one set of channels while air is heated in the other set of channels. Methane conversion rates and outlet gas compositions are given, and a total efficiency of the device is calculated

Modeling of a Solar Receiver for Superheating Sulfuric Acid

A volumetric solar receiver for superheating evaporated sulfuric acid is developed as part of a 100kW pilot plant for the Hybrid Sulfur Cycle. The receiver, which uses silicon carbide foam as a heat transfer medium, heats evaporated sulfuric acid using concentrated solar energy to temperatures up to 1000 °C, which are required for the downstream catalytic reaction to split sulfur trioxide into oxygen and sulfur dioxide. Multiple approaches to modeling and analysis of the receiver are performed to design the prototype. Focused numerical modeling and thermodynamic analysis are applied to answer individual design and performance questions. Numerical simulations focused on fluid flow are used to determine the best arrangement of inlets, while thermodynamic analysis is used to evaluate the optimal dimensions and operating parameters. Finally a numerical fluid mechanics and heat transfer model is used to predict the temperature field within the receiver. Important lessons from the modeling efforts are given and their impacts on the design of a prototype are discussed

Multi-Scale Model of Receiver-Reactors for Solar Redox Cycles

Multi-Scale Model of Receiver-Reactors for Solar Redox Cycle

Solar-driven Continuous Methane Reforming Reactor

Solar-driven Continuous Methane Reforming Reacto

Solar Hydrogen Generation via the HyS-Cycle – Solar Tower Pilot Plant for Sulphuric Acid Splitting

Solar Hydrogen Generation via the HyS-Cycle – Solar Tower Pilot Plant for Sulphuric Acid Splittin