Allan Lewandowski

Rapid solar-thermal dissociation of natural gas in an aerosol flow reactor

A solar-thermal aerosol flow reactor process is being developed to dissociate natural gas (NG) to hy drogen (H2) and carbon black at high rates. Concentrated sunlight approaching 10 kW heats a 9.4 cm long×2.4 cm diameter graphite reaction tube to temperatures ~2000 K using a 74% theoretically efficient secondary concentrator. Pure methane feed has been dissociated to 70% for residence times less than 0.1 s. The resulting carbon black is 20–40 nm in size, amorphous, and pure. A 5 million (M) kg/yr carbon black/1.67 M kg/yr H2 plant is considered for process scale-up. The total permanent investment (TPI) of this plant is

Performance and Reliability of Multijunction III-V Modules for Concentrator Dish and Central Receiver Applications

12.7 M. A 15% IRR after tax is achieved when the carbon black is sold for

Performance characterization of the SERI High-Flux solar furnace

0.66/kg and the H2 for

Modeling of a Multitube High-Temperature Solar Thermochemical Reactor for Hydrogen Production

13.80/GJ. This plant could supply 0.06% of the world carbon black market. For this scenario, the solar-thermal process avoids 277 MJ fossil fuel and 13.9 kg-equivalent CO2/kg H2 produced as compared to conventional steam-methane reforming and furnace black processing.

Field Survey of Parabolic Trough Receiver Thermal Performance

Over the last 15 years, Solar Systems have developed a dense array receiver PV technology for 500X concentrator reflective dish applications. This concentrator PV technology has been successfully deployed at six different locations in Australia, counting for more than 1 MWp of installed peak power. A new Multijunction III-V receiver to replace the current silicon Point-Contact solar cells has recently been developed. The new receiver technology is based on high-efficiency (>32%) Concentrator Ultra Triple Junction (CUTJ) solar cells from Spectrolab, resulting in system power and energy performance improvement of more than 50% compared to the silicon cells. The 0.235 m2 concentrator PV receiver, designed for continuous 500X operation, is composed of 64 dense array modules, and made of series and parallel-connected solar cells, totaling approximately 1,500 cells. The individual dense array modules have been tested under high intensity pulsed light, as well as with concentrated sunlight at the Solar Systems research facility and at the National Renewable Energy Laboratorys High Flux Solar Furnace. The efficiency of the dense array modules ranges from 30% to 36% at 500X (50 W/cm2, AM1.5D low AOD, 21C). The temperature coefficients for power, voltage and current, as well as the influence of Air Mass on the cell responsivity, were measured. The reliability of the dense array multijunction III-V modules has been studied with accelerated aging tests, such as thermal cycling, damp heat and high-temperature soak, and with real-life high-intensity exposure. The first 33 kWp multijunction III-V receiver was recently installed in a Solar Systems dish and tested in real-life 500X concentrated sunlight conditions. Receiver efficiencies of 30.3% and 29.0% were measured at Standard Operating Conditions and Normal Operating Conditions respectively

Rapid Solar-thermal Decarbonization of Methane in a Fluid-wall Aerosol Flow Reactor -- Fundamentals and Application

Abstract This paper describes a unique new solar furnace at the Solar Energy Research Institute (SERI) that can generate a wide range of flux concentrations to support research in areas including materials processing, high-temperature detoxification and high-flux optics. The furnace is unique in that it uses a flat, tracking heliostat along with a long focal length-to-diameter (f/D) primary concentrator in an off-axis configuration. The experiments are located inside a building completely outside the beam between the heiostat and primary concentrator. The long f/D ratio of the primary concentrator was designed to take advantage of a nonimaging secondary concentrator to significantly increase the flux concentration capabilities of the system. Results are reported for both the single-stage and two-stage configurations.

SolTrace: A Ray-Tracing Code for Complex Solar Optical Systems

O-splitting thermochemicalcycle using concentrated solar energy. The continuity, momentum,and energy governing equations that couple the rate of heat trans-fer to the Arrhenius-type reaction kinetics are formulated for anabsorbing-emitting-scattering particulate media and numericallysolved using a computational fluid dynamics code. Parametricsimulations were carried out to examine the influence of the solarflux concentration ratio (3000–6000 suns), number of tubes (1–10), ZnO mass flow rate (2–20 g/min per tube), and ZnO particlesize 0.06–1 m on the reactor’s performance. The reaction ex-tent reaches completion within1sresidence time at above 2000K, yielding a solar-to-chemical energy conversion efficiency of upto 29%.

A New Optical Evaluation Approach for Parabolic Trough Collectors: First-Principle OPTical Intercept Calculation

This paper describes a technique that uses an infrared (IR) camera to evaluate the in-situ thermal performance of parabolic trough receivers at operating solar power plants. The paper includes results to show how the glass temperature measured with the IR camera correlates with modeled thermal losses from the receiver. Finally, the paper presents results of a field survey that used this technique to quickly sample a large number of receivers to develop a better understanding of how both original and replacement receivers are performing after up to 17 years of operational service.

Solar Concentration of 50,000 Achieved With Output Power Approaching 1 kW

A graphite fluid-wall aerosol flow reactor heated with concentrated sunlight has been developed over the past five years for the solar-thermal decarbonization of methane. The fluid-wall is provided by an inert or compatible gas that prevents contact of reactants and products of reaction with a graphite reaction tube. The reactor provides for a low thermal mass that is compatible with intermittent sunlight and the graphite construction allows rapid heating/cooling rates and ultra-high temperatures. The decarbonization of methane has been demonstrated at over 90% for residence times on the order of 10 milliseconds at a reactor wall temperature near 2000 K. The carbon black resulting from the dissociation of methane is nanosized, amorphous, and ash-free and can be used for industrial rubber production. The hydrogen can be supplied to a pipeline and used for chemical processing or to supply fuel cell vehicles.

An assessment of linear Fresnel lens concentrators for thermal applications

SolTrace is an optical simulation tool designed to model optical systems used in concentrating solar power (CSP) applications. The code was first written in early 2003, but has seen significant modifications and changes since its inception, including conversion from a Pascal-based software development platform to C++. SolTrace is unique in that it can model virtually any optical system utilizingthe sun as the source. It has been made available for free and as such is in use worldwide by industry, universities, and research laboratories. The fundamental design of the code is discussed, including enhancements and improvements over the earlier version. Comparisons are made with other optical modeling tools, both non-commercial and commercial in nature. Finally, modeled results are shownfor some typical CSP systems and, in one case, compared to measured optical data.