Bennett Widyolar, Ph.D. Email & Phone Number

Tucson, Az, Us

Tucson, Az, Us

Arlington, Va, Us

Developed a novel asymmetric nonimaging optical design which "collapsed" the traditionally symmetric compound parabolic concentrator into an equivalent design with a flat, horizontal aperture. The flat horizontal aperture prevents self-shading, eliminating the need for row-to-row spacing and allowing collectors to be installed adjacent to one another, maximizing land-use efficiency. This also minimizes solar field cost (reducing total length of pipe, insulation, jacketing, and volume of heat transfer fluid) and maximizes solar field efficiency (reduces unnecessary heat losses and thermal mass allowing the system to reach operating temperatures faster).Fabricated 6-tube, 5 m2 prototype and performed one full year (2022) of performance testing while operating at approximately 100 C and generating low-pressure (atmospheric) steam. Performed comparitive testing between collectors with evacuated receiver tubes and those which had failed and lost vacuum. Also performed stagnation testing, demonstrating 300+ C stagnation.Subsequently fabricated and installed a 50 m2 pilot array with automatic temperature control using a controlled air-fluid heat exchanger. Developed hot water storage system and arduino-based PLC controller with HMI interface, successfully load-shifted collected solar energy with control valves and recirculation loop, delivered constant 185 F, 24 hours a day, over 3-month period.Designed, fabricated, and installed a 91 m2 solar thermal system on a local dairy which raises 1,000 gallons of hot water from 70F to 180F each day, prior to entering the dairy's hot water system where it is used for Clean-in-place sanitation of milking equipment and tanks. Performed thermal energy audit of dairy hot water system, proposed and implemented recommendations which lowered client’s fuel consumption by 50%.

Merced, California, Us

Managed two R&D grant projects through COVID.1) Developed a novel "seagull" nonimaging optical concentrator using MATLAB which more than doubled the concentration ratio from a commercial solar parabolic trough (from 23X to 50X). Verified optical performance using LightTools. Procured a SkyFuel SkyTrough DSP module and assembled and installed it at UC Merced's Castle Research Facility. Secured civil, structural, and electrical stamped engineering drawings. Built multiple 4-meter-long receiver prototypes, with selectively-coated absorber tubes, secondary reflector optics, and glass enclosures with custom-made end-caps with bellows and vacuum ports. Experimentally tested receiver tubes under high-vacuum (10e-4 mbar) at high temperatures with receiver tube maintained at 650 C for over 100 continuous hours, measured thermal emissivity of selective coating and minimal degradation over test. Experimentally verified optical performance on-sun.2) Developed a low-cost solar thermal collector using a selectively-coated aluminum minichannel absorber and a nonimaging optical reflector applied onto the outside of an evacuated glass tube. Fabricated and assembled multiple prototypes (spray-silvered) and tested performance up to 120 C using RhoGuard multi-metal (aluminum-safe) propylene glycol. Assembled a 27 m2 solar field of 240 tubes and tested array-level performance up to 120 C, demonstrating potential to achieve a levelized cost of heat of 1.5 cents per kWh at these temperatures over a 20 year lifetime.

Merced, California, Us

Worked on a combined heat and power (CHP) solar collector, a hybrid combination of photovoltaic and thermal (PV/T) systems. We cut interdigited back-contact Sunpower solar cells into strips, soldered them into 13-cell strings, and applied them to both the top and bottom of an aluminum minichannel, separated by a double-sided silicone adhesive tape. The bottom half-cylinder exterior was silver-coated, creating a nonimaging optical reflector which directed sunlight to the bottom string of solar cells. These solar cells generated electricity from incident sunlight. Energy which was not converted to electricity caused the solar cells to heat up, and this thermal energy was captured by circulating a mixture of propylene glycol and water through the minichannels. Together, the collector operated with a 57% solar-to-thermal efficiency and a simultaneous 12% solar-to-electrical efficiency for a combined efficiency of almost 70% at ambient temperatures. The collector reached a maximum (stagnation) temperature of ~ 80 C.Also worked on solar thermal evaporation of wastewater, using a 45 m2 array of compound parabolic concentrators and an ENCON thermal evaporator.

Merced, California, Us

Worked on a Spectral Beam Splitting (SBS) high temperature hybrid photovoltaic / thermal solar system funded by the ARPA-E FOCUS program. Designed a compound parabolic concentrator (CPC) secondary optic to further concentrate light from a 45-degree rim angle primary parabolic trough. The secondary CPC was coated with dual junction InGaP/GaAs solar cells to generate electricity. Photons which were unused were re-directed by the back-reflector behind the cells toward the central thermal receiver, which was selectively coated to maximize absorption of photons in the solar spectrum and minimize thermal re-radiation. Optical performance was measured by testing the receivers on-sun using water as the heat transfer fluid. We subsequently tested the system experimentally, on-sun, up to 650 C, using a particulate-based heat transfer fluid developed by the Gas Technology Institute.

Merced, California, Us

Travelled to Ulaanbaatar, Mongolia to install two pilot solar thermal systems. The first was on the roof of Mongolia National University (MNU), the second was at a Ger resort in the outskirts of the city.

Doctor Of Philosophy (Phd), Environmental Systems

Master'S Degree, Mechanical Engineering

Bachelor Of Applied Science (B.A.Sc.), Environmental Engineering

Education record