Request Expert

For 40 years he has been working in alternative energy systems. He created the design for the photovoltaic power system of the Mariner spacecraft that went to Venus and Mercury, with tilting panels to avoid overheating close to the sun. He worked on the power supply for the Voyager spacecraft, defining the thermoelectric design parameters that would ensure a very long life. He built a solar swimming pool heater that has lasted 34 years already, and wrote a do-it-yourself manual that went out to 100,000 people. He did a study to define the wind power potential of the Argentine patagonia region. He worked on the optimum design for solar water heating systems. He worked on the design of waste heat loops for Stirling engines.

He determined optimum tapered fin shapes for flat plate collectors, and studied the effects of selective coatings. He developed the "Heat Exchanger Factor" for double loop and single loop solar water heating systems using an antifreeze loop. These heat exchanger factors are used worldwide. He wrote an annotated bibliography (report S-101) for ASHRAE in 1975, and edited a volume on "Solar Collectors, Thermal Storage, and Materials" for MIT Press in 1990. He built a flat plate collector for heating a swimming pool that has been in operation since 1973, and wrote the associated do-it-yourself manual so others could build such heaters.

The was the Technical Director of the Thermophysical Property Laboratory for Dynatech Corp. in Cambridge, Massachusetts, designing and building instruments to determine the thermal conductivity of materials. He was involved in the thermal analysis and design of several spacecraft, in which a significant part of the work was the definition of the thermal conduction between various spacecraft parts. He developed intermeshing thermal conduction fins for use on the Apollo spacecraft. He developed cost-optimized thermal conduction fins for flat plate collectors. He gave lectures at MIT in both an undergraduate and a graduate course on heat transfer by thermal conduction.

He has been working in renewable energy systems for over 40 years, first in spacecraft solar power systems, and then in terrestrial renewable energy systems, mostly for solar domestic hot water heating and for solar swimming pool heating. He developed the "heat exchanger factor" used in solar water heating systems to permit the use of an antifreeze loop through the solar heat collector. He investigated the potential of renewable energy systems in Argentina, as the principal US team member on a joint US/Argentina program on the energy future of Argentina in the late 1970s. This included an evaluation of the wind energy potential of the Argentine patagonia, that has a huge and very windy area.

He has specialized in heat transfer and such associated fields as fluid flow and thermodynamics. He has worked on freeze-drying and on desalination, on the design of instruments for determining thermophysical properties of materials, on thermal control of space vehicles, and on spacecraft power system design, notably the JPL Venus-Mercury Flyby Mission (Mariner 10) and the JPL Voyager mission to the outer planets, and now to space beyond. The JPL spacecraft power work involved solar photovoltaic, solar
thermionic, and radioisotope thermoelectric power system design. In terrestrial solar energy applications, expert has worked on swimming pool heating, on the flat plate collector, on heat exchangers in solar water heating systems, and on gas water heaters for solar backup service and for stand-alone service. He developed the "Heat Exchanger Factor" for solar water heating which has become a standard part of the solar energy literature, and is used worldwide.

He has used the Bernouilli equation routinely in many internal and external fluid flow situations, such as explained below. The mathematics of external fluid flow is extremely complicated, and problems like the flight characteristics of a plane can only be studied in detail with wind tunnels or with enormously complex computer programs. Wind tunnels are used much less than they used to be, and the Boeing 787 was almost entirely designed and built on the basis of computer programs. It has never even flown yet, but hundreds of them have been sold already. Despite the complexity of the fluid flow, the Bernouilli equation however provides an extremely useful crutch for getting some understanding of external fluid flow. It can help to understand the air drag of cars or planes or projectiles in subsonic flow, to understand the lift of wings in subsonic flight, to understand curve-balls in baseball or a hook or a slice in golf. With a Pitot tube in airplanes the pilot can tell how fast the plane is going. There are hundreds of applications in which one can use the Bernouilli equation to get a better feel for what is going on.

His involvement in energy conservation has been primarily with the design of new and more efficient heating equipment. In heaters used to heat 1000 barrel tanks of heavy oil up to 200 ºF to allow the sand and water to settle out of the heavy oil, his design concepts made it possible to increase the heating efficiency from 50% to 80%. A similar efficiency improvement was possible in the “line-heaters” used in natural gas pipelines at the location of throttle valves, to compensate for the Joule-Thomson cooling effect. The single family solar water heaters developed under his supervision achieved solar fractions of well over 80%, instead of the 60% to 65% achieved by the normal “Two-Tank” system designs, thus saving a significant amount of the natural gas used for the backup heating.

He has extensive experience in fluid dynamics in internal flows, but not in external, threeidimensional flows. This has been in compressible as well as incompressible, in two phase as well as single phase internal flows. This has involved the emptying of xenon-filled tank volumes through long tubes into the vacuum of outer space for a spacecraft after launch, the design and sizing and optimizing of plumbing systems and other fluid loops, the optimization of heat exchangers by determining the flow rate and the heat exchanger geometry that produces adequate heat transfer without an excessive pressure drop, the optimization of compressors, the development of novel two-phase thermosyphon loops, and the handling of a large number of other such internal flow situations.

He calculated the convection heat losses to be expected from an unglazed solar swimming pool heater using boundary layer theory. He has extensive experience in the design and optimization of heat exchangers, in which the convection heat transfer coefficients must be estimated, often involving flow geometries that are different than those that have been used and tested before. He developed equations for the heat transfer in laminar flows in round tubes and between parallel plates, for heat transfer to chemically reacting gases with rate-limited reactions.

At JPL he was in charge of the analytical R&D and of the outside contracts used to ensure that the silicon germanium (SiGe) thermoelectric material and the high temperature thermal insulation materials in the Radioisotope Thermoelectric Generators (RTGs) used to power the Voyager spacecraft lasted long enough so that Voyager could complete its 12 year mission to the outer planets. The Voyager spacecraft have lasted not 12 years, but over 30 years already, and they are expected to last at least another 12 years or so, until 2020. In both the SiGe material, and in the thermal insulation material, the stability of the thermal conductivity was one of the most important concerns.

Helped develop the heaters used to heat large (750 barrel to 1,000 barrel) heavy oil tanks in the Lloydminster, Canada area up to about 85 degrees C, so that the sand and the water could settle out.Helped develop a freeze-drying system that was about three times faster than normal, by using an atmosphere with a partial pressure of hydrogen or helium to enhance the heat transfer.Helped develop a Monte Carlo ray-tracing computer program, to describe the radiation heat transfer inside of the service and command module of the Apollo spacecraft.Developed and built a solar heater for swimming pools, that still works properly after 34 years of service, and wrote a do-it-yourself manual for this heater that went out to 100,000 people who requested this manual from the Copper Development Association (the CDA), the client for this project.Helped develop the temperature instrumentation system for a concentrating solar collector system being tested at the UC Merced solar test facilities