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Case 97-12 Los Alamos National Lab: Thermoacoustic Engines A Case
Study of the R&D Value Mapping Project Institute for Policy Research and Development School
of Public Policy Georgia
Tech Atlanta,
GA 30332
Unedited Draft
This case was written
by Hans Klein with the assistance of Barry Bozeman. Comments or questions
should be directed to Hans Klein at 404.894.2258 or, by email,
hans.klein@pubpolicy.gatech.edu. The research was sponsored by the
Department of Energy, Division of Basic Energy Sciences, Contract ER45562.
The views presented here are the case author?s and do not necessarily
represent those of the Department of Energy, Los Alamos National Labs, or
the Georgia Institute of Technology. Los
Alamos National Lab: Thermoacoustic Engines I. Project description The Los Alamos National Laboratory (LANL) project on thermoacoustic engines spans the domains of basic scientific research and industrial application. The project seeks to apply the insights of thermal physics to develop a news means to achieve a well-established thermal transformation: heat transfer, the process which lies at the heart of all heat engines. Most heat engines achieve heat transfer with the use of moving parts, but the LANL approach uses acoustic standing waves to achieve displacement without moving parts. The simpler mechanics of a thermoacoustic engine promise economic advantages in their greater ease of manufacture and increased reliability of operation. This project developed in two major phases, each led by a different individual. The early phase is the research activity of physicist John Wheatley, who developed the theoretical foundations for such an engine and launched the LANL project in this area. The second phase was led by Greg Swift, a researcher who worked under Wheatley and who eventually took over the project and has since brought it close to industrial application. The most promising output of the project to date is a large-scale collaboration with an industrial firm to develop a natural gas liquefier. In addition, the LANL project has developed design software, has trained numerous researchers, and has published many research articles. II. Technical description As taught in introductory thermodynamics courses, there are two classes of heat engines. The first is a prime mover, in which heat flows through an engine from high to low temperature and generates work, and the second is a heat pump, in which work is absorbed by the engine and heat is pumped from low to high temperature. These heat flow-based processes underlie many practical heat engines, including an automobile motor and an air conditioner. Whether generating work or pumping heat, heat engines in use today employ moving parts. Most designs in current use achieve heat flows by the use of by crankshaft-coupled pistons or rotating turbines. While such designs have achieved a high degree of efficiency, their use of moving parts means that manufacturing costs, reliability, and maintenance remain an issue in their construction and operation. Ceteris paribus a heat engine without moving parts would offer clear advantages. Thermoacoustic heat engines and refrigerators currently being developed at Los Alamos National Laboratories employ no moving parts. Instead, these devices achieve heat flows by harnessing the movement of a sound wave. Within a thermoacoustic engine?s resonator chamber a standing wave agitates a gas to achieve the temperature, pressure, and displacement changes that most engines achieve with moving parts. The phase of the standing wave is such that a parcel of gas is at its most compressed state when at its left-most displacement and its most expanded state at its right-most displacement, thereby creating a temperature differential across the oscillation range. As they oscillate across the temperature differential gas parcels behave like members of a bucket brigade: each parcel picks up a little heat from one location and deposits it a little farther down at a cooler location. At one extreme, heat is absorbed from a hot heat exchanger, and at the other extreme heat is deposited at a cold heat exchanger. Overall, the standing wave sets in motion the heat flow for an engine. The benefits to be derived from such engines lie in their construction and operation rather than their efficiency. While it is hardly surprisingly that today?s experimental devices perform less efficiently than existing heat engines, even the final working versions will not achieve the efficiencies of existing devices. The benefits of the thermoacoustic device lies elsewhere. With no moving parts a thermoacoustic engine offer advantages in their construction and operation. Such an engine could be made of common materials and would not demand exacting mechanical tolerances, with the result that it would be cheap and easy to manufacture. Furthermore, its lack of moving parts make it highly reliable in operation so that it could operate unattended, in a hostile environment, and without skilled personnel. Although the work at Los Alamos is close to industrial application, it has grown out of a program of basic research in thermal physics and has required continued progress in basic science. The fundamentals of thermoacoustics at low amplitudes are reasonably well understood, yet other areas continue to require attention. For example, the practical problem of suppressing streaming heat convection within the resonator chamber lead to research on chamber geometry and the analysis of the optimum taper angle needed to suppress streaming. This research drew on and contributed to foundational theory, yet is also contributed to the design of the heat engine. III. Project History The history of BES-funded thermal physics research and its applications falls into two main parts. The first is the pioneering work in low-temperature physics done by John Wheatley . The second is the more applied technology development carried forward by Greg Swift following Wheatley?s departure from LANL. Another branch of research that grew from Wheatley?s work at LANL is also touched on, this one in fluid dynamics. John Wheatley and Low-Temperature Physics Although only 59 years old when he died unexpectedly in 1986 John Wheatley was recognized as one of the great low-temperature experimental physicists of the twentieth century. He was the only person in his research field to receive both its major awards, the Simon Memorial Prize of the Royal Society in 1966 and the Fritz London Award of the American Physical Society in 1975. Colleagues considered him to have only narrowly missed a Nobel Prize. In the 1980s Wheatley?s studies of the superfluid phases of the rare He-3 isotope of helium was considered one of the most significant topics in low-temperature physics. He developed techniques to make measurements in an environment a few thousandths of a degree above the absolute zero, an achievement that contributed both to low-temperature technology and to understanding the physics of the helium liquids. Wheatley also had a strong interest in the technology application of his research. At one point in his career he founded a company to bring some of his ideas into applications. In his later years he shifted from university to national lab and back again as his focus shifted between research and technology development. For most of his career Wheatley served on the faculty of two universities, the University of Illinois (UI) at Urbana and the University of California (UC) at La Jolla. Starting in 1952 his work at UI in 1952 was in magnetic resonance at low temperatures. This led him into the area of low-temperature physics, where he established the basic techniques of present-day low-temperature refrigeration and thermometry. Having created technology to cool to temperatures below 100 millikelvins he performed pathbreaking experimental work on helium-3's thermal conductivity, viscosity, and other transport properties. Before leaving UI Wheatley had developed a first version of a dilution refrigerator would eventually greatly lower the continuous cooling frontier to 4.5 millikelvins. From 1966 to 1981 Wheatley worked at the University of California (UC) at La Jolla where he continued his work on superfluid helium-3 and founded the Superconductivity, Helium, and Electronics (SHE) Corporation. SHE served as a means for him to exploit his inventions and to make his low-temperature devices more broadly available. Although founded in partnership with two other physicists, Wheatley guided the firm on a day-to-day basis. Many of his former students and post-docs found employment there. In his final years at UC Wheatley became interested in tackling a new problem, and his attention eventually landed on thermoacoustic engines. These would be a new development and would be sufficiently rich and complex to challenge one?s understanding. Furthermore, the promise that something practical could result from an engine with no moving parts appealed to him. In 1981 Wheatley moved to Los Alamos National Lab (LANL). One reason for this was that his increasing interest in technology seemed less suited to a university than a national lab. Another reason was that LANL possessed strength in low-temperature research and the lab?s leadership actively recruited him with offers of research funds and lab space. At LANL he had a dozen people working for him, comprised of students, post docs, technicians, and staff members. Wheatley?s research at LANL divided into four areas: heat engines that used liquid instead of gas (to avoid condensation problems,) low temperature hydrogen, thermoacoustic engines, and thermal convection. In 1985 he returned to the University of California, this time to the Los Angeles campus. With a joint appointment with Los Alamos, he retained some ties to LANL. Shortly after his return, he died. Bob Ecke and Thermal Convection After Wheatley left LANL in 1985, some of his research and development projects were carried forward under the direction of other scientists. After his death a year later there was a period of uncertainty about whether his work would be carried on and, if so, how. BES gave the researchers continued funding, and lab scientists picked up the duties of advising students and post docs. Work continued. Bob Ecke and Greg Swift, two scientists who had joined LANL as post docs in the 1980s, assumed leadership for two research streams. Bob Ecke had worked with John Wheatley in the area of thermal convection, an area of research related to the broader fields of non-linear systems and fluid dynamics. Ecke continued this research with an approach that made connections between mathematics and physics and that thereby allowed for demonstrations in concrete physical experiments. Ecke worked on the experimental confirmation of models of non-linearity, performing precision experiments to investigate a relatively well-known problem. Much of this took the form of experiments in fluid dynamics, especially boundary level turbulence. The main product of the research has been research publications in scientific journals for physics and fluid dynamics. Some practical applications have been explored or at least considered, however. One application is to understand how liquid plutonium eats through a holding container. Another future application would relate to pollution around buildings. The research community in the area of non-linear systems is quite large, numbering in the thousands when aeronautics researchers are included. Within the American Physical Society are some 500 to 1000 people, with perhaps 50 working on similar problems. Ecke estimated that he regularly interacts with 10 to 20 people in the field. Greg Swift and Thermoacoustic Engines A second strand of research, the project focused on here, was taken over by Greg Swift. After completing his Ph.D. in physics at UC Berkeley in 1980 Swift had come to LANL as a post doc. There he joined Wheatley?s engine research group, performing experiments on the thermodynamic behavior of liquids in heat engines. That research soon came to investigate engine designs based on acoustic technology that offered the significant advantage of not requiring any moving parts. After 1986 Swift carried the thermoacoustic research in an applied direction. An important event in that evolution was a 1987 meeting between Swift and Ray Radebaugh, a researcher at the National Institute of Standards and Technology (NIST) doing work on cryogenic refrigerators. Both were interested in exploring the marriage of their respective technologies in order to provide practical, heat-driven cryogenic refrigeration with no moving parts. Their first opportunity to pursue this technology came from funding from the Strategic Defense Initiative, which funded them to develop a cooling system for infrared sensors on satellites. The result of their efforts was successful proof-of-concept hardware capable of cooling to 90 Kelvin. So successful was their so-called ?Coolahoop? invention that it received an R&D100 award. Unfortunately, it suffered cancellation immediately thereafter, falling victim to a change in priorities in SDI away from longer-term research and toward near-term applications. The defense spending boom of the 1980s subsided, and the research group?s staff dropped to just 11 people. With refrigerator development interrupted, Swift?s group developed a software program called DELTAE (Design Environment for Low-amplitude Thermoacoustic Engines) for modeling and designing thermoacoustic and other one-dimensional acoustic apparatus. DELTAE was made publicly available on the World Wide Web to whoever wanted to download it, although an ?official? version that had been cleared by the Department of Energy?s software center (and that was therefore less up-to-date) was also made available. Meanwhile, as policy priorities in the U.S. government shifted, old funding opportunities disappeared and new ones arose. With the end of the cold war, defense funding grew less abundant; as concerns with international competitiveness grew, funding for commercial research increased. A new opportunity to continue refrigerator development soon arose. In 1992 the Tektronix Corporation expressed an interest in developing the thermoacoustic technology for application as a compact and reliable cooler for cryogenic electronics. The parties joined in a cooperative research and development agreement (CRADA) and received funding from the DOE?s Technology Transfer Initiative (TTI) as well as from Tektronix. During the next two years they made further improvements in the technology to reduce its size and raise its efficiency. However, in 1995 Tektronix changed its strategy and de-funded the project. Around this time another funding source became available. Cryenco, a small firm in the liquefied natural gas business, began funding development in 1994 in the hopes of creating a low-cost, high-reliability liquefier of natural gas. Simultaneously, the Fossil Energy group in DOE began funding the project. Working closely with Cryenco, Swift?s group began developing a prototype natural gas liquefier with a capacity of 500 gallons per day (about one fluid cup per minute.) If successful this technology could have a major impact on natural gas industry, allowing much smaller liquefaction facilities than are economically feasible today while reducing construction and operation costs. By mid-1997 Cryenco was investing approximately $600-$900,000 per year (about half its profits) in this project, and DOE/Fossil Fuel was investing about $400,000 per year. So close was their collaboration that Swift worked on site at Cryenco?s Denver headquarters for nearly twelve months in 1996 and 1997. That development has continued into 1998. In their pursuit of development funds Swift?s group proved itself able at entrepreneurship, adapting the thermoacoustic technology to different applications to take advantage of funding opportunities. Since 1987 they have reinvented their thermoacoustic heat engine as a defense technology, a commercial technology for instrumentation, and an energy technology. In so doing they have won funding support from SDI, TTI, and DOE/Fossil Fuel, as well as Tektronix and Cryenco. In this unpredictable environment the funding they receive from DOE/BES has provided valuable stability. BES funding has served as a ?flywheel? to maintain research activities even when external resources were scarce. At the same time, the BES funding has supported the basic research that underlies the thermoacoustic technology. In the past fifteen years the community of scholars working in this field has grown sharply. In the early 1980s when John Wheatley led the LANL group, the only other research institution investigating such topics was in Zurich Switzerland. By 1997 some 20 to 30 academic research groups were active. Furthermore, by 1997 there were widespread attempts underway to develop practical devices based on thermoacoustics not only in the U.S. but in Europe, Japan, and other places as well. IV. Project Outputs and Impacts LANL work on thermoacoustic engines and refrigerators shows great promise to revolutionize the field of natural gas liquefaction. If successful, different size devices could serve different functions. Applications for small-scale devices could include: local liquefaction at fleet-vehicle fueling stations; boil-off gas recovery at large-scale facilities; and recovery of landfill gas. Medium-scale devices could have applications where the capability of unattended operation confers major benefits, such as at remote locations or in hostile environments (e.g. offshore oil wells.) However, to date those impacts have not yet occurred. On a large scale thermoacoustic engines offer less comparative advantage. The technology remains promising, but has not yet conclusively proven its utility. Still, the research program has already impacted Cryenco and at least one other firm. Cryenco has practically ?bet the firm? on the technology, investing much of its surplus capital in development. Another firm has also been indirectly influenced by the LANL work on refrigeration. Macrosonix of Virginia, created by a scientist entrepreneur who visited LANL for a year, has developed products for home refrigerators. The BES-funded research at LANL has also produced other outputs. One important output is the DELTAE software package, which has been utilized by an estimated 100 outside groups. Another output is patents and licenses. Of the 6 to 10 patents produced, one ?mother patent? is broad and the others are more specific. Licenses of the technology have been specific to different fields of use. The license purchased by Tektronix covered the field of electronic equipment, while that of Cryenco covered the field of liquid natural gas. License fees were intentionally set low to create only a small threshold to purchasers, serving more to discourage casual users than to earn money for LANL. The program has also trained numerous graduate students and post docs. The breakdown of students is as follows: Ph.D. students
:
[Did we receive this data??] MS students : post docs : Finally, the research has led to numerous
publications. Swift?s 1988 survey article on thermoacoustic engines continues to be
widely referenced. More specific scientific articles have also been
numerous. [We don?t have numbers here either.] V. Conclusions The most remarkable feature of this project has been its relative success in moving scientific research to application. Wheatley and Swift have been committed to developing technology and realizing it in industrial applications. Even as they did basic scientific research they sought to create working technology. It would appear that the personal drive and entrepreneurship of both those men figured prominently in their programs. Their success attests to their desire and ability to overcome institutional barriers and categories in the research establishment. When Wheatley sought to diffuse his early refrigerator technology, he had to create his own firm and resist university disapproval. Later he had to come to Los Alamos to pursue these technological interests. When teaching beckoned again, he had to leave LANL for the university again. Similarly, Swift?s entrepreneurship kept development moving forward despite a series of setbacks. He successfully hopped from one funding source to another, always moving technology development forward. No one institutional setting was adequate for all they wanted to do. Wheatley worked in the university, the national lab, and the industrial firm. Swift worked in the national lab but also spent an entire year on site at an industrial firm. On the other hand, both succeeded in moving between institutions, building collaborations, or even creating new institutions (e.g. Wheatley?s SHE corporation.) This suggests that no one institution can accommodate the diverse activities of technology development and that successful development depends on entrepreneurial scientists? freedom to move among specialized institutions. Finally, BES funding played a vital role in supporting this entrepreneurship. In a context of uncertainty, it provided stability and security. When resources ran out, it served as flywheel to survive the dry periods. Although such financial support may not by itself lead to success, in the service of entrepreneurial scientists shifting among institutions and pursuing funding availabilities as they arise, a stable baseline of financial support can insulate research and development from sudden funding shortfalls.
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