ASHRAE Journal - April 2011 - 68

emerging technologies
market Factors
As discussed in last month’s column, conventional thermoelectric modules have an economic advantage over the vapor cycle where small cooling capacities are needed, generally if less than 170 Btu/h (50 W) of cooling capacity is needed. In this application, one or several thermoelectric modules can provide the required cooling capacity, with significantly less space and weight and at lower cost than a vapor cycle cooling system. This probably holds for thermotunneling devices as well, if they can be produced commercially, but not necessarily for electrocaloric and thermoelastic devices. Among the common air-conditioning and refrigeration products, the cooling capacity needed for residential refrigerators, from 340 Btu/h to 1360 Btu/h (100 W to 400 W) is a modest capacity requirement that potentially could be met by a few square inches of thermotunneling device. To be commercially viable in this context, an increased COP over vapor cycle and lower costs will be needed. For the larger capacity requirements for residential and commercial air conditioning and commercial refrigeration, increased COP over vapor cycle will be needed and the cost will need to be even lower.
2. Weaver, S., et al. 2007. “Thermotunneling based cooling systems for high efficiency buildings.” GE Global Research. 3. Tavkhelidze, A., V Svanidze, and L. Tsakadze. 2008. “Thermo. tunnel Refrigerator With Vacuum/Insulator Tunnel Barrier: A Theoretical Analysis.” http://tinyurl.com/thermotunnel. 4. Brown, D.R., et al. 2010. “The Prospects of Alternatives to Vapor Compression Technology for Space Cooling and Food Refrigeration Applications.” U.S. Department of Energy, Pacific Northwest National Laboratory. Contract DE-AC05-76RL01830. 5. Liu, P. F., et al. 2010. “Huge electrocaloric effect in Langmuir–Blodgett ferroelectric polymer thin films.” New Journal of Physics 12(2):23 – 35. 6. Rozic, B., and Z. Kutnjak. 2009. “Giant Electrocaloric effect in ferroelectric relaxor materials.” Proceedings of the SEM Annual Conference. http://tinyurl.com/rozic-b. 7. Tickner, N. “New ‘smart’ metal could mean cool cash for consumers, less CO2.” 2010. University of Maryland. http://tinyurl.com/ new-smart-metal. 8. Orcutt, M. 2010. “3 Next-gen air conditioning concepts.” Popular Mechanics 187(8). http://tinyurl.com/3-next-gen. 9. Energy Eff iciency and Renewable Energy. 2010. 2009 Buildings Energy Data Book. U.S. Department of Energy. http:// buildingsdatabook.eere.energy.gov/.

references
1. Thermotunneling Refrigeration System. U.S. Patent Application. IPC8 Class: AF25B2102FI.

John Dieckmann is a director and Alissa Cooperman is a technologist in the Mechanical Systems Group of TIAX, Cambridge, Mass. James Brodrick, Ph.D., is a project manager with the Building Technologies Program, U.S. Department of Energy, Washington, D.C.

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ASHRAE Journal

April 2011

ASHRAE Journal - April 2011

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