11. ADVANCED COOLING TECHNOLOGY

In U.S. residential and commercial buildings, space cooling (air conditioners) used about 3.4 Quads of primary energy in 2004, and refrigeration and freezers used about 2.3 Quads more.  In the industrial sector, process cooling used about 0.7 Quads.  In the transport sector, air conditioning is a large load that constrains down-sizing of hybrid vehicle engines; overall, A/C accounts for roughly one-fifth of the power required by a mid-sized sedan traveling at 60 mph on a hot summer day.  Combined, these various cooling requirements total roughly 7 Quads of primary energy per year.

Conventional air conditioners and refrigerators use mechanical vapor compression cycles for cooling.  Although the refrigerant gas used today is now safe for the ozone layer, per the Montreal Protocol, it is a strong greenhouse gas.  Per molecule, the refrigerant R-134a has 1300 times the direct Global Warming Potential of carbon dioxide over a 100-year period.  Current vehicular air conditioners leak 10 to 70 grams of R134-a year; the European Union (EU) requires that new model cars introduced in 2011 and all new cars by 2017 not use R134-a.  There are also large refrigerant losses from residential and commercial air conditioners and refrigerators.  Overall, these and other halocarbons contribute about 0.34 W/m2 of radiative forcing, as of 2000, which is nearly one-fourth of that due to CO2 alone, at 1.46 W/m2 (International Panel on Climate Change).

Given the large energy use for cooling and the use of hydrofluorocarbon refrigerants, both of which contribute significantly to global warming, there is a strong need for new cooling technologies that are more energy efficient than current technologies and do not use refrigerants that contribute to global warming.  New technologies that might be successfully developed for advanced cooling applications include (a) ThermoElectrics; (b) MagnetoCalorics; (c) ElectroCalorics; and (d) ThermoTunneling.  Important contributory technologies also include advanced heat exchangers and advanced dehumidification technologies.  These technologies should also be lighter, more compact, and more durable than conventional refrigeration technologies.  Use of these technologies would also allow reconfiguration of system designs.  For example, vehicles cooling systems would no longer be constrained to be positioned for belt-driven mechanical compression and could instead be placed where most convenient.  Some of these technologies, particularly ThermoElectrics (TE), have long been used for cooling applications, but commercially available units typically have efficiencies of just one-fifth to one-tenth that of mechanical vapor compression cycles.  Further advances in TE materials offer the potential for raising these efficiencies significantly above those of conventional mechanical systems.

In response to these needs, the Department of Energy is seeking the development of advanced technologies for space cooling in buildings and vehicles, and refrigeration for residential, commercial, and industrial applications.  Technologies of interest will significantly reduce energy consumption compared to conventional mechanical vapor compression cycles and will eliminate use of refrigerants that provide a net contribution to global warming, while achieving costs at or below current levels for comparable systems.  Grant applications must address the potential public benefits that the proposed technology would provide and should include a review of the state-of-the-art for both the technology application being targeted and the proposed technology.  The ease of implementation for the proposed technology is also important.  In Phase I, a preliminary design is required and the refrigeration cells should be defined with the best measurements available, including a description of the measurement methods used; the measurements should be within the state of the art.  However, as such measurements can be extremely difficult, for example, with nanoscale thermoelectrics, the grantee may devise a test to show the cooling level with the power supplied.  Grant applications are sought only in the following subtopics:

a. Buildings Refrigeration and Air Conditioning—Conventional air conditioners, heat pumps and refrigerators, which collectively use 5.3 quads of energy in the U.S. , achieve cooling through a mechanical vapor compression cycle (VCC).  Although the efficiency of the best VCC systems is on the order of 40–45% of Carnot efficiency, these efficiency numbers may be approaching asymptotic values, hence the opportunities for further improvements could be limited.  Continuing progress in materials and manufacturing techniques may make advanced cooling technologies more attractive for building applications.  Grant applications are sought for improved materials and manufacturing techniques that have the potential to provide improved cost vs. performance compared to conventional VCC technologies, with those that offer significantly improved efficiency being of greatest interest.  However, due to market sensitivity to installation and reliability issues, technologies must also have the potential for very high reliability and be able to be installed without reliance on skill sets not commonly available in most communities.  In order to be considered, a concept may address a particular segment of this broad applications area (e.g., commercial refrigeration).

Questions - contact Charles Russomanno (charles.russomanno@hq.doe.gov

b. Vehicular Air Conditioning—Grant applications are sought for vehicular air conditioning systems that must be able to withstand the accelerations, vibrations and temperature excursions typically experienced in vehicle use in the U.S. in addition to meeting the above characteristics of improved energy efficiency and no use of refrigerants with net greenhouse gas impacts.  The vehicles Heating, Ventilation and Air Conditioning (HVAC) system should be able to provide a nominal in cabin temperature of <70oF with a worst case ambient temperature of 122oF.  It is strongly recommended that the respondent communicate with a vehicle OEM (Original Equipment Manufacturer) for vehicle specific desired heating and cooling loads, installation space and vehicle interface parameters. The grant application should include a first approximation road map with the major milestones from Preliminary Design to a Production Model of a Vehicular HVAC System. This road map would form the basis for a follow on project.

Questions - contact Charles Russomanno (charles.russomanno@hq.doe.gov

c. Industrial Process Refrigeration—Many techniques such as absorption chillers have been introduced into industrial processing to capture waste heat and use the heat for refrigeration or cooling.   Grant applications are sought for the development and application of new materials to use industrial waste or secondary heat for refrigeration, as well as the development of new materials for refrigeration cycles for application in industry that will replace conventional refrigeration cycles based on ammonia and other refrigerants as the working fluid.  “Industry” is taken here in the broadest sense, to cover manufacturing, food processing, and space cooling in large commercial applications.  Grant applications are also sought to develop materials for refrigeration applications that will overcome current price/performance barriers to find wide spread application in industry.  It is recognized that current barriers preventing solid-state materials from widespread application in industrial refrigeration are of such a magnitude that commercialization of the refrigeration technology for use in industry cannot be a near-term objective.  

Questions - contact Charles Russomanno (charles.russomanno@hq.doe.gov

d. Utility and Industrial Heat Exchangers—In electrical utilities and in many process industries, improved heat transfer by heat exchangers represents the greatest potential for improving process energy efficiency.  Grant applications are sought for improved heat exchanger efficiency using improved heat exchanger design, materials of construction, or both.  Grant applications should characterize the target application, as well as analyze the potential benefits of the proposed new heat exchanger technology.  Heat exchanger costs, ease of retrofit and installation, and maintenance must be given careful consideration to make the innovation technology commercially viable.  

Questions - contact Charles Russomanno (charles.russomanno@hq.doe.gov

References:

1.      Fairbanks, J., “Thermoelectric Generators for Near-Term Automotive Applications and Beyond,” Plenary Presentation at European Thermoelectric Conference ’06, Cardiff, Wales, April 10-11, 2006 .  (Text and presentation slides available by email request.  Contact John Fairbanks at John.Fairbanks@hq.doe.gov.)

2.      Bell, L., “Role of Thermoelectrics in Vehicle Efficiency Increases,” 11th Diesel Engine Emissions Reduction Conference, Chicago, IL, August 21-25, 2005, U.S. DOE.  (Presentation slides available at:  http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2005/session6/2005_deer_bell.pdf)

3.      Service, R. F., “Semiconductor Advance May Help Reclaim Energy from ‘Lost’ Heat,” Science, 311: 1860, March 31, 2006 .  (ISSN 0036-8075 print) (Full text available at:  http://www.sciencemag.org/cgi/content/full/311/5769/1860a)

4.      Liu, J., “Thermoelectric Coolers and Power Generators Using Self-Assembled Ge Quantum Dot Superlattices,” University of California Energy Institute, September 1, 2004 .  (Paper FSE005) (Full text available at:  http://repositories.cdlib.org/ucei/basic/FSE005/)

5.      Dresselhaus, M. S., et al., “Investigation of Low-Dimensional Thermoelectrics.”  (Full report available at:  http://www-rcf.usc.edu/~scronin/pubs/d888.pdf)

6.      Gschneider, K. A., Jr., et al., “Recent Developments in MagnetoCaloric Materials,” Reports on Progress in Physics, 68(6): 1479-1539, May 2005.  (Abstract and ordering information available at:  http://www.iop.org/EJ/abstract/0034-4885/68/6/R04/)

7.      Zimm, C., et al., “Description and Performance of a Near-Room Temperature Magnetic Refrigerator,” Advances in Cryogenic Engineering, 43(Parts A and B), Kittel, P., ed., Plenum Press, New York, 1998.  (ISSN:  0065-2482) (ISBN:  0-306-45807-1)

8.      Mischenko, A. S., et al., “Giant Electrocaloric Effect in Thin-Film PbZr0.95Ti 0.05O3,Science, V.311(5765): 1270-1271, March 3, 2006 .  (ISSN:  0036-8075 print) (Abstract and ordering information available at:  http://www.sciencemag.org/cgi/content/short/311/5765/1270)

9.      Savin, M., et al., “Efficient Electronic Cooling in Heavily Doped Silicon by Quasiparticle Tunneling,” Applied Physics Letters, 79(10): 1471-1473, September 3, 2001 .  (ISSN: 0003-6951) (Abstract and ordering information available at:  http://apl.aip.org/apl/. Search by volume and page number.)

10.  Hishinuma, Y., et al., “Measurements of Cooling by Room-temperature Thermionic Emission Across a Nanometer Gap,” Journal of Applied Physics, 94(7): 4690-4696, October 1, 2003 .  (ISSN:  0021-8979)(Abstract and ordering information available at:  http://jap.aip.org/.  Search by volume and page number.)

11.  Saman, W. Y. and Alizadeh, S., “Modeling and Performance Analysis of a Cross-Flow Type Plate Heat Exchanger for Dehumidification/Cooling,” Solar Energy, 70(4): 361-372, 2001.  (Abstract and ordering information available at:  http://www.sciencedirect.com/.  Search by publication title and then bibliographic information, above.)

12.  Andrews, J. W., et al., “Independent Control of Sensible and Latent Cooling,” Technical Report, September 1991.  (Report No. BNL-46807) (Full text available at:  http://www.osti.gov/energycitations/basicsearch.jsp.  Search by title.)

13.  IPCC:  Intergovernmental Panel on Climate Change, “Climate Change 2001:  The Scientific Basis,” pp. 7 and 47, Cambridge University Press, July 2001.  (ISBN:  0521807670 print) (Full text available at:  http://www.grida.no/climate/ipcc_tar/wg1/.  On the right, under “Also available in PDF format:” click on “Title page, Table of….” Then scroll down to pages given above.)

 

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