Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China

Abstract In thermal radiation, taking heat flow as an extensive quantity and defining the potential as temperature T or the blackbody emissive power U will lead to two different definitions of radiation entransy flow and the corresponding principles for thermal radiation optimization. The two definitions of radiation entransy flow and the corresponding optimization principles are compared in this paper. When the total heat flow is given, the optimization objectives of the extremum entransy dissipation principles (EEDPs) developed based on potentials T and U correspond to the minimum equivalent temperature difference and the minimum equivalent blackbody emissive power difference respectively. The physical meaning of the definition based on potential U is clearer than that based on potential T, but the latter one can be used for the coupled heat transfer optimization problem while the former one cannot. The extremum entropy generation principle (EEGP) for thermal radiation is also derived, which includes the minimum entropy generation principle for thermal radiation. When the radiation heat flow is prescribed, the EEGP reveals that the minimum entropy generation leads to the minimum equivalent thermodynamic potential difference, which is not the expected objective in heat transfer. Therefore, the minimum entropy generation is not always appropriate for thermal radiation optimization. Finally, three thermal radiation optimization examples are discussed, and the results show that the difference in optimization objective between the EEDPs and the EEGP leads to the difference between the optimization results. The EEDP based on potential T is more useful in practical application since its optimization objective is usually consistent with the expected one.

Received: 26 October 2012
Revised: 21 December 2012
Accepted manuscript online:

PACS:

44.40.+a

(Thermal radiation)

Fund: Project supported by the Tsinghua University Initiative Scientific Research Program and the National Natural Science Foundation of China (Grant No. 51136001).

Zhou Bing (周兵), Cheng Xue-Tao (程雪涛), Liang Xin-Gang (梁新刚) A comparison of different entransy flow definitions and entropy generation in thermal radiation optimization 2013 Chin. Phys. B 22 084401

[1]

Bergles A E 1997 J. Heat Transfer 119 8

[2]

Bergles A E 2002 Exp. Therm. Fluid Sci. 26 335

[3]

Bejan A 1997 Advanced Engineering Thermodynamics (New York: Wiley)

[4]

Lerou P P P M, Veenstra T T, Burger J F, Brake H J M and Rogalla H 2005 Cryogenic 45 659

[5]

Li J and Kleinstreuer C 2010 J. Heat Transfer 132 122401

[6]

Ko T H 2006 Int. J. Therm. Sci. 45 1113

[7]

Fakheri A 2010 J. Heat Transfer 132 111802

[8]

Cheng X T and Liang X G 2013 Chin. Phys. B 22 010508

[9]

Guo Z Y, Li D Y and Wang B X 1998 Int. J. Heat Mass Transfer 41 2221

[10]

Meng J A, Liang X G and Li Z X 2005 Int. J. Heat Mass Transfer 48 3331

[11]

Ma L D, Li Z Y and Tao W Q 2007 Int. Comn. Heat Mass Transfer 34 269

[12]

Liu W, Liu Z C, Ming T Z and Guo Z Y 2009 Int. J. Heat Mass Transfer 52 4669

[13]

Liu Y, Cui J, Li W Z and Zhang N 2011 J. Heat Transfer 133 124501

[14]

Guo Z Y, Zhu H Y and Liang X G 2007 Int. J. Heat Mass Transfer 50 2545

[15]

Cheng X T, Liang X G and Guo Z Y 2011 Chin. Sci. Bull. 56 847

[16]

Chen Q and Ren J X 2008 Chin. Sci. Bull. 53 3753

[17]

Chen Q, Wang M R, Pan N and Guo Z Y 2009 Energy 34 1199

[18]

Xia S J, Chen L G and Sun F R 2010 Sci. China: Tech. Sci. 53 960

[19]

Xia S J, Chen L G and Sun F R 2009 Chin. Sci. Bull. 54 3587

[20]

Guo Z Y, Liu X B, Tao W Q and Shah R K 2010 Int. J. Heat Mass Transfer 53 2877

[21]

Qian X D and Li Z X 2011 Int. J. Therm. Sci. 50 608

[22]

Guo J F and Xu M T 2012 Appl. Therm. Eng. 36 227

[23]

Liu X B, Meng J A and Guo Z Y 2009 Chin. Sci. Bull. 54 943

[24]

Chen Q, Wu J, Wang M R, Pan N and Guo Z Y 2011 Chin. Sci. Bull. 56 449

[25]

Cheng X G, Li Z X and Guo Z Y 2003 J. Eng. Thermophys. 24 94 (in Chinese)

[26]

Yuan F and Chen Q 2011 Energy 36 5476

[27]

Wu J and Liang X G 2008 Sci. China: Ser. E 51 1306

[28]

Wu J 2009 "Potential Energy (Entransy) in Thermal Science and Its Application" Ph. D. dissertation (Beijing: Tsinghua University) (in Chinese)

[29]

Cheng X T, Xu X H and Liang X G 2011 Acta. Phys. Sin. 60 118103 (in Chinese)

[30]

Cheng X T and Liang X G 2011 Int. J. Heat Mass Transfer 54 269

[31]

Çengel Y A 2003 Heat Transfer: a Practical Approach, 2nd edn. (New York: McGrew-Hill)

[32]

Hou Z Q and Hu J G 2007 Thermal Control Technology in Spacecraft (Beijing: Chinese Scientific and Technological Press) (in Chinese)

Altmetric calculates a score based on the online attention an article receives. Each coloured thread in the circle represents a different type of online attention. The number in the centre is the Altmetric score. Social media and mainstream news media are the main sources that calculate the score. Reference managers such as Mendeley are also tracked but do not contribute to the score. Older articles often score higher because they have had more time to get noticed. To account for this, Altmetric has included the context data for other articles of a similar age.