Abstract

Gases which are strongly emitting only in the 8–13-μm wavelength range can be employed for radiative cooling to low temperatures. We carried out a general discussion of molecular vibration and rotation to identify a number of candidate gases. Three of the most promising ones—ammonia, ethylene, and ethylene oxide—were then studied in detail. Infrared transmittance spectra were recorded for 5–50 μm by spectrophotometry. These data were used to compute the basic cooling parameters and the relation between cooling power and temperature difference for pure and mixed gases. The results of some practical field tests of radiative cooling are reported.

© 1984 Optical Society of America

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References

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  1. F. Trombe, “Perspectives sur l’Utilization des Rayonnements Solaires et Terrestres dans Certaines Régions du Monde,” Rev. Gen. Therm. 6, 1285 (1967).
  2. S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
    [CrossRef]
  3. C. G. Granqvist, A. Hjortsberg, “Radiative Cooling to Low Temperatures: General Considerations and Application to Selectively Emitting SiO Films,” J. Appl. Phys. 52, 4205 (1981).
    [CrossRef]
  4. P. Berdahl, M. Martin, F. Sakkal, “Thermal Performance of Radiative Cooling Panels,” Int. J. Heat Mass Transfer 26, 871 (1983).
    [CrossRef]
  5. P. Berdahl, R. Fromberg, “The Thermal Radiance of Clear Skies,” Sol. Energy 29, 299 (1982).
    [CrossRef]
  6. T. S. Eriksson, C. G. Granqvist, “Radiative Cooling Computed for Model Atmospheres,” Appl. Opt. 21, 4381 (1982).
    [CrossRef] [PubMed]
  7. T. S. Eriksson, A. Hjortsberg, C. G. Granqvist, in Proceedings, Seventh International Conference on Vacuum Metallurgy—Special Meltings and Metallurgical Coatings (The Iron and Steel Institute of Japan, 1982), p. 696; T. S. Eriksson, E. M. Lushiku, C. G. Granqvist, “Materials for Radiative Cooling to Low Temperatures,” Proc. Soc. Photo-Opt. Instrum. Eng. 428, 105 (1983).
  8. T. S. Eriksson, C. G. Granqvist, “Infrared Optical Properties of Electron-Beam Evaporated Silicon Oxynitride Films,” Appl. Opt. 22, 3204 (1983).
    [CrossRef] [PubMed]
  9. D. Michell, K. L. Biggs, “Radiation Cooling of Buildings at Night,” Appl. Energy 5, 263 (1979).
    [CrossRef]
  10. B. Landro, P. G. McCormick, “Effect of Surface Characteristics and Atmospheric Conditions on Radiative Heat Loss to a Clear Sky,” Int. J. Heat Mass Transfer 23, 613 (1980).
    [CrossRef]
  11. P. Grenier, “Réfrigération Radiative. Effet de Serre Inverse,” Rev. Phys. Appl. 14, 87 (1979).
    [CrossRef]
  12. A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Emitting Ethylene Gas,” Appl. Phys. Lett. 39, 507 (1981).
    [CrossRef]
  13. E. M. Lushiku, A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Infrared-Emitting Ammonia Gas,” J. Appl. Phys. 53, 5526 (1982).
    [CrossRef]
  14. R. C. Weast, M. J. Astle, Eds., CRC Handbook of Chemistry and Physics (CRC Press, Boca Raton, 1979), pp. B-91–B-184, C-81–C-548.
  15. L. J. Bellamy, The Infra-red Spectra of Complex Molecules (Chapman & Hall, London, 1975).
  16. G. Herzberg, Infrared and Raman Spectra of Polyatomic Molecules (Van Nostrand, New York, 1945).
  17. W. J. Jones, in Infra-red Spectroscopy and Molecular Structure, M. Davies, Ed. (Elsevier, Amsterdam, 1963), pp. 111–165.
  18. T. K. McCubbin, W. M. Sinton, “Recent Investigations in the Far Infra-Red,” J. Opt. Soc. Am. 40, 537 (1950).
    [CrossRef]
  19. R. L. Hansler, R. A. Oetjen, “The Infrared Spectra of HCl, DCl, HBr, and NH3 in the Region from 40 to 140 Microns,” J. Chem. Phys. 21, 1340 (1953).
    [CrossRef]
  20. The optical constants of Al were obtained from J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Physics Data: Optical Properties of Metals, Part 2 (Fachinformationszentrum Energie, Physik, Mathematik GmbH, Karlsruhe, Germany, 1981), pp. 65–81.
  21. M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1980).
  22. F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

1983 (2)

P. Berdahl, M. Martin, F. Sakkal, “Thermal Performance of Radiative Cooling Panels,” Int. J. Heat Mass Transfer 26, 871 (1983).
[CrossRef]

T. S. Eriksson, C. G. Granqvist, “Infrared Optical Properties of Electron-Beam Evaporated Silicon Oxynitride Films,” Appl. Opt. 22, 3204 (1983).
[CrossRef] [PubMed]

1982 (3)

P. Berdahl, R. Fromberg, “The Thermal Radiance of Clear Skies,” Sol. Energy 29, 299 (1982).
[CrossRef]

T. S. Eriksson, C. G. Granqvist, “Radiative Cooling Computed for Model Atmospheres,” Appl. Opt. 21, 4381 (1982).
[CrossRef] [PubMed]

E. M. Lushiku, A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Infrared-Emitting Ammonia Gas,” J. Appl. Phys. 53, 5526 (1982).
[CrossRef]

1981 (2)

C. G. Granqvist, A. Hjortsberg, “Radiative Cooling to Low Temperatures: General Considerations and Application to Selectively Emitting SiO Films,” J. Appl. Phys. 52, 4205 (1981).
[CrossRef]

A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Emitting Ethylene Gas,” Appl. Phys. Lett. 39, 507 (1981).
[CrossRef]

1980 (1)

B. Landro, P. G. McCormick, “Effect of Surface Characteristics and Atmospheric Conditions on Radiative Heat Loss to a Clear Sky,” Int. J. Heat Mass Transfer 23, 613 (1980).
[CrossRef]

1979 (2)

P. Grenier, “Réfrigération Radiative. Effet de Serre Inverse,” Rev. Phys. Appl. 14, 87 (1979).
[CrossRef]

D. Michell, K. L. Biggs, “Radiation Cooling of Buildings at Night,” Appl. Energy 5, 263 (1979).
[CrossRef]

1975 (1)

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

1967 (1)

F. Trombe, “Perspectives sur l’Utilization des Rayonnements Solaires et Terrestres dans Certaines Régions du Monde,” Rev. Gen. Therm. 6, 1285 (1967).

1953 (1)

R. L. Hansler, R. A. Oetjen, “The Infrared Spectra of HCl, DCl, HBr, and NH3 in the Region from 40 to 140 Microns,” J. Chem. Phys. 21, 1340 (1953).
[CrossRef]

1950 (1)

Abreu, L. W.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

Bellamy, L. J.

L. J. Bellamy, The Infra-red Spectra of Complex Molecules (Chapman & Hall, London, 1975).

Berdahl, P.

P. Berdahl, M. Martin, F. Sakkal, “Thermal Performance of Radiative Cooling Panels,” Int. J. Heat Mass Transfer 26, 871 (1983).
[CrossRef]

P. Berdahl, R. Fromberg, “The Thermal Radiance of Clear Skies,” Sol. Energy 29, 299 (1982).
[CrossRef]

Biggs, K. L.

D. Michell, K. L. Biggs, “Radiation Cooling of Buildings at Night,” Appl. Energy 5, 263 (1979).
[CrossRef]

Born, M.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1980).

Catalanotti, S.

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

Chetwynd, J. H.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

Cuomo, V.

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

Eriksson, T. S.

T. S. Eriksson, C. G. Granqvist, “Infrared Optical Properties of Electron-Beam Evaporated Silicon Oxynitride Films,” Appl. Opt. 22, 3204 (1983).
[CrossRef] [PubMed]

T. S. Eriksson, C. G. Granqvist, “Radiative Cooling Computed for Model Atmospheres,” Appl. Opt. 21, 4381 (1982).
[CrossRef] [PubMed]

T. S. Eriksson, A. Hjortsberg, C. G. Granqvist, in Proceedings, Seventh International Conference on Vacuum Metallurgy—Special Meltings and Metallurgical Coatings (The Iron and Steel Institute of Japan, 1982), p. 696; T. S. Eriksson, E. M. Lushiku, C. G. Granqvist, “Materials for Radiative Cooling to Low Temperatures,” Proc. Soc. Photo-Opt. Instrum. Eng. 428, 105 (1983).

Fenn, R. W.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

Fromberg, R.

P. Berdahl, R. Fromberg, “The Thermal Radiance of Clear Skies,” Sol. Energy 29, 299 (1982).
[CrossRef]

Gallery, W. O.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

Granqvist, C. G.

T. S. Eriksson, C. G. Granqvist, “Infrared Optical Properties of Electron-Beam Evaporated Silicon Oxynitride Films,” Appl. Opt. 22, 3204 (1983).
[CrossRef] [PubMed]

E. M. Lushiku, A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Infrared-Emitting Ammonia Gas,” J. Appl. Phys. 53, 5526 (1982).
[CrossRef]

T. S. Eriksson, C. G. Granqvist, “Radiative Cooling Computed for Model Atmospheres,” Appl. Opt. 21, 4381 (1982).
[CrossRef] [PubMed]

C. G. Granqvist, A. Hjortsberg, “Radiative Cooling to Low Temperatures: General Considerations and Application to Selectively Emitting SiO Films,” J. Appl. Phys. 52, 4205 (1981).
[CrossRef]

A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Emitting Ethylene Gas,” Appl. Phys. Lett. 39, 507 (1981).
[CrossRef]

T. S. Eriksson, A. Hjortsberg, C. G. Granqvist, in Proceedings, Seventh International Conference on Vacuum Metallurgy—Special Meltings and Metallurgical Coatings (The Iron and Steel Institute of Japan, 1982), p. 696; T. S. Eriksson, E. M. Lushiku, C. G. Granqvist, “Materials for Radiative Cooling to Low Temperatures,” Proc. Soc. Photo-Opt. Instrum. Eng. 428, 105 (1983).

Grenier, P.

P. Grenier, “Réfrigération Radiative. Effet de Serre Inverse,” Rev. Phys. Appl. 14, 87 (1979).
[CrossRef]

Hansler, R. L.

R. L. Hansler, R. A. Oetjen, “The Infrared Spectra of HCl, DCl, HBr, and NH3 in the Region from 40 to 140 Microns,” J. Chem. Phys. 21, 1340 (1953).
[CrossRef]

Herzberg, G.

G. Herzberg, Infrared and Raman Spectra of Polyatomic Molecules (Van Nostrand, New York, 1945).

Hjortsberg, A.

E. M. Lushiku, A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Infrared-Emitting Ammonia Gas,” J. Appl. Phys. 53, 5526 (1982).
[CrossRef]

A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Emitting Ethylene Gas,” Appl. Phys. Lett. 39, 507 (1981).
[CrossRef]

C. G. Granqvist, A. Hjortsberg, “Radiative Cooling to Low Temperatures: General Considerations and Application to Selectively Emitting SiO Films,” J. Appl. Phys. 52, 4205 (1981).
[CrossRef]

T. S. Eriksson, A. Hjortsberg, C. G. Granqvist, in Proceedings, Seventh International Conference on Vacuum Metallurgy—Special Meltings and Metallurgical Coatings (The Iron and Steel Institute of Japan, 1982), p. 696; T. S. Eriksson, E. M. Lushiku, C. G. Granqvist, “Materials for Radiative Cooling to Low Temperatures,” Proc. Soc. Photo-Opt. Instrum. Eng. 428, 105 (1983).

Jones, W. J.

W. J. Jones, in Infra-red Spectroscopy and Molecular Structure, M. Davies, Ed. (Elsevier, Amsterdam, 1963), pp. 111–165.

Kneizys, F. X.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

Koch, E. E.

The optical constants of Al were obtained from J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Physics Data: Optical Properties of Metals, Part 2 (Fachinformationszentrum Energie, Physik, Mathematik GmbH, Karlsruhe, Germany, 1981), pp. 65–81.

Krafka, C.

The optical constants of Al were obtained from J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Physics Data: Optical Properties of Metals, Part 2 (Fachinformationszentrum Energie, Physik, Mathematik GmbH, Karlsruhe, Germany, 1981), pp. 65–81.

Landro, B.

B. Landro, P. G. McCormick, “Effect of Surface Characteristics and Atmospheric Conditions on Radiative Heat Loss to a Clear Sky,” Int. J. Heat Mass Transfer 23, 613 (1980).
[CrossRef]

Lushiku, E. M.

E. M. Lushiku, A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Infrared-Emitting Ammonia Gas,” J. Appl. Phys. 53, 5526 (1982).
[CrossRef]

Lynch, D. W.

The optical constants of Al were obtained from J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Physics Data: Optical Properties of Metals, Part 2 (Fachinformationszentrum Energie, Physik, Mathematik GmbH, Karlsruhe, Germany, 1981), pp. 65–81.

Martin, M.

P. Berdahl, M. Martin, F. Sakkal, “Thermal Performance of Radiative Cooling Panels,” Int. J. Heat Mass Transfer 26, 871 (1983).
[CrossRef]

McClatchey, R. A.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

McCormick, P. G.

B. Landro, P. G. McCormick, “Effect of Surface Characteristics and Atmospheric Conditions on Radiative Heat Loss to a Clear Sky,” Int. J. Heat Mass Transfer 23, 613 (1980).
[CrossRef]

McCubbin, T. K.

Michell, D.

D. Michell, K. L. Biggs, “Radiation Cooling of Buildings at Night,” Appl. Energy 5, 263 (1979).
[CrossRef]

Oetjen, R. A.

R. L. Hansler, R. A. Oetjen, “The Infrared Spectra of HCl, DCl, HBr, and NH3 in the Region from 40 to 140 Microns,” J. Chem. Phys. 21, 1340 (1953).
[CrossRef]

Piro, G.

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

Ruggi, D.

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

Sakkal, F.

P. Berdahl, M. Martin, F. Sakkal, “Thermal Performance of Radiative Cooling Panels,” Int. J. Heat Mass Transfer 26, 871 (1983).
[CrossRef]

Selby, J. E. A.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

Shettle, E. P.

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

Silvestrini, V.

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

Sinton, W. M.

Troise, G.

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

Trombe, F.

F. Trombe, “Perspectives sur l’Utilization des Rayonnements Solaires et Terrestres dans Certaines Régions du Monde,” Rev. Gen. Therm. 6, 1285 (1967).

Weaver, J. H.

The optical constants of Al were obtained from J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Physics Data: Optical Properties of Metals, Part 2 (Fachinformationszentrum Energie, Physik, Mathematik GmbH, Karlsruhe, Germany, 1981), pp. 65–81.

Wolf, E.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1980).

Appl. Energy (1)

D. Michell, K. L. Biggs, “Radiation Cooling of Buildings at Night,” Appl. Energy 5, 263 (1979).
[CrossRef]

Appl. Opt. (2)

Appl. Phys. Lett. (1)

A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Emitting Ethylene Gas,” Appl. Phys. Lett. 39, 507 (1981).
[CrossRef]

Int. J. Heat Mass Transfer (2)

P. Berdahl, M. Martin, F. Sakkal, “Thermal Performance of Radiative Cooling Panels,” Int. J. Heat Mass Transfer 26, 871 (1983).
[CrossRef]

B. Landro, P. G. McCormick, “Effect of Surface Characteristics and Atmospheric Conditions on Radiative Heat Loss to a Clear Sky,” Int. J. Heat Mass Transfer 23, 613 (1980).
[CrossRef]

J. Appl. Phys. (2)

C. G. Granqvist, A. Hjortsberg, “Radiative Cooling to Low Temperatures: General Considerations and Application to Selectively Emitting SiO Films,” J. Appl. Phys. 52, 4205 (1981).
[CrossRef]

E. M. Lushiku, A. Hjortsberg, C. G. Granqvist, “Radiative Cooling with Selectively Infrared-Emitting Ammonia Gas,” J. Appl. Phys. 53, 5526 (1982).
[CrossRef]

J. Chem. Phys. (1)

R. L. Hansler, R. A. Oetjen, “The Infrared Spectra of HCl, DCl, HBr, and NH3 in the Region from 40 to 140 Microns,” J. Chem. Phys. 21, 1340 (1953).
[CrossRef]

J. Opt. Soc. Am. (1)

Rev. Gen. Therm. (1)

F. Trombe, “Perspectives sur l’Utilization des Rayonnements Solaires et Terrestres dans Certaines Régions du Monde,” Rev. Gen. Therm. 6, 1285 (1967).

Rev. Phys. Appl. (1)

P. Grenier, “Réfrigération Radiative. Effet de Serre Inverse,” Rev. Phys. Appl. 14, 87 (1979).
[CrossRef]

Sol. Energy (2)

S. Catalanotti, V. Cuomo, G. Piro, D. Ruggi, V. Silvestrini, G. Troise, “The Radiative Cooling of Selective Surfaces,” Sol. Energy 17, 83 (1975).
[CrossRef]

P. Berdahl, R. Fromberg, “The Thermal Radiance of Clear Skies,” Sol. Energy 29, 299 (1982).
[CrossRef]

Other (8)

T. S. Eriksson, A. Hjortsberg, C. G. Granqvist, in Proceedings, Seventh International Conference on Vacuum Metallurgy—Special Meltings and Metallurgical Coatings (The Iron and Steel Institute of Japan, 1982), p. 696; T. S. Eriksson, E. M. Lushiku, C. G. Granqvist, “Materials for Radiative Cooling to Low Temperatures,” Proc. Soc. Photo-Opt. Instrum. Eng. 428, 105 (1983).

The optical constants of Al were obtained from J. H. Weaver, C. Krafka, D. W. Lynch, E. E. Koch, Physics Data: Optical Properties of Metals, Part 2 (Fachinformationszentrum Energie, Physik, Mathematik GmbH, Karlsruhe, Germany, 1981), pp. 65–81.

M. Born, E. Wolf, Principles of Optics (Pergamon, Oxford, 1980).

F. X. Kneizys, E. P. Shettle, W. O. Gallery, J. H. Chetwynd, L. W. Abreu, J. E. A. Selby, R. W. Fenn, R. A. McClatchey, Air Force Geophys. Lab. Tech. Rep. AFGL-TR-80-0067 (Feb.1980).

R. C. Weast, M. J. Astle, Eds., CRC Handbook of Chemistry and Physics (CRC Press, Boca Raton, 1979), pp. B-91–B-184, C-81–C-548.

L. J. Bellamy, The Infra-red Spectra of Complex Molecules (Chapman & Hall, London, 1975).

G. Herzberg, Infrared and Raman Spectra of Polyatomic Molecules (Van Nostrand, New York, 1945).

W. J. Jones, in Infra-red Spectroscopy and Molecular Structure, M. Davies, Ed. (Elsevier, Amsterdam, 1963), pp. 111–165.

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Figures (10)

Fig. 1
Fig. 1

Spectral IR transmittance measured with gas cells of length L. Upper curves in each part refer to air-filled cells, and lower curves refer to NH3 filled cells. Shaded areas indicate the absorption in the gas. Horizontal bars denote the 8–13-μm atmospheric window.

Fig. 2
Fig. 2

Spectral JR transmittance measured with gas cells of length L. Upper curves in each part refer to air-filled cells, and lower curves refer to C2H4 filled cells. Shaded areas indicate the absorption in the gas.

Fig. 3
Fig. 3

Spectral IR transmittance measured with gas cells of length L. Upper curves in each part refer to air-filled cells, and lower curves refer to C2H4O filled cells. Shaded areas indicate the absorption in the gas.

Fig. 4
Fig. 4

Basic cooling parameters ( e ¯ s 2 H and ηH) vs layer thickness t for NH3, C2H4, and C2H4O backed by reflecting Al.

Fig. 5
Fig. 5

Basic cooling parameters ( e ¯ s 2 H and ηH) for C2H4 + C2H4O mixtures with different composition. Results are shown for three values of the layer thickness t.

Fig. 6
Fig. 6

Radiative power Prad and nonradiative power loss Ploss vs temperature difference for gas layers of NH3, C2H4, and C2H4O backed by Al and for an ideal blackbody surface. Results are given for three values of the layer thickness t. The power loss is set to 1 W m−1 K−1. The curves for C2H4 and C2H4O are partially overlapping.

Fig. 7
Fig. 7

Radiated power Prad and nonradiative power loss Ploss vs temperature difference for gas layers of C2H4 + C2H4O backed by Al and for an ideal blackbody surface. Results are given for different mixing ratio and layer thickness t. The power loss is set to 1 W m−2 K−1.

Fig. 8
Fig. 8

Cutaway diagram of panel for testing radiative gas cooling. The large arrows indicate laminar gas flow.

Fig. 9
Fig. 9

Excerpt from an experiment for testing radiative cooling with a 10-cm thick slab of NH3. Tin and Tout denote the temperature at the gas inlet and outlet, respectively, in the panel shown in Fig. 8.

Fig. 10
Fig. 10

Excerpt from an experiment for testing radiative cooling with a 10-cm thick slab of C2H4. Tin and Tout denote the temperature at the gas inlet and outlet, respectively, in the panel shown in Fig. 8. Ta is the ambient temperature. At A, B, and C, the gas flow was adjusted to the shown rates.

Equations (12)

Equations on this page are rendered with MathJax. Learn more.

P rad = 0 π / 2 d ( sin 2 θ ) 0 d λ [ W ( λ , T s ) e s ( θ , λ ) - W ( λ , T a ) e a ( θ , λ ) e s ( θ , λ ) ] ,
e s ( θ , λ ) = 1 - R ( θ , λ )
= 1 - ½ [ R TE ( θ , λ ) + R TM ( θ , λ ) ] ,
e a = 1             for λ < 8 μ m ,
= 1 - [ 1 - e ¯ a 2 ( 0 ) ] 1 / cos θ             for 8 < λ < 13 μ m ,
= 1             for λ > 13 μ m ,
e ¯ s H 0 d λ W ( λ , T a ) [ 1 - R H ( λ ) ] / 0 d λ W ( λ , T a ) ,
e ¯ s 2 H 8 μ m 13 μ m d λ W ( λ , T a ) [ 1 - R H ( λ ) ] / 8 μ m 13 μ m d λ W ( λ , T a ) ,
η H e ¯ s 2 H / e ¯ s H ,
R H ( λ ) = 0 π / 2 d ( sin 2 θ ) R ( θ , λ )
Δ T T a - T s .
P c = P rad - P loss = P rad - κ Δ T ,

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