Calorimetric measurements of emittance of pipe surfaces: influence of enclosure diameter, test pipe length, and an argon atmosphere

Technical Report · Thu Oct 01 00:00:00 EDT 1981

OSTI ID:5487652

Reitter, T A

Additional results using a calorimetric technique for measuring the total hemispherical emittance of pipe surfaces from 400 to 600 K are described. Two different Pyrex pipe enclosures were used, one of 15 cm i.d. and the other of 30 cm i.d. An error analysis showed that the larger diameter Pyrex pipe should have a smaller error, but the difference was negligible for the 4.4-cm test pipe diameter used. Measurements on a short length of a previously-measured pipe agreed with earlier measurements, but only over the temperature range of the measurements. While the technique normally uses a vacuum to minimize nonradiative heat transfer, measurements were done succesfully with an argon atmosphere in a closed system. A nickel-plated pipe, measured first in a vacuum and then in an argon atmosphere, allowed calculation of an effective convective heat-transfer coefficient for use with test pipes of unknown emittances. Measurements done with an atmosphere have larger uncertainties than those done in vacuum. Measurements using this technique agreed with measurements made using a reflectance technique. It is believed that within the range of temperatures measured, emittance measurements made using the calorimetric technique have a relative error of no more than 10% when done in vacuum.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5487652
• Report Number(s): UCRL-53213; ON: DE82009040
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
PIPES
EMISSIVITY
SOLAR ABSORBERS
BLACK CHROME
CALORIMETRY
CONTROLLED ATMOSPHERES
DATA ANALYSIS
HEAT TRANSFER
NICKEL
SUBSTRATES
ATMOSPHERES
BLACK COATINGS
COATINGS
ELEMENTS
ENERGY TRANSFER
EQUIPMENT
METALS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SOLAR EQUIPMENT
SURFACE PROPERTIES
TRANSITION ELEMENTS
141000* - Solar Collectors & Concentrators