Method for measurement of emissivity and absorptivity of highly reflective surfaces from 20 K to room temperatures

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68081731%3A_____%2F16%3A00464050" target="_blank" >RIV/68081731:_____/16:00464050 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1088/0026-1394/53/2/743" target="_blank" >http://dx.doi.org/10.1088/0026-1394/53/2/743</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1088/0026-1394/53/2/743" target="_blank" >10.1088/0026-1394/53/2/743</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Method for measurement of emissivity and absorptivity of highly reflective surfaces from 20 K to room temperatures

Popis výsledku v původním jazyce

We present a cryogenic method for the measurement of total hemispherical emissivity and absorptivity of various materials at temperatures from 320 K down to approximate to 20 K. In absorptivity measurement the temperature of the examined sample is kept at approximate to 5 K-35 K. Radiative heat flow between two plane parallel surfaces of 40 mm in diameter disk samples placed in a vacuum, a sample and a disk with reference surface, is absorbed by a colder sample and sinks into an LHe bath via a thermal resistor (heat flow meter). Heat flow is measured by substitution method, using thermal output of an electrical heater for heat flow meter calibration. A great deal of attention is paid to the estimation of uncertainties associated with this method. Capabilities of the instrument are demonstrated by the absorptivity and emissivity measurement of the pure aluminium sample. The expanded fractional uncertainty (k = 2) in emissivity epsilon = 0.0041 measured at approximate to 30 K for pure aluminium is less than 11% and for values of emissivity epsilon > 0.0053 measured above 60 K the uncertainties are below 7%. The method was designed primarily for the measurement of highly reflective materials like pure metals, nevertheless high emissivity of the reference sample also enables the measurement of nonmetallic materials with reasonable accuracy.

Název v anglickém jazyce

Method for measurement of emissivity and absorptivity of highly reflective surfaces from 20 K to room temperatures

Popis výsledku anglicky

We present a cryogenic method for the measurement of total hemispherical emissivity and absorptivity of various materials at temperatures from 320 K down to approximate to 20 K. In absorptivity measurement the temperature of the examined sample is kept at approximate to 5 K-35 K. Radiative heat flow between two plane parallel surfaces of 40 mm in diameter disk samples placed in a vacuum, a sample and a disk with reference surface, is absorbed by a colder sample and sinks into an LHe bath via a thermal resistor (heat flow meter). Heat flow is measured by substitution method, using thermal output of an electrical heater for heat flow meter calibration. A great deal of attention is paid to the estimation of uncertainties associated with this method. Capabilities of the instrument are demonstrated by the absorptivity and emissivity measurement of the pure aluminium sample. The expanded fractional uncertainty (k = 2) in emissivity epsilon = 0.0041 measured at approximate to 30 K for pure aluminium is less than 11% and for values of emissivity epsilon > 0.0053 measured above 60 K the uncertainties are below 7%. The method was designed primarily for the measurement of highly reflective materials like pure metals, nevertheless high emissivity of the reference sample also enables the measurement of nonmetallic materials with reasonable accuracy.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

BJ - Termodynamika

OECD FORD obor

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Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Metrologia

ISSN

0026-1394

e-ISSN

—

Svazek periodika

53

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

11

Strana od-do

743-753

Kód UT WoS článku

000373376300005

EID výsledku v databázi Scopus

2-s2.0-84962454807