抄録
Radiative heat transfer is an important mode of heat transfer even in our life space at room temperature. Such radiative heat transfer is evaluated mostly by calculating the radiation energy exchange among surfaces in an enclosure. For this evaluation knowledge of hemispherical emittance of the constituent surfaces is required. However, there has not been a suitable technique for measuring the emittance of surfaces at room temperature. In the present work we develop a new apparatus for measuring total hemispherical emittance of real surfaces at room temperature. It consists of a radiation flux meter and a Peltier element cooler to cool the flux meter surface from the back, and measure the radiation net flux from the specimen surface to the surroundings to estimate the total hemispherical emittance of the specimen surface. This apparatus is effective to measure on-site total hemispherical emittance of surfaces at room temperature. The developed apparatus is applied to measure total hemispherical emittance of various surfaces in our life space, such as metals, human skin, cloth, floor mat, wood, glass, brick tiles, stone, cement, plant leaves, etc., to demonstrate the feasibility of the apparatus.
