温度補償型熱流計センサの測定誤差の対象材料依存性

抄録

This paper describes the error in the heat flux measurements with an expected transducer. In the heat flux measurements from a wall to environment with the usual heat flux transducer placed on the wall, the original heat flux q₀ and temperature θ₀ simultaneously change by placing the transducer. For the purpose of improvement on the measurement accuracy, the transducer with the function witch compensates the temperature change is expected. In this transducer, it is the essential matter that the measurement error Δq depends on incompleteness of the temperature compensation Δθ.
The relational formula Δq/q₀=-E(Δθ/θ₀) and this coefficient E are derived from the heat conduction equation and a certain integral formula of Bessel function. The analysis of E, as an example, is performed with a wall whose inner structure is composed of surface layer and inner layer. Then E depends on thermal conductivity and thickness of the surface layer λ₁, d, thermal conductivity of the inner layer λ₀, heat transfer coefficient of the wall surface α₀, and size (radius) of the transducer R.
E is represented by three non-dimensional parameters H=λ₀/(α₀R), λ₁/λ₀, d/R in general case, by two parameters (λ₁d)/(λ₀R), H in the case of d<<R and λ₀<<λ₁, and by one parameter λ₁/(α₀R) in the case of d>>R or λ₁=λ₀. E is found numerically in 0.05∼10, 000 on an approximate estimate. The required accuracy of temperature compensation is determined from E and the desired measurement accuracy, and numerical values of this are also described with typical wall materials and others.