Estimation of effective thermal conductivity and heat transfer coefficient of lithium orthosilicate pebble bed in carbon dioxide–air medium

Preliminary Investigation of Thermoelectric Electromotive Force Oscillation of NiCr/NiSi Thin Film Thermocouple in Dynamic Calibration

“…There are several energy transmission methods in NiCr/NiSi TFTC, including the thermal radiation from NiSi film surface layer toward natural air, thermal convection between NiSi film surface layer and natural air, thermal conduction from NiSi film surface layer to NiCr/NiSi TFTC system, as well as from NiSi film surface layer toward natural air. It can be known that the thermal conductivity ( λ ) of air λ Air is (5.30 ± 2.40) × 10 −2 W m −1 K −1 in temperature range of 273–1473 K. [ 43–51 ] However, λ of NiSi ( λ NiSi ) and NiCr ( λ NiCr ) is about three order of magnitude higher than λ Air . For example, λ NiCr is (77.61 ± 9.91) W m −1 K −1 in temperature range of 273–1473 K. [ 43–51 ] Compared with the convective heat transfer coefficient between NiSi film surface layer and natural air, as well as radiation heat transfer coefficient of NiSi film surface layer, the thermal conduction from NiSi film surface layer to NiCr/NiSi TFTC system dominates the energy transmission in dynamic calibration procedure.…”

“…It can be known that the thermal conductivity (𝜆) of air 𝜆 Air is (5.30 ± 2.40) × 10 −2 W m −1 K −1 in temperature range of 273-1473 K. [43][44][45][46][47][48][49][50][51] However, 𝜆 of NiSi (𝜆 NiSi ) and NiCr (𝜆 NiCr ) is three order of magnitude higher than 𝜆 Air . For example, 𝜆 NiCr is (77.61 ± 9.91) W m −1 K −1 in temperature range of 273-1473 K. [43][44][45][46][47][48][49][50][51] Compared with the convective heat transfer coefficient between NiSi film surface layer and natural air, as well as radiation heat transfer coefficient of NiSi film surface layer, the thermal conduction from NiSi film surface layer to NiCr/NiSi TFTC system dominates the energy transmission in dynamic calibration procedure. For simplifying the discussion process, only the thermal conduction from NiSi film surface layer to NiCr/NiSi TFTC system is considered, just as shown in Figure 9.…”

“…In general, 𝜆 Glass is 0.65-0.71 W m −1 K −1 , which is one order of magnitude lower than 𝜆 NiCr and 𝜆 NiSi . [43][44][45][46][47][48][49][50][51] As a result, compared with the transmission in NiCr film, it is hard for the thermal energy to transmit into glass substrate. So, the thermal energy transmitted to interface between NiCr film and glass substrate is bounced against, just as the olive and blue dash dot lines shown in Figure 13.…”