Study on the Radiation Characteristics of Large-Scale High-Temperature Objects under Rotating Conditions

Abstract Radiative heat loss from cement rotary-kiln shells at 200–400 °C is a promising source for waste-heat recovery, but shell rotation prevents direct thermoelectric attachment and makes narrow-gap radiation–convection coupling the key constraint. This work develops a rotation-inclusive CFD framework using steady RANS with the SST k–ω model and gray surface-to-surface radiation to evaluate a non-contact radiative collector. The predicted outlet temperature is validated by on-site infrared thermography using a UNI-T UTi165B+ imager with an emissivity setting of 0.9 and an accuracy of ±2%. Experimental points are reported with error bars and assessed using a ±4% parity band. For a single collector plate, a speed-dependent regime is identified. The area-averaged plate heat-flux density is about 1378 W m−2 at zero rotation, remains within 1324–1359 W m−2 for ω ≤ 0.15 rad s−1, and decreases to about 1234 W m−2 at 0.30 rad s−1 as throat velocity rises and forced convection intensifies. For circumferential multi-plate installation, the radiative fraction stays nearly constant at about 41–45% with less than 1% variation, indicating that circumferential non-uniformity is governed by changes in absolute radiative load. An annular integrated collector is proposed to suppress bypass flow and stabilize the gap field. At L = 10 mm, rotation sensitivity is reduced and the circumferential temperature spread is about 1 K except near apex regions. A transition near L ≈ 18 mm is indicated by crown-side cooling and an inlet–outlet effect reversal, which provides a criterion for gap selection.