SESSION 6

MATERIALS PROCESSING

Chairman: J.-F. Sacadura

THE EFFICIENCY OF THE RADIATION PROCESS IN THE CURING OF POWDER COATINGS WITH GASEOUS INFRARED HEATERS.

J. DEANS, M. KOGL, and B. LEEMA.
Department of Mechanical Engineering,
University of Auckland, Auckland, New Zealand.

ABSTRACT. This paper describes a study (1) which investigated the efficiency of the radiant heat transfer process during the curing of powder coated surfaces. Experiments were carried out using a porous ceramic radiant burner, fired with natural gas, these test measurements were subsequently interpreted using a Monte Carlo algorithm. This algorithm used non-grey calculation procedures based on the Edwards exponential wide band model for the absorption coefficients of the radiating flue gas components. The spectral properties of the powders were measured using a diffuse reflectance Fourier Transform infrared spectrometer.

The results show that the energy transferred to the powder during this process was limited to between 30 and 36% of the energy input from the burning gas and that this efficiency increased slightly with burner temperature and decreased with powder temperature. The quaiity of the cured surface tended to decrease with increasing burner temperature and it was closely related to the rate of heating of the powder.

THEORETICAL ANALYSIS ON DRYING OF POLYMER SOLUTION WITH CONTINUOUS OR INTERMITTENT HEATING BY HIGH-INTENSITY INFRARED RADIATION

Jyh-Jian CHEN, Jenn-Der LIN
Department of Mechanical Engineering
National Chiao Tung University, Hsin-Chu, Taiwan, R.O.C.

ABSTRACT. A theoretical study is performed that describes the heat transfer and moisture variation during drying process while the polymer solution is exposed to the high-intensity infrared radiation flux and hot air. We examine the effects of various parameters on the drying of coated film on a thick substrate. The effects of external heating conditions on drying are presented in terms of the drying rate, heat transfer as well as the moisture distribution. Numerical results show that the absorbed radiative heat energy in the polymer solution is dominant on drying rate of polymer solution during the process. The numerical results are also compared to widely-used thermal- lumped approximation to illustrate the validity of the approximation. While the intermittent heating is considered during drying, the energy consumption and flexible heating design are examined and we investigate the influences of various drying stages and external heating on the drying characteristics.