- 上一篇：破碎机的外文文献和中文翻译
- 下一篇：胀管换热器英文文献和中文翻译
Figs . 5 (d), 8(d), and 10(d) show the locations of the ferrite materials relative to the three experimental coils. The ferrites were placed either at the corners of the coil or in the middle between the copper- tube conductors with opposite current directions . Fig. 5( d) illustrates the locations of the ferrite materials in the reciprocated single -layer coil. The coil current directions of the vertical conductors were opposite to the adjacent others, and a repulsive proximity effect was induced between the vertical conductors during the induction heating process .Five ferrite slices with 4 mm thickness were used in the reciprocated single-layer coil. Three ferrite slices were inserted into the middle be-tween each adjacent vertical conductor to eliminate the proximity effect. Additionally, two ferrite slices were placed at the outside of c oil right/left boundaries to limit the effect area of magnetic flux .
Fig. 8(d) shows the locations of ferrite materials in the single-layer spiral coil. The circling coil current direction in the spiral coil induced a repulsive proximity effect at the spiral core. Therefore, the center of the heated surface had a lower temperature during the induction heating process[ 22] . A 4 mm diameter ferrite cylinder was inserted into the center of the spiral core to eliminate the proximity effect. Additionally, a 100 mm × 100 mm square ferrite slice (thickness: 4 m m) was placed over the spiral coil with 5 mm distance from coil surface to ferrite surface, to increase heating speed. Fig. 10 (d) shows the locations of the five ferrite slices used in the rectangular frame coil. Four ferrite slices were placed at the corners of the coil to increase the heating efficiency of the corner area, and a ferrite slice was placed at the middle of the coil inlet and outlet , where the copper-tube conductor had an opposite current direction
The reciprocated single-layer coil shows a large repulsive proximity effect between the adjacent copper- tube conductors with opposite current direction . In this experiment, five ferrite slices were used to Fig. 5 shows the thermal images of mold surface captured by the thermometer and infrared ray thermal imaging system after the mold surface was heated for 10 s and 20 s by reciprocated single-layer coil with/without ferrite slices.
Fig. 5(b) and (c) shows that repulsive proximity effect substantially limits the heating effect of the reciprocated single-layer coil on the mold surface. The maximum temperature inside the heating area ( inside black lines) increased only 5 and 10 °C after 10 and 20 s heating, respectively. Specifically, the center area shows a very small surface temperature increase.
Fig. 5( e) and ( f) shows that the ferrite slices effectively solve the heating problem in the reciprocated single-layer coil. The maximum temperature inside the heating area increased from 60 to 125 and 158 °C after 10 and 20 s heating. The temperature distribution shows that the temperature of the mol d surface under the copper tube was higher than that of the mold surface in contact with the ferrite slices, which result ed from the area of the mold surface in contact with the ferrite slices which also shows a proximity effect ( Fig. 2(b)).
The temperature profiles of the heated area during the conduction heating process were obtained by a nine-point measurement in experiments performed in a reciprocated single-layer coil and a single-layer spiral coil. Figs. 6 and 7 show temperature profiles obtained by the 9 point measurement at points P4 , P5 , P7 , and P8 during conduction heating. The experimental results show that the coil with out ferrite had a small temperature variation (Fig. 7(a)) that the coil with ferrite slices had a faster heating speed at beginning 5 s, and that the speed of increase in surface temperature slowed after 20 s ( Fig. 7(b) ). The experiment also confirms that the high resistivity (108 Ω-m ) of N i–Zn ferrite can avoid the ferrite slices to be heated by the induction heating coils . Therefore, the ferrite slices can maintain at a low temperature.