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汽车工业是个大消费领域,截止九一年的统计表明,汽车主要生产国年产汽车4,900万辆,车用电热器之所以还是个空白,主要原因有两个,一是受到电热材料的局限性,电热功率P=V~2S/pl,若电压从市电220V降至12V,热材料性能及长度不变,合金电热材料的截面积S必须扩大336倍才能保证原功率,尽管合金材料不断在进步,即使是使用十分昂贵的高档次合金电热材料(P很小)仍是避免不了大功率低压电热器的体积大,粗笨和成本高的矛盾。二是汽车电瓶容量受到限制,最大使用电流一般在10A左右,即12V的汽车电瓶最大功率也仅有120瓦,而人们普遍认为生煮熟的的电热功
The automobile industry is a big area of consumption. As of 1991, the statistics show that the major automobile producing countries produce 49 million vehicles annually. The reason why the automobile electric heater is still blank is due to two reasons, firstly, the limitation of electric heating materials , The electric power P = V ~ 2S / pl, if the voltage from the city 220V down to 12V, thermal properties and length of the same material, the cross-sectional area of the alloy heating material S must be expanded 336 times in order to ensure that the original power, Progress, even the use of very expensive high-grade alloy electric material (P small) still can not avoid the bulky, crude and high-power low-voltage electric heater contradictions. Second, the car battery capacity is limited, the maximum current use is generally about 10A, that is, the maximum power of 12V car battery is only 120 watts, while people generally believe that raw cooked electric power