Contrast experiments between gravity feeding and direct expansion refrigeration system were carried on, performance characteristics difference of the two refrigeration systems were found out.

并与直接膨胀供液制冷系统做同工况下的对比实验，分析两种系统的工作特性差异。

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The mechanism of filling accuracy and filling speed of gravity gravimetric filling machine were studied from the machine feeding material aspect.

本文根据食用碘盐物料特性和现有食用碘盐重力称重式充填机的不足 ，提出了提高充填机精度与速度的方法。

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