By changing the tube into D shape (semicircle), the pallet can fully contact with the tubes (re. picture 2), the cooling speed can be shortened by the contact surface increased.

• 如果把管子的形状改成D形（半圆形），托盘在管子上的接触为平面接触（如图2所示），接触面积比圆管大大增加，热量以最快的速度从托盘传至排管并由管内的冷剂蒸汽带走。