The comparison of heat transfer performance with three different fin spacing, three different Numbers of tube rows and three different Numbers of tubes under three constraints is carried out.

然后通过三种限制条件对不同翅片间距、不同管排数和不同管数下的换热板芯的传热性能进行了比较。

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By using new type tube arrangement, rationally adjusting support spacing of cooling tubes, and replacing cooling tubes, the old condenser was retrofitted in overhaul period.

通过采用新型排管方式、合理调整冷却管支撑间距，并同时更换冷却管材的方法在大修期内对凝汽器进行了改造。

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The spacing of these tubes acts as a photonic crystal.

ECONOMIST: New-age crystals

Though there is no reason to use Dr Knight's invention to replace existing optical fibres, it could, by varying the spacing of the air-filled tubes, make a handy filter allowing selected wavelengths (and the messages they carry) to enter or leave the waveguide while the others are contained.

ECONOMIST: New-age crystals