光滑管 meaning in English

plain tube
smooth pipe

The results of comparison and analysis show that the dac tube surpasses the plain tube on the aspects of not only heat transfer but also mass transfer
实验表明， dac强化管无论是在传热方面还是在传质方面，均明显优于光滑管，是一种高效的传热传质加强管。
The results showed that the total heat transfer coefficient of petal - shaped finned tube oil - cooler with helical baffles was 4 ~ 5 times as large as that of smooth tube oil - cooler with segmental baffles at the same oil pressure drop
结果表明，在相同油压降下，螺旋隔板花瓣管油冷却器的总传热系数是弓形隔板光滑管油冷却器的4 ~ 5倍。
The heat transfer and flow resistance performance of petal - shaped finned tube oil - cooler with helical baffles was studied , and compared the total heat transfer coefficient of petal - shaped fimed tube oil - cooler with helical baffles with that of smooth tube oil - cooler with segmental baffles
摘要研究了螺旋隔板花瓣管水冷壳管式油冷却器的传热和流阻性能，并与弓形隔板光滑管水冷壳管式油冷却器进行了性能对比。