Je was op zoek naar: reflux (Engels - Chinees (Vereenvoudigd))

reflux
回流

acid reflux
胃酸倒流

reflux condenser
冷凝管

to prevent liquid lost a reflux condenser shall be attached (see figure 37.4.2).
为了防止液体流失，应附加一个回流冷凝器(见图37.4.2)。

a reflux condenser subjects fluid to a process where a gas produced by heating is collected on the reflux condenser. the fluid is cooled until it condenses and runs back into the original fluid. usually it is put on a round-bottomed flask or several neck flasks.
冷凝管具有回流功能， 当加热产生的蒸气上升至冷凝管中时， 气体凝结下来回流到原液中。 通常它连接一个圆底烧瓶或一些长颈瓶 。

539. labour productivity (gross agricultural production per employee) in agriculture increased in the last years due to the reflux of the workforce from agriculture into other sectors of the national economy (especially in the services' sectors) as well outside the country.
539. 近年来，由于大量农业劳动力涌向国民经济其他部门(尤其是服务行业)和国外，农业劳动生产率(每名农业工人创造的农业生产总值)有所上升。