Heat Transfer during Boiling in Pipes with Uniform Continuous Wall Roughness in the Form of a Metric Thread and Twisted Tape Insert

摘要

The experimental study results of heat transfer during boiling of R134a refrigerant in a horizontal pipe with a wall roughness in the form of a metric thread with a full cutting profile with the depth Δ=0.45 mm and the pitch t=1 mm as well as with a smooth twisted tape inserted with a degree of swirling s/d=3; 6 are presented. The studies were carried out in the range of operating parameters: the Reynolds number for the fluid circulation rate Re= 16 000-33 000, heat flow density q=70-136 kW/m~2, steam weight fraction calculated with the supplied heat flow at the outlet of the working section reached x=0.113-0.323.