Experimental study of flow inside the three-dimensional tubes（1EHT and 3EHT）and equivalent smooth tube was conducted to investigate the influence of different structures of tube wall on condensation characteristics. All the three tested stainless-steel tube have the same outer diameter. The working fluid was R134a. The 1EHT was enhanced by elliptical dimples and petal arrays while the 3EHT was enhanced by rectangle grooves. The test apparatus included a 2m horizontal, straight test section with an active length cooled by water circulated in a surrounding annulus. Constant condensation temperature was maintained at 45℃(318K) when refrigerant quality varied from inlet 0.8 and outlet 0.2. Mass flux was controlled from 70 kg/m2s to 170 kg/ m^2^s. In a comparison of condensation heat transfer performance, the 1EHT1 tube has the best heat performance followed by the 3EHT tube. It is about 1.45 times of the 1EHT1 tube and 1.16 times of 3EHT tube. As the mass velocity increased the HTC increase accordingly. Several condensation heat transfer correlations were employed to predict the experimental results and their predictive accuracy were compared. And the data of another working fluid at the same operation conditions were compared to present the influence of different refrigerants on heat transfer performance.

 

Keywords: Condensation; enhanced tube; three-dimensional surface; two-phase flow; low mass flux.


Condensation Characteristics of Flows Inside the Three-Dimensional Enhanced and Smooth Tubes

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

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