Investigation on Pressure Drop Characteristics During Refrigerants Condensation Inside Internally Threaded Tubes

Xiangrui Meng, Jian Wang, Qian Sun and Xinling Ma ()
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Xiangrui Meng: School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, China
Jian Wang: School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, China
Qian Sun: School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, China
Xinling Ma: School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, China

Energies, 2025, vol. 18, issue 10, 1-22

Abstract: This study investigates the influence of geometric parameters of internally threaded tubes on heat transfer and resistance characteristics. Experimental analyses were conducted on pressure drop for 9.52 mm outer diameter tubes with various industry-standard geometric parameter combinations. Using R410A as the working fluid under turbulent flow conditions ( Re = 20,000–60,000), experimental parameters included the following: mass velocity 50–600 kg/(m 2 ·s), condensation temperature 45 ± 0.2 °C, and geometric ranges of thread height ( e = 0.0001–0.0003 m), helix angle ( α = 17–46°), crest angle ( β = 16–53°), and number of ribs ( Ns = 50–70). Results demonstrate that the newly developed correlation based on Webb and Ravigururajan friction factor models shows improved prediction accuracy for R410A condensation pressure drop in ribbed tubes. Model II achieved a mean absolute percentage error (MAPE) of 7.08%, with maximum and minimum errors of 27.66% and 0.76%, respectively. The standard deviation decreased from 0.0619 (Webb-based Model I) to 0.0362. Integration of SVR machine learning further enhanced tube selection efficiency through optimized correlation predictions.

Keywords: R410A; internally threaded tube; condensation heat transfer; friction factor correlation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2025
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