Two-phase thermosyphon loop with different working fluids used in data centers

Abstract

The two-phase thermosyphon loop (TPTL) is an effective cooling technology used in data centers. TPTLs filled with different working fluids typically have various operating characteristics that influence their practical applications. A comparative experiment was conducted on CO2, R134a, and R410A TPTLs, and differences in their operating states and thermal performances were analyzed. The optimal filling ratio of the CO2 TPTL was 45%, while that of the R134a and R410A TPTLs was 35%. At their optimal filling ratios, all the three TPTLs successively underwent the pre-start, oscillatory, and stable operation stages as the heat transfer quantity increased. The oscillations of the CO2 TPTL were periodic, whereas those of the R134a and R410A TPTLs were irregular. The normal working load ranges of the CO2, R134a, and R410A TPTLs were 550–1200, 760–1160, and 790–1300 W, respectively. When the heat transfer quantity was 1000 W, the driving temperature difference of CO2 TPTL was 2.4 °C lower than that of R410A TPTL and 6.0 °C lower than that of R134a TPTL.