Conclusion

From a theoretical point of view, the operation of two-phase gravity loops seems reasonably well understood. In practice, however, the sizing of such systems is hampered by the difficulty of correctly assessing heat exchange coefficients and head losses. Indeed, there is currently no reliable method of predicting these quantities for geometries more complex than simple circular ducts. As a result, applications of these systems remain limited to cases where a certain empiricism in design remains acceptable.

Two-phase thermocapillary pumped fluid loops (TPFCL) have now reached sufficient maturity to be offered as a commercially available technology, after more than 30 years of initial development for the space industry. Nevertheless, research into these systems continues, with the aim of gaining a better understanding of the complex, tightly-coupled phenomena responsible...