Single-phase thermosyphon heat transport device, a future prospect for heat removal applications: An experimental comparison with heat pipe and two-phase closed thermosyphon

Abstract

Over the years, the passive mode of heat transportation has gained immense popularity, which includes two-phase devices viz. Heat pipe (HP) and Two-phase closed thermosyphon (TPCT). But recently, the thermosyphon heat transport device (THTD) entered the pool, wherein the heat transfer fluid (HTF) in liquid phase transports heat by natural circulation (thermosyphon). Hence, to gauge their efficacy, in the present experimental investigation, the three devices (with the same geometry and HTF) are compared by imposing isothermal (40°C–90 °C) and isoflux (50–900 W) heating conditions.In isothermal mode, HP transports heat with a minimal temperature gradient compared to TPCT and THTD. The thermal resistance (TR) of TPCT and THTD is 5.4 to 10.1 times and 6.6 to 10.1 times respectively greater than HP. For isothermal temperatures below 80 °C, the TR of THTD is less than TPCT (viscous limit). Later the trend reverses as the TPCT outperforms, while THTD experiences HTF boiling. Further, the heat extracted by HP is 2.1 to 3.9 times and 3 to 3.5 times greater than TPCT and THTD respectively. Hence, its application is justified if cost is not a concern, while THTD (with high-temperature HTF) is suggested over TPCT on an economic basis. Even the isoflux mode showed a similar trend of TR. The system response (based on time constant) depicted both HP and TPCT have similar and nearly constant values over the heat load range, while in THTD, it decreases with an increase in heat load and approaches the other two. Hence, a high-temperature HTF would lead to competitive results. Further, concerning the heat transport distance, as the TR of THTD remained the same compared to the increment in TPCT, the application of the former is justified in long-distance heat transportation. Ultimately, HP is the front-runner, while TPCT and THTD perform on par depending on operating conditions and geometry.