EXPERIMENTAL INVESTIGATION OF LOOP HEAT PIPE APPLIED IN A RAILING-TYPE COLLECTOR SOLAR WATER HEATER

This paper presents an experimental examination of a railing-type collector solar water heater (RTCSWH), employing a loop heat pipe (LHP) as a heat transfer device. The structure and characteristics of the RTCSWH are also outlined. The LHP is a high-efficiency heat transfer device capable of transporting thermal energy over long distances without the need for other mechanical forces, such as pumps. This makes LHPs particularly suitable for applications involving solar water heaters. We conducted various experiments to investigate the start-up behavior and thermal storage efficiency under various filling ratios with different heat loads and tilt angles. The experimental results revealed that 70% is the ideal filling ratio for an RTCSWH and that the heat load presents critical limitations with regard to stable operations. The highest thermal storage efficiency obtained in this study was 77%. We also determined that when a railing-type collector has a nonzero tilt angle, loose limitations pertaining to heat load can be relaxed without sacrificing stable operations. We also investigated the characteristics of the start-up behavior, including oscillation, overshoot, dry out, and failure.