Experimental investigation of simultaneous electricity generation and heat transfer in a thermosyphon heat pipe

• Published in: Thermal science and engineering progress 2024-03, Vol.49, p.102495, Article 102495
• Main Authors: Maleknezhad, Abolfazl, Ghahremani, Amirreza, Behshad Shafii, Mohammad
• Format: Article
• Language: English
• Subjects: Electromagnetic induction; Energy harvesting module; Oscillating magnet; Thermosyphon heat pipe
• ISSN: 2451-9049
• DOI: 10.1016/j.tsep.2024.102495

•Converting low-grade energy of waste heat to electricity in a THP is investigated.•Novel hybrid THP which can transfer heat and generate electricity is developed.•Highest average and maximum peak-to-peak open circuit voltages are 1 V and 1.34.•Thermal-electric index reveals that optimal condition happens at 20 %, 60°, and 100 W. This experimental research proves the idea of converting low-grade energy of waste heat to electricity in a thermosyphon heat pipe (THP). In this experiment, a novel hybrid thermosyphon is developed, which can transfer heat and generate electricity simultaneously. A magnet is placed in front of the gaseous flow which is moving toward the condenser with a high velocity. The vapor drag force which is exerted on the magnet, causes an oscillation in it. A solenoid is placed on the outer wall of the adiabatic section, and electricity is induced in it due to the oscillation of the magnet. The oscillating magnet thermosyphon heat pipe (OM-THP) is tested at three different inclination angles of 90, 60, and 30 degrees. Each inclination angle is also tested in four different charging ratios of 10, 20, 30, and 40 percent. Water is selected as the working fluid. The initial heat input is 25 W and increases with an increment of 25 W. The results indicate that increasing heat input enhances the voltage induced in the solenoid. The OM-THP has greater electrical performance in a vertical position, though at 60° inclination angle, the OM-THP provides better thermal performance (lower thermal resistance). It is revealed that the 20 % charging ratio has the maximum induced voltage. In other words, there is an optimum charging ratio that results in the most magnet's oscillation. The maximum average peak-to-peak open circuit voltage is measured as 1 V, which happens at a 20 % charging ratio, vertical position, and 100 W heat input. The thermal electric index is calculated for the operating conditions of the OM-THP, to determine the optimum operating condition of the present thermosyphon regarding thermal and electrical efficiency. The thermal electric index indicates that the best operating condition of the hybrid thermosyphon is 60° inclination angle, 20 % charging ratio, and 100 W heat input.