Experimental investigation of the thermal performance of a two-phase closed thermosyphon at different operating conditions

• It is aimed to find effective working fluid in two phase closed thermosyphon.
• Experimental investigation is carried out on the TPCT performance.
• Design and production of TPCT type heat pipe.
• Water, ethylene glycol and ethanol are the best working fluid for different operating conditions.

In this study, the thermal performance of a two-phase, closed thermosyphon (TPCT) was investigated experimentally. In the experiments, we used water, ethanol, and ethylene glycol as the working fluids and considered different operating conditions, such as inclination angles (30, 60, and 90°), heat inputs (200, 400, and 600 W), and flow rates of cooling water (10, 20, and 30 L/h). Initially, an experimental test rig was designed and built, and, then, a series of rigorous tests was conducted on the TPCT. In the experiments, the temperature distribution on the wickless heat pipe or the thermosyphon's surface and the temperature differences of the cooling water were measured. The data were used to calculate the thermal resistance and efficiency of the TPCT, and the results are presented graphically and discussed in detail. The efficiency of the TPCT for each working fluid at different operating conditions varied between averages of 30 and 95%, which was in good agreement with published results. The results indicated that water was the best working fluid when the heat inputs were 200 W and the flow rates of the cooling water were 10 L/h. Ethylene glycol was the best working fluid when the heat inputs were 200 W and the flow rates of the cooling water were 30 L/h. Ethanol was the best working fluid when the heat inputs were 600 W and the flow rates of the cooling water were 10 L/h. In addition, it was found that the inclination angle and heat inputs had significant effects on the efficiency of the TPCT.