EXPERIMENTAL ANALYSIS OF A WICKLESS HEAT PIPE FOR SOLAR APPLICATIONS

The experimental facility called T.O.S.C.A. (Thermal fluid dynamics Of Solar Cooling Apparatus) is designed and built in the laboratory of ENEA CASACCIA to test the heat pipe performance. The object of this research is to evaluate the most important parameter that affects the heat transfer in such apparatus. The cooling loop is constituted of a collector. Pressurized water flows inside the collector cools the heat pipe. The condenser section of the heat pipe is immersed in the free stream of the water. The heat pipe is heated by an heater made with an electrical thread wrapping on a length of 85% of the total length. We apply available electrical power, however most of the tests are made with a power of 70W and 155W. Flow rate and pressure of the cooling water are constant. We measured the wall temperature of the heat pipe in the three different zone of the heat pipe: evaporator, adiabatic part and condenser; two other thermocouple are inserted in the collector to measure the heat transferred using a power balance. Several tests are made to study the influence of the amount of working fluid inside the heat pipe. We use two different fluids: water and oil. We tested also the influence of power and coolant flow rate on the behaviour of the heat pipe while the inclination is constant and equal to 45°.