Experimental study of flat plate solar collector performance with twisted heat pipe

In this work, a system of heat pipe is implemented to improve the performance of flat plate solar collector. The experiment rig consists of sun light simulator, flat plate, heat pipe (wickless), heat exchanger, and measurement instruments. The model is represented by twisting portion of the evaporator section and also inclined by an angle of 30 degrees with a constant total length of 1140 mm. In this model the evaporator, adiabatic and condenser lengths are 780mm, 140mm and 230mm respectively. The omitted energies from sun light simulator are 200, 400, 600, 800 and 1000 W/m(2) which is close to the normal solar energy in Iraq. The working fluid for all models is water with fill charge ratio of 30% and the efficiency of the solar collector is investigated with three values of condenser inlet water temperatures, namely (12, 16 and 20 degrees C). The experimental result showed an optimum volume flow rate of cooling water in condenser at which the efficiency of collector is a maximum. This optimum agree well with the ASHRA standard volume of flow rate for conventional tasting for flat plate solar collector. When the radiation incident increases the thermal resistance of thermosyphon is decreases, where the heat transfer from the evaporator to condenser increases. The experimental results showed the performance of solar collector with twisted evaporator greater than other types of evaporator as a ratio 13.5 %.