EXPERIMENTAL INVESTIGATION OF INDIVIDUAL EVACUATED TUBE HEAT PIPE SOLAR WATER HEATING SYSTEMS

lar water heating systems with heat pipes of three diameter groups 16, 22 and 28.5 mm. The first third had evaporator lengths 1150, 1300 1550 second group an additional length 1800 all were fixed condenser 200 Ethanol at 50% fill charge ratio the volume was used as working fluid. Each pipe section inserted in a storage tank into evacuated glass tube Owens- Illinois type. combined form active solar collector unique design.The resulting ten tested outdoors under meteorological conditions Baghdad, Iraq. Experiments carried out no load, intermittent continuous load conditions. Some tests, without reflectors. overall system efficiency found to improve by maximum 55%. employing mm (HP7) showed best performance higher temperatures, useful energy gain various System predicted theoretically using electrical analogy derived from balance. An agreement within 14% obtained between theoretical experimental values.