Design of Solar Water Heater Using Collector Cylindric Parabolic and Coil Heater as Absorber at Focus Point

¹ Center for Research and Standardization of Industry Medan, Indonesia, Jl. Sisingamangaraja No. 24 Medan 20217, Indonesia
² Faculty of Mechanical Engineering, Medan Institute of Technology, Medan, Indonesia

Abstract

Solar thermal water heating systems have been developed to replace conventional heating. Therefore, the design of a parabolic cylinder collector-type solar heating unit with a coil-shaped heater (absorber) has been carried out. The cylindrical collector is made of an aluminum plate covered with a reflective sticker and the base is insulated, having a diameter, height, length, and position of the focal point 150, 60, 200, and 22.4 cm, respectively. The coil water heater of 3/8-inch diameter copper pipe having a diameter, pitch, and length of 20, 3, and 200 cm, respectively. The concentration ratio between collector area and heating pipe area (absorber) is 3.6. The results of heating trials conducted from 10:00 to 16:00 WIT, in Duplo to 100 liters of water circulated through the heating pipe at a speed of 0.017 kg/sec, indicate that heating is affected by fluctuations in radiation intensity. Thermal efficiency is inversely proportional to heating time. the lower the time when the difference between the temperature of the incoming and outgoing water gets smaller, or in other words in the evening the water temperature approaches a steady state. The achieved maximum water-heating temperature is 53C in the average radiation range during the test is 687-693 W/m².