THERMAL EFFICIENCY OF FLAT PLATE SOLAR COLLECTORS USING COCONUT SHELL AND BAMBOO CARBON ABSORBERS IN SOLAR WATER HEATERS

Abstract

Utilizing solar energy through solar water heaters is one solution to reduce dependence on fossil fuels and support the use of environmentally friendly energy. The performance of this system is influenced by the ability of the absorber plate to absorb and conduct heat. The problem in this study is how the effect of carbon-based absorber coatings on improving the thermal performance of flat plate solar collectors compared to absorbers without carbon coatings. The study was conducted experimentally using a 75 × 75 cm collector with a 3 mm cover glass and copper pipes. Testing was carried out for three days for each absorber variation with a 20-minute interval at 08.00–16.00. The parameters measured included inlet and outlet water temperatures, collector temperature, pipe temperature, and solar radiation intensity. Thermal efficiency was calculated based on the ratio of energy absorbed by water to solar radiation energy. The results showed that the collector without carbon coating had an efficiency of 18.7% with a water volume of ≥50°C of 15.77 liters. Bamboo carbon increased the efficiency to 21.2% with a volume of 23.66 liters, while coconut shell carbon provided the best performance with an efficiency of 25.4% and a volume of 28.51 liters. It was concluded that coconut shell carbon is the most effective absorber coating and has the potential as an efficient and sustainable local material.