Perpustakaan Digital ITB

Solar water heaters are a promising solution for reducing energy consumption in domestic applications, particularly in regions with abundant sunlight, such as Indonesia. However, it is reported that only less than 1% of Indonesian households currently use solar water heaters, with cost being one of the key constraints. This study aims to optimize the design of a thermosyphon (natural circulation) solar water heater for residential use, focusing on achieving a balance between cost-effectiveness and thermal performance. The methodology employed a CFD-derived empirical fitting and validation, which were integrated into a Simulink model to simulate the coupled system’s behavior. Key design parameters, including pipe diameter, collector aspect ratio, collector area, and the number of risers, collector tilt angle, were considered in the analysis. Various design variations were analyzed, including performance-sensitivity and solar economic cost optimization, to identify the most cost-effective solution. The findings indicate that the collector aspect ratio has minimal impact on performance once it exceeds an aspect ratio of 1.5, with only slight improvements in solar savings fraction (SSF) and efficiency observed beyond this point. Similarly, the number of risers showed relatively constant returns after 8 risers. In terms of collector area, on the other hand, shows a continuous rise in SSF while dropping efficiency while increasing the area. Moreover, collector tilt angle shows a decreasing trend due to solar irradiance’s sensitivity to incidence angle. Due to its independency to cost, a 30o angle is therefore chosen to adapt for the most common roof angle. Lastly, riser and header pipes are decided not to be included in the costoptimization despite it’s high influence to cost, due to its sensitivity to the buoyancy-driven flow phenomena which requires additional considerations. The optimized system design was able to meet 80% of the year-long hot water demand, despite a lower efficiency at 17%, and is projected to save over 20 million IDR over 20 years of use. Compared to other products in the market (Solahart), the design demonstrates superiority, offering a relatively competitive solar savings fraction, while achieving the highest solar savings, despite having the cheapest manufacturing cost.