SIMULASI NUMERIK UNTUK PERBAIKAN DESAIN PIPA PESAT DI PEMBANGKIT LISTRIK TENAGA MINIHIDRO UNIVERSITAS ANDALAS

Based on the feasibility study report conducted by PLN, it is evident that the Limau Manis River area at Andalas University has the potential for stable river flow, with an average discharge of 1.40 m³/s, making it a suitable location for development as an energy source for a Mini Hydro Power Plant (PLTM). However, the PLTM is only capable of producing around 230 kW of power, which is significantly lower than its theoretical potential of 400 kW. This condition indicate that the current design is still not optimal, as evidenced by energy losses in the water distribution system, particularly in the penstock. This study aims to simulate five alternative penstock designs to determine the most efficient branching geometry for use at PLTM Universitas Andalas. The penstock evaluation was based on flow characteristics, flow distribution, pressure loss, and system output power using the CFD method with the assumption of steady and incompressible. Each model was simulated from the inlet in the stilling basin to the outlet to the turbine housing to obtain a quantitative comparison of the five penstock designs. The CFD simulation results show a pipe flow rate of 0.72 m³/s. The total output power is 412 kW. This exceeds the current PLTM power of 399 kW at a flow rate of 0.7 m³/s. the five design plans produce smaller pressure losses compared to the channel design currently used by the PLTM of 0.47 %, with a range of pressure loss values from all design plans of 0.01 % and 2 % then sharp turns and valves are the cause of the formation of flow eddies and increased local pressure and also Y branching with the addition of elbows is highly recommended to minimize energy losses and improve hydraulic performance. T-branching tends to result in flow dominance in one main branch, and Y-branching shows a more even flow distribution with relatively small power differences between branches.