Analysis of hydrodynamics and thermal dispersion by numerical modelling in Sele Strait, West Papua

¹ Undergraduate Program of Civil Engineering, Universitas Udayana, Jalan Raya Kampus Unud Jimbaran Bukit, Bali, Indonesia
² Department of Civil Engineering, Faculty of Science and Defense Engineering, Republic of Indonesia Defense University, Bogor, Indonesia
³ PT Geovaruna Teknologi Indonesia, Jl. Dakota No.42e, Sukaraja, Cicendo, Bandung, Indonesia

^* Corresponding author: alvinyesaya@unud.ac.id

Abstract

Indonesian standard for wastewater quality regulates 40°C for the maximum outfall temperature. Meanwhile, the seawater temperature below 30°C is utilized for the cooling facility which the intake area is close to the outfall source. This research examine the hydrodynamics and thermal dispersion condition in PT Kilang Pertamina Internasional Kasim process plant in Sele Strait, West Papua. This study uses a two-dimensional numerical model Mike21 for a one-year simulation. Considering the limited field data, the ERA5 reanalysis satellite was utilized for the model input boundary. It also finds the discharge from the river with a temperature assumption of 26.5°C also in the boundary. The model validated with tidal field data with an R-squared number is 0.86. The hydrodynamics model shows the current speed in the intake area varied between 0-0.5 m/s. Two-scenario thermal simulation model (outfall condition 37°C & 40°C) shows that the frequency of 27°C water temperature is 81.5% and 85.8% respectively. Both scenarios give less than 10% for the temperature above 30°C. It concludes that the intake and outfall design planned is proper in the Kasim process plant.