ANALYSIS OF AIR-COOLED CONDENSER EFFECTIVENESS UNDER TROPICAL AMBIENT TEMPERATURE VARIATIONS IN LOW-ENTHALPY GEOTHERMAL SYSTEMS

Richard Alexander (Master of Energy Program, School of Postgraduate Studies, Universitas Diponegoro, Semarang, Indonesia)
Agus Setyawan (Universitas Diponegoro)
Udi Harmoko (Universitas Diponegoro)

Trends in Mechanical Engineering Research
Vol 4, No 1 (2026): JUNE

The performance of Air-Cooled Condensers (ACC) in low-enthalpy geothermal systems is strongly influenced by ambient temperature as the primary cooling medium. This study analyzes the effect of tropical ambient temperature variations on ACC effectiveness using the effectiveness-NTU method and linear regression based on 1,415 operational data points. The results show that the calculated ACC effectiveness ranges from 49.93% to 64.46% within an ambient temperature range of 18.63°C to 29.56°C. Ambient temperature shows a very strong positive correlation with ACC effectiveness, with r = 0.9984 and R² = 0.9967. The increase in effectiveness at higher ambient temperatures is associated with a reduction in the theoretical maximum heat transfer rate (Qmax), rather than an improvement in actual cooling performance. The developed model can be used as a simple predictive tool for operational management of low-enthalpy geothermal systems in tropical regions.