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All Journal Equilibrium Journal of Chemical Engineering
Farida Diyah Hapsari
Universitas Pattimura
Chemical Engineering, Chemistry & Bioengineering Chemistry Energy Engineering Materials Science & Nanotechnology

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Performance Analysis of a 1-1 Shell-and-Tube Intercooler for Compressed Air Cooling Systems Farida Diyah Hapsari; Hana Nikma Ulya; Esther Mutiara Santallum Ekklesia Tibalia; Sabrianah Badaruddin; Alif Nur Laili Rachmah
Equilibrium Journal of Chemical Engineering Vol 10, No 1 (2026): Volume 10, No 1 July 2026 (First Online)
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v10i1.116048

Abstract

This study presents an evaluation of a 1-1 shell-and-tube heat exchanger (Intercooler-2) utilized in a multi-stage air compressor. The evaluation was conducted using plant operational data and classical heat exchanger analysis methods, including heat balance, overall heat transfer coefficient under clean (Uc) and operating (Ud) conditions, dirt factor (Rd) and pressure drop (ΔP). The calculation results show a heat transfer rate of 557,640.622 Btu/h with a true temperature difference of 113.774 °F, indicating an adequate thermal driving force. The flow on the shell side is in the turbulent regime (Re ≈ 79,952), while the tube side shows laminar flow (Re ≈ 829), which limits the optimization of convective heat transfer of water as a cooling medium. The overall heat transfer coefficient under clean conditions of 25.627 Btu/h.ft².°F decreased to 23.125 Btu/h.ft².°F due to a fouling factor (Rd) of 0.004. The pressure drop values on both sides are still well below the permitted limits, so the unit is declared operationally feasible. However, the presence of fouling and laminar flow regime on the tube side indicates the potential for performance improvement thru optimization of water flow rate and periodic cleaning. This study emphasizes the importance of periodic performance evaluation to maintain the efficiency and reliability of heat exchanger operations in air compression systems.
Gamma Spectrometric Analysis of Natural Radionuclides and Radiological Hazards in Ilmenite Sand Esther Mutiara Santallum Ekklesia Tibalia; Farida Diyah Hapsari; Tamaratritania Citta Trisnantari; Geraldi Rahanra; Muhammad Ikhsan Taipabu
Equilibrium Journal of Chemical Engineering Vol 10, No 1 (2026): Volume 10, No 1 July 2026 (First Online)
Publisher : Program studi Teknik Kimia UNS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/equilibrium.v10i1.116251

Abstract

Ilmenite sand, categorized as Naturally Occurring Radioactive Material (NORM), contains radionuclides derived from the uranium and thorium decay series. The present work investigates radionuclide concentrations in ilmenite sand collected from a mineral processing facility to evaluate associated radiological hazards using gamma spectrometry. Activity measurements were performed with a gamma spectrometry system calibrated for energy and efficiency using a Eu-152 reference source. Environmental background radiation was measured separately to correct spectral data during analysis. Prior to measurement, samples were dried, homogenized, and sealed in airtight containers to establish radioactive equilibrium between parent radionuclides and their progeny. Radionuclide activities were quantified based on characteristic gamma-ray peak energies. The measured activity concentrations were 472.98 Bq/kg for Ra-226, 302.20 Bq/kg for Th-232, and 10.68 Bq/kg for K-40. Radiological hazard parameters, including radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), and absorbed dose rate, were subsequently calculated. The estimated annual effective dose was 0.492 mSv/year, remaining below the recommended public exposure limit of 1 mSv/year. These findings indicate that, despite relatively elevated radionuclide activities, the resulting radiation exposure levels remain within acceptable safety limits. Overall, gamma spectrometry demonstrates reliable capability for radionuclide identification and radiological risk assessment in mineral-based materials.
Co-Authors Alif Nur Laili Rachmah Esther Mutiara Santallum Ekklesia Tibalia Esther Mutiara Santallum Ekklesia Tibalia Geraldi Rahanra Hana Nikma Ulya Muhammad Ikhsan Taipabu Sabrianah Badaruddin Tamaratritania Citta Trisnantari