SINTEK JURNAL: Jurnal Ilmiah Teknik Mesin

Performance Evaluation and Optimization of Chiller Systems: A Data-Driven Approach to Enhancing Energy Efficiency

Rupdin Marbun; Teddy Ardiansyah; Nofirman Nofirman — Sun, 01 Jun 2025 00:00:00 +0000

Chiller systems account for a significant portion of energy consumption in industrial and commercial HVAC operations, often exceeding 50% of total power usage. However, inefficiencies such as elevated condenser pressure, inadequate heat transfer, and excessive compressor workload contribute to increased energy demand. This study presents a comprehensive performance evaluation of water-cooled centrifugal chiller systems based on 30 operational test scenarios. Key efficiency indicators—including Coefficient of Performance (COP), Specific Energy Consumption (SEC), and isentropic efficiency—were analyzed to identify performance gaps. The results revealed COP values ranging from 1.92 to 4.07, with an average between 2.8 and 3.2, indicating suboptimal performance relative to industry benchmarks (COP > 4). SEC values between 1.07 and 1.25 kW/ton further highlight opportunities for energy optimization. High condenser pressure (>7.5 barg) and negative subcooling (-4.1 K to 0 K) were identified as major contributors to inefficiency. The study emphasizes that optimizing water flow rates and maintaining proper heat exchanger conditions can significantly improve system performance. Unlike previous research relying on AI or IoT-based diagnostics, this work adopts a practical, data-driven approach, offering actionable insights for facility managers seeking to enhance energy efficiency and operational reliability.

The Influence of Cutting Methods and Feed Rate on Dimensional Accuracy and Surface Roughness of HMR Panel

Bahtiar Rahmat, Wahyu Widiyanto, Agung Ari Purwanto, Muhammad Fahrudin — Sun, 01 Jun 2025 00:00:00 +0000

This study investigates the influence of cutting methods and feed rates on the dimensional accuracy and surface roughness of HMR (High Moisture Resistance) panels. The aim is to determine the optimal cutting parameters that yield precise dimensions and smooth surfaces in CNC machining. Two cutting methods—single and double passes—were applied using feed rates of 2, 4, and 6 m/min. Dimensional accuracy was measured using a digital caliper, while surface roughness was evaluated with a surface tester. The results indicate that the double-pass cutting method significantly improves both dimensional accuracy and surface finish. Statistical analysis using ANOVA revealed that feed rate has a significant effect on surface roughness (p < 0.05), whereas dimensional accuracy is primarily influenced by the cutting method. These findings provide practical insights for optimizing CNC machining processes in furniture manufacturing using HMR panels.

The Effect of Variation in Electrode Type and Area on Electrical Productivity of MFC With Sago Stem Substrate

Muhammad Nizar Ramadhan, Rizal Hamdani — Sun, 01 Dec 2024 00:00:00 +0000

Microbial Fuel Cells (MFC) offer a promising solution for developing efficient and environmentally friendly alternative energy sources. MFCs convert chemical energy into electrical energy through anaerobic reactors equipped with anode and cathode electrodes containing substrates and microbes. This study investigates the effect of electrode type and area on the production of current, voltage, and power density using sago stem substrates in an MFC system enhanced with Lactobacillus plantarum. These bacteria play a critical role in facilitating electrolysis, thereby increasing electrical energy output. A dual-chamber MFC design was employed, testing electrode materials (copper, aluminum, nickel, and graphite carbon) and areas (30 cm², 40 cm², and 60 cm²). Measurements of current, voltage, and power density were taken over 36 hours. Results indicate that electrode area significantly influences voltage and current, while electrode type determines power density. The highest average power density, 432.953 mW/m², was achieved using nickel electrodes with a 30 cm² surface area. These findings underscore the importance of optimizing electrode properties to enhance the performance of MFCs.

Experimental Analysis of Climate Parameters Effect on Structural Steel Atmospheric Corrosion Rate in Medan City Environment

Sun, 01 Dec 2024 00:00:00 +0000

This study aims to explore the important role of weather parameters i.e. humidity, rainfall, temperature, and wind speed on the corrosion rate in the Medan City atmospheric environment. Three forms of material with low carbon steel type were prepared in this investigation. The exploration process was conducted for six months starting from June to December 2023, in the open area of the Engineering Faculty, Universitas Muhammadiyah Sumatera Utara. Corrosion rate assessment is carried out monthly using the weight loss method and climate parameter data is obtained from the Medan City Meteorology and Geophysics Agency (BMKG). The dimensions, initial preparation, data collection, post-test material preparation, and corrosion rate calculations refer to the ASTM G1 and G50 standards. Regression analysis and Pearson correlation explain the relationship between corrosion rate and climate parameters. The investigation showed that the corrosion rate fluctuated monthly from 0.1 to 0.5 mpy. By referring to corrosion resistance data on metal materials, it was found that the corrosion level was in the good resistance category "outstanding". Based on the regression analysis results, humidity, local temperature, and rainfall play an important role in the atmospheric corrosion rate in Medan City. The percentage of closeness between variables is ± 98% and the standard deviation is ± 0.0001. Further development is needed to determine other parameters that also play an important role in atmospheric corrosion rate and forming a random forest model for predicting future corrosion rates.

Optimisation of Air-water Harvester Machine Performance With Variations of Inlet Air Flow Velocities

Mirmanto Mirmanto, Made Wirawan, Ahmad Tarmisi — Sun, 01 Dec 2024 00:00:00 +0000

In the dry season, some parts of Indonesia experience drought and clean water crisis which results in scarcity and difficulty in drinking water. One way to overcome this problem is to present a water-producing device from air called a water harvester machine. The purpose of this study was to examine the effect of the inlet air velocity of 4 m/s, 5 m/s, and 6 m/s on the mass of water produced and the rate of heat transfer. This study was conducted experimentally with R134a refrigerant working fluid, and a 1 PK rotary compressor and centrifugal fan. The results showed that the highest water mass, which was 5.99 kg, was obtained at an air velocity of 6 m/s. The highest heat transfer rate, which was 2080.2 W, was also obtained at a speed of 6 m/s. This can be caused by the high inlet air velocity, the inlet air mass flow rate is also high so that the water vapor content that enters is greater. As a result, the mass of water produced is greater and the rate of heat transfer that occurs is also greater.