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Stefan Mardikus
Magister Teknik Mesin UNDIP Jl.Prof. Sudarto, SH - Tembalang, Semarang E-mail: stefanmardikus@ymail.com
Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Computer Science & IT Electrical & Electronics Engineering Energy Engineering Industrial & Manufacturing Engineering

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Efisiensi dan Efektivitas Sirip Berpenampang Trapesium yang Tersusun Atas Dua Bahan Seen, Michael; Sugiana , Kharisma; Mardikus, Stefan
Jurnal Teknologi Vol. 12 No. 1 (2024): Jurnal Teknologi
Publisher : Universitas Jayabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31479/jtek.v12i1.354

Abstract

Abstrak Salah satu strategi untuk mengurangi panas pada sistem permesinan melalui penggunaan sirip. Sirip memperluas permukaan bidang yang bersentuhan dengan fluida sehingga dapat meningkatkan laju perpindahan panas dari suatu objek ke fluida di sekitarnya. Bahan atau material sirip merupakan salah satu faktor yang berpengaruh terhadap karakteristik sirip. Dalam perancangan sirip penting untuk mengetahui karakteristik dari sirip karena berkaitan dengan distribusi suhu, laju aliran panas, efisiensi dan efektivitas sirip tersebut. Penelitian ini bertujuan untuk mengetahui efisiensi dan efektivitas dari sirip yang tersusun atas dua bahan. Penelitian dilakukan secara komputasi numerik dengan metode beda-hingga cara eksplisit. Material penyusun sirip divariasiakan menjadi tembaga – tembaga, tembaga – aluminium, tembaga – besi, tembaga – baja, dan tembaga – zink. Hasil penelitian menunjukkan sirip dengan susunan material yang berbeda memberikan hasil yang berbeda. Sirip dengan material yang memiliki nilai konduktivitas, kalor jenis, dan massa jenis yang relatif lebih tinggi mempunyai laju perpindahan panas yang lebih tinggi. Efisiensi dan efektivitas tertinggi dicapai oleh sirip dengan material tembaga, yaitu 0,85 dan 15,79. Sedangkan efisiensi dan efektivitas terendah dimiliki oleh sirip dengan susunan material tembaga dan baja, yaitu 0,80 dan 14,796. Keywods: Finite difference method, Fin material, Unsteady state
The Study of 3D Simulation on Heat Transfer Enhancement on Fin Tube Heat Exchanger Using Delta Wing and Winglet Vortex Generators Mardikus, Stefan; Putri, Claudia Agata; Seen, Michael; Rines, Rines; Lukiyanto, Y. B.; Purwadianto, Doddy; Winarbawa, Heryoga; Dyaksa, Gilang Argya; Kusbandono, Wibowo
International Journal of Applied Sciences and Smart Technologies Volume 06, Issue 2, December 2024
Publisher : Universitas Sanata Dharma

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24071/ijasst.v6i2.10467

Abstract

The vortex generator is one of the methods to improve heat transfer augmentation on flow characteristics in the air side of the fin and tube heat exchanger. There are some models of vortex generators to produce longitudinal vortices when the airflow passes the surface of the vortex generator. In the previous studies, the longitudinal vortices were able to reduce the wake region phenomenon behind the tube heat exchanger. This research aims to investigate the thermal performance of heat transfer on the collaboration between two models of vortex generators namely delta wing and winglet vortex generators on plate fin and tube heat exchanger. The simulation used four models (1) without the vortex generator (2) with the delta wing vortex generators (3) with delta winglet (4) with the combination of delta wing and winglet. The study was generated with computational fluid dynamics. The boundary conditions were set in the inlet as velocity and the outlet as pressure outlet. The airflow of velocity is represented by Reynolds numbers in the range of 4000 - 8000 with an interval of 500. The wall temperature of the tube is given at 400 Kelvin and the temperature of the airflow is given at 300 Kelvin. The epsilon model was used in the turbulence model of the simulation. The result explained that the thermal performance of heat transfer on delta winglets improved the airflow to induce longitudinal vortices and then reduced the wake region to improve the heat transfer coefficient more than other vortex generator models
Characteristics of Straight Trapezoidal Cross-Sectional Fins under Unsteady Conditions Seen, Michael; Purwadianto, Doddy; Dyaksa, Gilang Argya; Winarbawa, Heryoga; Rines, Rines; Mardikus, Stefan; Kusbandono, Wibowo; Lukiyanto, Y. B.
International Journal of Applied Sciences and Smart Technologies Volume 06, Issue 1, June 2024
Publisher : Universitas Sanata Dharma

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24071/ijasst.v6i1.7989

Abstract

The aim of this research is to understand the characteristics of fins with a trapezoidal cross-section. The shape of the fin's cross-section is one of the influential factors affecting fin characteristics. In the design of fins, it is crucial to comprehend the characteristics of the fin as they relate to temperature distribution, heat transfer rate, and the efficiency of the fin. The research was conducted using numerical computation with an explicit finite difference method. Variations were made in the length of side 3 of the trapezium to 0 m, 0.02 m, and 0.04 m. The research results indicate that increasing the width of the fin enhances the temperature distribution, flow rate, and efficiency achievable by the fin. Significant improvement occurred when varying the side length from 0 m to 0.02 m, whereas subsequent variations did not considerably alter the efficiency. The highest efficiency achieved was 0.90 when the length of side 3 was 4 cm at the 300 seconds.
The Effect of Flexible Resin and Standard Resins Mixtures Variations on Dimensional Accuracy Using SLA 3D Printing Dyaksa, Gilang Argya; Aji Nugraha, Felix Krisna; Astyanto, Achilleus Hermawan; Mardikus, Stefan; Seen, Michael; Rines, Rines; Lukiyanto, Yohanes Baptista; Purwadianto, Doddy; Winarbawa, Heryoga; Kusbandono, Wibowo; Sugiharto, Budi; Hermawan, Oktavianus Nekson; Putra, Mahendra Pratama
International Journal of Applied Sciences and Smart Technologies Volume 07, Issue 1, June 2025
Publisher : Universitas Sanata Dharma

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24071/ijasst.v7i1.12272

Abstract

The present study investigates the effect of the concentration of flexible resin on the dimensional accuracy of mixtures product manufactured by 3D printing using SLA technology. Specimens were designed and according to the ASTM D412 standard. Ten variations of resin mixtures were examined. The concentrations of the flexible resins were varied from 10% to 100%. Measurements of accuracy dimension were conducted on the fabricated specimens, and the average deviation was used to estimate the dimensional accuracy. The study reveals the least deviation in dimensions in the 10% flexible resin containing mixture and the highest in the 60% flexible resin containing mixture. The results explain the fabrication tendency of flexible resins in dimensional accuracy for 3D printing.
Enhancing the Cooling Effectiveness Utilizing a Tapered Fin Having Capsule-Shaped Cross-Sectional Area Numerically Simulated Using Finite Difference Method Pratama, Nico Ndaru; Setyahandana, Budi; Purwadianto, Doddy; Dyaksa, Gilang Argya; Winarbawa, Heryoga; Seen, Michael; Rines, Rines; Mardikus, Stefan; Kusbandono, Wibowo; Lukiyanto, Y.B
International Journal of Applied Sciences and Smart Technologies Volume 07, Issue 2, December 2025
Publisher : Universitas Sanata Dharma

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24071/ijasst.v7i2.12362

Abstract

This paper reports the results of our research on improving the cooling of an engine using fins. This problem is important to discuss because various parts of the world have utilized machining technology. When the engine operates, it produces heat. This heat reduces the efficiency of the engine's performance. In this problem, we developed a tapered fin method with a capsule cross-section to enhance cooling performance. The fin consists of two different materials that are perfectly joined. In this paper, the fin analysis is performed using the explicit finite difference numerical method. This method simulates the heat distribution on the fins. The results of our research include temperature distribution, heat flow rate, efficiency, and fin effectiveness in unsteady-state conditions with variations in material composition. The highest heat flow rate, fin efficiency, and fin effectiveness were achieved with a fin material composition of copper and aluminum, yielding an efficiency value of 0.89 and an effectiveness of 20.7. Our research results offer potential for the industry to design fins for innovative applications.
Design of a Speed Sensorless Control System on a DC Motor using a PID Controller Harini, Bernadeta Wuri; Gunadi, Theodore Galeno; Mahardika, Shakuntala Gema; Pangestu, Sirilus Praditya; Putri, Regina Chelinia Erianda; Mardikus, Stefan
International Journal of Applied Sciences and Smart Technologies Volume 07, Issue 2, December 2025
Publisher : Universitas Sanata Dharma

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24071/ijasst.v7i2.13271

Abstract

The speed sensorless control system on a DC motor is a DC motor speed control system that does not use a speed sensor to measure the motor speed. The motor speed value is estimated by an observer from the stator current and voltage that are measured using a sensor. This study uses an R observer method.  The difference between the estimated speed and the reference speed is then used by the PID controller to adjust the motor speed to match the desired reference speed. PID parameter tuning using heuristic method. With a setpoint of 6800 RPM and using a combination of Kp = 0.5, Ki = 0.05, and Kd = 0.34, a speed value of 6792.76 RPM was obtained. Sensorless motor speed control using a PID controller produces an optimal system with a low Steady State Error (SSE) value of around 0.1%, very small oscillations of 0.39%, a fast rise time of 4 seconds, and a fast settling time of 6 seconds.
Co-Authors Achilleus Hermawan Astyanto Aji Nugraha, Felix Krisna Bernadeta Wuri Harini Budi Setyahandana Budi Sugiharto Doddy Purwadianto Gilang Argya Dyaksa Gunadi, Theodore Galeno Hermawan, Oktavianus Nekson Heryoga Winarbawa Lukiyanto, Y. B. Lukiyanto, Y.B Lukiyanto, Yohanes Baptista Mahardika, Shakuntala Gema Pangestu, Sirilus Praditya Pratama, Nico Ndaru Putra, Mahendra Pratama Putri, Claudia Agata Putri, Regina Chelinia Erianda Rines, Rines Seen, Michael Sugiana , Kharisma Wibowo Kusbandono