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All Journal Jurnal Teknologi Communications in Science and Technology Jurnal Listrik, Instrumentasi, dan Elektronika Terapan International Journal of Renewable Energy Development
Astuti, Wijayanti Dwi
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Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Earth & Planetary Sciences Electrical & Electronics Engineering Energy Engineering

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Prediction of Onset Temperature in Standing Wave Thermoacoustic Engine with Mesh Screen Stack Murti, Prastowo; Astuti, Wijayanti Dwi; Setiawan, Ikhsan; Irsyadi, Fakih; Hudati, Imroatul
Jurnal Teknologi Vol 16, No 1 (2024): Jurnal Teknologi
Publisher : Fakultas Teknik Universitas Muhammadiyah Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24853/jurtek.16.1.27-32

Abstract

A thermoacoustic engine is a engine that converts thermal energy into acoustic energy, which can be used to generate electricity or cooling. This engine is attractive because it consists only of a stack, heat exchangers, and a resonator. The stack serves as the primary component for the energy conversion process and consists of porous materials like an array of stainless steel mesh screens. To generate the acoustic energy, a minimum temperature difference is necessary between the two sides of the stack, called the onset temperature difference. However, the calculation for prediction of onset temperature on the stack made of mesh screen has not been addressed. Therefore, the objective of this paper is to propose a method that can be used to estimate the onset temperature difference in standing wave thermoacoustic engine with stacks made of mesh screen arrays. The onset temperature difference is predicted numerically using linear stability theory and matrix transfer methods. Experimental verification is carried out by using standing wave thermoacoustic engine from pervious study. The results showed that the lowest onset temperature difference (TH - TC = 140ºC) is obtained when rh = 0.497 mm. Furthermore, the numerical and experimental onset temperature difference comparisons show a qualitative agreement, allowing the onset temperature prediction method to be used in designing standing wave thermoacoustic engines with stacks made of mesh screens.
Analysis of a standing wave thermoacoustic engine with multiple unit stages Murti, Prastowo; Setiawan, Ikhsan; Rosafira, Jihan Zeinyuta; Widyaparaga, Adhika; Astuti, Wijayanti Dwi; Biwa, Tetsushi
International Journal of Renewable Energy Development Vol 13, No 4 (2024): July 2024
Publisher : Center of Biomass & Renewable Energy (CBIORE)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.61435/ijred.2024.60098

Abstract

The thermoacoustic engine is an eco-friendly technology capable of harnessing solar and waste energy for electricity generation, in conjunction with a linear alternator, and can function as a heat pump. This engine type holds significant appeal due to its simplistic design, devoid of any mechanical moving components, comprising only a stack sandwiched between heat exchangers within a resonator. When the temperature gradient across the stack reaches the critical threshold (onset temperature), the working gas undergoes spontaneous oscillation. Typically, a high onset temperature is necessary to induce gas oscillation in a thermoacoustic engine due to viscous losses within the system. A method to lower the onset temperature by increasing the number of unit stages consisting of stacks and heat exchangers so that the engine can utilize low-grade thermal sources has been developed to overcome this challenge. However, this method has only been applied to traveling-wave thermoacoustic engines. Its application in standing-wave engines, which offer a more compact and straightforward structure, remains unexplored. This research aims to examine how the number of unit stages in a standing-wave thermoacoustic engine influences the onset temperature and acoustic field. The onset temperature is estimated using a fundamental hydrodynamics equation and the investigation of the acoustic field throughout the engine using DeltaEC software. Results showed that the strategic positioning of multiple unit stages is essential to achieve a low onset temperature. The minimum onset temperature, approximately 92°C, is obtained when three- or four-unit stages are installed. Additionally, increasing the number of unit stages does not affect the acoustic impedance and phase difference between pressure and velocity in the stack, while simultaneously enhancing both acoustic power output and thermal efficiency.
Design of Direct Digital Synthesizer (DDS) Based on Field Programmable Gate Array (FPGA) for Electrical Impedance Tomography (EIT) Rifai, Isnan Nur; Astuti, Wijayanti Dwi; Hendry, Jans; Santoso, Ardhi Wicaksono; Aji, Alief Purnomo
Jurnal Listrik, Instrumentasi, dan Elektronika Terapan Vol 6, No 1 (2025)
Publisher : Departemen Teknik Elektro dan Informatika Sekolah Vokasi UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/juliet.v6i1.102579

Abstract

Direct Digital Synthesizer (DDS) systems play a critical role in high-precision signal generation for applications like medical imaging and RF communications. This research explores the development of a DDS system using Field-Programmable Gate Array (FPGA) technology, with a focus on optimizing signal accuracy, resource efficiency, and signal-to-noise ratio (SNR). The study implemented two DDS designs on an FPGA: one based on the CORDIC algorithm and the other using a Look-Up Table (LUT) approach. Key components of the system included a phase accumulator, phase register, and frequency calculation algorithms. The system's performance was evaluated by measuring signal output accuracy and SNR, utilizing the ISL6961IAZ DAC and RF Transformers PWB2010LC for signal conversion and transmission. The results showed that the DDS achieved near-target frequencies, with outputs of 100.4 kHz for a target of 100 kHz and 498.8 kHz for a target of 500 kHz. The LUT-based design demonstrated superior signal fidelity, achieving an SNR of 106 dB compared to 92 dB for the CORDIC-based design. However, resource utilization analysis revealed a trade-off between logic efficiency and memory usage: the CORDIC design consumed 26% of logic elements and only 1% of memory, while the LUT-based design used 8% of logic elements and 77% of memory. These findings highlight the importance of balancing design choices based on application-specific requirements for precision, resource constraints, and performance.
Synergetic effect of ZnO/NiO nanocomposite on the enhancement of photocatalytic degradation efficiency of dyes molecules Iasya, Yurin Karunia Apsha Albaina; Khoerunnisa, Fitri; Dwi, Sadina Sahitya; Putri, Restiani Alia; Nurhayati, Mita; Arrozi , Ubed Sonai Fahruddin; Permana, Yessi; Handayani, Murni; Astuti, Wijayanti Dwi; Da, Oh Wen; Irnanda, Istifhamy
Communications in Science and Technology Vol 10 No 1 (2025)
Publisher : Komunitas Ilmuwan dan Profesional Muslim Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21924/cst.10.1.2025.1583

Abstract

The discharge of organic dyes into water systems poses severe risks to human health and aquatic ecosystems. A remarkable technique that is increasingly recognized for dyes degradation is photocatalysis. This work aims to investigate the role of zinc oxide/nickel oxide (ZnO/NiO) nanocomposites in enhancing photocatalytic degradation efficiency of dyes molecules. The nanocomposites were prepared using a simple ultrasonication technique and analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The XRD pattern of the ZnO/NiO nanocomposites exhibited characteristic peaks aligned with the ZnO and NiO phases, referring to JCPDS standards. The SEM images of nanocomposites featured the rod and irregular flake-like structures with the average size of 80 nm. The nanocomposites showed the highest dye photodegradation efficiency (RB 93.65% and MO 94.82%) in view of a larger semicircular diameter and lowest band gap energy as verified by Nyquist plot and DFT calculation. These results emphasized the synergistic effect of ZnO/NiO nanocomposites in promoting dye photocatalytic degradation.
Co-Authors Adhika Widyaparaga Aji, Alief Purnomo Arrozi , Ubed Sonai Fahruddin Biwa, Tetsushi Da, Oh Wen Dwi, Sadina Sahitya Fitri Khoerunnisa HENDRY, JANS Hudati, Imroatul Iasya, Yurin Karunia Apsha Albaina Ikhsan Setiawan Irnanda, Istifhamy IRSYADI, FAKIH Murni Handayani Nurhayati, Mita Prastowo Murti, Prastowo Putri, Restiani Alia Rifai, Isnan Nur Rosafira, Jihan Zeinyuta Santoso, Ardhi Wicaksono Yessi Permana