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Pengaruh Jejari Hidrolik Stack terhadap Beda Suhu Onset pada Prime Mover Termoakustik Gelombang Berdiri Murti, Prastowo; Widyaparaga, Adhika; Setiawan, Ikhsan; Utomo, Agung Bambang Setio; Nohtomi, Makoto
Jurnal Spektra Vol 16, No 2 (2015): Spektra: Jurnal Fisika dan Aplikasinya
Publisher : Jurnal Spektra

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

AbstrakPrime mover termoakustik adalah sebuah alat yang digunakan untuk mengkonversi panas menjadi kerja dalam bentuk bunyi. Panas yang digunakan dapat berasal dari sumber panas yang tak terpakai dan melimpah seperti insenerasi alat-alat rumah sakit, pabrik industri, geotermal, dan energi surya. Untuk dapat mulai menghasilkan bunyi (kondisi onset) dibutuhkan beda suhu minimum antara ujung-ujung stack yang disebut 15(∆T)onset">   Semakin kecil beda suhu onset 15(∆T)onset">  maka suhu sumber panas yang diperlukan semakin rendah. Stack merupakan jantung dari prime mover termoakustik dan tempat terjadinya osilasi paket gas akibat adanya perbedaan suhu antara kedua sisinya. Pada penelitian ini, stack yang digunakan adalah lembaran-lembaran mesh (kasa kawat) stainless-steel yang tersusun rapat dengan jejari hidrolik 0,71 mm, 0,59 mm, 0,50 mm, dan 0,34 mm dengan panjang 4 cm, 5 cm, dan 6 cm. Dalam penelitian ini, panjang resonator adalah 1,28 m dan udara digunakan sebagai medium dengan tekanan atmosfer. Telah ditemukan bahwa jejari hidrolik stack mempengaruhi beda suhu onset 15∆Tonset">  pada prime mover termoakustik. Jejari hidrolik optimum pada 0,59 mm. Selain itu, ditemukan juga bahwa stack yang lebih panjang membutuhkan waktu yang lebih lama untuk mencapai kondisi onset dibandingkan dengan stack yang lebih pendek. Untuk mendapatkan 15∆Tonset">   lebih rendah dan waktu onset lebih cepat, perlu dilakukan penelitian tambahan tentang pengaruh beberapa paramater lain seperti panjang resonator, kalor input dan tekanan gas.Kata kunci : prime mover termoakustik, Stack mesh stainless steel, jejari hidraulik, beda suhu onset 15∆Tonset"> , waktu onset AbstractThermoacoustic prime mover is a device to convert heat into work in the form of sound. The heat used here can be obtained from unused and abundant heat source such as incineration hospital equipment, geothermal, and solar energy. A minimum onset temperature difference 15∆Tonset">  between stack ends is needed to produce the sound. Low onset temperature differences are desired when we intend to utilize low quality of heat sources. Stack is the main part of thermoacoustic prime mover in where the gas parcels oscillate due to a large temperature gradient along the stack. The stack used in this research is a pile of stainless-steels wire mesh screen with various hydraulic radius of 0.71 mm, 0.59 mm, 0.50 mm, and 0.34 mm and various stack length of 4 cm, 5 cm, and 6 cm. The length of resonator is 1.28 m and air as the working medium at atmosphere pressure is used to fill the resonator. It is found that the hydraulic radius is affecting the 15∆Tonset">  in the thermoacoustic prime mover. Hydraulic radius optimum at 0,59 mm. In addition, it is also found that longer stacks need longer time to reach the onset 15 "> condition. Investigation on the influences of other parameters, such as resonator length, heat input, and gas pressure, are required in order to have low 15∆Tonset"> .Keywords: themo-acoustic prime mover, stack mesh stainless steel screen, hydraulic radius, onset  Themperature difference 15 ∆Tonset"> , onset time.
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.
Numerical study of a thermoacoustic refrigerator with different stack geometries Murti, Prastowo; Dwi Astuti, Wijayanti; Febrinawarta, Burhan; Putra Pratama, Arief
Journal of Engineering and Applied Technology Vol. 6 No. 02 (2025): (August)
Publisher : Faculty of Engineering, Universitas Negeri Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21831/jeatech.v6i02.85682

Abstract

This study examines the performance of a thermoacoustic refrigerator with various stack geometries as a potential eco-friendly alternative to conventional refrigeration systems that rely on chlorofluorocarbons (CFCs). Thermoacoustic refrigerators create a cooling effect using sound waves and environmentally friendly gases such as helium. The stack, a crucial component where energy conversion occurs, must be optimized to maximize cooling efficiency. However, no studies have previously investigated the impact of stack geometries under a uniform system configuration. Thus, this study aims to numerically evaluate how different stack geometries and materials affect the performance of thermoacoustic refrigerators while maintaining consistent system geometry and properties to ensure fair comparison. The research focuses on three types of stack geometries: parallel plate, ceramic honeycomb, and wire mesh screen. Using DeltaEC software, the performance of these stacks was analyzed with a constant hydraulic radius. The results show that the wire mesh screen stack provides the highest cooling power (330 W) and coefficient of performance (COP) of 0.81, outperforming the other geometries. These findings highlight the potential of optimized stack designs to improve the efficiency of thermoacoustic refrigerators, promoting their development as a sustainable cooling technology.