scholarly journals Porous Cores in Small Thermoacoustic Devices for Building Applications

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2941 ◽  
Author(s):  
Fabio Auriemma ◽  
Elio Di Giulio ◽  
Marialuisa Napolitano ◽  
Raffaele Dragonetti
Keyword(s):  
Numerical Procedure ◽  
Acoustic Power ◽  
Prime Mover ◽  
Heat Power ◽  
Resonator Length ◽  
Design Constraints ◽  
Main Design ◽  
The Core ◽  
Suitable Solution ◽  
Fixed Input

The thermoacoustic behavior of different typologies of porous cores is studied in this paper with the goal of finding the most suitable solution for small thermoacoustic devices, including solar driven air coolers and generators, which can be used in future buildings. Cores provided with circular pores, with rectangular slits and with arrays of parallel cylindrical pins are investigated. For the type of applications in focus, the main design constraints are represented by the reduced amount of the input heat power and the size limitations of the device. In this paper, a numerical procedure has been implemented to assess the behavior of the different core typologies. For a fixed input heat power, the maximum acoustic power delivered by each core is computed and the corresponding engine configuration (length of the resonator and position of the core) is provided. It has been found that cores with parallel pins provide the largest amount of acoustic power with the smallest resonator length. This conclusion has been confirmed by experiments where additive manufactured cores have been tested in a small, light-driven, thermoacoustic prime mover.

scholarly journals Performance analysis of the thermoacoustic refrigerator with the standing wave and air as a working fluid

2018 ◽  
Vol 44 ◽  
pp. 00063 ◽  
Author(s):  
Jakub Kajurek ◽  
Artur Rusowicz
Keyword(s):  
Temperature Difference ◽  
High Reliability ◽  
Power Input ◽  
Acoustic Power ◽  
Operating Frequency ◽  
Working Fluid ◽  
Resonator Length ◽  
Environmental Friendliness ◽  
The Impact ◽  
Thermoacoustic Refrigerator

Thermoacoustic refrigerator is a new and emerging technology capable of transporting heat from a low-temperature source to a high-temperature source by utilizing the acoustic power input. These devices, operating without hazardous refrigerants and owning no moving components, show advantages of high reliability and environmental friendliness. However, simple to fabricate, the designing of thermoacoustic refrigerators is very challenging. This paper illustrates the impact of significant factors on the performance of the thermoacoustic refrigerator which was measured in terms of the temperature difference generated across the stack ends. The experimental device driven by a commercial loudspeaker and air at atmospheric pressure as a working fluid was examined under various resonator length and operating frequencies. The results indicate that appropriate resonator’s length and operating frequency lead to an increase in the temperature difference created across the stack. The maximum values were achieved for operating frequency equalled to 200 and 300 Hz whereas resonator length corresponded to the half-length of the acoustic wave for these frequencies. The results of experiment also confirm that relationship between these parameters is strongly affected by the stack spacing, which in this research was equalled to 0.4 mm.

CFD Aerodynamic and Reactive Study of an Innovative Lean Combustion System in the Frame of the NEWAC Project

2010 ◽  
Author(s):  
Alessandro Marini ◽  
Lorenzo Bucchieri ◽  
Antonio Peschiulli
Keyword(s):  
Numerical Procedure ◽  
Research Programme ◽  
Injection System ◽  
Combustion System ◽  
Lean Burn ◽  
The Core ◽  
Numerical Tests ◽  
Lean Combustion ◽  
Annular Combustor ◽  
The Eu

This paper deals with the very last activities carried out by EnginSoft in the frame of the EU funded research programme NEWAC. The work regards the pre-production numerical tests performed on the single annular combustor with the purpose of verify its performance in reactive frame. The core of this study is the innovative lean-burn injection system technology, developed by University of Karlsruhe and AVIO for medium OPR. Such device has been widely investigated in previous activities in order to optimise the combustor layout and the numerical procedure for this work [1].

Minimum Induced Drag of a Three-Surface Ultra High Capacity Aircraft

1995 ◽  
Vol 209 (3) ◽  
pp. 195-201
Author(s):  
L P Ruiz-Calavera ◽  
R Martínez-Val ◽  
R Gómez-Blanco
Keyword(s):  
Structural Design ◽  
Vortex Lattice ◽  
Lift Coefficient ◽  
High Capacity ◽  
Surface Loading ◽  
Design Constraints ◽  
Main Design ◽  
Induced Drag ◽  
Aerodynamic Properties ◽  
Method Model

The aerodynamic properties of a particular three-surface ultra high capacity airplane are determined by means of a hybrid vortex-lattice/panel method model. The study includes effects of aerodynamic and structural design limitations. It is shown that stable or slightly unstable configurations are compatible with low values of induced drag, and that the main design constraints are the maximum allowed lift coefficient of wing sections and the canard surface loading.

scholarly journals Analysis of Pyramidal Horn Antenna for J-Band Application

2016 ◽  
Author(s):  
Muralidhar Bhanarkar ◽  
Ganesh Waghmare ◽  
Vaijjanath Navarkhele
Keyword(s):  
Axial Length ◽  
Beam Width ◽  
Horn Antenna ◽  
Research Paper ◽  
Antenna Design ◽  
Design And Development ◽  
Design Constraints ◽  
Main Design ◽  
Pyramidal Horn ◽  
Radar Applications

In this research paper, design and development of pyramidal horn antenna for J-band application is reported. It is particularly designed for 17 dB gain and half beam width about 25 degrees at 6.93 GHz. Horn aperture, horn axial length and distance from the throat of the antenna to aperture are the main design constraints which are calculated and used for the antenna design and simulation. Beam width in E-plane and H-plane horn is calculated and it is 19.18 dB and 22.86 dB respectively. The reported antenna design shows good performance for J-band in radiometry, satellite, and radar applications.

POWER BACKUP SUPPLY FOR CONSUMERS OF THE FIRST CATEGORY

2021 ◽  
Vol 2021 (4) ◽  
pp. 47-53
Author(s):  
Alexey Kirichek
Keyword(s):  
Comparative Analysis ◽  
Heat Power ◽  
Suitable Solution ◽  
First Category ◽  
Micro Turbine ◽  
Problem Setting

The paper is dedicated to the methods of heat-power backup supply. A search for a solution to update a process of power backup supply to consumers of the first category is carried out. There is carried out a comparative analysis of all accessible systems for power backup supply including those which were not used earlier for the most significant consumers. As a solution in the paper there are offered micro-turbine installations as the most efficient and convenient in operation. The method is based on the principle of comparison allowing the choice of the most suitable solution. The investigation results are a fundamentally new solution for this field of researches as micro-turbine installations were not used earlier for power backup supply of consumers of the first category. Various versions of power backup supply are presented, problem setting is carried out taking into account the requirements made, the objects under investigations are described and conclusions on the best version for heat-power backup supply of the consumers of the first category are presented.

scholarly journals Influence of resonator length on the performance of standing wave thermoacoustic prime mover

2016 ◽  
Author(s):  
Wahyu Nur Achmadin ◽  
Ikhsan Setiawan ◽  
Agung Bambang Setio Utomo ◽  
Makoto Nohtomi
Keyword(s):  
Standing Wave ◽  
Prime Mover ◽  
Resonator Length

scholarly journals Development of High-Fidelity Numerical Methodology Based on Wavenumber-Frequency Transform for Quantifying Internal Aerodynamic Noise in Critical Nozzle

2019 ◽  
Vol 9 (14) ◽  
pp. 2885
Author(s):  
Garam Ku ◽  
Songjune Lee ◽  
Cheolung Cheong ◽  
Woong Kang ◽  
Kuksu Kim
Keyword(s):  
Surface Pressure ◽  
Numerical Procedure ◽  
Acoustic Power ◽  
High Accuracy ◽  
Piping System ◽  
High Fidelity ◽  
Pressure Relief ◽  
Critical Nozzle ◽  
Eddy Simulation ◽  
Large Eddy

In industrial fields dealing with high-temperature and high-pressure gas such as chemical, petrochemical, and offshore oil production plants, piping systems with valves are frequently used to protect the relevant system and equipment from being damaged by such gases. However, excessive noise is sometimes generated by the valve flow in the piping system, causing so-called acoustic induced vibration in the pipe wall. Therefore, it is of great importance to design the related system to avoid this phenomenon. In this study, a high-fidelity numerical procedure is proposed to assess the acoustic power generated by pressure relief devices in a pipe. The method consists of three sequential steps: high accuracy large eddy simulation, wavenumber-frequency transform, and duct acoustic theory. The critical nozzle is selected as a target system since it is commonly used as a flowmeter and thus there are a lot of relevant data for comparison. First, the steady Reynold-Averaged Navier–Stokes (RANS) solver is used to predict the flow rate of the two-dimensional axisymmetric critical nozzles, and its validity is confirmed by comparing the predicted results with the measured ones. There is good agreement between the two results. Then, a high accuracy Large Eddy Simulation (LES) technique is performed on the three-dimensional critical nozzle, and the steady-state RANS result is used as the initial condition to accelerate the convergence of the unsteady simulation. The validity of the unsteady LES results is also confirmed by comparing them with measured surface pressure data. The wavenumber-frequency transform is taken on the LES results, and the compressible surface pressure components matching the acoustical duct modes are identified in the wavenumber-frequency pressure diagram. The inverse wavenumber-frequency transform taken on the compressible pressure components leads to the acoustic power spectrum. These results reveal that the current numerical procedure can be used to more accurately predict the acoustic power generated by pressure relief device in the piping system.

scholarly journals Experimental Study of Resonance Frequency at Prime Mover Thermoacoustic Standing Wave

2017 ◽  
Vol 1 (2) ◽  
pp. 157
Author(s):  
Danang D. Cahyadi ◽  
Yoga N. Adhitama ◽  
Ikhsan Setiawan ◽  
Agung B. S. Utomo
Keyword(s):  
Experimental Study ◽  
Resonance Frequency ◽  
Penetration Depth ◽  
Second Order ◽  
Acoustic Energy ◽  
Prime Mover ◽  
Resonator Length ◽  
First Order ◽  
Resonance Frequencies ◽  
Prime Movers

<p class="Abstract">Thermoacoustic prime movers work by using thermal energy to produce acoustic energy in the form of sound wave through thermoacoustic effect which occurs in a porous medium called stack. This paper describes an experimental study on the relation between the order of resonance frequencies generated by a thermoacoustic prime mover and the length of the resonator and the viscous penetration depth. Extending the resonator length will decreasing the resonance frequency which result in the increasing in the viscous penetration depth. Generally, the generated sound consists of only one frequency, that is the first-order one. However, under certain conditions, the sound has only the second-order frequency or comprises two frequencies of the first-order and second-order resonance frequencies. This phenomenon can be explained by considering the comparison between the effective hydraulic radius of stack () and the viscous penetration depth (). It is found that the first-order frequency appears when , while when   (with  calculated by using the first-order frequency) then the second order frequency is produced so that  is back to a smaller value and therefore the condition of  is recovered. In addition, when of  the thermoacoustic prime mover will<em> </em>generate the first and second order frequencies together.</p>

scholarly journals Model-Based Parallelizer for Embedded Control Systems on Single-ISA Heterogeneous Multicore

2019 ◽  
Vol 19 ◽  
pp. 7470-7484 ◽  
Author(s):  
ZHAOQIAN ZHONG
Keyword(s):  
Control Systems ◽  
Multicore Processors ◽  
Control Design ◽  
Embedded Control ◽  
Design Constraints ◽  
Heterogeneous Multicore ◽  
Embedded Control Systems ◽  
The Core ◽  
Model Based ◽  
Parallel Code

This paper presents a model-based parallelization approach to parallelize embedded systems on single-ISA heterogeneous multicore processors, especially processors with the ARM big.LITTLE architecture, wherein the core assignment of the Simulink blocks is determined based on the control design constraints and characteristics of the big.LITTLE architecture. The proposed approach uses a hierarchical clustering method on Simulink blocks to reduce the problem scale, and an integer linear programming (ILP) formulation to determine the core assignment solution, considering load balancing and minimization of inter-core communication across cores with different performances. Finally, we generate the parallel code of the model based on the core assignment solution for execution on the processors. We evaluate the proposed approach by comparing it with existing methods and generating the parallel code on a single-board computer with the big.LITTLE architecture to determine its effectiveness.

scholarly journals Design and Implementation of Efficient 8-Bit SIPO Shift Register

2020 ◽  
Vol 22 (12) ◽  
Author(s):  
Sandeep Kakde ◽  
◽  
Rajesh Thakare S ◽  
Shailesh Kamble ◽  
Umakant Mandawkar ◽  
...  
Keyword(s):  
Single Phase ◽  
Digital Circuits ◽  
Shift Register ◽  
Design Constraints ◽  
Flip Flop ◽  
Main Design ◽  
Design And Implementation ◽  
Analog And Digital Circuits ◽  
Conventional Type ◽  
Bit Serial

Area and power are main design constraints in analog and digital circuits. In this paper, a low-power 8-bit shift register is implemented by using true phase single clock (TSPC) D- flip flop which is based on single clock and two clocked transistors. The proposed design successfully solves the long discharge path problem which is bound to occur in conventional type of D-Flip Flop. This paper describes 8 bit serial in parallel out (SIPO) shift register using True Single-Phase Clock(TSPC) technique which reduces an area in terms of transistor count by 85.29%.

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