Optimum Design Factors Research Articles

Optimal design and flow-field pattern selection of proton exchange membrane electrolyzers using artificial intelligence

The design of a proton exchange membrane (PEM) electrolyzer and various hardware options remain key research areas for green hydrogen production technology. We have proposed an approach to select optimum design factors, including a flow-path design for the PEM electrolyzer using a machine learning (ML) technique for the first time. Efficient multiple ML models employing k-nearest neighbors and decision tree regression approaches predict the optimal hydrogen-generating system design for the PEM electrolyzer cell. The proposed ML model was trained and validated using 1062 design data points. The model predicts 17 parameters of the electrolyzer assembly for five input parameters: the hydrogen production rate, electrode area, anode flow area, cathode flow area, and type of cell design (e.g., single or stack). The model shows an absolute mean square error of 0.31 when compared to the experimental results (e.g., potential), which indicates that the model has excellent reliability. Finally, this study presents that the ML model can predict the optimal design of a PEM electrolyzer for commercial-scale hydrogen production rates at 50–3000 mL/min. This research will contribute to reducing the cost and time required to develop future water electrolyzers for hydrogen production.

A system level optimization of on-chip thermoelectric cooling via Taguchi-Grey method

In this paper, a framework for the system level optimization of the thin-film thermoelectric cooler (TFTEC) in 3D electronic packaging is developed based on Taguchi-Grey method. The influences of the size effect, the geometric effect, the parasitic effect and the localized hotspot are comprehensively considered. An L25 (56) orthogonal array is employed to assess the influences of the leg height, the fill-ratio, the electrode height, the gap distance, the hotspot size and the hotspot heat flux on the passive and active cooling effects of the TFTEC. The results show that the electrode height, acting as the primary factor, contributes 45.5% and 45.3% on the passive cooling and active cooling, respectively. The contribution ratios of hotspot size and hotspot heat flux to passive cooling reach 21.4% and 14.7%, respectively. The contribution ratios of leg height and gap distance to active cooling reach 25.7% and 18.8%, respectively. The optimum design factors for maximizing the cooling effects are also approached by the Grey relational analysis. A passive cooling of 16.82 °C and a maximum active cooling of 12.29 °C are achieved, leading to a total localized cooling of 29.11 °C for a chip hotspot.

Soft multi-modal thermoelectric skin for dual functionality of underwater energy harvesting and thermoregulation

Sustaining a long-term but viable power source for underwater electronics has been an engineering conundrum due to a lack of feasible physical mechanisms to harvest energy in the underwater environment. In this regard, thermoelectricity, which converts heat into electricity, can suggest a potent solution, since the ocean and other water bodies maintain the constant water temperature and therefore serve as a permanent thermal differential. In addition to energy harvesting, the same thermoelectric device can be also utilized to both heat and cool, thereby providing an effective means of controlling the temperature of the arbitrary subject in the underwater environment. In this light, we present a soft and stretchable multi-modal thermoelectric skin (TES) that can both (i) generate electricity across the temperature differential between the ocean water and the human body and (ii) thermoregulate the body temperature in the underwater environment. The soft and elastic nature of TES enables an intimate and thorough contact with the deformable and irregular surfaces of the human skin, therefore maximizing the heat conduction at the human-device interface that the rigid or flexible thermoelectric devices can not fully attain. To the authors’ best knowledge, TES produces the highest electrical power density when compared to the stretchable thermoelectric devices reported so far, mainly owing to its optimum design factors. Along with the outstanding device performance, the underwater environment further boosts the thermoelectric efficiency of TES both in energy harvesting and thermoregulatory perspectives due to the much more favorable thermal properties of water than those of air. Furthermore, to verify the practical usage of TES and demonstrate its high wearability, we incorporated multiple TES units into the neoprene dry-suit. The TES units can self-power multiple embedded sensors that wirelessly monitor the physiological condition and further provide the spatial information of the tactical diver, such that the TES units and embedded system can function as a wearable underwater rescue platform. Lastly, the temperature feedback loop algorithm embedded in the thermoregulatory system allows the TES units to constantly regulate the temperature of the human body and thus prevent underwater hypo-/hyperthermia.

SOME ENGINEERING FACTORS AFFECTING THE PERFORMANCE OF A SMALL ROTARY BAKING OVEN.

This research was carried out to study some engineering factors affecting on the performance of a small rotary baking oven to select the optimum design factors suitable for baking loaves. The aim of this study was to achieve maximum of the thermal efficiency for baking and better quality specification of the baked loaves (loaf color percentage, loaf maturity percentage and loaf height). Baking oven tray with variable thicknesses of 2, 3, 4 and 5 mm, baking oven chamber heights of 15, 20, 25 and 30 cm and the baking oven walls insulation density of 40, 50 and 60 kg/m³ were studied. The optimum design factors of the baking oven which achieve best quality of the baked loaf and optimum thermal specification were obtained at baking chamber height of 15 cm, baking oven walls insulation density of 60 kg/m³ and 3mm baking oven tray thickness for optimum thermal specification of the oven and 2mm for the best quality of the loaves.

A parametric analysis to evaluate the performance metrics of power generation system involving Trilateral Flash Cycle using three different working fluids for low grade waste heat

With the accelerated growth in population and technology progress in day-to-day life, the traditional fuels demands have increased significantly. Despite the execution of many renewable sources (solar, wind, geothermal, biomass), the modern issues such as high investment and power costs have slowed down their development. In this context, improvisation of the existing power generation ways is required by evolving a highly effective thermal system to extract renewable energy available for low grade waste heat. At present, many of the applicable practices are engrossed on high temperature heat extraction rather than low-grade heat in spite of being expensive. In this work, innovative technology has been recommended by amalgamation of the Trilateral Flash Cycle (TFC) with an expander (reaction turbine) in a binary system to offer improved operation, economical and broader employment of the existing resources. TFC can extract heat more efficiently from hydrothermal means to improve power generation directly and decrease the emissions of greenhouse gas. A theoretical analysis using a computer based model for TFC with simple reaction turbine for three proposed diameters at various rotational speeds and operating fluids is performed. Results of output powers and turbine efficiencies of the recommended system are compared. Also, this design concludes the optimum design factors for the turbine under explicit operational settings and the factors affecting the efficiency and nozzle flow area are discussed for the TFC system.

Efficiency Enhancement of a Dual-axis Solar PV Panel Tracker Using Water-Flow Double Glazing Technique

إنّ زاويةَ سقوط أشعةِ الشمس على سطحِ اللوح الشمسي ودرجة حرارته يُؤثّرانِ سلبياً على الطاقة الكهربائية للوح وكفاءته. أن مشكلة زاويةِ السقوط عادةً ما يتم حلها بإستخدام منظومة التتبع (المقتفي) الشمسي ذات المحورِين والذي يُبقي اللوح بشكل مستمر متعامد مع أشعةِ الشمس طِوال اليوم. هذا يُؤدّي إلى أقصى إمتصاصِ للإشعاعِ الشمسيِ والضروريِ لإنتاج الكميةِ القصوى مِن الطاقةِ وعند مستوىات عالية مِن الكفاءة الكهربائية. لحَلّ مشكلةَ الحرارة فقد تمّ استخدام تقنية الغرفة الزجاجية (المزججة) والتي يتدفقِ خلالها الماء بوصفها طريقة تبريد جديدةِ لتخفيض درجة حرارة اللوح. في هذه البحث، تمّ تصميم منظومِة التزجيج المقترحة بالتكامل مَع منظومة التتبع ثنائية المحاور واجريت التجارب المختبرية عليها لغرض تحسين كفاءةَ اللوح الشمسي، لاسيما في المناخِ الحارِ. نظام التزجيج المُقتَرَحِ يُمْكِنُ أَنْ يُؤدّي وظيفتين بشكل آني، أولاً، يعَمَل أداة تبريد لتقليل الحرارةِ المَخْزُونة في داخل اللوح أثناء عَملها وثانياً مرشِحا بصريا للطيفِ الضوئي. تمّ حساب معاملات التصميمُ الأمثل وبمستويات مختلفة لقيم نظامِ التزجيج وفقاّ لطريقةِ تاكوتشي. تمّ تنفيذ تجارب الإختبارِ في مدينةِ بغداد في العشرين والحادي والعشرين مِنْ يوليو/تموز 2016 على منظومة التتبع في حالتين مع إستعمال مقترح منظومة التزجيج وبدونها. تبُين النتائِج المستحصلة بأنّ، درجةَ الحرارة اللوح الشمسي بإستعمال منظومة التزجيج هَبطت بشكل ملحوظ بمقدار 44% وزادت كفاءتها الكهربائية بحاولي36.6 % عند بالمقارنة مع المنظومة التقليدية عند قيمة اشعاع شمسي 1213 W/m2.

Efficiency Enhancement of a Dual-axis Solar PV Panel Tracker Using Water-Flow Double Glazing Technique

The fall angle of sun rays on the surface of a photovoltaic PV panel and its temperature is negatively affecting the panel electrical energy produced and efficiency. The fall angle problem was commonly solved by using a dual-axis solar tracker that continually maintains the panel orthogonally positioning to the sun rays all day long. This leads to maximum absorption for solar radiation necessary to produce maximum amount of energy and maintain high level of electrical efficiency. To solve the PV panel temperature problem, a Water-Flow Double Glazing WFDG technique has been introduced as a new cooling tool to reduce the panel temperature. In this paper, an integration design of the water glazing system with a dual-axis tracker has been accomplished and experimentally tested in order to enhance the PV panel efficiency, especially at hot climates. The proposed glazing system can simultaneously perform two functions, firstly, working as a cooling tool for reducing the stored heat in the PV panel during its work and secondly as an optical filter for sun light spectrum. Optimum design factors with their levels for the glazing system were calculated according to Taguchi method. Test experiments were carried out in Baghdad city on the 20th and 21st July 2016 on the tracker with and without using the WFDG system. The obtained results show that, the PV panel temperature with using the WFDG system was significantly dropped by 44% and its efficiency increased maximally by 36.6% at solar irradiance of 1213W/m2 as compared with conventional one.

Efficiency Enhancement of a Dual-axis Solar PV Panel Tracker Using Water-Flow Double Glazing Technique

The fall angle of sun rays on the surface of a photovoltaic PV panel and its temperature is negatively affecting the panel electrical energy produced and efficiency. The fall angle problem was commonly solved by using a dual-axis solar tracker that continually maintains the panel orthogonally positioning to the sun rays all day long. This leads to maximum absorption for solar radiation necessary to produce maximum amount of energy and maintain high level of electrical efficiency. To solve the PV panel temperature problem, a Water-Flow Double Glazing WFDG technique has been introduced as a new cooling tool to reduce the panel temperature. In this paper, an integration design of the water glazing system with a dual-axis tracker has been accomplished and experimentally tested in order to enhance the PV panel efficiency, especially at hot climates. The proposed glazing system can simultaneously perform two functions, firstly, working as a cooling tool for reducing the stored heat in the PV panel during its work and secondly as an optical filter for sun light spectrum. Optimum design factors with their levels for the glazing system were calculated according to Taguchi method. Test experiments were carried out in Baghdad city on the 20th and 21st July 2016 on the tracker with and without using the WFDG system. The obtained results show that, the PV panel temperature with using the WFDG system was significantly dropped by 44% and its efficiency increased maximally by 36.6% at solar irradiance of 1213W/m2 as compared with conventional one.

Failure analysis of CPT-based direct methods for axial capacity of driven piles in sand

ABSTRACTDue to variety of current pile bearing capacity methods based on cone penetration test (CPT) measurements, there is always a need for evaluating performance of existing methods to make proper choices of methods as well as safety factors for optimum design. In this regard, geotechnical databases are known as useful tools which facilitate evaluation of existing methods. This paper deals with axial bearing capacity of driven piles in sand using CPT-based methods. A database of seventy-six records is employed to analyze different criteria of interpreting static pile load test results to select the most consistent approach with the CPT-based methods. Then, performance of nine commonly used direct CPT-based methods was evaluated. Finally, via a failure probability and cost optimisation approach, optimum safety factors are presented and discussed. Analysis of different failure criteria shows that the Hansen 80% criterion leads to more consistent results with the CPT-based methods. In addition, almost all of the investigated methods showed promising performance. The attained safety factors range from 1.6 to 3.1 for all records, 1.4 to 3.1 for piles in compression, and 1.4 to 2.2 for the piles in tension. Then, efficiency of methods was evaluated and the methods with higher efficiency are introduced.

Determination on the optimum design factors of BMP for nonpoint pollutant treatment through long-term monitoring

Determination on the optimum design factors of BMP for nonpoint pollutant treatment through long-term monitoring

A study on the optimum design for the valve plate of a swash plate-type oil hydraulic piston pump

Numerous studies have been conducted on hydraulic systems operating under high pressure. However, such systems are difficult to realize because of mechanical limitations as a result of tribological problems between relative sliding parts. Design techniques, manufacturing techniques, and tribological characteristics must be improved or innovated to operate such systems under increased pressure. The stress distributions and optimum design factors needed to satisfy these requirements under maximum pressure are determined by analyzing the stress on the valve plate of a hydraulic axial piston pump. This pump is among the most important relative sliding parts. As per the result of the analysis conducted using an orthogonal array, the extent of the influence of the design factors on maximum stress value is ordered as follows: [z > M > h > r]. Moreover, the maximum stress value of the optimum model is 13.3% lower than that of the standard model. Results also show that the stress characteristic of the optimum model is more stable than that of the standard model.

Reliability of complex chemical engineering processes

This paper presents a stochastic performance modelling approach that can be used to optimise design and operational reliability of complex chemical engineering processes. The framework can be applied to processes comprising multiple units, including the cases where closed form process performance functions are unavailable or difficult to derive from first principles, which is often the case in practice. An interface that facilitates automated two-way communication between Matlab® and process simulation environment is used to generate large process responses. The resulting constrained optimisation problem is solved using both Monte Carlo Simulation (MCS) and First Order Reliability Method (FORM); providing a wide range of stochastic process performance measures. Adding such capabilities to traditional deterministic process simulators provides a more informed basis for selecting optimum design factors; giving a simple way of enhancing overall process reliability and cost-efficiency. Two case study systems are considered to highlight the applicability and benefits of the approach.

Analysis of High Vacuum System Based on the Applications of Vacuum Materials

In this study, the outgassing effects of selected vacuum materials on the vacuum characteristics were simulated by the VacSim Multi simulation tool. This investigation examined the feasibility of reliably simulating the outgassing characteristics of common vacuum chamber materials (aluminum, copper, stainless steel, nickel plated steel, Viton A). The optimum design factors for these vacuum systems were suggested based on the simulation results. The baking- out effects of the modeled systems and materials on the performance of the vacuum system were also analyzed. The simulation predicted that the overall outgassing effect was more significant in the turbomolecular pump system than in the diffusion pump system and that the utilization of a booster pump has a greater effect on the evacuation time than on the ultimate pressure.

Optimal design of a solar driven heat engine based on thermal and thermo-economic criteria

To study the optimum design factors and the optimal thermo-economical performances an optimal performance analysis of a solar driven heat engine system at maximum thermo-economical objective function conditions is done numerically. In the present investigation, thermodynamic analysis and NSGAII algorithm are employed to optimize objective function associated to the power output, thermal efficiency for a Solar driven engine system. Three decision-making procedures are applied to optimized answers from the results. The error through investigation is shown using error analysis.

CSOs 처리를 위한 실증규모 응집침전시스템의 설계평가

도시유역에서 강우시에 발생되는 합류식 하수관거 월류수(CSOs; Combined Sewer Overflows)을 처리하기 위해 물리화학적 처리기법을 적용한 실증규모의 응집침전시스템을 개발하였다. 이에 앞서 응집침전시스템은 lab-test를 통해 도출된 최적의 설계조건이 실증규모로 증설할 시에 설계인자가 제대로 반영되었는지 평가가 필요하며, 최적조건에 따라 설계에 반영하였다 하더라도 대상원수의 유입특성에 따라서도 처리결과에 대한 평가가 다를 수가 있다. 이에 본 연구에서는 청주하수 처리장에 유입되는 CSOs를 대상으로 각각 <TEX>$1m^3$</TEX>/일과 <TEX>$100m^3$</TEX>/일의 CSOs를 처리할 수 있는 실험실규모 및 실증규모의 장치를 통해 실험을 수행하였다. 실증규모의 시스템을 운전하여 lab-test에서 도출된 설계인자와의 상사성을 검토하고, 이를 바탕으로 높은 처리효율을 유지하기 위한 운전인자를 적용하여 CSOs를 처리함에 있어 그 가능성을 평가하였다. 그 결과, 실험실 규모의 설계조건과 상사성을 만족하는 인라인믹서와 응집반응조의 조건을 도출할 수 있었으며, pilot-test를 운전하기 위한 적정 응집제 주입량을 도출하였고, 결과적으로 실증규모의 시스템에서도 CSOs를 대상으로 높은 효율의 응집침전처리를 가능하게 할 수 있었다. A pilot scale coagulation system, which has a function of physicochemical treatment, was developed to treat Combined sewer overflows(CSOs). This coagulation system requires evaluation of optimum design factors whether it has reflected those of lab scale system, moreover, the pilot scale system can be evaluated differently according to the characteristics of influent CSOs even though it has reflected lab scale's design factors. We conducted an experiment using lab scale system that could treat <TEX>$1m^3$</TEX> of CSOs in a day, and also pilot-scale system with <TEX>$100m^3/day$</TEX> CSOs flowed into the Cheongju sewage treatment plant. Therefore the aim of this study is to evaluate a hydraulic similarity between the design factors of pilot scale and those of lab scale coagulation system, and to evaluate feasibility of the coagulation system for the CSOs treatment with optimum operation conditions. From the result of pilot-test, we drew the optimum operation factors of in line mixer and flocculator having similarities with those of lab scale system as well as the optimum coagulant dose. Finally we confirmed that the coagulation system has feasibility to treat the CSOs with high removal efficiency.

Novel Claw Pole Eddy Current Load for Testing DC Counter Rotating Motor - Part II: Design and Modeling

Eddy current brakes are electromechanical devices used as variable mechanical loads for testing electrical machines. Accurate modeling of eddy current loss is an important t factor for optimum design of eddy brake systems. In this second part, we propose novel formulations of eddy current loss in novel claw-pole eddy brake system. The proposed model for eddy current loss in novel claw-pole eddy brake system depends on the size of the claw poles. Also, in this paper, the flux density is measured by using the magnetic circuit of the novel claw pole. The model results are compared with experimental results and they are found to be in good agreement.

Multistage Soil Filter System for Rainwater Collection and Use

Rainwater collection and use is usually considered for runoff from building roofs. Runoff from impervious layers such as roads and pavements, however, has hardly been used as water supply due to its high pollutant concentration. If runoff from roads will be treated and used properly, though, it can be a good water resource and will contribute minimally to a non-point source. In this study, a multistage soil filter system (MSFS) composed of a gravel layer, a functional-media layer with zeolite, a sand layer, and a lawn layer, was developed to treat the runoff from roads and green areas. To evaluate the performance of MSFS, its removal rate of total suspended solids (TSS) was investigated based on the rainfall intensity and the thickness of each layer. The experiment results were compared with the predicted values using the MinitabTM program. The TSS removal rates ranged from 82 to 96%, with various combinations of experiment conditions. The predicted removal rates well fitted with the removal rates obtained from the experiment. An equation was formulated for predicting the TSS removal rate based on the rainfall intensity and the thickness of each layer. The optimum design factors for MSFS considering its TSS removal rate could be derived based on such equation. Based on the study results, it is expected that MSFS can contribute to securing water resources and to controlling non-point sources.

Dispersion of elastic guided waves in piezoelectric infinite plates with inversion layers

In this work, we study the dispersion of elastic waves in piezoelectric infinite plates with ferroelectric inversion layers. The motivation is to analyze the effect of ferroelectric inversion layers on wave dispersion and resonant behavior under impulsive line loads. A semi-analytical finite-element (SAFE) method has been adopted to analyze the problem. Two model problems are considered for analysis. In one, the plate is composed of a layer of 36° rotated y-cut LiNbO 3 with a ferroelectric inversion layer. In the other, material is PZT-4 with a ferroelectric inversion layer. Comparison with experimental results, reported in the literature for isotropic materials, shows a very good agreement with theoretical predictions obtained using SAFE method. Furthermore, comparison of the resonance frequencies of the S 1 modes, calculated using KLM approximation ( f 0 = C d /2 h) and SAFE method, are illustrated for each problem. The frequency spectra of the surface displacements show that resonant peaks occur at frequencies where the group velocity vanishes and the phase velocity remains finite, i.e., a minimum in the dispersion curve below the cut-off frequency. The effect of the ratio of the thicknesses of the inversion layer (IL) and the plate on the frequencies and strength of the resonant peaks is examined. It is observed that for PZT-4 with 50% IL to plate thickness ratio the frequency for the second resonant peak is about twice that for the first one. Results are presented showing the dependence of resonant frequencies on the material properties and anisotropy. Materials selection for single-element harmonic ultrasound transducers is a very important factor for optimum design of transducers with multiple thickness-mode resonant frequencies. The theoretical analysis presented in this study should provide a means for optimum ultrasound transducer design for harmonic imaging in medical applications.

1301 小型低比速度ポンプの高効率・高信頼性に関する研究

It is well known that centrifugal pump efficiency becomes worse with the decrease of pump size and specific speed. The small-sized pump with low specific speed, in which the impeller outlet velocity was larger, was designed by an optimum design method combined with blade surface singularity method The results show as follows : The semi-open impeller designed by the optimum design method, yielded the highest efficiency of 61% among test impellers in narrow tip clearance c/b_2. In larger c/b_2,however, the leakage loss becomes dominant and the efficiency of impeller with larger blade outlet angle is higher. This fact implies that the c/b_2 should be considered as an additional factor for optimum design.

Influence of design parameters on the heat transfer and flow friction characteristics of the heat exchanger with slit fins

This study systematically analyzes the effect of various design parameters on the heat transfer and pressure drop characteristics of the heat exchanger with a slit fin. The Taguchi method, known to be a very reasonable tool in a parametric study, is employed in the present work. Only seven cases of experimental factors are considered because of the difficulty in producing samples and the manufacturing cost. Eighteen kinds of scaled-up models are made by compounding levels on each factor, and the heat transfer and flow characteristics of each model are analyzed. The results allow us to quantitatively estimate the various parameters affecting heat exchanger performance, and the main factors for optimum design of a heat exchanger are selected. The optimum design value of each parameter is presented and the reproducibility of the results is discussed.