Low-temperature cold source conditions can significantly improve the thermal performances of organic Rankine cycle (ORC) systems. In this study, the thermal performances of an ORC system operated in ...Harbin at different working-fluid mass flow rates (0.037–0.188 kg/s) were experimentally investigated, and they were compared with the performances of the same ORC system operated in Taipei which had much higher cold source temperature (30.4 °C vs. 9.6 °C). The results showed that the thermal efficiency and electricity generation efficiency of the ORC system in Harbin increased initially and then decreased (3.1%–6.4% and 2.8%–4.5%, respectively) with the increases in the liquid working-fluid mass flow rates. As compared with the system operated in Taipei, the system operated in Harbin had higher thermal efficiency (4.7% vs. 4.5%, increased by 5.2%) and electricity generation efficiency (3.1% vs. 2.9%, increased by 8.6%) because the lower cooling water temperature resulted in a lower condensation pressure. The results obtained from this study not only compare the thermal performances of the same ORC system operated in different regions but also demonstrate the potential applications of ORC systems in cold areas.
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•Thermal performances of the same system in Harbin and Taipei were compared.•The Harbin ORC was operated at a low-temperature cold source condition (9.6 °C).•The Harbin ORC had a higher thermal efficiency of 6.4%.•The Harbin ORC had a higher electricity generation efficiency of 4.5%.
In analog computing, multimode fibers (MMFs) have been explored for their potential in performing computations by exploiting the inherent parallelism of light propagation through different transverse ...modes. However, traditional approaches using MMFs encounter challenges due to limitations in spatial-domain encoding, which limit computational speed and accuracy. Innovative research seeks to overcome these limitations, by leveraging novel techniques in temporal encoding and employing step-index few-mode fibers (FMFs), and enhance the computational capabilities of analog systems. In this work, we consider a 13 m FMF to implement up to 7-bit header classification at 28.5 Gb/s, when utilizing the information that is included in only one-bit duration. By activating a small number of spatial modes with proper dispersive optical characteristics, we are able to limit the complexity of the spatial transformation and solve this computing task efficiently. The selective activation of supported modes is performed by testing varying input displacement conditions between the optical beam encoding information and the FMF input tip. At the output of the fiber, we obtain multiple time series that correspond to different spatial sub-patterns of the output beam overall pattern. Finally, we train a logistic regression classifier that uses samples from these time series, and evaluate its performance in classification tasks. Notably, even in the presence of inter-header interference, our system achieves successful 6-bit header classification - a feat unattainable with conventional step-index MMFs.
•A 3DOFs theoretical model for analyzing the frictional vibration of a wiper-windscreen system is proposed.•An analytic formula of friction coefficient is used instead of single-valued function in ...traditional analysis.•The mechanism of the wiper-windscreen frictional vibration are theoretically and experimentally analyzed.•The effects of different wiping speeds and accelerations on reversal vibration are analyzed experimentally.
This paper studies the frictional vibration aspects of the automobile wiper-windscreen contact system and builds a numerical model that matches the test equipment. The reversal vibration of the contact system is examined by the dynamics part of a theoretical model with the derived analytical formulas. The fluid lubrication characteristics are investigated by the friction part of the model with solutions of the friction coefficient-negative slope formula for relative velocity and the friction coefficient formula in the time domain. The nonlinear dynamic response of the theoretical model of the wiper blade is calculated with the Runge-Kutta method and the results of the frictional vibration are well reproduced in real motions. The validity of the model is confirmed by parallel analyses of the simulated results and the experimental ones of the wiper-windscreen system. It is concluded that properly reducing the length of blade tip is an effective way to reduce vibrations of the system. The influences of the wiping speed and acceleration after reversal on the system vibrations are also analyzed through experimental investigations. The theoretical and experimental results presented in this paper can be reference to structural optimization of the wiper blade and vibration and noise control of the wiper-windscreen contact system.
•TFS coupling experimental and numerical technology is proposed.•A novel friction reduction structure is proposed for blade cooling.•The friction reduction mechanism of the cross bridge is ...revealed.•The action mechanism of cooling performance on solid strain is revealed.•The heat transfer uniformity and overall strain are improved.
To supply the higher safety design demands of the new generation of gas turbines, it is urgent to solve the difficulties in mid-chord region of high-temperature turbine blades, including excessive friction loss of traditional two-pass channel, lack of experimental data, lack of stress-strain characteristics in the solid domain and so on. Therefore, this research aims to propose an integrated method of the high-efficiency and low-friction cooling design and Thermo-Fluid-Solid (TFS) coupling analysis. Firstly, a turbine blade rotating cooling experimental system is designed and built independently. Then, a novel friction reduction method with cross bridge structure is proposed. The friction reduction mechanism and the effect mechanism of the cooling performance on the solid strain are revealed through experimental test and TFS coupling numerical study. The results show that the cross brige has an excellent friction reduction effect on the channel. The influence of ‘peak cutting and valley filling’ effectively enhances the heat transfer uniformity as well as successfully reduces the overall strain. The average Nu/Nu0 of the leading edge surface decreases by 14.7% (stationary condition) and 16.4% (rotating condition), respectively. And the Nu/Nu0 of the trailing edge surface achieves a maximum improvement effect of 3.3%. The f/f0 of each channel decreases initially and followed by an increase as Ro increasing. Among them, the channel with two and three cross bridges can achieve friction reduction effects of 24.7–37.3% and 32.2–40.9%, respectively. The strain is related to the Nu/Nu0 of each region, and the value of the rotating trailing edge surface is generally higher than that of the rotating leading edge surface.
Ammonium phosphate fire extinguishing agents, due to their excellent cost-effectiveness and suitability for forest fires, have become one of the most commonly used fire suppressants for forest fire ...control. Among them, NH4H2PO4 fire extinguishing agent is the most widely applied. In this study, NH4H2PO4 (>90%) as the main component of dry powder fire extinguishers was selected as the suppressant to investigate the reaction mechanism of NH4H2PO4 interacting with red pine wood pyrolysis gas flames. Initially, we constructed a Bunsen burner experimental system suitable for NH4H2PO4/red pine wood pyrolysis gas/air. Although experimental methods yield the most intuitive empirical conclusions, measuring only the laminar flame speed of red pine wood pyrolysis gas/NH4H2PO4/air mixture does not adequately analyze the inhibitory mechanism of NH4H2PO4 on red pine wood pyrolysis gas flames. Additionally, due to limitations in experimental equipment and methods, it is not feasible to extend equivalence ratios and NNH4H2PO4 doses to large or small working conditions. Therefore, in this study, we utilized Chemkin software to construct theoretical models of flames under different conditions and performed calculations. We comprehensively analyzed the kinetic regulatory mechanisms of NH4H2PO4 interacting with red pine wood pyrolysis gas flames from aspects such as chemical inhibition, sensitivity of elementary reactions, elementary reaction yields, and chemical reaction pathways.
•The laminar flame velocity of NH4H2PO4 interacting with the pyrolysis gas flame of red pine was measured.•A comprehensive analysis of the dynamic regulation mechanism of NH4H2PO4 interaction with pyrolysis gas flame of red pine.•The inhibition mechanism of phosphorus-containing active substances on pyrolysis gas flame of red pine wood was elucidated.•Provide theoretical and experimental reference for development of more efficient fire extinguishing agents for forest fires.
•Dynamic modeling and simulation of an off-grid microgrid in Japan.•Real-time experimental validation of the simulation model by an indoor test system architecture.•The 48-hour validation results ...reveal minor inaccuracies.•Simulation with real-time simulation, reveals the sufficiency factor above 1.•It demonstrated the necessity of comprehending hybrid microgrids in Japan.
Microgrids are essential for creating next-generation energy systems because they allow loads, energy storage systems (ESS), and distributed energy resources (DER) to be efficiently and seamlessly integrated. This study presents the dynamic modeling and simulation of an off-grid direct current (DC) microgrid consisting of the photovoltaic (PV) panel, wind turbine, battery, and a DC load incorporating simple, comprehensible, and well-established component-based power control strategies for quality power output. In addition, the main emphasis is on the real-time experimental validation of the dynamic simulation model achieved by designing and developing an indoor test system architecture. A 48-hourly meteorological dataset from Fukuoka, Japan, was used to validate the developed model. The results show a reasonable range of Root-mean-square deviation (RMSE), suggesting that the simulation model can precisely depict the model the dynamic operation of a hybrid DC microgrid system. Furthermore, detailed scenario analysis for sunny, windy, rainy, and cloudy considering real-time meteorological conditions for 72 h of simulation reveals that the proposed microgrid system can effectively meet the load in any situation with a sufficiency factor above 1, making it a self-sustaining hybrid renewable microgrid for residential areas in Japan. The study highlights the significance of understanding microgrid operation energy management with actual implementation.
Pipeline internal flow has a significant influence on the transportation process of the entire deep ocean mining. Since the internal flow is a solid-liquid mixed fluid, the CFD-DEM coupling method is ...adopted for numerical simulation. The pipeline internal flow field at different flow rates and particle concentration is simulated by connecting program Fluent and EDEM, and the distribution of pressure and wall shear stress is calculated. A laboratory experiment is carried out by establishing a vertical lifting pipeline experiment system. The movement characteristics and laws of nodules with different flow rates and particle sizes during the lifting process are further analyzed. The result is basically consistent between numerical simulation and experiment, which verifies the reliability of the simulation. The results show that the internal flow velocity and the particle concentration affect the stress and transportation performance of the mining pipeline. Relevant recommendations for the stability and efficiency of the deep-sea mining pipeline transportation system are summarized through the results. The research provides theoretical and technical references for the optimization design, performance prediction, and operation control of the deep ocean mining pipeline system.
•The influence of parameters of deep-sea mining pipeline system is explored using the CFD-DEM coupling method.•A newly designed laboratory vertical lifting pipeline experiment platform is built.•The characteristics of the solid-liquid mixed flow and particle path are collected by high-speed camera equipment.•Some references for the structural design and process optimization of the deep-sea mining pipeline system are provided.
Organ chips can recapitulate organ-level (patho)physiology, yet pharmacokinetic and pharmacodynamic analyses require multi-organ systems linked by vascular perfusion. Here, we describe an ...'interrogator' that employs liquid-handling robotics, custom software and an integrated mobile microscope for the automated culture, perfusion, medium addition, fluidic linking, sample collection and in situ microscopy imaging of up to ten organ chips inside a standard tissue-culture incubator. The robotic interrogator maintained the viability and organ-specific functions of eight vascularized, two-channel organ chips (intestine, liver, kidney, heart, lung, skin, blood-brain barrier and brain) for 3 weeks in culture when intermittently fluidically coupled via a common blood substitute through their reservoirs of medium and endothelium-lined vascular channels. We used the robotic interrogator and a physiological multicompartmental reduced-order model of the experimental system to quantitatively predict the distribution of an inulin tracer perfused through the multi-organ human-body-on-chips. The automated culture system enables the imaging of cells in the organ chips and the repeated sampling of both the vascular and interstitial compartments without compromising fluidic coupling.
Abstract Background The behavior of shape memory alloys that admit large reversible deformations in response to thermal excitation has been extensively studied in recent years. Yet, the number of ...works dealing with springs made from these alloys is rather limited in spite of their attractiveness in various applications. Objective To bridge this gap we designed and constructed an experimental system for characterizing the behavior of the springs. It enables precise control of the three state variables: temperature, elongation, and force. Methods Control of the sample temperature is achieved by immersing it in a water-filled thermal bath, where the water temperature is adjusted using a thermoelectric Peltier device. A tension-compression motorized unit sets the spring elongation and a force gauge is used for measuring the force exerted on the spring. The data is continuously monitored and acquired with a self-coded LabVIEW program. An important aspect is the calibration procedure developed for identifying the spring load-free state and ensuring the repetitiveness of the measurements. Results Experiments in which the elongation or the force were measured as a function of the temperature demonstrate the role of the phase transformations. Isothermal experiments enabled to characterize the variations of the force versus the elongation at different temperatures. Conclusions The proposed system facilitates the execution of highly accurate experiments through which the complex history-dependent behavior of shape memory springs can be revealed and studied.
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