Effectiveness of CFD simulation for the performance prediction of phase change building boards in the thermal environment control of indoor spaces

This is the post-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2013 ElsevierThis paper reports on a validation study of CFD models used to predict the effect of PCM clay boards on the control of indoor environments, in ventilated and non-ventilated situations. Unlike multi-zonal models, CFD is important in situations where localised properties are essential such as in buildings with complex and large geometries. The employed phase change model considers temperature/enthalpy hysteresis and varying enthalpy-temperature characteristics to more accurately simulate the phase change behaviour of the PCM boards compared to the standard default modelling approach in the commercial CFD codes. Successful validation was obtained with a mean error of 1.0 K relative to experimental data, and the results show that in addition to providing satisfactory quantitative results, CFD also provides qualitative results which are useful in the effective design of indoor thermal environment control systems utilising PCM. These results include: i) temperature and air flow distribution within the space resulting from the use of PCM boards and different night ventilation rates; ii) the fraction of PCM experiencing phase change and is effective in the control of the indoor thermal environment, enabling optimisation of the location of the boards; and iii) the energy impact of PCM boards and adequate ventilation configurations for effective night charging.This work was funded through sponsorship from the UK Engineering and Physical Sciences Research Council (EPSRC), Grant No: EP/H004181/1

Coupled TRNSYS-CFD simulations evaluating the performance of PCM plate heat exchangers in an Airport Terminal building displacement conditioning system

This is the post-print version of the Article. The official published version can be accessed from the link below. Copyright @ 2013 Elsevier.This paper reports on the energy performance evaluation of a displacement ventilation (DV) system in an airport departure hall, with a conventional DV diffuser and a diffuser retrofitted with a phase change material storage heat exchanger (PCM-HX). A TRNSYS-CFD quasi-dynamic coupled simulation method was employed for the analysis, whereby TRNSYS® simulates the HVAC and PID control system and ANSYS FLUENT® is used to simulate the airflow inside the airport terminal space. The PCM-HX is also simulated in CFD, and is integrated into the overall model as a secondary coupled component in the TRNSYS interface. Different night charging strategies of the PCM-HX were investigated and compared with the conventional DV diffuser. The results show that: i) the displacement ventilation system is more efficient for cooling than heating a space; ii) the addition of a PCM-HX system reduces the heating energy requirements during the intermediate and summer periods for specific night charging strategies, whereas winter heating energy remains unaffected; iii) the PCM-HX reduces cooling energy requirements, and; iv) maximum energy savings of 34% are possible with the deployment of PCM-HX retrofitted DV diffuser.This work was funded by the UK Engineering and Physical Sciences Research Council (EPSRC), Grant No: EP/H004181/1

SeamlessExpressiveLM: Speech Language Model for Expressive Speech-to-Speech Translation with Chain-of-Thought

Expressive speech-to-speech translation (S2ST) is a key research topic in seamless communication, which focuses on the preservation of semantics and speaker vocal style in translated speech. Early works synthesized speaker style aligned speech in order to directly learn the mapping from speech to target speech spectrogram. Without reliance on style aligned data, recent studies leverage the advances of language modeling (LM) and build cascaded LMs on semantic and acoustic tokens. This work proposes SeamlessExpressiveLM, a single speech language model for expressive S2ST. We decompose the complex source-to-target speech mapping into intermediate generation steps with chain-of-thought prompting. The model is first guided to translate target semantic content and then transfer the speaker style to multi-stream acoustic units. Evaluated on Spanish-to-English and Hungarian-to-English translations, SeamlessExpressiveLM outperforms cascaded LMs in both semantic quality and style transfer, meanwhile achieving better parameter efficiency

Unveiling the multiregional circular economy pathways for global dysprosium constraints

Dysprosium (Dy) is added to neodymium-iron-boron (NdFeB) permanent magnets to improve the high-temperature performance in many low-carbon technology products. Due to the expected demand expansion, supply uncertainties, and reserve limitations, there is a significant focus on implementing Dy reduction strategies in various industrial communities. This study provides a multiregional analysis of global Dy supply and demand considering climate and general targets from 2022-2050. It also evaluates the role of resource decoupling strategies in global Dy demand reduction. Results indicate that global Dy supply and demand appear to be complex, with demand likely expanding and exceeding primary supply capacity in the coming decades (up to 14 kt by 2050), owing mainly as a response to climate targets. Several resource decoupling strategies considered in this study show a promising role for reducing the Dy consumption (4.5-8.5 kt). Rare-earth exploration, supply diversification, and international collaboration can also shrink future Dy shortage.</p

A Systematic Framework for Quantifying Production System-Specific Challenges in Life Cycle Inventory Data Collection

Understanding the environmental impacts of production setups and process parameters is a necessity for process optimization and new process development within sustainable manufacturing. Previous research studies have focused on developing standard methodologies and frameworks for parametrically modelling the life cycle inventories of unit manufacturing processes. However, these approaches do not fully account for the challenges associated with implementing life cycle inventory models in real-world production setups. Therefore, the time- and cost-intensiveness associated with constructing such models limit their use for identifying sustainability-focused process improvements in complex, real-world production processes. To address the above challenges, this paper proposes a framework to identify process inventory data that have a significant influence on process resource consumption, taking into consideration the difficulties and variabilities in measuring these data. The overarching goal is to identify feasible process improvements from the perspective of process monitoring for sustainable manufacturing. The application of the proposed framework is presented using a case study on a real-world through-feed centerless grinding production process for rotor manufacturing. This study reveals grinding time is the most sensitive process parameter among the other time-related parameters. The manual nature of the process, lack of a data acquisition system, non-standardized sequence of operation, and inability to capture in-process measurements without disrupting real-time production significantly contributes to the difficulty and variability of measuring grinding time

Can Circular Economy Strategies Limit the Prospective Dysprosium Demand in the European Union?

Dysprosium (Dy) is a high critical rare earth element, which is basically used for improving the thermo-magnetic properties in various low carbon products. This research provides a detailed examination on the evolution of Dy demand, in-use stock, and end-of-life (EoL) under ambitious climate targets and demand shrinkages that can be expected due to the implementation of two circular economy strategies: material efficiency and end-of-life recycling in 13 product sectors in the European Union from 2022 to 2050. Our results indicate that future Dy demand, in-use stock accumulation, and EoL generation are likely to be exacerbated by High-APS (Announced Pledges Scenario) and High-NZE (Net Zero Emissions by 2050 Scenario). Moreover, the circular economy strategies used in this study will contribute to significant decreases in the future Dy demand when such strategies are combined and applied in a high magnitude under High-APS and High-NZE scenarios. Recent efforts in the partial and full elimination of Dy mainly in high-tech products such as wind turbines and electrical vehicles are admirable, however, it is necessary to more focus on improving the implementation of circular economy strategies in manufacturing processes to mitigate future Dy supply uncertainties in the European Union

Rub-impact analysis in rotor dynamic systems

Considering the needs of high rotating speed and high efficiency in the modern machines, the decreasing clearance between the rotor and the stator is a necessary design. To improve the performance efficiency of these kinds of machines, the radial clearance between the rotating rotor and the stator becomes smaller and smaller. As a result, it is easier for rotor-stator rub to happen and the normal operation of machines will be affected more severely. When a rub-impact happens, the partial rub arises at first. During a complete period, the rub and impact interactions occur between the rotor and stator once or fewer times. Gradual deterioration of the partial rub will lead to the full rub and then the vibration will affect the normal operation of the machines severely. The majority of works was focused on the development of some mathematical models in order to make the rubbing phenomenon more accurately to be understood in the past few decades. Now in our work general model of a rub-impact rotor-bearing system is set up and the corresponding governing motion equations are given. The rubbing model consists of the following forces i.e., radial elastic impact and the tangential Coulomb type of friction. Through numerical calculations, rotating speeds, unbalance and stiffness values are used as control parameters to investigate their effect on the rotor-dynamic system with the help of time histories, phase plane plots, whirl orbits. Complicated motions, such as periodic, quasi-periodic even chaotic vibrations, are observed under different operating conditions. Stator flexibility effects are also studied using a modified Jeffcott rotor model .Numerical methods employed in our work are Newmark’s method and Runge-Kutta method .The Graphs that have been obtained from both methods were compared Finite Element Model of the rotor dynamic system is developed with 2-noded Timoshenko beam elements. The rotary degrees of freedom are eliminated by static condensation. The Campbell diagram is obtained by accounting both gyroscopic effect and Viscous damping matrices. The Newmark time integration scheme is adopted again by incorporating the intermittent rubbing forces at the central node simulating the rigid disk stator interactions and we are trying to get the results, to compare with the obtained results. The thesis is organized as follows: Chapter-1 describes introduction to rotor dynamic problem and literature survey. Chapter-2 deals with the dynamic modeling and equations of motion of various models considered in the present work. Chapter-3 describes the results part as solution of these equations. Chapter-4 gives summary and conclusions of the work

Recovery of Xanthan Gum from Palm Oil-Based Fermentation Broth by Diafiltration with Flat Polysulfone Microfiltration (MF) Membrane

Xanthan gum recovery from palm oil-based broth by diafiltration was carried out using flat microfiltration (MF) membrane. Optimization of process parameters such as transmembrane pressure (TMP), crossflow velocity (CFV), ionic strength (IS) and diafiltration factor (DF) was performed by Taguchi method using signal-to-noise (S/N) ratio of larger-the-better criterion yielding the following optimum conditions: level 1, level 2, level 3, and level 2, respectively, corresponding to Xanthan recovery of 68 %. Analysis of variance (ANOVA) showed the significance of TMP on providing a driving force for Xanthan’s transmembrane transport (XTT), whereas little effect of DF indicated the evidence of sieving action by cake layer on XTT, which was also responsible for complete rejection of oil indicated by the absence of fatty acid component in permeate upon GC-MS analysis. On the contrary, better XTT was observed during MF operation on zero-oil broth due to absence of oily cake layer rendering CFV more effective

Tracing the multiregional evolution of the global dysprosium demand-supply chain

Dysprosium (Dy) is a critical rare earth element, indispensable for realizing low-carbon technologies. A holistic understanding of global Dy supply-demand chains is essential for ensuring its future sustainable supply and use. This study conducts the first multiregional analysis of Dy flows and stocks to comprehensively trace the global Dy cycle from 1988 to 2021. Results show a rising demand for Dy-comprising intermediate and final products with complex trade fluctuations since 2000. In total, 22,009 tons of intermediate products, primarily as neodymium-based permanent magnets (NdFeB), accumulatively entered the global manufacturing phase, of which China accounted for approximately 55%. Dy use was notable in the United States and Japan for internal combustion engine (ICE) vehicles manufacturing and for industrial machinery production in the European Union. Less than 3% of globally mined Dy was recycled. Considering the growing global demand for Dy, alternate supply sources, and regional efforts to promote recycling and circular economy strategies are required.</p