On the effect of turbulence models on CFD simulations of a counter-current spray drying process

Accurate modeling of the flow field by means of capturing turbulence is crucial in CFD simulations. However, choosing the appropriate turbulence model remains quite challenging for simulating spray drying applications. Only a few studies have touched on this issue, although experimentally validated comparisons throughout the dryer are rare. This work aims to provide an assessment of five different turbulence models (RNG k − ε standard, BSL and SST k − ω as well as transition SST) in terms of the predicted flow field throughout a lab-scale counter-current spray dryer. None of the tested models could initially provide a satisfactory match with locally measured temperatures within the chamber. The popular choice RNG k − ε model led to highest discrepancies, while the k − ω variants performed only slightly better. All these models under-predicted the dissipation of the central hot air jet. Modification to the k − ω variant's characteristic constant to allow increased production of turbulence led to satisfactory agreement between the measurements and simulation results. Extended analysis revealed that different turbulence models produced significantly different drying histories. Only the k − ω SST variant with modified constant could provide predictions close to measured outlet particle moisture content and air conditions. The RNG model proved unsuitable due to unrealistic results with particle injection as well. The differences in predictions with injection among the models were attributed to different transient self-sustained air fluctuation behavior predicted within the chamber. This work will be useful in the selection of turbulence models which is fundamental to accurate CFD modeling of spray dryers

Priorities for energy efficiency measures in agriculture.

This report provides a compilation of energy efficiency measures in agriculture, their opportunities and constraints to implement energy efficient agricultural systems across Europe as a result of the AGREE (Agriculture & Energy Efficiency) Coordination and Support Action funded by the 7th research framework of the EU (www.agree.aua.gr). The report dwells on earlier reports of the consortium, which listed potential energy efficiency measures (Project Deliverable 2.3: Energy Saving Measures in Agriculture – Overview on the Basis of National Reports) and identified trade-offs and win-win situations of various energy efficiency measures in agriculture (Project Deliverable 3.1: Economic and environmental analysis of energy efficiency measures in agriculture). It shows research gaps in crop production, greenhouse production, animal husbandry and system approaches, which can be regarded as priorities for energy efficiency measures in agriculture. The report is na important input for the strategic research agenda, which is one of the main outputs of the AGREE project

Computational fluid dynamics simulation of spray dryers: transient or steady state simulation?

[EN] Self-sustained fluctuating airflow behaviour in spray drying chambers is in essence an unsteady phenomenon requiring the transient CFD simulation framework. There is currently, however, a mixture of steady state and transient CFD simulations of spray dryers practised and reported in the literature. The choice between steady state and transient approach significantly affects the computation time of the simulation and subsequently the adoption of this approach by industry. This paper firstly examines in detail the bottleneck in computation time of the transient simulation approach. Based on past reports, this review paper then presents a discussion and provides several recommendations on the use of steady state and transient simulation approach for spray dryers.Afshar, S.; Jubaer, H.; Chen, B.; Xiao, J.; Chen, XD.; Woo, MW. (2018). Computational fluid dynamics simulation of spray dryers: transient or steady state simulation?. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 395-402. https://doi.org/10.4995/IDS2018.2018.7563OCS39540

Economic and environmental analysis of energy efficiency measures in agriculture. Case Studies and trade offs.

This report is the result of the collaboration of the partners of the AGREE work-package “Economic and environmental analysis”, which is based on case study analyses of the partners in seven countries of the EU. The case studies show economic and environmental trade-offs in the different regions in the EU, for which each partner is responsible. Nevertheless prior to the reporting of the case studies an intensive discussion on a common methodological approach has been accomplished and applied to the case studies. The case studies show a wide range of different perspectives of energy efficiency in agriculture, but they are all based on the common methodology presented in Chapter 3. In Chapter 4, the case studies are presented, with authors indicated at the beginning of each section. Each section of Chapter 4 ends with a synthesis analysis of the results from the different case studies. Chapter 5 summarizes and concludes the report by highlighting the major findings of the analyses. The report builds upon the “State of the Art in Energy Efficiency in Europe” published separately by the AGREE consortium (Gołaszewski et al. 2012), which shows the status quo of energy use and possible energy efficiency measures in agriculture across different production systems and regions in Europe. This report presents an economic and environmental analysis based on in-depth case studies which show the potential for, and constraints on, energy efficiency measures in agriculture with respect to the specific environments in Europe

Legal Certification and Official Recognition Process of Lands Under the Land Laws of Bangladesh

There is interest in the research article whether the article looks at the different approaches to guarantee land rights and suggests distinctive settle land. It is likewise proposed to feature the issues of the current land organization of Bangladesh and to recommend the reorganization of the land organization for legitimate administration of land. The land pivots the existence of individuals of Bangladesh. The current land laws, land organization, and land the executives in Bangladesh are not just brimming with multifaceted design, procedural troubles, and fumble yet besides not open and receptive to the interest of the commoners of the country. Besides, the current system to settle the land question isn't efficient, practical, quiet, and modern. If the land laws are unveiled vivacious and land organization is made well - organized in the feeling of good administration, e-administration, and advancement, the land interest of the commoners is maintained and land questions are settled with public fulfillment and certainty, a progressive change may achieve in the financial improvement of the commoners

A skipping adaptive P&O MPPT for fast and efficient tracking under partial shading in PV arrays

This work presents a new Maximum Power Point Tracking (MPPT) scheme which predicts the local peak positions precisely and tracks the global peak under partial shading effectively. In addition to that, a skipping mechanism is integrated into it, which helps the MPPT to avoid scanning several sections of the I-V or P-V curve. Consequently, the global peak tracking gets accurate and faster than existing MPPT techniques. Several rigorous experiments are carried out in Matlab/Simulink to verify the behaviour of the MPPT. It is observed that under deep shading where the global peak resides on the left zone in voltage profile, tracking speed gets significantly faster. Furthermore, the proposed scheme is implemented in hardware through buck-boost converter in conjunction with dSpace DS1104 board to justify the applicability. Tracking results under several partial shading shows that the proposed method outperforms other MPPT techniques namely Modified Incremental Conductance (MIC), Ant colony optimization-P&O (ACO-P&O) and Cuckoo Search (CS) by a significant margin. Tracking speed is improved by 2 to 3 times depending on the shading pattern and efficiency is well ensured over 99% under all cases

Computationally inexpensive simulation of agglomeration in spray drying while preserving structure related information using CFD

Controlled agglomeration during spray drying offers several advantages for both powder manufacturers and consumers, and thus it is commonly implemented by industry. The implementation, however is largely based on experience, given the scarcity of comprehensive prediction tools. A resource-efficient approach to numerically treat agglomerates and yet provide an indication of their structures is desired to perform realistic simulations without the need for high-performance computing. In this work, a new numerical model for the treatment of coalescence and agglomeration was implemented and evaluated at two distinct scales with significantly different particle number densities within a Eulerian-Lagrangian CFD framework. The model could accurately predict the trends in the final particle size distributions and distinguish realistic agglomerate structures occurring under different conditions. Challenges were encountered as a result of how the underlying collision detection routine handles high particle number density. Several strategies are proposed to overcome these challenges. This work constitutes significant progress towards achieving an efficient prediction tool to estimate final powder properties and will prove useful in performing large-scale simulations to design and control agglomeration