Boiling of new refrigerants: a state-of-the-art review

The industrial conversion to new alternative refrigerants is now one of the major driving forces in two-phase flow and boiling heat transfer research. A state-of-the-art review is presented here to quantify what has been done so far, assess the strengths and weaknesses in current boiling correlations and two-phase flow pattern maps, and identify future research requirements and objectives.     

Product configuration: a review of the state-of-the-art and future research

Being able to provide companies with a number of advantages in delivering customised products, product configuration has received increasing attention from the academia and lasting interests from industries in the past several decades. While several surveys and reviews have been reported shedding light on specific issues in product configuration, a general overview is missing. By systematically presenting important concepts, definitions and issues underlying product configuration, such a review is of paramount importance to develop practical solutions, which ultimately contributes to efficient design, development and implementation of product configurators in practice. This study, thus, tries to fill this gap by reviewing the state-of-the-art research on product configuration. It touches on the major issues, definitions and concepts in product configuration along with the corresponding studies, such as configuration ontology, system design and development, and configuration solving. Based on the review, future research is highlighted as well.     

Water vortex hydropower technology: a state-of-the-art review of developmental trends

With the explosive growth of global energy demand coupled with effects of climate change, there is a significant shift towards green energy generation in recent years. Of the various renewable energy resources available, micro-hydro-power and pico-hydro-power remain very popular in both developed and developing countries. Since 2006, significant growth has spurted in the use of artificial free-surface vortices to generate low and ultra-low-head hydropower following the development of the so-called gravitational water vortex hydropower plant. The technology works on the principle of harnessing hydroelectric power from the high angular velocity experienced in the core of a whirlpool generated in a vortex chamber. In this article, a state-of-the-art review is undertaken on the vortex hydropower technology including a historical review of the technology, the underlying hydraulic principles of such devices, overview of research and technologies that have been deployed to date together with an evaluation of their performance and key findings. Currently, there are 19–22 known live vortex hydropower technologies operating internationally with key academic and commercial research activity in Europe and Asia. The average efficiency from these sites was found to be in the region of 53% which is lower than conventional propeller turbines but higher than waterwheel systems. It was found that the vortex plant, due to its ability to sustain relatively high efficiencies at low heads and small to medium flow rates, addresses a gap in the current turbine application chart. Its key advantage lies in the high-power densities produced compared with conventional technologies. The system also demonstrates potential to be able to function as a fish passage; however, stronger validation is required to prove this for a range of turbine systems. Finally, the authors propose a number of areas that should be investigated that should provide immediate improvements to the turbine in terms of performance.     

Prediction methods for pool boiling heat transfer: A state-of-the-art review

Prediction of heat transfer in the evaporator of a refrigeration unit should be as accurate as possible for the successful operation of the whole appliance. The predictive methods used at present are empirical or semi-empirical, particularly for the heat transfer conditions relevant in practice, because theoretically consistent calculation of the heat transfer coefficient in nucleate boiling is not yet possible. One of these which is included in the VDI Heat Atlas and has been updated recently, is presented in the first main part below and is compared with experimental data for 55 fluids. In the second part, eight more prediction methods from the literature are tested using the same experimental database, and the deviations between measurement and calculation are discussed in detail together with the different results calculated with the various methods.     

Reliability of safety-critical systems: A state-of-the-art review

Safety-critical systems are designed to prevent catastrophic consequences from failure, such as injury or death to humans and environmental damage. These must be carefully designed to ensure reliability requirements. The purpose of this paper is to identify the number of models in the reliability analysis of safety-critical systems. To achieve this goal, we conducted a systematic review of 40 shortlisted studies. The selected studies are classified based on various techniques used in safety-critical systems. This paper summarizes the literature review in the field of reliability of safety-critical systems. The limitations of the literature are exquisitely represented. The international safety norms and applications of safety-critical systems are discussed systematically in this paper. This paper emerges research trends, research challenges and insights of the researcher for future research direction in the area of safety-critical systems.     

Stabilizers for nitrate ester-based energetic materials and their mechanism of action: a state-of-the-art review

Aliphatic nitrate esters are currently the most widely used energetic ingredients in single-, double-, and triple-base propellants. These nitrate esters are unstable at ambient conditions, and stabilizing agents should be incorporated into the energetic compositions to inhibit and slow down the decomposition reactions that can occur. However, the currently used stabilizers present a number of environmental and human health issues. To overcome these shortcomings, many stabilizers have been appeared in the past few decades and continue to be developed. Furthermore, several analytical techniques have been introduced to monitor the stability of nitrate ester-based energetic materials as well, since the existing ones could not be efficiently applied. Therefore, this review paper discusses and summarizes the current and emergent stabilizers as well as their mechanisms of action. A critical and analytical examination of their advantages and drawbacks is made.     

Solar refrigeration options – a state-of-the-art review

A state-of-the-art review is presented of the different technologies that are available to deliver refrigeration from solar energy. The review covers solar electric, solar thermal and some new emerging technologies. The solar thermal systems include thermo-mechanical, absorption, adsorption and desiccant solutions. A comparison is made between the different solutions both from the point of view of energy efficiency and economic feasibility. Solar electric and thermo-mechanical systems appear to be more expensive than thermal sorption systems. Absorption and adsorption are comparable in terms of performance but adsorption chillers are more expensive and bulkier than absorption chillers. The total cost of a single-effect LiBr–water absorption system is estimated to be the lowest.     

高层建筑抗风优化设计和风振控制相关问题研究

黏弹性材料在消声降噪、精密仪器减振和建筑结构防震减灾等领域存在较多应用。炭黑、白炭黑等填料体系是黏弹性材料的重要组成部分。该文采用随机序列吸附方法,建立了不同体积炭黑填充黏弹性材料的代表体积单元(RVE)模型,基于有效体积分数对有限元模型进行修正,从细观尺度对不同体积分数炭黑填充黏弹性材料的弹性力学行为和动态耗能指标进行了计算分析,与经验值和试验结果进行了对比验证。结果表明：采用有效体积分数建模时,RVE方法计算得到不同体积分数下炭黑填充黏弹性材料的应力-应变曲线、动态耗能指标均能与试验和理论结果较好吻合。

     

Flow boiling of ammonia and hydrocarbons: A state-of-the-art review

A comprehensive review of flow boiling heat transfer, two-phase pressure drops and flow patterns of ammonia and hydrocarbons applied in air-conditioning, refrigeration and heat pump systems is presented in this paper. First, experimental studies of flow boiling of ammonia and hydrocarbons are addressed. Then, the prediction methods for flow boiling heat transfer, two-phase pressure drops and flow patterns are described. Next, comparisons of four flow boiling heat transfer and four two-phase pressure drop methods to the experimental data in smooth tubes derived from the available studies are presented. In addition, comparison of flow patterns to a flow map is presented. Based on the comparisons and analysis, recommendations on these methods are given. Furthermore, research needs on flow boiling and two-phase flow of ammonia and hydrocarbons have been identified. It is suggested that more experimental data be obtained through well conducted experiments and new prediction methods or modified ones based on the available methods be made for ammonia and hydrocarbons. In addition, the effect of oil on ammonia and hydrocarbon flow boiling and two-phase flow should be studied in order to have conclusive evidence of its effect.     

Order allocation in purchasing management: a review of state-of-the-art studies from a supply chain perspective

Supplier selection (SS) and order allocation (OA) are strategic decisions that have a substantial effect on a company’s performance. However, order allocation is often neglected, since it results from supplier selection and is considered supplementary: little attention has been paid to its specific nature and complexity. Consequently, the authors conducted a systematic literature review specifically regarding order allocation methods. The research aimed to evaluate how often and when the issue has been dignified with an individual focus, independently of the supplier selection problem. This study conducted a comprehensive examination of the order allocation models and solutions, criteria for order quantity allocation, features of suppliers, items, planning periods, and demand most commonly considered in the literature. Finally, it aimed to discover whether supply chain configurations and trends have been considered in efforts to find a solution to the problem. The scientific contribution of this study is threefold: (i) to expand the review of scientific literature regarding order allocation models, (ii) to identify research gaps and highlight research opportunities, and (iii) to suggest a research agenda for the development of order allocation models according to the requirements of current trends in supply chain management.     

Soft-computing-based approaches to the group technology problem: A state-of-the-art review

This paper presents a state-of-the-art review synthesizing the literature on the use of soft-computing-based approaches, e.g. neural networks and fuzzy models to the group technology problem. The objectives of this paper are to discuss the trend and to identify the gaps for performing future research in this area.     

Tool path generation of ultra-precision diamond turning: A state-of-the-art review

With the increasing market demand for optical complex surface parts, the application of multi-axis ultraprecision single-point diamond turning is increasing. A tool path generation method is very important to decrease manufacturing time, enhance surface quality, and reduce cost. Compared with the tool path generation of the traditional multi-axis milling, that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency. This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues: cutter location(CL) points calculation, the topological form of tool path, interpolation mode, and G code optimization.     

Safety analysis of safety-critical systems for their applicability on NPP systems: A state-of-the-art review

Since any risk in the safety-critical systems (SCSs) might lead to a terrible disaster, the utmost quality attribute of these systems is safety. Researchers are putting their efforts to ensure the safety of such systems. This paper summarizes the state-of-the-art in the area of the safety attribute of such critical systems. The in depth literature survey is performed to explore the several methods/models used for safety analysis of the SCS. The limitations of such methods are also shown regarding their applicability in SCS of the nuclear power plant (NPP). We also propose a framework to perform safety analysis, which can deal with these limitations and demonstrated the approach on a case study of NPP. Further, the direction for future work is advised to extend the further scope of research based on the case study.     

Fire behaviour of FRP-strengthened reinforced concrete structural elements: A state-of-the-art review

The last two decades have seen increasing applications of fibre reinforced polymer (FRP) materials in civil engineering structures due to their many advantages over traditional strengthening and reinforcing materials. Among the most common applications is bonding or wrapping FRP products (strips or sheets) to the exterior of reinforced concrete (RC) members to increase their strength or deformability. However, widespread application of FRP strengthening systems in buildings, where structural fire ratings are required, is hindered due to unknowns surrounding the reduction in their mechanical and bond properties at elevated temperatures. This paper presents a state-of-the-art review on the fire performance of FRP-strengthened RC structural elements. The review addresses first the mechanical behaviour at high temperature of the constituent materials of FRPs and how their bond to concrete is affected when heated. The paper then discusses available experimental and numerical studies on the fire behaviour of FRP-strengthened RC beams, slabs, and columns. Available design guidance is also discussed. Finally, recommendations for future research are given.     

Sustainable development of process facilities: state-of-the-art review of pollution prevention frameworks

Pollution prevention (P2) strategy is receiving significant attention in industries all over the world, over end-of-pipe pollution control and management strategy. This paper is a review of the existing pollution prevention frameworks. The reviewed frameworks contributed significantly to bring the P2 approach into practice and gradually improved it towards a sustainable solution; nevertheless, some objectives are yet to be achieved. In this context, the paper has proposed a P2 framework 'IP2M' addressing the limitations for systematic implementation of the P2 program in industries at design as well as retrofit stages. The main features of the proposed framework are that, firstly, it has integrated cradle-to-gate life cycle assessment (LCA) tool with other adequate P2 opportunity analysis tools in P2 opportunity analysis phase and secondly, it has re-used the risk-based cradle-to-gate LCA during the environmental evaluation of different P2 options. Furthermore, in multi-objective optimization phase, it simultaneously considers the P2 options with available end-of-pipe control options in order to select the sustainable environmental management option.     

Pool boiling heat transfer to hydrocarbons and ammonia: A state-of-the-art review

Interest has grown in recent years to extend the use of hydrocarbons and ammonia as working fluids in refrigeration to new domains of application, despite their flammability. In the context of pool boiling heat transfer, this has created increasing research activities, particularly with regard to hydrocarbons. In contrast with this, only a few new experimental results have been added to the data set existing for ammonia in the literature. So this review will concentrate on hydrocarbons, while ammonia will be treated in a comparatively brief part.The review starts with the state-of-the-art that had been reached at about 1990. It continues with the data set for propane being taken as an example to highlight various reasons for the experimental data scatter that is found when different sources are compared for the same substance. In the main part, new results of 12 (aliphatic) hydrocarbons are discussed regarding the influence of heat flux q and reduced saturation pressure p^* = p_s/p_c on the heat transfer coefficient α, and also the variation in α₀ caused by the differences in the thermophysical properties of the 12 hydrocarbons at constant q₀ and . It is shown that the dependencies of the heat transfer coefficient α on heat flux q and reduced pressure p^*, and on the thermophysical properties of the various fluids at constant values q₀ and can be correlated by general semi-empirical functions with comparatively narrow limits of error that do not reach far beyond the experimental scatter occurring when different sources are compared for the same substance. Before treating ammonia in a final section, the review on hydrocarbons closes with short discussions for mixtures of hydrocarbons, for the bundle effect, and for the behaviour of enhanced tubes.     

Rapid one-of-a-kind product development via the Internet: a literature review of the state-of-the-art and a proposed platform

The historical background of Internet-based product design and manufacturing systems for rapid development of one-of-a-kind (OKP) products is systematically reviewed. By reviewing the existing OKP systems and recent approaches of Internet-based design and manufacturing systems, the requirements for the next generation of OKP systems and the current techniques that can be used to implement Internet-based product design and manufacturing systems for the rapid production of OKP products will be discussed. The problems that emerged from recent developments are reviewed and sorted. The future trends of Internet-based collaborative design, decision support, manufacturing support, supply chain management, workflow management, Internet techniques for product design and manufacturing, product modelling, STEP-based data environment, concurrent engineering, etc., will also be discussed. The reviewed state-of-the-art approaches are used directly or indirectly as references for the development of a new generation OKP systems. A reference system structure for building an Internet-based integrated product development system is then proposed to facilitate rapid development of OKP products.     

A state-of-the-art review on delayed ettringite attack on concrete

The paper presents a critical review of the sulphate attack related to ettringite formation. This process is associated with expansion. However, not necessarily any ettringite-related expansion is related to the sulphate attack. For example, early ettringite formation which occurs immediately (within hours) in a plastic fresh mixture does not produce any damaging expansion and is associated with the regulation of setting time of Portland cement paste. Expansion after the hardening of cement paste can be advantageously used for the development of chemical prestress in expansive cements. Delayed ettringite formation (DEF) occurs at late ages and the related heterogeneous expansion in a hardened concrete can produce cracking and spalling. Two different types of DEF are examined depending on the sulphate source: DEF caused by external sulphate attack or internal sulphate attack.     

Nanomaterials and the environment: a review for the biennium 2008-2010

Applications of nanotechnology are touching almost every aspect of modern life. The increased use of engineered nanomaterials (ENMs) in consumer products, chemical and medical equipment, information technology, and energy, among others, has increased the number of publications (informative and scientific) on ENMs. By the 1950s, very few papers were committed to nanomaterials (NMs), but in 2009, more than 80,000 journal articles included the concept nanotechnology. The objective of this review is to compile and analyze publications on NMs in the biennium 2008-2010. This review includes the most recent publications in risk assessment/toxicity, characterization and stability, toxicity, fate and transport of NMs in terrestrial ecosystems, and new ENMs. Carbon nanotubes, metallic, metal oxides and hydroxides nanoparticles, quantum dots, and polystyrene NPs are included.     

Safety culture: a survey of the state-of-the-art

This paper discusses the evolution of the term ‘safety culture’ and the perceived relationship between safety culture and safety of operations in nuclear power generation and other hazardous technologies. There is a widespread belief that safety culture is an important contributor to safety of operations. Empirical evidence that safety culture and other management and organizational factors influence operational safety is more readily available for the chemical process industry than for nuclear power plant operations. The commonly accepted attributes of safety culture include good organizational communications, good organizational learning, and senior management commitment to safety. Safety culture may be particularly important in reducing latent errors in complex, well-defended systems. The role of regulatory bodies in fostering strong safety cultures remains unclear, and additional work is required to define the essential attributes of safety culture and to identify reliable performance indicators.