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This paper presents a novel single-phase non-isolated bidirectional buck converter topology. The proposed converter uses a basic switching cell structure with a coupled inductor and an interleaving switching scheme. This article addresses a crucial challenge in bidirectional DC-DC conversion by prioritizing reducing output current ripples and minimizing filter inductor size. The employed method includes using MOSFETs with fast recovery diodes to mitigate reverse recovery and body diode losses. Furthermore, the optimization of the switching frequency of the output inductor to be twice the actual switching frequency contributes to reducing the component size of the converter. The coupled inductor also helps to reduce stress on components by distributing currents among its legs. The experimental result demonstrates the proposed converter has a very low ripple current as compared to the conventional converter. The low current ripples and smaller filter inductor size enabled by high-frequency operation have improved the efficiency and size of the converter. A common ground between input and output terminals ensures robust performance without common mode current concerns. Overall, the proposed converter represents a significant improvement in DC-DC converters, promising enhanced efficiency, reliability, and compactness in bidirectional DC-DC conversion systems. In order to verify the performance of the proposed converter, a 460 W buck converter prototype was built and tested. [ABSTRACT FROM AUTHOR]

A global model is proposed to simulate the drying process of used nuclear fuel assemblies under vacuum drying conditions. The transient model consists of a coupled mass and energy conservation equation with appropriate source and sink terms. The classic Hertz-Knudsen expression is employed to resolve the evaporation rate and the associated water mass depletion in the system. Both latent heat of vaporization and residual decay heat are considered as sink and source in the energy conservation, respectively. The model is employed to simulate vacuum drying of spent nuclear fuel rod storage systems. Multistage stepwise vacuuming of the system is emulated, and several parametric studies are conducted to identify their role in the drying process. The predicted temporal profiles show that the proposed model is able to capture qualitative trends of the water removal rate, hence the dryness level of the system. The model prediction is also compared against experiments where the amount of residual water after a standard vacuum drying procedure is quantified. The predictions are found to compare favorably with the experimental measurements. [ABSTRACT FROM AUTHOR]

Creating efficient public transport systems that attract users is a challenging task in contexts where the control of public transport is divided between various actors. Recent research on public transport has therefore seen increasing focus on issues like coordination, collaboration and steering in complex governance settings. However, more is known about what needs to be done than how to implement the necessary changes. This paper presents a systematic literature review with a focus on developing the understanding on how to improve the conditions for public transport. The reviewed articles are analysed for increasing the understanding of the critical challenges in the planning and implementation of measures to increase public transport travel; the working practices for dealing with problems described in the literature; and the advantages and disadvantages of different working practices. Based on the analysis an analytical framework is developed that can be used to study and evaluate working practices for managing critical challenges. The framework consists of three interconnected factors (i) actors, (ii) institutions (laws and rules that govern the interaction of the actors), and (iii) work processes (phases in the interaction between the actors). Drawing on the results of the systematic review a number of key issues for establishing working practices for dealing with the challenges are emphasized for each of the factors. [ABSTRACT FROM AUTHOR]

Green public procurement is believed to have the potential to contribute to environmental improvement and diffusion of green technologies. The aim of this paper is to compare and analyse how two Swedish regions use public procurement to promote the introduction of renewable fuels in their public bus transport systems. The method is a qualitative comparative case study, based on interviews and document studies. The paper addresses the questions of what the strategic motivations are for using public procurement to stimulate renewable fuels, and what the practical challenges have been in relation to five important factors identified from previous research: strategies, requirements, costs, size and knowledge. In one region, procurement is used in a strategic way to create a local market for biofuels, which poses higher demands on political backing, information and knowledge, the way requirements are set, and an acceptance of increased costs. In the other region, procurement is used instrumentally to increase the share of biofuels in a cost-effective way that gives room for more flexibility and reduces the demands on the procurers. This paper highlights the importance of context when assessing green public procurement schemes and analyses the case-specific influence of factors on the outcome of green public procurement. [ABSTRACT FROM AUTHOR]

This article investigates optimal sizing and realtime control of electrical and thermal distributed energy resources (DERs) in smart buildings. Initially, a comprehensive system architecture is presented considering both electrical and thermal DERs. Then, the DERs are optimally sized through a planning optimization problem with respect to minimization of the total initial investment cost, replacement cost, operations-and-management cost and environmental cost normalized by energy delivered from renewables and controllable non-renewables. Finally, the DERs are optimally controlled in a realtime through a one-slot-look-ahead (OSLA) optimization technique with respect to minimization of load scheduling delay cost, energy procurement cost, energy storage degradation cost, DERs operations-and-management cost, and environmental deterioration cost. The proposed OSLA based technique has the following distinct features and benefits: (i) it introduces a customer-oriented specific duration based modelling that makes it useful for practical customer energy needs and available budget limitation; (ii) it relies on the current states of the system inputs only making it applicable in general scenarios; (iii) it employs special techniques of problem modification, transformation, approximation and separation with a significantly lower computational complexity making it useful for practical implementation. Performance of the proposed approach is validated through simulations. Results show that the proposed algorithm can reduce the monthly energy consumption bill of BEMS customers by 20.53%. Also, it can execute 88.15% of customer load tasks accurately accounting for realtime changes in system inputs. • DERs are sized through a new planning optimization approach. • DERs are controlled through a new operations optimization algorithm. • Monthly energy consumption cost is reduced by 16.01%–20.53%. • Adaptation capability is enhanced by 23.22%–60.70%. • Computational complexity is reduced from O (mn 2) to O (n). [ABSTRACT FROM AUTHOR]

This article investigates optimal sizing and realtime control of electrical and thermal distributed energy resources (DERs) in smart buildings. Initially, a comprehensive system architecture is presented considering both electrical and thermal DERs. Then, the DERs are optimally sized through a planning optimization problem with respect to minimization of the total initial investment cost, replacement cost, operations-and-management cost and environmental cost normalized by energy delivered from renewables and controllable non-renewables. Finally, the DERs are optimally controlled in a realtime through a one-slot-look-ahead (OSLA) optimization technique with respect to minimization of load scheduling delay cost, energy procurement cost, energy storage degradation cost, DERs operations-and-management cost, and environmental deterioration cost. The proposed OSLA based technique has the following distinct features and benefits: (i) it introduces a customer-oriented specific duration based modelling that makes it useful for practical customer energy needs and available budget limitation; (ii) it relies on the current states of the system inputs only making it applicable in general scenarios; (iii) it employs special techniques of problem modification, transformation, approximation and separation with a significantly lower computational complexity making it useful for practical implementation. Performance of the proposed approach is validated through simulations. Results show that the proposed algorithm can reduce the monthly energy consumption bill of BEMS customers by 20.53%. Also, it can execute 88.15% of customer load tasks accurately accounting for realtime changes in system inputs. • DERs are sized through a new planning optimization approach. • DERs are controlled through a new operations optimization algorithm. • Monthly energy consumption cost is reduced by 16.01%–20.53%. • Adaptation capability is enhanced by 23.22%–60.70%. • Computational complexity is reduced from O (mn 2) to O (n). [ABSTRACT FROM AUTHOR]

Two-phase flow instabilities in microchannels exhibit pressure and temperature fluctuations with different frequencies and amplitudes. An active way to suppress the dynamic instabilities in the boiling microchannels is to introduce synthetic jets into the channel fluid. Thus, the bubbles can be condensed before they clog the channel and expand upstream causing flow reversal. The present work experimentally investigated the effects of synthetic jets on microchannel flow boiling. An array of synthetic jets was introduced into the microchannel flow. The strength and frequency of the jets were controlled by changing the driving signals of the piezoelectric driven jet actuator. It is found that the bubbles were effectively condensed inside the jet cavity. The boiling flow reversals were notably delayed by the synthetic jets. Meanwhile, the pressure fluctuation amplitudes were suppressed to some extent. It was also observed that synthetic jets can help to uniformize the heat sink temperature distribution. [ABSTRACT FROM AUTHOR]

Abstract: Many cities around the world have taken a pioneering role in tackling climate change and they will be key players in a possible transition to a future low carbon society. However, cities are at the same time constrained and act in a world of multi-level governance where local decision makers are dependent on both higher political levels and other actors in society. In this situation network governance has emerged as a promising ‘new mode of governance’ where cities can increase both the legitimacy and implementation capacity of an ambitious climate agenda. In network governance the municipality is a facilitator rather than commander and implementer. However, there are also some important potential problems with network governance relating to its democratic legitimacy (politics increasingly carried out by closed elites) and its capacity to lead to radical change (networks of established interests tend to preserve status quo). The aim of this paper is to critically analyse the role of network governance in urban low carbon transitions. The paper builds on original empirical research from the Swedish context which is supplemented by experience found in the literature from other cases. The paper draws from, and merges, two different theoretical perspectives on governance: network governance and transition governance. The literature on network governance asks whether this mode of governance is legitimate and effective, while the literature on transition governance explores what governance configurations are needed in order to steer towards a (low carbon) transition. The findings of the paper show that the effects of network governance are mixed both regarding its policy outputs and its democratic legitimacy. On the implications of network governance for urban low carbon transitions it is argued that while network governance can contribute to niche developments and innovation at the urban level, the elitist character of networks risks maintaining existing unsustainable patterns and defining possible urban futures in too narrow terms. [Copyright &y& Elsevier]

Colonization of HVAC systems by microbes may lead to release of hazardous bioaerosols containing allergens, irritants, odorants, or infectious agents to indoor air, possibly adversely affecting system performance. Unlike the many common materials used in HVAC systems, copper and copper alloys have been shown in laboratory investigations to kill bacteria and fungi on contact after several hours. This study tested copper's antimicrobial properties in comparison with aluminum in full-scale, carefully controlled air-conditioning systems, four with copper heat exchanger assemblies and four with aluminum assemblies, at identical airflow rates, temperatures, humidity, and input microbe levels. Fungal and bacterial loads on copper surfaces in heat exchangers were lower than on aluminum surfaces by factors of 3500 and more than 500, respectively, over a 4-month period. No statistically significant difference in the release of airborne microbes was detected between copper and aluminum heat exchangers. The moderate conditions employed in this study, while still within the range commonly found in HVAC systems, possibly prevented the high microbial loading on aluminum heat exchanger surfaces from translating into significant differences in airborne concentrations between copper and aluminum systems. [ABSTRACT FROM AUTHOR]

The article examines the MAC protocol design issues for a wireless body area network (WBAN) based patient monitoring system. Also cited are the classifications of MAC protocols, namely, scheduled MAC protocols, and the random access MAC protocols, as well as the key requirements of a WBAN, including the ability to operate in a power constrained environment and the ability to support various medical applications.

The thermal conductivity of the fuel in today's light water reactors, uranium dioxide (UO2), can be improved by incorporating a uniformly distributed heat-conducting network of a higher-conductivity material: silicon carbide (SIC). The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 (97% theoretical density). This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and development of a formal methodology for producing the resultant composite oxide fuel. Calculations of the effective thermal conductivity (ETC) of the new fuel as a function of percent SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The ETCs are obtained at different temperatures from 600 to 1600 K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. The heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for the thermal conductivity calculations and to estimate the reduction in centerline temperatures achievable within such a fuel rod. Later, the computer codes COMBINE-PC and VENTURE-PC were employed to estimate the fuel enrichment required to maintain the same burnup levels corresponding to a volume percent addition of SiC. [ABSTRACT FROM AUTHOR]

Abstract: Heat transfer and fluid flow characteristics through a porous medium were investigated using numerical simulations and experiment. For the numerical simulations two models were created: a two-dimensional numerical model and a Fluent™ computational fluid dynamics (CFD) porous media model. The experimental investigation consisted of a flow channel with a porous medium section that was heated from below by a heat source. The results of the numerical models were compared to the experimental data in order to determine the accuracy of the models. The numerical model was then modified to better simulate a matrix heat exchanger. This numerical model then generated temperature profiles that were used to calculate the heat transfer coefficient of the matrix heat exchanger and develop a correlation between the Nusselt number and the Reynolds number. [Copyright &y& Elsevier]

In this paper, a hybrid resource management system for the uplink in Universal Mobile Telecommunications System wideband code-division multiple access (WCDMA) with components in the Node-B and user equipment (UE) has been proposed. A rate scheduler in the client focuses on average packet delays as a means of abstracting application-specific requirements from the rest of the resource management scheme. It controls uplink transmission through variable spreading gain to optimize resource usage while meeting target delays. Service change requests from the distributed rate schedulers are collectively processed through interservice and intraservice priority queuing in a manner that is shown to exhibit fairness in allocation of resources when cumulative load exceeds system capacity. The performance of the proposed algorithm is explored through discrete-event simulations for three classes of traffic, namely voice, video, and data, over the WCDMA uplink in the presence of short-term Rayleigh fading, automatic repeat request, forward error correction, target transmission delays to meet the respective quality of service, and frame error rate targets in a ‘multicell’ environment. The authors analyze two alternatives for distributed resource management with the UE or Node-B in control of rate scheduling and observe the fairness in resource allocation of both systems. Priority of speech, video, and data traffic is respected and reflected in 95th percentile transmission delays for heavily loaded systems. [ABSTRACT FROM AUTHOR]

Abstract: A dynamic model of a centrifugal compressor capable of system simulation in the virtual test bed (VTB) computational environment is presented. The model is based on first principles, i.e. the dynamic performance including the losses is determined from the compressor geometry and not from the experimentally determined characteristic performance curves. In this study, the compressor losses, such as incidence and friction losses, etc., are mathematically modeled for developing compressor characteristics. For easy implementation in the VTB platform, the non-linear governing equations are discretized in resistive companion (RC) form. The developed simulation model can be applied to virtually any centrifugal compressor. By interfacing with a composite system, such as a Brayton cycle gas turbine, or a fuel cell, the compressor dynamic performance can be evaluated. The surge line for the compressor can also be determined from the simulation results. Furthermore, the model presented here provides a valuable tool for evaluating the system performance as a function of various operating parameters. [Copyright &y& Elsevier]

Abstract: A sequentially coupled finite element model of the friction stir welding process has been utilized to study the residual stresses caused by the thermal cycles during friction stir welding of metals. This is a two step simulation process. In the first step, the thermal history is predicted from an input torque based thermal model. The temperature history generated by the thermal model is then sequentially coupled to a mechanical model that predicts the residual thermal stresses. The model does not deal with the severe plastic deformations within the weld nugget and the thermo-mechanically affected regions, a fact that may cause modeled results to deviate from experimentally measured residual stresses. The model is three-dimensional and uses temperature dependent material and thermo-physical properties. Three different materials, AA-2024, AA-6061 and SS 304 L, have been studied. [Copyright &y& Elsevier]

Abstract: A polymer-supported palladium(II) salen-type complex exhibited catalytic activity in the cross-coupling reaction of various aryl bromides and heteroaryl bromides with phenylboronic acid in a mini-continuous flow reactor system at elevated temperatures in a phosphine-free system. The reaction was also performed in batch using a number of different solvent systems in order to optimise conditions. The catalytic mini-reactor can be used repeatedly over several cycles in the Suzuki–Miyaura cross-coupling reaction. While the diameter of the flow channel is 3mm, the macroporous resin supported catalyst is solvent expanded to completely fill the channel. Consequently, the liquid path is through the micro channels of the macroporous resin structure. Intensification of the process over the stirred batch reaction is through increased reagent-catalyst contact and results in a 20-fold increase in the rate of reaction. The residence/space time on the reactor is 10.5min, compared to 24h in batch, which means that a diversity of starting materials can be screened over a short period of time. To demonstrate the utility of the system, a diversity of aryl and heteroaryl bromides have been studied. [Copyright &y& Elsevier]

The planning of facilities to improve the environment is often carried through in the form of locally based construction projects. These projects can be complex, involving a variety of issues and a number of different actors from both the public and private sectors. By drawing on previous research on project planning, an analytical model for analysing the issues connected with the planning and implementation of environmental projects is developed. The main argument of the paper is the importance of considering how context-specific factors affect project design and project management. The empirical material is taken from the planning of two biogas projects in Sweden and it is showed how differences in factors such as the actors involved, the organisational framework and the political setting lead to two markedly distinct planning approaches. The results of the paper, which also highlight the importance of a flexible planning approach, are relevant not only for biogas but also for other projects with similar characteristics. [ABSTRACT FROM AUTHOR]

The aim of the paper is to compare the planning for wind power in three municipalities and analyze how it has influenced three important aspects of the wind power development: the siting of turbines, the ownership of turbines and citizen participation. The paper shows that the planning strategies of the municipalities differed considerably and that this in turn has led to differences in the development of wind power. A general conclusion is that there seems to be a dilemma in municipal planning between, on the one hand, the promotion of wind power and, on the other hand, the organization of a planning that effectively regulates the siting of turbines and allows for citizen participation. The results show that there is a need to support and strengthen municipal planning capacities, and efforts in that direction are being undertaken by state and regional authorities in Sweden. The results, however, also imply the need for stronger policy measures in order to avoid large differences between the way wind power is handled at the municipal level. [ABSTRACT FROM AUTHOR]

Recent studies have suggested that the heat buildup of construction materials may be significantly reduced, without affecting the material color, by the incorporation of scattering particles.The scattering particles were found to alter the near infrared diffuse reflectance of the material, depending on their refractive index, volume percent, and particle size combination. In addition, a theoretical model was developed and correlated well with the experimentally measured values, accurately predicted increases in diffuse reflectance and drops in temperature. Thus, the model may be effectively used to design dark colored polymeric materials with reduced heat buildup properties. [Copyright &y& Elsevier]

This paper develops a model to predict the nugget development during resistance spot welding (RSW) of Al-alloys. The model employs a coupled thermal-electrical-mechanical analysis and accounts for phase change and convective transport in the weld pool. The contact area and the pressure distribution are determined from a coupled thermal – mechanical model. The model calculates time varying interface pressure. The knowledge of interface pressure allows for accurate prediction of interfacial heat generation. Temperature-dependent thermal-electrical-mechanical properties are used. The predicted nugget shape and size agree well with experimental data. The proposed model can be applied to predict the effects of the welding parameters and the electrode shapes on the nugget development. [ABSTRACT FROM AUTHOR]

Current freight transport is highly dependent on fossil fuels and there is a need for a transition to alternative fuels and technologies. Biogas is a type of biofuel that has the potential to reduce climate emissions from freight transport, while providing additional benefits such as recycling of nutrients and increased energy security. This paper uses theories on the diffusion of green technologies to analyse the barriers and drivers for the increased use and diffusion of biogas in freight transport. The empirical focus is on the region of Västra Götaland in Sweden, and qualitative interviews have been conducted with demand-side actors such as transport buyers, haulage companies and vehicle manufacturers. The results confirm the important barriers observed in previous research, such as the higher costs of biogas, financial uncertainties and lack of infrastructure, as well as the interplay between barriers. The main drivers are an increased focus on sustainability both within the sector and from wider society, as well as the environmental properties of biogas. Specific barriers have also been identified such as a fragmented freight market structure with a mix of large and small transport companies, tight profit margins and reduced capacity for investments. There is also a division of labour and responsibilities between transport companies and transport buyers, which makes it unclear who will drive the transition to alternative fuels. In general, the study shows that the different types of uncertainty are perceived by the actors as being a significant barrier that needs to be better conceptualised in diffusion theory. [Display omitted] • Barriers and drivers for the diffusion of biogas in freight transport are analysed. • Case study on perceptions of demand-side actors in freight transport in Sweden. • Important barriers are higher costs, financial uncertainties and lack of infrastructure. • Important drivers are increased sustainability focus and environmental properties of biogas. • Uncertainty is a major barrier that should better conceptualised in diffusion theory. [ABSTRACT FROM AUTHOR]

Presents information on a study which investigated the particle deposition in a horizontally oriented tube with abrupt contraction. Approaches to model the particle deposition problem; Results; Conclusions.

• Existing models require a-priori knowledge on system inputs. • A-priori knowledge may not be available in real-time scenarios. • The proposed algorithm does not require a-priori knowledge on system inputs. • The proposed algorithm requires a minimum complexity of O (1). • The proposed algorithm is suitable for practical implementation. Energy storage control, load scheduling, and indoor user comfort management are perceived as key management solutions for electric industry in the building sector. Nevertheless, requirement of a-priori knowledge on system inputs (i.e. , renewable energy generation process, load arrival process, and dynamic price signals) raises concerns about the ability of existing building energy management solutions to accurately adapt to real-time needs in energy generation, demand, storage, and indoor comfort feel. Conversely, with the consideration of unknown dynamics of system inputs, a one-slot-look-ahead virtual queue stability based Lyapunov optimization technique is employed in this article for a real-time energy and comfort optimization in grid-connected solar integrated smart buildings. The goal is to minimize an average aggregated system cost through a real-time joint optimization of electrical and thermal load scheduling delays, energy procurement cost from controllable generators and external grid, electrical and thermal energy storage degradation, and indoor user comfort feel. It is also shown that the joint optimization problem is separable into subproblems which are sequentially solved to obtain all solutions in closed-forms. The solutions are proved as asymptotically optimal, and can be easily implemented in real-time building energy and comfort management scenarios especially when the statistics of system inputs are unknown and arbitrary. The proposed algorithm is validated through simulations where it is tested in different weather conditions. Results show that the proposed algorithm can achieve an average monthly energy procurement-and-operations cost reduction up to 16.37%, while meeting building's energy and comfort requirements. [ABSTRACT FROM AUTHOR]

Experiences of ageing and care are closely tied to structural location in terms of race, class, gender and sexuality among others. In South Africa, lesbian, gay, bisexual and transgender (LGBT) people's experiences of ageing and care are profoundly influenced by the patriarchal, postapartheid context. This study, the first of its kind in South Africa, was an exploratory study of the experiences of ageing and care among LGBT elders in two provinces in South Africa. Findings indicate that LGBT elders' experiences of ageing and care are influenced by intersectionality and lack of access to care. In particular, the ageing and care experiences of black and Coloured LGBT elders, especially lesbian, bisexual and transgender women, are disproportionately impacted. Implications of these exploratory findings are that national ageing and care policies need to specifically name LGBT elders as a key group and that services be rolled out for LGBT elders. [ABSTRACT FROM AUTHOR]

A case study of a 2760 g female infant was born at a community hospital at 39 weeks and 2 days to a 19-year-old G1P0 mother via spontaneous vaginal delivery, with pregnancy was complicated by intrauterine growth restriction. Topics include transferred to a level 4 neonatal intensive care unit for endocrinology evaluation and a brain magnetic resonance imaging; and Intraventricular hemorrhage was ruled out etiology of infant's central diabetes insipidus was attributed to presumed meningitis.

The large share of carbon emitted by energy-intensive industries in the extraction and processing of basic materials must be limited to decarbonise society and the economy. Ways in which the state can govern industrial decarbonisation and contributes to green state theory are explored by addressing a largely ignored issue: the green state's industrial relations and its role in industrial governance. With insights from a Swedish case study, the tension between the state's economic imperative and ecological concerns in greening industry are shown to persist. However, as the energy-intensive industry's previously privileged position in the economy is weakening, industry is opened to decarbonisation strategies. While the case exposes a number of governance challenges, it also suggests potential areas where the state can pursue decarbonisation in energy-intensive industry and points the way to an active role of the green state in governing industrial decarbonisation and greening industry. [ABSTRACT FROM AUTHOR]

The toxicity of the organic dyes presents in the environment due to polluted discharge from industries is a real dilemma in the world. Here, the problem was addressed with the synthesis of new quaternary mineral cupric antimony oxychloride (CAO) during the study of Cu–Sb–O–Cl system in absence of solvents. The morphological analysis showed that synthesized matrix is rough and uneven with round and cylindrical shapes. The composition of nanomaterial verified the elemental composition as Cu, Sb and Cl. The XRD analysis revealed that synthesized product CAO is crystalline in nature where crystallite size was estimated in the range of 2–8 nm. The bond vibrations were studied through Fourier transforms infrared spectroscopy to confirm the symmetric and asymmetric vibrations in the matrix. The material parameters (grain size, dislocation line density, stresses and miller indices) of the synthesized material CAO were calculated using powder X-ray diffraction analysis. Thermogravimetric analysis was performed to study the decomposition behaviour and stability of the CAO. The copper ternary compound was used to mitigate the effect of organic dyes like Sunset yellow (26%), Methylene blue (23%), Brilliant green (20%), Methyl orange (14%) in the dyes polluted wastewater. [ABSTRACT FROM AUTHOR]

The great hopes in Brussels that a circular bioeconomy will help bridge the growing divide between urban and rural areas and allow the hinterlands to prosper from 'green growth' are addressed in this article, which reflects on insights from three Nordic case studies of brown, green and blue biomass use at different levels of technology readiness. A closer examination of the forward, backward, fiscal and final demand linkages at regional level from increased biomass utilization, from eastern Finland and northern Sweden to Jutland and North Atlantic islands, suggests that linkages are and will remain relatively weak, predominantly dashing the expectations. As suppliers and exporters of natural resources, disadvantaged regions may all too easily get locked into a 'staples trap', where the value creation evaporates owing in part to the steep start‐up costs and the associated boom‐and‐bust cycles, which place them in a weak position vis‐à‐vis the resource manufacturers and consumers. To make the prospects of development, employment and prosperity in the hinterlands materialize, measures are needed to strengthen the regional‐level economic linkages. Regional‐level revolving funds based on benefit‐sharing instruments related to natural resources can be used to bolster economic development, as reflected in such schemes present in both China and Canada. We call for further research into whether and how such approaches can be replicated successfully by channeling revenues from biomass cultivation to regional‐scale revolving funds, with mandates to strengthen long‐term economic linkages and prosperity within the hinterlands. © 2022 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley & Sons Ltd [ABSTRACT FROM AUTHOR]

The generation gap is a serious, challengeable problem in the emerging society in Pakistan. It refers to parents or elders' disagreements, conflicts, inconsistencies, and differences in several matters such as attitude, behaviour, beliefs, values, politics, closeness, modern technology, cultural changes, and communication. The present study was designed to analyse the causes and consequences of the generation gap among the Pashtun community. A quantitative research method was used to select 400 samples of the current population and collect data through a well-designed questionnaire. The validity and reliability of the questionnaire were examined by ten PhD scholars from different universities. The Cronbach's Alpha for the data is .969. The data was analysed using SPSS version 26. The results were shown in the form of a one-way ANOVA and a frequency distribution table. The data revealed a statistically significant (0.05) relationship between various variables such as technological advancement, living patterns, behaviour, social norms, communication gaps, unemployment, poverty, socioeconomic status, and religiosity. Both parents and children are responsible for the generation gap, but it can be reduced by understanding, loving, caring, sharing, communicating, and maintaining friendly relations. [ABSTRACT FROM AUTHOR]

BACKGROUND: Systemic magnesium has been used to minimize postoperative pain with conflicting results by clinical studies. It remains unknown whether the administration of perioperative systemic magnesium can minimize postoperative pain. The objective of the current investigation was to evaluate the effect of systemic magnesium on postoperative pain outcomes. METHODS: A wide search was performed to identify randomized controlled trials that evaluated the effects of systemic magnesium on postoperative pain outcomes in surgical procedures performed under general anesthesia. Meta-analysis was performed using a random-effect model. Publication bias was evaluated by examining the presence of asymmetric funnel plots using Egger regression. RESULTS: Twenty randomized clinical trials with 1,257 subjects were included. The weighted mean difference (99% CI) of the combined effects favored magnesium over control for pain at rest (<=4 h, -0.74 [-1.08 to -0.48]; 24 h, -0.36 [-0.63 to -0.09]) and with movement at 24 h, -0.73 (-1.37 to -0.1). Opioid consumption was largely decreased in the systemic magnesium group compared with control, weighted mean difference (99% CI) of -10.52 (-13.50 to -7.54) mg morphine IV equivalents. Publication bias was not present in any of the analysis. Significant heterogeneity was present in some analysis, but it could be partially explained by the sole intraoperative administration of magnesium compared with the intraoperative and postoperative administration. None of the studies reported clinical toxicity related to toxic serum levels of magnesium. CONCLUSION: Systemic administration of perioperative magnesium reduces postoperative pain and opioid consumption. Magnesium administration should be considered as a strategy to mitigate postoperative pain in surgical patients. [ABSTRACT FROM AUTHOR]

Background: Systemic magnesium has been used to minimize postoperative pain with conflicting results by clinical studies. It remains unknown whether the administration of perioperative systemic magnesium can minimize postoperative pain. The objective of the current investigation was to evaluate the effect of systemic magnesium on postoperative pain outcomes. Methods: A wide search was performed to identify randomized controlled trials that evaluated the effects of systemic magnesium on postoperative pain outcomes in surgical procedures performed under general anesthesia. Meta-analysis was performed using a random-effect model. Publication bias was evaluated by examining the presence of asymmetric funnel plots using Egger regression. Results: Twenty randomized clinical trials with 1,257 subjects were included. The weighted mean difference (99% CI) of the combined effects favored magnesium over control for pain at rest (<4h, -0.74 [-1.08 to -0.48]; 24 h, -0.36 [-0.63 to -0.09]) and with movement at 24 h, -0.73 (-1.37 to -0.1). Opioid consumption was largely decreased in the systemic magnesium group compared with control, weighted mean difference (99% CI) of-10.52 (-13.50 to -7.54) mg morphine IV equivalents. Publication bias was not present in any of the analysis. Significant heterogeneity was present in some analysis, but it could be partially explained by the sole intraoperative administration of magnesium compared with the intraoperative and postoperative administration. None of the studies reported clinical toxiciry related to toxic serum levels of magnesium. [ABSTRACT FROM AUTHOR]

Abstract: Flow boiling performance of a Cu microchannel coated with Al2O3 nanoparticle has been investigated experimentally. Experiments were performed in a single microchannel having hydraulic diameter of 672μm using de-ionized (DI) water as the coolant. Surface morphology of the microchannel was modified by depositing nanoparticles through pool boiling of ethanol based alumina (Al2O3) nanofluid. Flow boiling, along with single-phase convective heat transfer experiments were performed at different mass flux and different inlet sub-cooling. Results from the microchannel with bare surface are used as the reference data. Nanoparticles deposited surface was found effective in enhancing the critical heat flux (CHF); up to 39% enhancement in CHF was observed in this experimental range. However, the heat transfer coefficient (HTC) was observed to be reduced marginally for the nanoparticles coated surface compared with the bare surface. [Copyright &y& Elsevier]

Abstract: Non-equilibrium classical molecular dynamics simulation was carried out to study the temperature dependence of thermal transport across nanogap confined liquid. The research was focused on the temperature response behavior of nanoconfined liquid subjected to different temperature environment. The simulation was carried out with simplified molecular model. It was found that the molecular mobility and thermal conductance of liquid reduces significantly due to the confinement in a nanometer scale cavity. The simulation also reveals that thermal resistance responses oppositely to the change in temperature for the nanoconfined liquid compared to the bulk liquid; thermal resistance of the nanoconfined liquid was observed to decrease with the increase of temperature following a power law relation (R t/R t_inital∼0.9837(T/T initial)−0.617) whereas it increases for the bulk liquid. Thermal resistance of the confined liquid and its dependence on temperature was also observed to strongly depend on the gap thickness. [Copyright &y& Elsevier]

This comparison of the effects of national approaches to encouraging local climate mitigation initiatives in four municipalities in Norway and Sweden suggests that the development of such initiatives depend not only on the comprehensiveness and ambitions of central government efforts, but more crucially on characteristics of the targeted municipalities. We argue that local coalitions of committed individuals forming implementation structures of varying cohesiveness are important for understanding variations in the effects of government programmes on the development of local mitigation initiatives. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations have been employed to investigate the boiling phenomena of thin liquid films adsorbed on a nanostructured solid surface. The molecular system was comprised of the following: solid platinum wall, liquid argon, and argon vapor. A few layers of the liquid argon were placed on the nanoposts decorated solid surface. The nanoposts height was varied keeping the liquid film thickness constant to capture three scenarios: (i) liquid-film thickness is higher than the height of the nanoposts, (ii) liquid-film and nanoposts are of same height, and (iii) liquid-film thickness is less than the height of the nanoposts. The rest of the simulation box was filled with argon vapor. The simulation was started from its initial configuration, and once the equilibrium of the three phase system was established, the wall was suddenly heated to a higher temperature which resembles an ultrafast laser heating. Two different jump temperatures were selected: a few degrees above the boiling point to initiate normal evaporation and far above the critical point to initiate explosive boiling. Simulation results indicate nanostructures play a significant role in both cases: Argon responds very quickly for the nanostructured surface, the transition from liquid to vapor becomes more gradual, and the evaporation rate increases with the nanoposts height. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics (CFD) is used increasingly to simulate the distribution of airborne contaminants in enclosed spaces for exposure assessment and control, but the importance of realistic boundary conditions is often not fully appreciated. In a workroom for manufacturing capacitors, full-shift samples for isoamyl acetate (IAA) were collected for 3 days at 16 locations, and velocities were measured at supply grills and at various points near the source. Then, velocity and concentration fields were simulated by 3-dimensional steady-state CFD using 295K tetrahedral cells, the k-ɛ turbulence model, standard wall function, and convergence criteria of 10−6 for all scalars. Here, we demonstrate the need to represent boundary conditions accurately, especially emission characteristics at the contaminant source, and to obtain good agreement between observations and CFD results. Emission rates for each day were determined from six concentrations measured in the near field and one upwind using an IAA mass balance. The emission was initially represented as undiluted IAA vapor, but the concentrations estimated using CFD differed greatly from the measured concentrations. A second set of simulations was performed using the same IAA emission rates but a more realistic representation of the source. This yielded good agreement with measured values. Paying particular attention to the region with highest worker exposure potential—within 1.3 m of the source center—the air speed and IAA concentrations estimated by CFD were not significantly different from the measured values (P = 0.92 and P = 0.67, respectively). Thus, careful consideration of source boundary conditions greatly improved agreement with the measured values. [ABSTRACT FROM PUBLISHER]

Nanoparticle Enhanced Ionic Liquids (NEILs) are the new heat transfer fluids for direct absorption solar collectors and are comprised of small vol/wt percentage of nanoparticles in base ionic liquids (ILs). In the present paper, NEILs are synthesized by dispersing Al 2 O 3 nanoparticles in 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonylimide ([C 4 mim][NTf 2 ]) ILs. The radiative properties of NEILs are investigated with different sizes and shapes (one rod-shaped type sized 10 × 100nm and four spherical sizes of 10 nm, 30 nm, 60 nm, and 90 nm) of Al 2 O 3 nanoparticles. Five different concentrations (0.02%, 0.04%, 0.06%, 0.08%, and 0.1% wt) of NEILs were synthesized to investigate the concentration effect on radiative properties. The addition of Al 2 O 3 nanoparticles greatly increased the light absorption capabilities of the ionic liquid [C 4 mim][NTf 2 ], with at least a 26% decrease in transmittance observed with only 0.02% wt of nanoparticles. Differences in UV–vis absorption were more apparent in smaller concentrations; as much as 20% difference between nanoparticle types and larger concentrations varied in transmittance by as little as 5% between nanoparticle types. Nanofluids made of rod-shaped nanoparticles typically generated higher percentage transmittance values in 0.02%, 0.04%, and 0.06% wt of nanoparticles and were therefore less able to absorb light. Nanofluids made of 10 nm spherical nanoparticles yielded smaller percentage transmittance values at higher concentrations, as little as 2.7% transmission at 0.1% wt, and were therefore better able to absorb light. After completing the nanoparticle size and shape studies, three more NEILs were created from the ideal nanoparticle size and concentration in [C 2 mim][NTf 2 ], [C 6 mim][NTf 2 ], and [C 10 mim][NTf 2 ] ILs. This investigation revealed an increase in percentage transmittance with increasing carbon chain length. [C 2 mim][NTf 2 ] was determined to be the best-absorbing NEILs transmitting as little as 2.2% of light. Plausible reasons for the experimental results are discussed. • Addition of nanoparticles enhances the absorption ability of the base ionic liquids. • NEILs made of 10 nm nanoparticles yielded smaller percentage transmittance values at 0.1% wt concentration. • A shorter carbon chain length on the cation of the ionic liquids corresponded to a smaller percent transmittance. [ABSTRACT FROM AUTHOR]

This paper presents a wireless sensor network system that has the capability to monitor physiological parameters from multiple patient bodies. The system uses the Medical Implant Communication Service band between the sensor nodes and a remote central control unit (CCU) that behaves as a base station. The CCU communicates with another network standard (the internet or a mobile network) for a long distance data transfer. The proposed system offers mobility to patients and flexibility to medical staff to obtain patient’s physiological data on demand basis via Internet. A prototype sensor network including hardware, firmware and software designs has been implemented and tested. The developed system has been optimized for power consumption by having the nodes sleep when there is no communication via a bidirectional communication. [ABSTRACT FROM AUTHOR]

The impact of a worker's location, orientation, and activity was studied in an experimental room (2.86 m × 2.35 m × 2.86 m) at known flow rates of 5.5 m3/min and 3.3 m3/min. A person in the room, wearing a full-facepiece, air-supplied respirator represented a worker. Propylene tracer gas was emitted at a constant rate from a 1-m pedestal at the center of the room and a continuous air sample was drawn from a point midway between the worker's mouth and nose. Breathing zone concentration (BZC) was monitored at 12 worker locations within the room for a stationary worker. At each location, BZCs were measured separately for four worker orientations: east, west, south, and north. BZCs of a walking worker were also monitored along the path defined by the 12 worker locations used in the stationary experiments. In a separate set of experiments, area concentration was monitored to see whether the worker's activity disturbed the contaminant concentrations at a fixed sampling point located behind the source looking from the direction of air inlet (location: 1.34 m, 1.20 m, 0.45 m). The following average differences in BZC over the 12 fixed locations were observed: 43% higher for near-field than for far-field locations; 20% higher when the worker was facing the source than when facing away (p-values for all four conditions: < 0.033), and 30% higher for a moving worker than for a stationary worker (p-values for all four conditions: < 0.01). When the worker was walking, the concentration at the fixed area sampling point was generally lower than the area concentration when the worker was absent or stationary in the room, possibly due to greater mixing of room air by the worker's movement. Because a worker's activities may be irregular and complicated, incorporating them as parameters in mathematical models is often not feasible. Instead, these findings may be used to assess uncertainty or adjust exposure estimates from simple models. [ABSTRACT FROM AUTHOR]

Abstract: An improved one-dimensional dynamic model of a tubular SOFC stack capable of system simulation in the virtual test bed (VTB) simulation environment is presented in this paper. This model is based on the electrochemical and thermal modeling, accounting for the voltage losses and temperature dynamics. The modeling of an external reformer is also included in this study. A detailed parametric analysis of working conditions and cell configuration of the solid oxide fuel cell (SOFC) stack is the main focus of this paper. The following operating parameters are investigated: pressure ratio, temperature, mass flow rate, external reforming degree and stream to carbon (S/C) ratio. The cell geometric parameters studied include cell diameter and cell length. Elevated operating pressure improves the cell performance. Whereas, higher operating temperature decreases both the Nernst potential and the irreversible losses, resulting in an initial increase then a decrease in cell efficiency. It was found that a higher S/C ratio yields a lower H2 concentration and partial pressure, which has a negative effect on the Nernst potential. Increased cell diameter is found to increase the power due to a larger activation area at the same time and due to longer current path length there is an increase in the ohmic loss. Increased length of the cell has the undesired affect of an increased pressure drop. [Copyright &y& Elsevier]

Diverging channels, also known as diffusers, represent common natural and industrial outlets to lakes, reservoirs, and rivers. If the outflow in a diffuser has a larger density than the ambient water, the inflow may plunge and form a density underflow. In this paper, a three-dimensional numerical study was conducted to gain insight into the mechanism of negatively buoyant flows in diffusers with a sloping bottom. Of particular interest is the formation of separated flows such as wall-jet and free-jet flows. Various cases of plunging and the associated density current in a diffuser with different divergence angles and inflow densimetric Froude numbers are considered. The model successfully simulates the formation of attached flow, wall jets, and free jets in a negatively buoyant environment. The onset, evolution, and stabilization of a stall and the subsequent development of a wall jet in a negatively buoyant flow are investigated in detail. Computed results also show favorable agreement with some published experimental data on density current generated by the plunging of cold water in ambient warm water in a diverging channel. [ABSTRACT FROM AUTHOR]

For many years exposure to airborne contaminants has been estimated by air or biological monitoring. In occupational settings, mathematical models increasingly are employed as adjuncts to monitoring, for instance, during process design or in retrospective epidemiological studies. Models can make predictions in a wide variety of scenarios, can be used for rapid screening, and may reduce the need for monitoring in exposure assessment. However, models make simplifying assumptions regarding air flow and contaminant transport. The errors resulting from these assumptions have not been systematically evaluated. Here we compare exposure estimates from the single-zone completely mixed (CM-1), two-zone completely mixed (CM-2), and uniform diffusivity (UD) models with workroom concentration fields predicted by computational fluid dynamics (CFD). The room air flow, concentration fields, and the breathing zone concentration of a stationary worker were computed using Fluent V4.3 for factorial combinations of three source locations, three dilution air flow rates and two emission rate profiles, constant and time-varying. These numerical experiments were used to generate plausible concentration fields, not to simulate exactly the processes in a real workroom. Thus, ''error'' is defined here as difference between model and CFD predictions. For both constant and time-varying emission sources, exposure estimates depended on receptor and source location. For the constant source case, ventilation rate was shown to be inconsequential to CM-1 model error. CM-1, CM-2, and UD models differed in their agreement with CFD. UD was closest to CFD for estimating concentration in the simulated breathing zone (BZ) near the source, although large errors resulted when the model was applied to the plane of possible breathing zones. CM-1 performed better for this plane but underestimated the near-source BZ exposure. For the near-source BZ location, CM-2 replicated CFD predictions more closely than CM-1 did, but less closely than UD did. Error in CM-1 model estimation of short-term average exposure to a time-varying source was highly dependent on ventilation rate. Error decreased as ventilation rate increased. [ABSTRACT FROM AUTHOR]

We explore peoples' dispositions and practices with regard to social–ecological transformations based on a sustainable welfare policy strategy in Sweden. We draw on Bourdieu's concept of habitus to highlight the relations between social positions, dispositions, and position‐takings. Using data from an own survey, we identify habitus types and place these in the space of social positions. We apply principal component analysis to a large set of questions about social, ecological, and climate change related topics and identify eight underlying eco–social dispositions. These are used for cluster analyses that find typical constellations of eco–social dispositions within the Swedish population: variants of eco–social habitus. We find seven habitus types and describe their social characteristics, political preferences, and practices. Finally, the seven habitus are plotted onto the map of social positions, the Bourdieusian social space, highlighting their relations—proximities, tensions, and contestations—to each other. We find evidence that political struggles around social–ecological transformations reproduce existing social structures but are also connected to new "eco–social" divisions that appear between groups in similar positions. In the conclusion we discuss the implications for social–ecological transformations based on sustainable welfare. [ABSTRACT FROM AUTHOR]

High performance miniaturized electronic devices require enhanced, compact and reliable thermal management system. As an efficient compact space cooling technique, flow boiling in microchannels has recently gained wide acceptance. However, weak buoyancy effects and microgravity in avionics and numerous space systems operations hinder the performance of flow boiling microchannel thermal management system due to poor bubble departure capacity and unfavorable development of flow regimes. Here we report the flow boiling silicon nanowires (SiNWs) microchannels which can favorably regulate two-phase flow regimes by enhancing explosive boiling, minimizing bubble departure diameter, and smoothing flow regime transition. Extensive experimental investigations along with high speed visualizations are performed. The experiments are performed with the dielectric fluid HFE-7100 in a forced convection loop for wide range of heat and mass fluxes. High speed flow visualizations have been employed at up to 70 k frames per second (fps) to understand the boiling mechanism in terms of bubble dynamics, flow patterns, and flow regime developments for SiNWs microchannels. These studies show that SiNWs reduce intermittent flow regimes (slug/churn), improve rewetting and maintain thin liquid film at wall. Therefore, flow boiling in SiNW microchannels is promising to thermal management owing to its high heat transfer rate with low pressure drop and negligible microgravity sensitivity. [ABSTRACT FROM AUTHOR]

Highlights • Five parallel microchannels are interconnected by micro-slots. • Micro-slots can enable high frequency nucleate boiling. • Highly coordinated, rapid and sustainable nucleate boiling are realized. • The HTC and CHF are significantly enhanced on the present design. • The enhancements of HTC and CHF are ∼175% and ∼76%, respectively. Abstract Flow boiling in microchannels using dielectric fluids is one of the most desirable cooling solutions for high power electronics. However, it is challenging to promote the flow boiling performances, particularly critical heat flux (CHF), due to their unfavorable thermophysical properties. Flow boiling in parallel and isolated microchannels has been extensively studied. In this study, five parallel microchannels (W = 200 µm, H = 250 µm, L = 10 mm) are interconnected by 4 × 28 micro-slots (20 µm wide and 250 µm deep) starting from the middle section to the channel outlet. Our visualization study shows that these micro-slots designed as artificial nucleation sites can enable high frequency nucleate boiling by drastically reducing the bubble waiting time and remaining fully activated, simultaneously. More importantly, such rapid switch on–off harmonically coordinated nucleate boiling in the neighboring channels creates a highly desirable periodic rewetting mechanism to substantially delay CHF conditions and enhance heat transfer rate. Flow boiling in this innovative microchannel configuration has been systematically characterized with mass flux ranging from 462 kg/m2∙s to 1617 kg/m2∙s. Compared to plain-wall microchannels with inlet restrictors (IRs), flow boiling heat transfer coefficient (HTC) is enhanced up to ∼172% at a mass flux of 462 kg/m2·s primarily owing to the enhanced latent heat transfer including nucleate boiling and thin film evaporation. The peak value of effective HTC is ~60 kW/m2·K in the fully developed boiling regime. Moreover, CHF is substantially enhanced by ∼76% at a mass flux of 1155 kg/m2·s owing to the rapid and periodic rewetting enabled by these micro-slots. Such drastic enhancements have been achieved without compromising two-phase pressure drop. [ABSTRACT FROM AUTHOR]

Highlights • Experimental study was conducted to systematically investigate the influence of nickel oxide layers formed during a practical application on the condensation heat transfer. • The condensation was significantly enhanced by the coexistence of the hydrophilic nickel oxide and the hydrophobic carbon contents. • The maximum condensation heat transfer performance achieved was on a sample surface containing carbon to nickel oxide contents ratio of 3–1. • Increasing or decreasing the thicknesses of nickel oxide layers other than the optimum case is unfavorable to condensation heat transfer. Abstract The search for durable surfaces offering sustainable high rates of condensation is very essential for many applications. Most of the metal surfaces are subject to oxidization when exposed to water vapor and air, as is the case during the condensation under saturation conditions. Due to the relative stability of nickel and nickel oxide (NiO) among other common metals, they were considered herein as the substrates for condensing saturated water vapor under the atmospheric conditions. The main objective of this study was to investigate the influence of NiO layer(s) that would be formed during practical applications on the condensation performance. To mimic such oxide formation, different thicknesses of NiO layers were deposited by atomic layer deposition (ALD) method on the surface of smooth nickel tubes. The influence of the oxide layers on the condensation rate was then experimentally characterized, and the droplet dynamic was analyzed. Due to the presence of the large amount of hydrophobic carbon contents in the deposited NiO-ALD layers, especially at the initial stages of the ALD deposition process, a suitable wettability contrast degree with the corresponding deposited hydrophilic NiO was established. Thus bi-philic wettable surfaces were achieved. The degree of contrast in the wettability was varied by the number of the deposited NiO-ALD layers. It was found that samples with a higher carbon to NiO ratio exhibited a higher condensation heat transfer performance, reaching a maximum heat flux and heat transfer coefficient (HTC) of about 3.9 and 4.2 times that of the filmwise condensation (FWC) at subcooling temperatures of 11.0 °C and 3.5 °C, respectively. [ABSTRACT FROM AUTHOR]

Highlights • The impact of geometrical surface modifications on the thermal performance of the spray cooling system was studied. • The maximum heat transfer enhancement was 80%, for surface modified with four circular and radial grooves. • A significant effect of nozzle differential pressure has been found on spray cooling thermal performance. Abstract An experimental investigation was conducted to study the impact of geometrical surface modification on the thermal performance of a spray cooling system. All experiments were performed using a closed loop spray cooling system. Deionized water was used as the working fluid. Three different modified surfaces were examined and compared with a plain copper surface under the same operating conditions. The first surface (M1) was modified with four circular grooves each having a width and depth of 0.5 mm and a pitch of 1.5 mm. The second and third surfaces (M2) and (M3) were modified with four circular grooves each overlaid with four and eight radial grooves, respectively. Each radial groove had width and depth of 0.5 mm. All surfaces were tested at three nozzle differential pressures: 80 kPa, 140 kPa, and 185 kPa. The nozzle-to-surface distance, coolant inlet temperature, surface temperature, and chamber pressure were maintained at 10 mm, ∼22 °C, <100 °C, and atmospheric pressure, respectively. The results indicated that the nozzle differential pressure had a significant effect on the spray cooling thermal performance of all surfaces. Furthermore, surface (M3) had the highest heat transfer enhancement ratio at all operating conditions, followed by surfaces (M2), and (M1), where the maximum heat transfer enhancements were 80%, 36.3%, and 28.7%, respectively. Thus, signifying that using surfaces modified with a combination of circular and radial grooves can enhance spray cooling heat transfer performance. [ABSTRACT FROM AUTHOR]

Highlights • Numerically investigated the heat transfer and pressure drop in a three-dimensional surface roughness nuclear fuel rod. • Heat transfer coefficient enhanced by 86% at Re = 4.18 × 10 5 compared to the smooth surface. • Pressure drop increased by 15.75% within Re ranging 4.50 × 10 4 - 1.07 × 10 5 . Abstract The paper focuses on the numerical studies of heat transfer and pressure drop in a simulated nuclear fuel rod with three-dimensional surface roughness. Two-dimensional numerical simulations utilizing SST k - ω turbulent model were performed to evaluate heat transfer and pressure drop on the smooth and rough section of the heater rod. The numerical results were compared with experimental data obtained from a heater element which simulates a single Inconel-Nickel fuel rod for pressurized water reactor (PWR). The length of the rod was 2152.6 mm, and an outer diameter 9.5 mm, of which the outer surface of a 304.8 mm long section of the Inconel fuel rod was modified with three-dimensional (Diamond-shaped blocks) surface roughness. The angle of corrugation for each diamond block was 45°, and the length of each side of the diamond block was 1 mm. The numerically computed local heat transfer coefficient, overall Nusselt number, and pressure drop across the test rod shows good agreement with the corresponding experimental results. For the simulated rough surface, heat transfer coefficient was enhanced by 86% at Re = 4.18 × 10 5 as compared to the smooth surface, and pressure drop was found to increase by 15.75% within Re range of 4.50 × 10 4 - 1.07 × 10 5 . Plausible reason of the heat transfer enhancement of the three-dimensional surface roughness was discussed in the paper. [ABSTRACT FROM AUTHOR]