Side Flows Research Articles

Consumption and production of edible insects in an urban circularity context: Opinions and intentions of urban residents

The success of emerging urban agriculture initiatives is partly determined by the acceptance and active involvement of residents. Edible insects can contribute to urban agriculture and to the transition to a circular economy by converting organic side flows into high-value biomass. This explorative online survey (N = 750) assessed the opinions and intentions of residents of Amsterdam city, the Netherlands (18–75 years old) about consumption and production of edible insects for food on household, neighborhood (i.e., centralized facilities for neighbored households), and industrial scales utilizing various side flows. Of the proposed scenarios, industrial insect production was perceived as more attractive (24.9 % of all respondents), than neighborhood (16.3 %) and household (6.7 %) production. Respondents indicated a higher preference for drivers (environmental, economic, expert support, and safety) related to purchasing industrially produced insects (median-5 of 7-point scale) than to participating in neighborhood or household production. Accordingly, most barriers were associated with household production (e.g., inconvenience, economic reasons, lack of knowledge and available information, median-5-6) rather than neighborhood (safety concerns, median-5) and industrial (no defined barriers, median 4) production. Nature (vegetal, animal, or mixed) and source of insect feed were considered important to the respondents, and >80 % of the respondents prefer feed mentioning on the labels of insect-containing food products. The findings suggest that urban initiatives on insect production should consider the current state of acceptance of this idea and the willingness to participate in it, as well as ensure its simplicity, safety, and low monetary cost. Relevant information and expert support should be made available to residents. Moreover, as edible insects are still a novel food concept in Amsterdam, further introduction of insects into the diet might make all proposed scenarios more attractive and meaningful for residents, contributing to the development of circular urban ecosystems in the future.

Energy relationships in transient pipe flow with fluid–structural interaction

During water hammer wave propagation, pressure and velocity fields vary over time due to transformations between strain and kinetic energies. In the literature, some energy expressions have been applied to explore energy transformations during water hammers, which account for various effects including friction stress, leaks, blockages, air pockets, and side flows. However, there are no energy expressions for water hammers that consider the fluid–structural interaction (FSI) effect, such as a buffer blocked riser subjected to heave motion. Therefore, in this study, the energy expressions for transient flow with FSI are obtained from the governing equations of the extended water hammer model. Moreover, based on continuum mechanics theory, general energy expressions are developed for the classical, the extended, and the partitioned shell–based water hammer models. Using the partitioned shell–based water hammer model, a buffer–blocked riser subjected to heave motion was investigated for energy transformation. Accounting for the fluid–structural interaction, there are three resonances in the dynamic response of riser while the heave motion frequency varies in the range of ocean wave frequencies. These three resonant frequencies are correlated to the frequency of pressure wave, the fundamental frequencies of fluid–filled riser that only accounted for fluid mass and the empty riser.

The fluid flow and heat transfer characteristics of R-32 in a small Tube

Due to the Global Warming effect considerations, refrigerants with lower value of the Global Warming Potential will be the next generation refrigerants which are used in the air-conditioner systems. Currently, a new developed refrigerant R-32 has proposed to substitute R-410A. Therefore, many air-conditioning manufactures have determined refrigerant R-32 in their products and some studies have been discussed in recent years. However, the information of refrigerant R-32 on saturation temperature around 10°C is still insufficient, and the heat transfer coefficient (HTC) of refrigeration system around -20°C to -40°C has not been clarified. In this study, two-phase HTCs and pressure drops of refrigerant R-32 are measured in a horizontal tube with 4.0 mm inner diameter, and at saturation temperature of 10°C. The test section is a double pipe heat exchanger, where refrigerant flows in the tube side and water flows in the annular side. Also, modified Wilson Plot method was used to calculate the single-phase HTCs and pressure drops of R-32 refrigerant. In this study, two-phase experiments were conducted at vapor qualities ranging from 0.1 to 0.9 where the range of mass fluxes was 200 to 600 kg m−2 s−1 and heat fluxes ranging from 26 to 46 kW m−2. The results showed that the two-phase test results agreed well with the correlations of Shah (Shah, 1982), Gungor and Winterton (Gungor and Winterton, 1986), and Liu and Winterton (Liu and Winterton, 1991). However, the accuracy of results at different flow conditions was different, this was attributed to the change in the enhancement factor of each flow boiling model.

De-risking of green investments through a green bond market – Empirics and a dynamic model

A substantial increase of green investments is still required to reach the Paris Agreement’s emission targets. Yet, capital markets to expedite innovative green investments are generically constrained. Literature has shown that governments could de-risk such investments. Empirical beta pricing and yield estimates reveal some public involvement in the green bond market, especially for long maturity bonds. We provide empirical evidence that Governments and Multilateral organizations can de-risk green investments by supporting the issuance of green bonds in contrast to private green bonds - that show higher yields, volatility and beta prices - and conventional energy bonds, that are more volatile due to oil price variations. Since lower betas also mean lower capital costs, we use these empirical results and run a dynamic model with two types of firms, modeling the economic behavior of innovators (renewable energy firms) and incumbents (fossil fuel firms). Our model reveals that de-risked interest rates, from the cost side, and mark-ups and profit flows, from the market side, improve new entrants’ performance. As innovators normally have low mark-ups, inducing higher profit flows and lower capital costs allows a better default risk control and debt repayment which keep the firms in the market for a longer period of time and maintain low debt levels. Subsidies and carbon taxation can complement the role of the de-risked interest rate and expedite the energy transition.

Pengaruh Laju Aliran Fluida Helical Coil Terhadap Efektivitas Kondensor Minyak Atsiri Cengkeh Berbasis Shell

One of the main tools in the process of making essential oils is a condenser. The simple use of condensers is still used for essential oil processing by small business groups of Clove essential oil in Suli Village, Central Maluku. This is what encourages this research to be carried out. This research includes designing and testing the condenser model using COMSOL Multiphysics 4.5 Software to determine the optimal efficiency of the condenser by varying the mass flow rate of cold fluid on the shell side. The condenser used in this study is a helical coil condenser where hot fluid flows on the tube side and cold fluid flows on the shell side. Tube and shell materials are made of stainless steel 304, with a tube diameter of 1.905 cm, shell diameter 30 cm, shell height 57 cm, coil diameter 24 cm, coil height 50 cm. mass flow rate variations of 0.25, 0.51, 0.76, 1.01, and 1.26 kg / s. The results showed that the effectiveness of the condenser was effective at the mass flow rate m ̇ = 1.26 kg/s where the effectiveness (ɛ) was 91%.

Primary cementing of horizontal wells. Displacement flows in eccentric horizontal annuli. Part 2. Computations

Abstract

Flowfield of a helicopter submerged inlet with power output shaft

The submerged inlet is an attractive configuration for advanced helicopters due to its high stealth performance and low external drag. In this paper, a submerged inlet, integrated with a ROBIN helicopter fuselage and a simplified power output shaft, is experimentally and numerically investigated to obtain the basic flow characteristics under a freestream velocity of 23.6 m/s. The results indicate that the pylon ahead of the inlet induces a horseshoe vortex. Though the vortex is ingested into the inlet, it has little effect on the internal flows and can be neglected. When the airflow enters into the inlet, it interacts with the shaft with a large incidence angle, yielding a vortex pair. At the leeside of the shaft, the two side flows of the shaft impinge at the center plane, generating a local high-pressure region at the azimuthal angle of 180°, which forces the boundary layer to roll up a counter-rotating vortex pair. In addition, the airflow adjacent to the cowl lip accelerates rapidly, resulting in a local low-pressure region at the azimuthal angle of 0°. Therefore, the inlet duct has a strong circumferential pressure gradient, which originates from an azimuthal angle of 180° to 0° and induces a vortex pair at the azimuthal angle of 0°. The three vortex pairs are the main origins of the distortion at the duct exit plane, among which the one near the cowl lip with the azimuthal angle of 0° plays the dominant role. Additionally, as the velocity ratio increases from 3.9 to 5.5, the circumferential pressure gradient and the cowl lip vortex get intensified, which causes that the total-pressure recovery coefficient drops by 0.5% and the distortion index increases by 28%. A submerged inlet, integrated with a ROBIN helicopter fuselage and a simplified power output shaft, is experimentally and numerically investigated. Three vortex pairs, which locate at the azimuthal angle of 0°, the leeside of the shaft, and 180° of the inlet surface, are the main origins of the distortion of the inlet, among which the one near the cowl lip with the azimuthal angle of 0° plays the dominant role. As the velocity ratio increases, the circumferential pressure gradient gets intensified, leading to stronger vortex pairs.

Environmental assessment of the valorisation and recycling of selected food production side flows

Residues from the food manufacturing industry require management options with the best overall environmental outcome. The identification of sustainable solutions depends however, on many influencing factors such as energy input, transport distance, and substituted product. This study shows the influence of the choice of substituted products on the overall greenhouse gas (GHG) emissions for three specific food side-flows and their treatment in the European Union: animal blood, apple pomace and brewers’ spent grain (BSG). In a direct comparison of possible treatment options, it is notable that the conversion to food ingredients (valorisation) does not always result in reduced environmental net impacts (GHG savings), which means that other options at lower levels of the waste hierarchy might be more beneficial to the environment. The further use of apple pomace or BSG for the production of food ingredients is only advantageous if the processing emissions are smaller than the emissions from the substituted products. The use of food side-flows as animal feed shows environmental advantages in all scenarios, as the use of conventional feed, such as soybean meal or hay, is reduced and so are the GHG emissions. The anaerobic digestion of food side-flows is associated with significant GHG emissions, but alternative energy also display a high GHG factor when based on fossil resources. The measuring of circularity in the food sector is a challenge in itself due to the complexity of renewable materials. This study shall help to understand the interwoven influences of certain parameters to the results.

Decision-Making Process in the Circular Economy: A Case Study on University Food Waste-to-Energy Actions in Latin America

Economies have begun to shift from linear to circular, adopting, among others, waste-to-energy approaches. Waste management is known to be a paramount challenge, and food waste (FW) in particular, has gained the interest of several actors due to its potential impacts and energy recovery opportunities. However, the selection of alternative valorization scenarios can pose several queries in certain contexts. This paper evaluates four FW valorization scenarios based on anaerobic digestion and composting, in comparison to landfilling, by applying a consistent decision-making framework through a combination of linear programming, Life Cycle Thinking (LCT), and Analytic Hierarchy Process (AHP). The evaluation was built upon a case study of five universities in Costa Rica and portrayed the trade-offs between environmental impacts and cost categories from the scenarios and their side flows. Results indicate that the landfill scenario entails higher Global Warming Potential and Fresh Water Eutrophication impacts than the valorization scenarios; however, other impact categories and costs are affected. Centralized recovery facilities can increase the Global Warming Potential and the Land Use compared to semi-centralized ones. Experts provided insights, regarding the ease of adoption of composting, in contrast to the potential of energy sources substitution and economic savings from anaerobic digestion.

The Transboundary Nature of the Allende–Piedras Negras Aquifer Using a Numerical Model Approach

AbstractThe Allende–Piedras Negras (APN) aquifer is located between the states of Texas (United States [U.S.]) and Coahuila (Mexico). The Rio Grande crosses the aquifer, acting as a natural and political divide between the countries. However, it remains unclear whether the APN aquifer can be considered a truly transboundary aquifer flow system, which would potentially require joint management by two different administrative jurisdictions. The main purpose of this study was to evaluate the transboundary nature of this aquifer. This was achieved by developing a detailed hydrogeological model to analyze the direction of volumetric fluxes within the APN aquifer using Visual MODFLOW. The model simulated a spatially averaged cumulative drawdown of 0.76 m for the entire aquifer over an 18‐year modeling period (2000–2017). The flow convergence zone, previously located below the Rio Grande, has shifted to the U.S. side in most locations, driven by higher pumping rates of the wells located near the river. This shift of the convergence zone from one country to the other means that groundwater recharge from one side flows underneath the river to the other side. This qualifies the APN aquifer as a “transboundary groundwater flow system.” The procedure followed in this study may be applied to other aquifers that straddle the U.S.–Mexico border and may motivate future modeling studies on other poorly studied transboundary aquifers around the world and thereby enable bi‐national aquifer management.

Two-phase flow in microfluidic-chip design of hydrodynamic filtration for cell particle sorting.

As one of the flow-based passive sorting, the hydrodynamic filtration using a microfluidic-chip has shown to effectively separate into different sizes of subpopulations from cell or particle suspensions. Its model framework involving two-phase Newtonian or generalized Newtonian fluid (GNF) was developed, by performing the complete analysis of laminar flow and complicated networks of main and multiple branch channels. To predict rigorously what occurs in flow fields, we estimated pressure drop, velocity profile, and the ratio of the flow fraction at each branch point, in which the analytical model was validated with numerical flow simulations. As a model fluid of the GNF, polysaccharide solution based on Carreau type was examined. The objective parameters aiming practical channel design include the number of the branches and the length of narrow section of each branch for arbitrary conditions. The flow fraction and the number of branches are distinctly affected by the viscosity ratio between feed and side flows. As the side flow becomes more viscous, the flow fraction increases but the number of branches decreases, which enables a compact chip designed with fewer branches being operated under the same throughput. Hence, our rational design analysis indicates the significance of constitutive properties of each stream.

A combined framework for the life cycle assessment and costing of food waste prevention and valorization: an application to school canteens

About one third of global edible food is lost or wasted along the supply chain, causing the wastage of embedded natural and economic resources. Life cycle methodologies can be applied to identify sustainable and viable prevention and valorization routes needed to prevent such inefficiencies. However, no systemic approach has been developed so far to guide practitioners and stakeholders. Specifically, the goal and scoping phase (e.g. problem assessed or system function) can be characterized by a large flexibility, and the comparability between food waste scenarios could be not ensured. Within the Horizon2020 project Resource Efficient Food and dRink for the Entire Supply cHain, this study aimed to provide practitioners with guidance on how to combine life cycle assessment and environmental life cycle costing in the context of food waste. Recent literature was reviewed to identify relevant methodological aspects, possible commonly adopted approaches, main differences among studies and standards and protocols, main challenges, and knowledge gaps. Basing on this review, an analytical framework with a set of recommendations was developed encompassing different assessment situations. The framework intends to provide a step by step guidance for food waste practitioners, and it is composed of a preliminary section on study purpose definition, three decision trees—respectively on assessment situation(s), costing approach, and type of study (footprint vs. intervention)—and two sets of recommendations. Recommendations can be applied to all levels of the food waste hierarchy, stating a generic order of preference for handling food chain side flows. This consistent and integrated life cycle approach should ensure a better understanding of the impact of specific interventions, thus supporting informed private and public decision making and promoting the design of sustainable and cost-efficient interventions and a more efficient food supply chains.

Perovskite oxide based composite hollow fiber membrane for CO2 transport

Membrane technologies have been widely investigated for CO2 separation, especially inorganic membranes which could overcome the barrier of low melting point, and then been applied for combustion activities. Compared with molecular sieving membranes (MSMs), the mechanism during CO2 separation process on electrolyte membranes (EMs) is more complicated. Mixed ionic and electronic conductors, such as perovskite oxides, has been proved with superior activity than oxygen ion conductors because of the additional surface reaction path. To further demonstrate the applicability of perovskite oxides contained membrane for CO2 separation, in this work, CO2 transport via La0.6Sr0.4Co0.2Fe0.8O3-δ and carbonates composite membrane with hollow fiber microstructure was thoroughly investigated under various gas flow directions. This membrane presents the best permeability when CO2+N2 (feed gas) flows at shell side and He (sweep gas) flows at tube side in parallel model. In addition, it also presents excellent thermal shock resistance after six times rising and cooling operation with almost no performance degradation.

The Use of Industrial Waste Materials for the Simultaneous Removal of Ammonium Nitrogen and Phosphate from the Anaerobic Digestion Reject Water

The European Union’s circular economy strategy aims to increase the recycling and re-use of products and waste materials. According to the strategy, the use of industry waste materials and side flows is required to be more effective. In this research, a chemical precipitation method to simultaneously remove ammonium and phosphate from the reject water of anaerobic digestion plant using calcined paper mill sludge and fly ash as a precipitant, was tested. Paper mill sludge is a waste material formed in the paper-making process, and fly ash is another waste material formed in the power plant. Objective of this research was to test whether these industrial waste streams could be used as low cost precipitation chemicals for ammonium and phosphate removal from wastewaters and whether the precipitate could be suitable for fertilizer use. Results indicated that calcined paper mill sludge had high removal efficiency for both ammonium (97%) and phosphate (73%). Fly ash also had good removal efficiency for both ammonium nitrogen (74%) and phosphate (59%) at 20 ± 2 °C. The precipitates contained high concentrations of nitrogen and phosphate and could be used as a recycled fertilizer. Other possible mechanisms for the removal of phosphate and ammonium were considered.Graphic

Neutralizing global warming impacts of crop production using biochar from side flows and buffer zones: A case study of oat production in the boreal climate zone

Rapid climate change mitigation requires carbon sequestration in addition to greenhouse gas emission reductions. Agriculture may have a high potential for carbon sequestration due to improved practices. However, it is not known how the global warming impacts of crop production could be mitigated especially within an agricultural system. The aim of this study is to evaluate possibilities to neutralize global warming impacts in crop production using biochar produced from side flows and buffer zone biomass. A life cycle assessment methodology is utilized in this research for oat production in the boreal climate zone. Global warming impact reductions are compared for three different side flow utilization options. Traditionally, side flows have been utilized in energy or fodder production, and these options are compared to biochar production at a system level. The potential to use buffer zone biomass for biochar production is also studied. Willow has been selected as a biomass source in buffer zones. Oat production leads to greenhouse gas emissions especially due to the use of fossil and mineral fertilizers in cultivation and heat energy, electricity and fuels in various process phases. The production of one metric ton of oat flakes from cradle to gate generates 700 kg of CO2eq emissions. Biochar and energy production from side flows enables a greater reduction in global warming impacts than the feed use of side flows. Buffer zones in willow biomass and biochar production may enable the full neutralization of the global warming potential of oat production within an agricultural system. Further research with actual measurements is required especially on biochar impacts on soil emissions such as N2O. This research shows that it could be possible to neutralize global warming impacts from crop production using available technologies and available biomass in agricultural systems. A framework is created for carbon neutral crop production using side flows and buffer zone biomass through biochar.

Company perspectives on the development of the CE in the seafaring sector and the Kainuu region in Finland

Abstract Circular economy is among the contemporary policy goals at both EU and national level in Finland encompassing growing focus on, for example, resource efficiency, life cycle thinking and sustainability considerations. This study presents two case studies on company perspectives on the development of the circular economy. The sectoral study aimed at assessing the perspectives of both companies and public authorities on circular economy development in the seafaring sector whereas the sectoral study aimed at assessing the implications of the key elements of circular economy for companies in the Kainuu region in Finland. The results indicate that there is a need for more awareness building and capacity-development to promote more proactive approaches to the advancement of a circular economy encompassing focus on, for example, material and energy efficiency, development of both international and sectoral guidelines and best practices, life cycle thinking and assessment, recycling/reuse, whole supply chains, waste minimization and utilization of by-products and side flows. The role of supportive public steering measures is also significant. Companies had positive perspectives on future development in this field and were willing to implement various measures to promote circular economy.

A study on the effect of double-tip inclined angle on micro-scratching process using smooth particle hydrodynamic method

Multi-tip micro/nano-scratching technology has been widely used in precision manufacturing. In this study, the smooth particle hydrodynamic based on micro-scratching model is proposed to study the effect of double-tip inclined angles on such a scratching process. A series of simulations were conducted with the double-tip tilting with 0°, 5°, and 10° on the oxygen-free copper surfaces. In this article, the formation of burrs and scratching forces was illustrated and analyzed based on the simulation results. It is noted that when the double-tip tilted, the burrs generated more and side flows curled seriously during scratching process. With an increase in the scratching distance, more burrs generate on both sides of the groove. The tangential, thrust, and lateral forces are all affected by the extrusion of side flows and the protrusion in middle. Moreover, the scratching forces of tangential and thrust showed that the double-tip scratching process can be divided into three stages: initial scratching stage, transition scratching stage, and stable scratching stage. During transition scratching stage, the most violent scratching forces generated in the condition of the double-tip tilting with 10°.

Entropy generation in a heat exchanger working with a biological nanofluid considering heterogeneous particle distribution

Entropy generation rates considering particle migration are evaluated for a biologically produced nanofluid flow in a mini double-pipe heat exchanger. The nanofluid is used in tube side and hot water flows in annulus side. Silver nanoparticles synthesized through plant extract method from green tea leaves are utilized. Particle migration causes non-uniform concentration distribution, and non-uniformity intensifies by increase in Reynolds number and concentration. The results indicate that at high concentrations and Reynolds numbers, particle migration can have a great effect on entropy generation rates. For water inlet temperature of 308K, the contribution of friction in nanofluid entropy generation is much more than that of heat transfer. However, as the water inlet temperature increases to 360K, the heat transfer contribution increases such that at low Reynolds numbers, the thermal contribution exceeds the frictional one. For total heat exchanger, Bejan number is smaller than 0.2 at water inlet temperature of 308K, while Bejan number has a large value at water inlet temperature of 360K. Furthermore, entropy generation at the wall has an insignificant contribution, such that for Re=1000 and φm=1%, the total entropy generation rates for the nanofluid, wall, and water are 0.098810, 0.000133, and 0.041851W/K, respectively.

Food supply chain side flows management through Life Cycle Assessment and Life Cycle Costing: a practitioner’s perspective

Urged by the importance of resource efficiency and circular economy agenda policy makers, many stakeholders are seeking alternatives for current surplus food or side flows within the food supply chain. Any new valorisation or intervention aimed to prevent food waste will however be associated with impacts (monetary and environmental). To allow informed decision making at all levels, from individual stakeholder to policy level, robust, consistent and science based approaches are required. The EU H2020 funded project REFRESH (Resource Efficient Food and dRink for the Entire Supply cHain) aims to contribute to food waste reduction throughout the food supply chain, and evaluate the environmental impacts and life cycle costs. This paper presents a guidance document being developed within REFRESH on how to apply Life Cycle Assessment (LCA) and environmental Life Cycle Costing (E-LCC) and how to combine them in the context of food waste. Recommendations are given on the scoping on footprint studies as well as on change-oriented studies on interventions for side flows from the food supply chain. The overall aim of the current research is contribute to a better scoping practice of LCAs and LCCs of side flows in a food waste context.

Dynamic modelling of ORC-based solar thermal power plant integrated with multitube shell and tube latent heat thermal storage system

In this paper, dynamic model for organic Rankine cycle (ORC) based solar thermal power plant integrated with latent heat thermal energy storage (LHTES) system is developed to understand its interaction with other components in the power plant for extending electricity generation after sunset. A multitube shell and tube latent heat thermal storage system is considered, in which phase change material (PCM) is stored in the shell side and heat transfer fluid (HTF) flows through the tubes. The multitube shell and tube latent heat storage is modelled considering an elemental unit obtained by encircling each HTF tube to the extent within which the surrounding PCM and HTF exchanges heat. A reduced order model coupled with the enthalpy technique is developed for analysing heat transfer in the LHTES system during charging and discharging periods. The model is validated with the experimental results reported in literature. Simplified transient energy equations are used to model collector and heat exchanger. Further, a latent heat thermal storage system is designed to generate 200kWt after sunset and the overall performance of the solar thermal power plant is evaluated for ten days of operation under Indian conditions.