The economic potential of a small scale flow-through tank system for trout production

1995 ◽  
Vol 47 (1) ◽  
pp. 59-72 ◽  
Author(s):  
C.M. Gempesaw ◽  
J.R. Bacon ◽  
I. Supitaningsih ◽  
J. Hankins
2010 ◽  
Vol 54 (04) ◽  
pp. 268-280
Author(s):  
Dipti P. Mishra ◽  
Sukanta K. Dash ◽  
P. Anil Kishan

This paper discusses the computation of air entrainment in to the louvers of a cylindrical funnel as a result of a high-velocity isothermal air jet placed inside the funnel having different lengths of protrusion and different funnel diameters. The experimental setup consists of a cylindrical Perspex tube with circular louvers cut around it. The flow through the nozzle is measured with a rotameter, and the velocity at the cylinder outlet is measured with a hot wire anemometer. The numerical simulation is carried out by solving the conservation equations of mass and momentum for the funnel with a surrounding computational domain so that the suction can take place at the louver entry. The resulting equations have been solved numerically using finite volume technique in an unstructured grid employing eddy viscosity based two-equation k-e turbulence model of Fluent 6.3. It has been found from the experiment and the CFD computation that there exists an optimum funnel diameter for which the mass ingress into the funnel is highest, and also there exists an optimum protrusion length of the nozzle that entrains maximum air flow into the funnel. For isothermal air suction the mass ingress into the funnel does not depend on the inclination of the funnel, whereas for low velocity and high temperature of the nozzle fluid the mass ingress in to the funnel depends on the inclination of the funnel. After a critical nozzle velocity (Gr/Re2 < 0.5), the mass ingress into the funnel does not again depend on the inclination of the funnel. An approximate relation for the entrance length of a sucking pipe has also been developed from the present CFD solution. The original contribution of the paper is the setting of a computational methodology for computing various conditions of suction flow in to a funnel while having the numerical confidence by comparing the CFD result with a small-scale experimental measurement in the laboratory.


Holzforschung ◽  
2016 ◽  
Vol 70 (6) ◽  
pp. 495-501 ◽  
Author(s):  
Binh T.T. Dang ◽  
Harald Brelid ◽  
Hans Theliander

Abstract The molecular weight distribution (MWD) of dissolved lignin as a function of time during kraft cooking of Scots pine (Pinus silvestris L) has been investigated, while the influence of sodium ion concentration ([Na+]) on the MWD was in focus. The kraft cooking was performed in a small scale flow-through reactor and the [Na+] was controlled by the addition of either Na2CO3 or NaCl. Fractions of black liquors (BL) were collected at different cooking times and the lignin was separated from the BL by acidification. The MWD of the dissolved lignin was analyzed by GPC. Results show that the weight average molecular weight (Mw) of dissolved lignin increases gradually as function of cooking time. An increase of [Na+] in the cooking liquor leads to Mw decrement. Findings from cooks with constant and varying [Na+] imply that the retarding effect of an increased [Na+] on delignification is related to the decrease in lignin solubility at higher [Na+].


Author(s):  
A. C. Verkaik ◽  
A. C. B. Bogaerds ◽  
F. Storti ◽  
F. N. van de Vosse

When blood is pumped through the aortic valves, it has a time dependent flow with a relatively high speed, resulting in Reynolds numbers between 1500 and 3000. Hence, flow is in the transitional regime between laminar and turbulent flow. Transitional flow contains small scale fluctuations, see Figure 1, and may result in local high deformation rates.


1978 ◽  
Vol 192 (1) ◽  
pp. 213-223 ◽  
Author(s):  
A. D. Gosman ◽  
A. Melling ◽  
J. H. Whitelaw ◽  
P. Watkins

A study was made of axisymmetric, laminar and turbulent flow in a motored reciprocating engine with flow through a cylinder head port. Measurements were obtained by laser-Doppler anemometry and predictions for the laminar case were generated by finite-difference means. Agreement between calculated and measured results is good for the main features of the flow field, but significant small scale differences exist, due partly to uncertainties in the inlet velocity distribution. The measurements show, for example, that the mean velocity field is influenced more strongly by the engine geometry than by the speed. In general, the results confirm that the calculation method can be used to represent the flow characteristics of motored reciprocating engines without compression and suggest that extensions to include compression and combustion are within reach.


2019 ◽  
pp. 24-30 ◽  
Author(s):  
Liliya Benovska

The paper investigates the strengthening of intraregional differentiation of the development of territorial communities in Ukraine under the influence of decentralization reform and administrative-territorial reform. The types of asymmetries of territorial communities’ development are identified, among them: organizational, functional, social, budgetary, institutional. The conducted analysis of organizational asymmetries related to the formation of territorial communities has made it possible to identify significant gaps by number and area of ??the united territorial communities (UTCs). The capacity and the size of the population of community are interrelated, because the large communities have greater opportunities for business development due to the availability of labor resources and the ability to hold infrastructure objects and institutions of communal property. Instead, small-scale UTCs are usually financially feasible only if they have budget-generating companies. Unfortunately, the creation of a significant part of UTCs has taken place without taking into account the capacity requirements and contrary to the requirements of the methodology in order to obtain additional authority and resources. As a result of violations, there were problems of the possibility of further functioning of newly formed territorial communities. Among the UTCs created during the years of reform, there is a strong differentiation by level of their financial capacity. The ratio between the minimum and maximum values of own revenues of UTCs’ budgets per inhabitant (asymmetric scale) is about 40 times. The distribution of UTCs’ revenues depending on the population size are analyzed and it is found out that with each subsequent year of power decentralization reforms the territorial communities with higher financial capacity were formed. The lack of sufficient economic potential for UTCs’ development is confirmed to be the reason of low level of financial capacity of their overwhelming majority. Attention is drawn to the necessity of leveling the risk of increasing differentiation and the gap between UTCs and territories that have not gone through the process of unification. The measures for overcoming intraregional development differentiations are proposed, among which is the necessity to adhere to certain criteria concerning population size, share of transfers in income, share of managerial expenses while the formation of a UTC; maximum use of endogenous factors of territorial communities’ development; elimination of conflict situations between the center and the periphery when planning the development of the territory, etc.


Author(s):  
Felix Reichmann ◽  
Moritz-Julian Koch ◽  
Norbert Kockmann

Gas-liquid flow in microchannels has drawn much attention in the last years in research fields of analytics and applications such as oxidations or hydrogenations. High interfacial area leads to increased mass transfer and intensified reactions. Since surface forces are increasingly important on small scale, bubble coalescence is detrimental and leads to Taylor bubble flow in microchannels. To overcome this limitation, we have investigated the gas-liquid flow through nozzles and particularly the bubble breakup behind the nozzle. Two different regimes of bubble breakup were identified, laminar and turbulent with different mechanisms. Although turbulent breakup is not common in microchannels, its mechanisms were studied for the first time and can give new insight for two-phase flow mechanisms.


2009 ◽  
Vol 45 (2) ◽  
pp. 209-220 ◽  
Author(s):  
CHRISTOPH REIBER ◽  
RAINER SCHULTZE-KRAFT ◽  
MICHAEL PETERS ◽  
VOLKER HOFFMANN

SUMMARYLittle bag silage (LBS) is seen as a low-cost alternative suitable for resource-poor smallholders to alleviate dry-season feed constraints. Within a research project carried out by the International Center for Tropical Agriculture and partners in Honduras, LBS was tested and its use encouraged during farmer training and field days. The present study highlights the most relevant technological and socio-economic potential and constraints of LBS. Surveys and experimental results revealed great vulnerability of plastic bags to pests, particularly rodents, accompanied by high spoilage losses. The main constraints to wider adoption include availability of i) suitable and affordable plastic bags, and ii) appropriate chopping equipment and storage facilities on smallholder farms. LBS proved to be useful and could play an important role in participatory research and extension activities, as a demonstration, experimentation and learning tool that can be used to get small-scale silage novices started with a low-risk technology.


Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3149
Author(s):  
Ansgar Weickgenannt ◽  
Ivan Kantor ◽  
François Maréchal ◽  
Jürg Schiffmann

This study investigates the technical and economic feasibility of replacing throttling valves with smale-scale, oil-free turbomachinery in industrial steam networks. This is done from the perspective of the turbomachine, which has to be integrated into a new or existing process. The considered machines have a power range of P=[0.5,…,250 kW] and have been designed using real industrial data from existing processes. Design guidelines are developed, which take into account the thermodynamic process as well as engineering aspects of such a turbomachine. The results suggest that steam conditioning prior to heat exchange could be completed by small expanders to produce mechanical work, reducing exergy destruction and improving site-wide energy efficiency compared to throttling valves. Cost estimates for such machines are presented, which serve as a basis for case-specific investment calculations. The resulting payback times of less than 18 months highlight the economic potential such solutions.


2020 ◽  
Author(s):  
Anna Canning ◽  
Arne Körtzinger ◽  
Peer Fietzek ◽  
Gregor Rehder

Abstract. Comparatively the ocean and inland waters are two separate worlds, with concentrations in greenhouse gases having orders of magnitude in difference between the two. Together they create the Land-Ocean Aquatic Continuum (LOAC), which comprises itself largely of areas with little to no data in regards to understanding the global carbon system. Reasons for this include remote and inaccessible sample locations, often tedious methods that require collection of water samples and subsequent analysis in the lab, as well as the complex interplay of biological, physical and chemical processes. This has led to large inconsistencies, increasing errors and inevitably leading to potentially false upscaling. Here we demonstrate successful deployment in oceanic to remote inland regions, over extreme concentration ranges with multiple pre-existing oceanographic sensors combined set-up, allowing for highly detailed and accurate measurements. The set-up consists of sensors measuring pCO2, pCH4 (both flow-through, membrane-based NDIR or TDLAS sensors), O2, and a thermosalinograph at high-resolution from the same water source simultaneously. The flexibility of the system allowed deployment from freshwater to open ocean conditions on varying vessel sizes, where we managed to capture day-night cycles, repeat transects and also delineate small scale variability. Our work demonstrates the need for increased spatiotemporal monitoring, and shows a way to homogenize methods and data streams in the ocean and limnic realms.


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