Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Stedelijke hittestress
Spijker, Joop - \ 2018
heat resistance - heat - climatic change - drought - global warming - policy - green roofs
Gastcollege Hogeschool Van Hall Larenstein
De keerzijde van houtstook in open haarden en kachels
Hein, L.G. - \ 2018
Milieu (2018)9. - ISSN 0920-2234 - p. 41 - 45.
biomass - biobased economy - wood - stoves - heat - bioenergy - biofuels
Het toenemende gebruik van conventionele open haarden en houtkachels levert geen bijdrage aan de
vermindering van de opwarming van de aarde. Voor het klimaat is het beter het huis te ver warmen
met de cv-ketel. Daarentegen leveren pelletkachels wel klimaatwinst ten opzichte van de cv-ketel.
Verder worden voor alle vormen van houtstook de gezondheidseffecten van fi jnstof uit deze bronnen,
zeker ook voor de stoker zelf, sterk onderschat. Een eerste, voorlopige inschatting is dat het stoken
van hout jaarlijks leidt tot 900 à 2700 voortijdige sterfgevallen in Nederland. Tenslotte lijken de emis-
sies van houtstook in de Nederlandse emissieregistratie sterk onderschat te worden. Aanvullende
maatregelen voor het tegengaan van het stoken van hout zijn wenselijk vanuit zowel gezondheids- als
Factsheets SYSTEMIC Outreach Location
Schoumans, O.F. ; Regelink, I.C. ; Ehlert, P.A.I. - \ 2018
Wageningen : Wageningen University & Research - 23 p.
EU H2020
Sustainable woodfuel for food security : A smart choice: green, renewable and affordable
Sooyeon, Laura Jln ; Schure, J.M. ; Ingram, V.J. ; Yoo, Byoung Il ; Reeb, Dominique ; Xia, Zuzhang ; Perlis, Andrea ; Nordberg, Mats ; Campbell, Jeffrey ; Muller, Eva - \ 2017
FAO - ISBN 9789251099629 - 35 p.
biobased economy - biofuels - bioenergy - wood - biomass - heat - biobrandstoffen - bio-energie - hout - biomassa - warmte
With food insecurity, climate change and deforestation and forest degradation remaining key global issues, this paper highlights the role of sustainable woodfuel in improving food security. Food insecurity and a high dependence on woodfuel as a primary cooking fuel are characteristics common to vulnerable groups of people in developing regions of the world.With adequate policy and legal frameworks in place, woodfuel production and harvesting can be sustainable and a main source of green energy. Moreover, the widespread availability of woodfuel, and the enormous market for it, presents opportunities for employment and for sustainable value chains, providing further rationale for promoting this source of energy. This paper explains how sustainable woodfuel is closely linked to food security and provides insights in how the linkages could be strengthened at all stages of woodfuel production, trade and use.
LED’s zijn geschikt om snel dips en pieken in natuurlijk licht op te vangen
Gelder, Arie de - \ 2016
led lamps - roses - heat exchangers - heat - thermal radiation - light - artificial light - greenhouse horticulture
Biomassa voor de energievoorziening van tuinbouwclusters
Zwart, H.F. de; Ruijs, M.N.A. ; Visser, H.J.M. - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1393) - 34 p.
bio-energie - glastuinbouw - haalbaarheidsstudies - economische haalbaarheid - warmte - kooldioxide - elektriciteit - biomassa - biobased economy - biochar - verbranding - opwekking van elektriciteit - warmteproductie - bioenergy - greenhouse horticulture - feasibility studies - economic viability - heat - carbon dioxide - electricity - biomass - combustion - electricity generation - heat production
Biomass combustion in combination with a cluster of greenhouses to provide heat, CO2 and electricity can provide a partly solution to the sustainability of the horticultural sector. A biomass gasification plant could also provide valuable biochar, the result of partial combustion of biocarbon. This was shown to have attractive characteristics to be used in high quality potting soil. Despite the high value of the biochar (contributing for 16% of the income from the plant), the economic feasibility of a biomass combustion plant depends heavily on governmental subsidies (SDE +). When the developed technology is used on a practical scale, a biomass plant of 8 MW thermal power and 1.4 MW of electrical power is a sound size. Such a plant fits well with a horticultural cluster of 15 hectares, consisting of 6 ha Tomato, 6 ha Pepper and 3 hectares of Chrysanthemum. The biomass plant produces over 91% of the heating and 95% of the CO2 requirement and 67% of the electricity counsumed. However during winter a lot of electricity will have to be bought, which is compensated with selling to the public grid in summer. The biomass combustion plant will mainly run on biomass is supplied from elsewhere. The biomass from the local cluster covers only 0.3% of the combusted amount. If all available biomass from Netherlands territory would be used to heat greenhouses about 20% of greenhouse industry could make use of system like described in this report.
Meer voedsel, minder broeikasgas : landbouw en voedselproductie na Parijs
Verhagen, Jan ; Vellinga, Pier - \ 2016
climatic change - climate adaptation - agriculture and environment - greenhouse gases - agricultural production - groundwater depletion - heat - salinization - emission reduction - food production - food security

De klimaatconferentie in Parijs markeert het retour van de fossiele brandstoffen, vindt scheidend hoogleraar Pier Vellinga. Hij hoopt dat nu ook de uitstoot van broeikasgassen uit de landbouw omlaag gaat. Wageningse wetenschappers zijn daar al mee bezig, maar ook proberen ze de gevolgen van klimaatverandering het hoofd te bieden. Hoe valt er voldoende te produceren bij verdroging, hitte en verzilting?

Letter : Rising temperatures reduce global wheat production
Asseng, S. ; Ewert, F. ; Martre, P. ; Rötter, R.P. ; Cammarano, D. ; Kimball, B.A. ; Ottman, M.J. ; Wall, G.W. ; White, J.W. ; Reynolds, M.P. ; Alderman, P.D. ; Prasad, P.V.V. ; Lobell, D.B. ; Aggarwal, P.K. ; Anothai, J. ; Basso, B. ; Biernath, C. ; Challinor, A.J. ; Sanctis, G. De; Doltra, J. ; Fereres, E. ; Garcia-Vila, M. ; Gayler, S. ; Hoogenboom, G. ; Hunt, L.A. ; Izaurralde, C. ; Jabloun, M. ; Jones, C.D. ; Kersebaum, K.C. ; Koehler, A.K. ; Müller, C. ; Naresh Kumar, S. ; Nendel, C. ; O’Leary, G. ; Olesen, J.E. ; Palosuo, T. ; Priesack, E. ; Eyshi Rezae, E. ; Ruane, A.C. ; Semenov, M.A. ; Shcherbak, I. ; Stöckle, C.O. ; Stratonovitch, P. ; Streck, T. ; Supit, I. ; Tao, T. ; Thorburn, P. ; Waha, K. ; Wang, E. ; Wallach, D. ; Wolf, J. ; Zhao, Z. ; Zhu, Y. - \ 2015
Nature Climate Change 5 (2015). - ISSN 1758-678X - p. 143 - 147.
climate-change - spring wheat - dryland wheat - yield - growth - drought - heat - co2 - agriculture - adaptation
Crop models are essential tools for assessing the threat of climate change to local and global food production(1). Present models used to predict wheat grain yield are highly uncertain when simulating how crops respond to temperature(2). Here we systematically tested 30 different wheat crop models of the Agricultural Model Intercomparison and Improvement Project against field experiments in which growing season mean temperatures ranged from 15 degrees C to 32 degrees C, including experiments with artificial heating. Many models simulated yields well, but were less accurate at higher temperatures. The model ensemble median was consistently more accurate in simulating the crop temperature response than any single model, regardless of the input information used. Extrapolating the model ensemble temperature response indicates that warming is already slowing yield gains at a majority of wheat-growing locations. Global wheat production is estimated to fall by 6% for each degrees C of further temperature increase and become more variable over space and time.
Photopyroelectric assessment of the thermal effusivity of fresh hen egg and of rehydrated egg powders
Szafner, G. ; Nemeth, C. ; Bicanic, D.D. ; Doka, O. - \ 2015
Journal of Thermal Analysis and Calorimetry 120 (2015)1. - ISSN 1388-6150 - p. 363 - 368.
conductivity - diffusivity - parameters - products - heat - spectroscopy - temperature - milk
The availability of thermo-physical data of foods and their constituents is of general importance to food industry. The thermal effusivity e is one among the relevant thermodynamical quantities. The latter is normally calculated from the relationship e = (¿¿c)½, where c is specific heat, ¿ is the density, and ¿ is the thermal conductivity. The necessity for performing the time consuming independent measurements of these three quantities is the major reason that the existing database with effusivity of foods is not very wide. This paper describes the application of the inverse photopyroelectric (IPPE) technique that allows the determination of effusivity from a single measurement. This approach was used to directly measure thermal effusivity of fresh egg yolk, egg white, and white/yolk blends. In addition, thermal effusivity of rehydrated egg powders (white, yolk, and the whole egg powder) has been measured and compared to that of the fresh hen egg. In case of the egg white, effusivity of rehydrated egg powders was practically the same as that of the fresh egg. However, the difference in effusivity between fresh egg yolk and rehydrated egg yolk, and between the blend of fresh egg and the rehydrated whole egg power was significant. Finally, thermal effusivity of rehydrated egg yolk, egg white, and the whole egg powder was determined as a function of dilution factor.
Estimation of the refractive index structure parameter from single-level daytime routine weather data
Boer, A. van de; Moene, A.F. ; Graf, A. ; Simmer, C. ; Holtslag, A.A.M. - \ 2014
Applied Optics 53 (2014)26. - ISSN 1559-128X - p. 5944 - 5960.
obukhov similarity functions - water-vapor - optical turbulence - sonic anemometer - surface fluxes - energy-balance - temperature - radiation - land - heat
Atmospheric scintillations cause difficulties for applications where an undistorted propagation of electromagnetic radiation is essential. These scintillations are related to turbulent fluctuations of temperature and humidity that are in turn related to surface heat fluxes. We developed an approach that quantifies these scintillations by estimating Cn2 from surface fluxes that are derived from single-level routine weather data. In contrast to previous methods that are biased to dry and warm air, our method is directly applicable to several land surface types, environmental conditions, wavelengths, and measurement heights (lookup tables for a limited number of site-specific parameters are provided). The approach allows for an efficient evaluation of the performance of, e.g., infrared imaging systems, laser geodetic systems, and ground-to-satellite optical communication systems.We tested our approach for two grass fields in central and southern Europe, and for a wheat field in central Europe. Although there are uncertainties in the flux estimates, the impact on Cn2 is shown to be rather small. The Cn2 daytime estimates agree well with values determined from eddy covariance measurements for the application to the three fields. However, some adjustments were needed for the approach for the grass in southern Europe because of non-negligible boundary-layer processes that occur in addition to surface-layer processes.
Data-based perfect-deficit approach to understanding climate extremes and forest carbon assimilation capacity
Wei, S. ; Yi, C. ; Hendrey, G. ; Eaton, T. ; Rustic, G. ; Wang, S. ; Liu, H. ; Krakauer, N.Y. ; Wang, W. ; Desai, A.R. ; Moors, E.J. - \ 2014
Environmental Research Letters 9 (2014). - ISSN 1748-9326
net ecosystem exchange - drought - respiration - algorithm - heat - reduction - feedbacks - model
Several lines of evidence suggest that the warming climate plays a vital role in driving certain types of extreme weather. The impact of warming and of extreme weather on forest carbon assimilation capacity is poorly known. Filling this knowledge gap is critical towards understanding the amount of carbon that forests can hold. Here, we used a perfect-deficit approach to identify forest canopy photosynthetic capacity (CPC) deficits and analyze how they correlate to climate extremes, based on observational data measured by the eddy covariance method at 27 forest sites over 146 site-years. We found that droughts severely affect the carbon assimilation capacities of evergreen broadleaf forest (EBF) and deciduous broadleaf forest. The carbon assimilation capacities of Mediterranean forests were highly sensitive to climate extremes, while marine forest climates tended to be insensitive to climate extremes. Our estimates suggest an average global reduction of forest CPC due to unfavorable climate extremes of 6.3 Pg C (~5.2% of global gross primary production) per growing season over 2001–2010, with EBFs contributing 52% of the total reduction.
Detection of Entrainment Influences on Surface-Layer Measurements and Extension of Monin–Obukhov Similarity Theory
Boer, A. van de; Moene, A.F. ; Graf, A. ; Schüttemeyer, D. ; Simmer, C. - \ 2014
Boundary-Layer Meteorology 152 (2014)1. - ISSN 0006-8314 - p. 19 - 44.
convective boundary-layer - temperature-humidity correlation - sonic anemometer - analytical-model - mixed-layer - turbulence - fluxes - transport - water - heat
We present a method to detect influences of boundary-layer processes on surface-layer measurements, using statistics and spectra of surface-layer variables only. We validated our detection method with boundary-layer measurements. Furthermore, we confirm that Monin–Obukhov similarity functions fit well to temperature-variance data obtained at two different homogeneous surfaces. However, we found that humidity variance measurements deviate from the universal functions above one of the two studied surfaces for days on which entrained air reached the surface layer. These results confirm that Monin–Obukhov similarity theory should be used with care in the analysis of surface-layer data. Finally, we propose the use of an extra term in flux-variance relations that depends on the entrainment ratio for humidity and on the boundary-layer height. If boundary-layer measurements are not available, we show how the entrainment ratio for humidity can be approximated from the skewness of the humidity distribution
Energy efficient drying strategies to retain nutritional components in broccoli broccoli (Brassica oleracea var. italica)
Jin, X. ; Sman, R.G.M. van der; Straten, G. van; Boom, R.M. ; Boxtel, A.J.B. van - \ 2014
Journal of Food Engineering 123 (2014). - ISSN 0260-8774 - p. 172 - 178.
ascorbic-acid - tomato halves - vitamin-c - optimization - heat - temperature - consumption - degradation - health - trends
This work concerns the combined optimization of the retention of bioactive components and energy efficiency during drying of broccoli. Kinetics for the degradation of glucosinolates, vitamin C and drying of broccoli are used to calculate optimal drying trajectories for the control variables air flow rate and temperature. It is shown from plots of the optimal drying trajectories in moisture–temperature state diagrams with degradation and drying rates, that areas with high degradation rates are circumvented. The optimized drying strategies result in significant improvement of energy efficiency (65%) and vitamin C retention of 55%.
Concentratie gewasbeschermingsmiddelen na verhitting dompelbad bloembollen
Bulle, A.A.E. ; Lans, A.M. van der; Aanholt, J.T.M. van - \ 2014
Lisse : Praktijkonderzoek Plant & Omgeving BBF - 19
bloembollen - dompelbaden - fungiciden - ontsmettingsmiddelen - warmte - ph - effecten - projecten - gewasbescherming - ornamental bulbs - dips - fungicides - disinfectants - heat - effects - projects - plant protection
De meest gebruikte methode van ontsmetting van bloembollen en –knollen is een dompeling in een mix van fungiciden. In het proces van bolontsmetting worden partijen bollen na elkaar ontsmet in hetzelfde dompelbad. Met een partij bollen kan een dompelbad behoorlijk vervuild raken met bijvoorbeeld (stengel)aaltjes, mijten en sommige virussen. Hiermee vindt vervolgens verspreiding plaats naar andere partijen bollen. De middelen in het dompelbad doden deze organismen niet allemaal. Verspreiding van organismen via een dompelbad zou sterk verminderd kunnen worden wanneer het bad gedurende een half uur verhit kan worden tot 65°C. Het is echter niet bekend of de gewasbeschermingsmiddelen in het bad, voornamelijk fungiciden, bestand zijn tegen een dergelijke verhitting. Doel van dit project was na te gaan of verhitting van dompelbadvloeistof gevolgen heeft voor de concentratie, de effectiviteit en de pH van de dompelvloeistof. Een dompelbad met een mix aan fungiciden is een aantal keren verhit gedurende 30 minuten op 65°C. Al na een eerste verhitting was een duidelijk verschil in kleur en schuimlaag te zien in vergelijking met een normaal koud bad (20°C). Ondanks dat de dompelvloeistof voortdurend in beweging werd gehouden, ook tijdens de periode van afkoeling, ontstond er residu op de bodem van het verhitte bad. In plaats van een mix is vervolgens voor vier fungiciden, Brabant captan (captan), Mirage Elan (prochloraz), Rudis (prothioconazool) en Securo (pyraclostrobin + folpet), die afzonderlijk in oplossing waren gebracht, twee keer een serie analyses bepaald na een aantal keren verhitting. Ondanks het soms grillige verloop in opeenvolgende metingen vallen een aantal aspecten op: • van captan, folpet en prothioconazool werden voornamelijk de afbraakproducten gemeten. Er zijn geen grote verschillen gemeten in concentraties van deze stoffen tussen een koud en een verhit dompelbad. • de concentratie prochloraz was wisselend tussen een verhit en een normaal koud bad • in de concentratie pyraclostrobin zijn grote fluctuaties gezien, waarbij zelfs een hogere concentratie dan de beginwaarde werd gemeten. Dit was zowel bij een verhit als bij een koud bad het geval. Wanneer een mix aan fungiciden in het dompelbad aanwezig is daalt de pH sterk na verhitten. Al na één keer verhitten was de pH-waarde gedaald naar 1.7. Bij verhitting van dompelbaden met één fungicide werd duidelijk dat de pH vooral bij captan en folpet sterk daalde. In een normaal dompelbad daalde de pH bij captan en folpet licht. Bij andere middelen daalde de pH lichtt of bleef stabiel. In dompelvloeistof waaraan een kunstmatige besmetting met Fusariumsporen was toegevoegd, bleek dat de dompeloplossingen met Brabant captan, Mirage Elan, Rudis of Securo na negen keer verhitten nog een goede bestrijding van Fusariumsporen gaven. In deze labproef was duidelijk te zien dat bij koude dompelvloeistof veel bacteriën uitgroeiden en na verhitting van de dompelvloeistof geheel niet. Voor de vier onderzochte fungiciden lijkt verhitting mogelijk, mits bij verlies van middelen voldoende wordt aangevuld en mits de pH voldoende op peil wordt gehouden. Verhitting van het dompelbad lijkt, gezien dit onderzoek, mogelijk. Op deze manier kunnen schadelijke organismen in het dompelbad worden gedood en kan verspreiding worden beperkt. De resultaten van dit project geven aan dat als een combinatie van fungiciden wordt verhit er reacties kunnen optreden waardoor de concentratie en daarmee de werking niet meer gegarandeerd is. Voor iedere combinatie zal bepaald moeten worden of verhitting mogelijk is zonder negatieve gevolgen. Bollen zijn niet bestand tegen de hoge temperatuur van 65°C. Verhitting zal dus moeten worden uitgevoerd op een moment dat geen bollen worden gedompeld, bijvoorbeeld aan het eind van de dag.
Fibril Formation from Pea Protein and Sesequent Gel Formation
Munialo, C.D. ; Martin, A.H. ; Linden, E. van der; Jongh, H.H.J. de - \ 2014
Journal of Agricultural and Food Chemistry 62 (2014)11. - ISSN 0021-8561 - p. 2418 - 2427.
beta-lactoglobulin gels - amyloid fibrils - ph 2.0 - electrostatic interactions - functional-properties - circular-dichroism - globular-proteins - heat - gelation - behavior
The objective of this study was to characterize fibrillar aggregates made using pea proteins, to assemble formed fibrils into protein-based gels, and to study the rheological behavior of these gels. Micrometer-long fibrillar aggregates were observed after pea protein solutions had been heated for 20 h at pH 2.0. Following heating of pea proteins, it was observed that all of the proteins were hydrolyzed into peptides and that 50% of these peptides were assembled into fibrils. Changes on a structural level in pea proteins were studied using circular dichroism, transmission electron microscopy, and particle size analysis. During the fibril assembly process, an increase in aggregate size was observed, which coincided with an increase in thioflavin T binding, indicating the presence of ß-sheet aggregates. Fibrils made using pea proteins were more branched and curly. Gel formation of preformed fibrils was induced by slow acidification from pH 7.0 to a final pH of around pH 5.0. The ability of pea protein-based fibrillar gels to fracture during an amplitude sweep was comparable to those of soy protein and whey protein-based fibrillar gels, although gels prepared from fibrils made using pea protein and soy protein were weaker than those of whey protein. The findings show that fibrils can be prepared from pea protein, which can be incorporated into protein-based fibrillar gels.
Seasonal dependence of the urban heat island on the street canyon aspect ratio
Theeuwes, N.E. ; Steeneveld, G.J. ; Ronda, R.J. ; Heusinkveld, B.G. ; Hove, L.W.A. van; Holtslag, A.A.M. - \ 2014
Quarterly Journal of the Royal Meteorological Society 140 (2014)684. - ISSN 0035-9009 - p. 2197 - 2210.
warmte - steden - stedelijke planning - warmtebalans - seizoenvariatie - meteorologie - nederland - heat - towns - urban planning - heat balance - seasonal variation - meteorology - netherlands - boundary-layer - energy-balance - climate zones - model - temperature - parameterization - simulation - schemes - cabauw - field
In this paper we study the relation between the urban heat island (UHI) in the urban canyon and street geometry, in particular the aspect ratio. Model results and observations show that two counteracting processes govern the relation between the nocturnal UHI and the building aspect ratio: i.e. trapping of longwave radiation and shadowing effects. In general, trapping of longwave radiation supports the UHI, whereas shadowing effects reduce the UHI. The net effect depends on the UHI definition and the amount of available shortwave radiation penetrating the canyon. In summer, autumn and spring the shadowing effects can already reduce the UHI starting at an aspect ratio between 0.5 and 1. The analysis is carried out using several methods. Firstly, the single-column model version of the Weather Research and Forecasting model (WRF) is used extensively. Two separate runs, one rural and one urban, are used to estimate the UHI. Secondly, the urban canyon temperature at the two meter level is introduced, which allows for direct comparison between modelled and observed air temperatures within the urban canyon. Finally, the model is evaluated for all four seasons. The results of this research provide important insights for urban planning on how to use the aspect ratio to mitigate the UHI in the urban canyon
Moisture Sorption Isotherms of Broccoli Interpreted with the Flory-Huggins Free Volume Theory
Jin, X. ; Sman, R.G.M. van der; Maanen, J.F.C. van; Deventer, H.C. van; Straten, G. van; Boom, R.M. ; Boxtel, A.J.B. van - \ 2014
Food Biophysics 9 (2014)1. - ISSN 1557-1858 - p. 1 - 9.
water activity - glassy-polymers - drying methods - carrot slices - tissue-damage - quality - vegetables - mixtures - heat - pretreatment
In this work, the Flory Huggins Free Volume theory is used to interpret the sorption isotherms of broccoli from its composition and using physical properties of the components. This theory considers the mixing properties of water, biopolymers and solutes and has the potential to describe the sorption isotherms for varying product moisture content, composition and temperature. The required physical properties of the pure components in food became available in recent years and allow now the prediction of the sorption isotherms with this theory. Sorption isotherm experiments have been performed for broccoli florets and stalks, at two temperatures. Experimental data shows that the Flory Huggins Free Volume (FHFV) theory represents the sorption isotherm of fresh and blanched broccoli samples accurately. The results also show that blanching affects the sorption isotherm due to the change of composition via leaching solutes and the change of interaction parameter due to protein denaturation
(Voor)droging van zuiveringsslib in kassen met en zonder restwarmte
Meddeler, Barry ; Reitsma, Berend ; Zwart, Feije de - \ 2013
Amersfoort : Stowa (Stowa rapport 2013-38) - ISBN 9789057736148 - 88
slib - bio-energie - slibzuivering - warmte - biobrandstoffen - sludges - bioenergy - sludge treatment - heat - biofuels
In deze STOWA rapportage zijn de kansen van slibdroging in kassen voor de Nederlandse situatie beschreven. Er wordt inzicht gegeven in de potenties van de techniek van kassendroging aan de hand van (voornamelijk Duitse) praktijkervaringen en literatuur. Daarnaast zijn met modelberekeningen vier praktijkcasussen doorgerekend om de haalbaarheid voor Nederland in te schatten.
Efficiency of and interference among multiple Aquifer Thermal Energy Storage systems; A Dutch case study
Bakr, M. ; Oostrom, N. van; Sommer, W.T. - \ 2013
Renewable Energy 60 (2013). - ISSN 0960-1481 - p. 53 - 62.
ground-water - heat - heterogeneity - transport - solute - model
This paper describes the analysis of a real case of multiple Aquifer Thermal Energy Storage systems. The Hague, the capital city of the province of South Holland in the Netherlands, is densely populated with many ATES systems. A total of 19 ATES systems are installed in an area of 3.8 km(2) with a total of 76 functioning wells. The analysis focuses on the development of a coupled groundwater flow and heat transfer model over a period of 10 years. Results are then post-processed to evaluate efficiency of each individual well and system. Efficiency of the ATES systems has ranged between 68% and 87%. The analysis showed that efficiency tends, in general, to increase over time and stabilize at an asymptotic value after few years. Analysis of interference among individual wells of an ATES system and wells of other systems showed that interference could, in fact, have a positive impact on the efficiency of a well/system. Interference can increase efficiency of an ATES system since it can help in trapping energy (cold or warm) within the capture zone of all operating ATES systems. In the study area, the interference phenomenon affects efficiency, in general, positively where it increases the efficiency of individually operating wells by a maximum of 20%. However, the phenomenon also affects efficiency of some wells negatively where it reduces the efficiency of individually operating wells by a maximum of 25%. In average, systems in the study area are positively affected by interferences among each other with an overall average of 3.2% for all wells (over the 10 years operation period). (C) 2013 Elsevier Ltd. All rights reserved.
Modulation of the Gelation Efficiency of Fibrillar and Sherical Aggregates by Means of Thiolation
Munialo, C.D. ; Jongh, H.H.J. de; Broersen, K. ; Linden, E. van der; Martin, A.H. - \ 2013
Journal of Agricultural and Food Chemistry 61 (2013)47. - ISSN 0021-8561 - p. 11628 - 11635.
whey-protein isolate - bovine beta-lactoglobulin - sulfhydryl-groups - rheological properties - succinylated caseins - gels - heat - stability - ph - temperature
Fibrillar and spherical aggregates were prepared from whey protein isolate (WPI). These aggregates were thiolated to a substantial degree to observe any impact on functionality. Sulfur-containing groups were introduced on these aggregates which could be converted to thiol groups by deblocking. Changes on a molecular and microstructural level were studied using tryptophan fluorescence, transmission electron microscopy, and particle size analysis. The average size (nm) of spherical aggregates increased from 38 to 68 nm (blocked variant) and 106 nm (deblocked variant) after thiolation, whereas the structure of fibrillar aggregates was not affected. Subsequently, gels containing these different aggregates were prepared. Rheological measurements showed that thiolation decreased the gelation concentration and increased gel strength for both WPI fibrillar and spherical aggregates. This effect was more pronounced upon thiolation of preformed fibrillar aggregates. The findings suggest that thiolation at a protein aggregate level is a promising strategy to increase gelation efficiency.
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