Volume 16 - 2014

https://doi.org/10.30955/gnj.001448

Abstract

The solar evaporative crystallization process at Lake Katwe was studied using brine evaporation rates, thermal, convection, and radiation energy losses as well as reported meteorological data around the salt lake basin. A simulation model of a salt pan was developed on a lumped basis to study its behaviour with the effects of the different factors affecting the evaporation process investigated. Moreover, an analysis to assess the possibility of increased productivity of the salt pans through implementation of parabolic solar collector technology to enhance brine evaporation was done. Results showed that the brine evaporation rates and temperature of the salt pan are strongly influenced by in-situ weather conditions. Furthermore, a thermal-fluid analysis of the proposed system showed that the pond solution layer temperature increases thereby increasing the evaporation flux hence leading to increased salt production rate.

Combustion of biofuels-diesel blends in an isothermal oven

Toledo M., Jiménez J., Cárdenas L., Gers R., Espinoza J., Pages:1145-1151

DOI:

Paper Topic:

Sustainable Energy

Issue:

https://doi.org/10.30955/gnj.001462

Abstract

In this work, combustion process of diesel and biofuel blends is studied experimentally in an isothermal oven. Blends with respectively 20%, 40% and 60% of Ethanol (E20, E40, E60), 20%, 40% and 60% of Methanol (M20, M40, M60), and 20%, 40%, 60%, 80% and 100% of Biodiesel (B20, B40, B60, B80, B100), are comparatively analyzed focusing on wall temperature of the isothermal oven and emissions products from combustion. It is found that wall temperature drops with biodiesel content in blends and is higher compared with pure diesel, whatever the content of biodiesel. For diesel-ethanol and diesel-methanol blends the wall temperature is less than pure diesel. Unburned HCs and NO_X emissions are very low for all blends and CO emissions increase with higher ethanol and methanol blends.

For industrial applications that need high temperature (as drying, cooking, sterilization, others) the combustion of diesel-biodiesel blends are recommended.

Wind energy location prediction between meteorological stations using ANN

Maran P.S., Ponnusamy R., Venkatesan R. and Bing A.B. , Pages:1135-1144

DOI:

Paper Topic:

Sustainable Energy

Issue:

https://doi.org/10.30955/gnj.001478

Abstract

Wind Energy is one of the important sources of renewable energy. There is a need to prepare the availability of wind energy in the area where there is no measured wind speed data. For this type of situation, it seems to be necessary to predict the wind energy potential using such as wind speed using artificial neural network (ANN) method. Soft computing techniques are widely used now days in the study of wind energy potential estimation. In this study the wind energy potential between neighborhood meteorological tower stations is predicted using Artificial Neural Network technique. One of the most suitable areas of Tamil Nadu for wind power generation is some locations in the districts of Tirunelveli, Thoothukudi, Kanyakumari, Theni, Coimbatore, and Dindigul. Along the southeast coastline of Tamil Nadu there are no valleys and mountains besides the mountains are situated away from the sea coast in many regions. Therefore, these regions are exposed to northerly winds that are not as strong as the southerly winds.

CFD simulation of multiphase flow in an airlift column photobioreactor

Samira García Edgardo Paternina Oscar R. Pupo Antonio Bula Leonardo Di Mare , Pages:1121-1134

DOI:

Paper Topic:

Sustainable Energy

Issue:

https://doi.org/10.30955/gnj.001483

Abstract

A Computational Fluid Dynamics (CFD) simulation using CFX, ANSYS 11.0, has been carried out using a multiphase flow model with an Eulerian-Eulerian approach for an airlift column photobioreactors (PBR). Transient simulations were performed for three inlet air flow, 2, 3 and 5 l/min. The contours for gas holdup, air and water velocity showed that the presence of gas phase (air bubbles) is lower in the downcomer but larger in the riser, which leads to require a vigorous mixing in the riser that will be sufficient for a continuous flow. For air, velocity vectors show that they are smaller in the downcomer than in the riser. Nevertheless, water velocity vectors are organized, pointing down in the downcomer and up in the riser. Water shear stress rate contours analysis showed that, shear stress rate regions are considerably larger in the riser, but lower in the downcomer. Due to fewer restrictions to the liquid phase in the riser, a large amount of energy is dissipated by gas liquid interactions. In the downcomer region, gas phase is almost inexistent, and so are the bubble collisions. Finally, the kinetic energy is larger at the top region of the riser, meanwhile is lower at the downcomer. Similar results are observed for energy dissipation rate.

Synthesis, characterisation and catalytic performance of Cu- and Co-modified Fe-Al co-precipitated catalysts for the steam reforming of ethanol

Souza G. Ruoso C. Marcilio N.R. Perez-Lopez O.W., Pages:1111-1120

DOI:

Paper Topic:

Sustainable Energy

Issue:

https://doi.org/10.30955/gnj.001469

Abstract

This paper reports the synthesis and the investigation of the properties and performance of Fe-Al catalysts modified with Cu or Co for the steam reforming of ethanol. The materials were prepared by the precipitation method with different Fe/Al ratios. The samples were characterised by the S_BET, TG/DTG, XRD, H₂-TPR and TPO/DTA analyses. The increase in the Fe/Al ratio leads to a decrease in the specific surface area and shifts the reduction peaks towards higher temperatures. The partial substitution of Fe by Co or Cu modifies the structure of the materials because higher specific surface areas and crystallites of iron oxides with smaller sizes are formed. The promotion also improves the reducibility of the iron species. These changes provide higher activity and selectivity towards H₂ and CO for the modified samples and for the samples with lower Fe/Al ratio. The Co-containing catalyst showed the best performance because this sample exhibited the highest conversions and selectivity towards both H₂ and CO and the lowest formation of coke according to the TPO analysis.

Spatial and seasonal patterns of precipitation in Greece: the terrain segmentation approach

Demertzi K, Papamichail D, Aschonitis V, Miliaresis G, Pages:988-997

DOI:

Paper Topic:

Hydrology and water resources

Issue:

https://doi.org/10.30955/gnj.001457

Abstract

The aim of the study is to investigate the spatial and seasonal variation of precipitation in Greece using multi-temporal data analysis techniques. Mean monthly precipitation grids of 1 km² resolution of the period 1950-2000 were used in the analysis. Cross correlation quantified spatio-temporal patterns which are summarized as follows a) the absolute correlations of precipitation versus elevation and longitude are minimized during the winter period, b) the latitude dependency of precipitation presents a seasonal shift where winter precipitation tends to be higher in northern Greece, while summer precipitation tends to be higher in southern Greece. Principal components analysis indicated that the first two components account for the 92.8% of variance in the spatio-temporal variability of precipitation in Greece. Cluster analysis segmented the terrain to 27 regions with distinct seasonal variability of precipitation. The majority of irrigated agricultural land (plains of Macedonia, Thessaly and Thrace) belong to clusters which present the lowest values of annual precipitation (<600 mm year^-1). The derivation of precipitation signatures for each region of Greece using the proposed terrain segmentation approach can support environmental decision and agricultural planning at a regional (country) scale in relation to water resources management.

Effect of wastewater and grey water reuse on the germination and early growth of barley and onions

Al-Tabbal J. Ammary B., Pages:998-1005

DOI:

Paper Topic:

Water and Wastewater Treatment

Issue:

https://doi.org/10.30955/gnj.001416

Abstract

This paper evaluates the effect of wastewater reuse on the germination and growth at early stages of barley and onions. Treated wastewater, partially treated industrial wastewater, grey water, and car wash water, in addition to tap water as control were used to test their effect on germination percentage and speed of barley and onions and on the early growth stages of barley. Results have shown that germination percentage and germination velocity of onions and barley were significantly reduced when treated wastewater and car wash water were used. All water qualities produced higher shoot lengths and lower root lengths of barley compared to tap water, with car wash water producing the highest shoot to root length ratio followed by treated wastewater. The shoot dry weight to root dry weight of barley of all irrigation water types used were not significantly different. The effect of wastewater reuse on germination and early growth of barley and onion has not been studied. The recommendation that resulted from this research is that these types of wastewaters should be avoided during the early growth phases of barley and onions.

Spatio-temporal change assessment using normalize difference vegetative index and spectral analysis techniques for vegetation cover on Wadi Auranah

Mahar G.A. Alamri N. Aburizaiza O.S., Pages:955-965

DOI:

Paper Topic:

Ecosystems and Natural Resources Management

Issue:

https://doi.org/10.30955/gnj.001414

Abstract

Wadi Auranah is one of the potential wadis in respect of land use, located on the western shield (Hijaz escarpment) of Saudi Arabia. A spatio-temporal change assessment of this wadi (valley) was conducted with the help of landsat data. The results of the spectral analysis and NDVI for vegetation changes assessment reveals a continuous increasing trend of land cover biomass in specific parts of the wadi. Geological review of geologic map supports soil fertility. It is observed from field assessment of the study area that has potential for more land more to be cultivated. About 73 km² of vegetation land cover has been increased in the last 20 years. Treated wastewater is the main source of water supply that is used for afforestation and cultivation purpose.

Assessment model application of water supply system management in crisis situations

Pietrucha-Urbanik K., Pages:893-900

DOI:

Paper Topic:

Water Resources Management

Issue:

https://doi.org/10.30955/gnj.001443

Abstract

Due to the fact that water systems belong to critical infrastructure, diverse methods of its management assessment during crisis situations are applied. In these methods both technical aspects and human factors, that have an impact on safety of water supply to the recipient, are considered. Also assessment tools for water supply were applied for failure assessment in the water supply system (WSS) management. The safety functioning of WSS is associated with analysis of relations between threats, reducing the frequency of their appearing, and, if threats appear, with the identification of their causes and reducing their negative consequences. Undesirable events are the result of phenomena independent from the human will, as well as those related to human activity, that in a significant way influence the WSS functioning. Crisis situations that are affected by such undesirable events having nonrandom (rare events do not have the statistical stability), but also not-determined character, demand specific and interdisciplinary research methods.

Modeling the 3-d flow around a cylinder using the SAS hybrid model

Stamou A. Papadonikolaki G., Pages:901-918

DOI:

Paper Topic:

General

Issue: