Photovoltaic Evaporative Chimney I–V Measurement System

The photovoltaic evaporative chimney is a novel solar-cooling system that serves a double purpose: it increases the efficiency of the photovoltaic (PV) panels and it cools down a water stream which can be used to dissipate the heat from a refrigeration cycle. One of the major issues arising from the operation of the chimney is the temperature stratification in the panel due to the movement of the air in the chimney. This effect can trigger the activation of the bypass diodes of the module, creating local maximum power points (MPP) that can compromise the grid-tied inverter tracking. To fill this gap, this paper deals with the design and implementation of an I–V curve measurement system to be used in the performance analysis of the system. The I–V curve tracer consists of a capacitive load controlled by a single board computer. The final design includes protections, capacitor charging/discharging power electronics, remote commands inputs, and current, voltage, irradiance, and temperature sensors.The results show that the modules bypass diodes are not activated during the tests, and no local MPPs appear. Moreover, the curves measured show the benefits of the photovoltaic chimney: the cooling effect increases the power generated by the PV panels by around 10%.

Concentrated Buffalo Whey as Substrate for Probiotic Cultures and as Source of Bioactive Ingredients: A Local Circular Economy Approach towards Reuse of Wastewaters

Waste reduction and reuse is a crucial target of current research efforts. In this respect, the present study was focused on providing an example of local investment in a simple process configuration that converts whey into value-added compounds and allows recovery of a clean water stream. In particular, buffalo milk whey obtained during mozzarella manufacturing was ultrafiltered in-house on spiral membrane modules (20 kDa), and the two obtained fractions, namely the retentate and the permeate, provided by the dairy factory, were further processed during this work. The use of an additional nanofiltration step allowed the recovery of high-quality water to be reused in the production cycle (machine rinsing water within the facility) and/or in agriculture, also reducing disposal costs and the environmental impact. The ultrafiltration retentate, on the other hand, was spray-dried and the powder obtained was used as the main substrate for the cultivation of Lactobacillus fermentum, a widely studied probiotic with anti-inflammatory, immunomodulatory and cholesterol-lowering properties. In addition, the same sample was tested in vitro on a human keratinocytes model. Resuspended concentrated whey powder improved cell reparation rate in scratch assays, assisted through time-lapse video-microscopy. Overall these data support the potential of buffalo whey as a source of biologically active components and recyclable water in the frame of a local circular economy approach.

Fabrication of High Flux Polysulfone/Mesoporous Silica Nanocomposite Ultrafiltration Membranes for Industrial Wastewater Treatment

The inclusion of nanosphere particles like mesoporous silica MSNS~500(nm) inside the membrane substance matrix substantially enhanced water permeability and dye rejection. The dry/wet stage conversion method was employed for fabricating all membranes. The influence of different concentrations for MSNS (0–8% wt.%) in the existence of povidone (PVP) acting in the role of pore-forming on the behavior of the PSF-UF membrane was investigated. Results revealed that as soon as MSNS level grew up till 6 wt. percent, the rejection of Methylene blue (MB) dye gradually increased. The morphological properties of UF-produced membranes PS/PVP/SiO2 were investigated using scanning electron microscopy. They demonstrated a considerable degree of MB rejection of 84.7 percent, as well as an increase in MSNS concentration to 6 wt. percent. Besides, as the MSNS concentration raised to 6 wt.%, the membrane's permeability dropped from 429.2 L/m2.h for PS/PVP to 136 L/m2.h for PS/PVP/SiO2 (6%) membrane. Only water was permitted to pass across the hydrophilic UF fabricated membrane on the feed side, improving the quality of the water stream on permeate portion, making the fabricated membranes appropriate for industrial treatment of wastewater. The addendum of the polyvinylpyrrolidone acting as an additive to the investigated membranes enhanced their efficiency.

The results of a complex study of the Turchu limestone hollow (polje). Western Georgia, Caucasus

Based on the complex studies (geographical-geological, karst-speleological, and geophysical studies), conducted by the authors in the study area, karst forms such as sinkholes and ponors were identified, the width (2-17 m) of the Quaternary deposits located on the limestones were determined, the average and maximum discharges of the streams flowing on the bottom of the hollow were calculated. Studies have also shown that relatively heavy rains and snowmelt periodically flood the relatively low, western part of the hollow and create a temporary lake that soon dries up through the ponors at the bottom of the hollow, where the water stream are discharged. The closed shape of the Turchu hollow the limestone bottom covered with Quaternary deposits and the events described above indicate the corrosive origin of the hollow, which has been practically confirmed by our georadiological and electrometric studies. It is notable that the role of tectonic movements in the origin of the hollow along with the corrosive processes, which had a periodic character, and together with the uplifting of the area caused the lowering of the levels of underground waters and, consequently, the activation of karst processes.

Determination of Flow Characteristics of Ohashi River through 3-D Hydrodynamic Model under Simplified and Detailed Bathymetric Conditions

The Ohashi River is a narrow water stream that connects two brackish lakes in Japan. Intermittent saline water intrusion often occurs in Lake Shinji from Lake Nakaumi through Ohashi River. In this study, two approaches were discussed to reproduce the hydrodynamic conditions of a morphologically complex river. In the first approach, the river sinuosity was straightened. The straightening of the river resulted in a higher flow velocity and water flux coefficient due to the reduction in the flow path and the resistance, and this approach was found to be appropriate for the reproduction of the flow velocity. However, the river shape was visually quite different from the actual river morphology. In the second approach, the prime focus was given to the shape and bathymetry to quantitively reproduce the flowrate of the saline water intrusion. This approach resulted in an underestimation of the flow velocity, which was compensated by increasing the cross-sectional area of the river. A slower flow velocity causes up to a 3-h time lag for the water mass to pass through the Ohashi River, which in principle should affect the temporal variations of the water temperature and salinity. Fortunately, as the typical time scale for water temperature and salinity fluctuations in the Ohashi River is a few days, a 3-h time lag did not cause any problems.

Hydrocyclone optimisation to separate oil and water in the separator

The conventional 3-phase separator installed cannot anticipate the increase in fluid flow so that the oil content carried into the produced water from the separator consistently exceeds the upper operating threshold. This study aimed to test the application of a hydrocyclone device to a 3-phase horizontal separator. Hydrocyclones are widely used as auxiliary devices to optimise oil separation by minimising oil carried into the produced water stream. This study made a comparison between installing a hydro cyclone at the inlet with a 3-phase horizontal separator. Applying a hydrocyclone at the inlet of a 3-phase horizontal separator increases the efficiency of the separation process in production. Proper design improvements with Hysys and flow characteristics with CFD can reduce the oil content carried in the produced water stream below 20 mg/l. The results of this study can support de-bottlenecking to increase production to a production target of above 375 kbps. A robust application of engineered hydrocyclones with correct production and operating shrouds has been experienced to optimise the separation process by up to 92%.

Piezoelectric Power Generation from the Vortex-Induced Vibrations of a Semi-Cylinder Exposed to Water Flow

The aim of this work is to design a piezoelectric power generation system that extracts power from the vibration of a cantilever beam. A semi-cylinder placed in a water stream and attached to the beam is excited into vortex-induced vibrations (VIV), which triggers the piezoelectric deformation. The mechanical system is modelled using parametric equations based on Hamilton’s extended principle for the cantilever beam and the modified Van der Pol model for the bluff body (the semi-cylinder). These equations are simulated using the MATLAB software. The dimensions of the model, the flow velocity and the resistance are treated as design parameters and an optimization study is conducted using MATLAB to determine the combination of optimal values at which maximum power is extracted. The key findings of this research lie in the identification of the effect of changing the design parameters on output power. In addition to the numerical simulation, a finite element analysis is carried out on the bluff body and the hydrodynamic forces and velocity profiles are observed. It is determined that the vibration amplitudes increase with increasing diameter of the bluff body, length of the bluff body and water velocity.

Outlook on the Carbon-Based Materials for Heavy Metal Removal

Carbon-based materials, including graphene (GR), carbon nanotubes (CNTs), activated carbon, and biochar, are the most common materials often applied to separate heavy metals from the water stream. A key feature of carbon adsorbent is the functional group of its adjustable surfaces. Both GR and CNTs exhibit the most favorable materials and may be the right choice in the future because of their excellent nature and unique structure. In order to commercialize the use of carbon absorbent in the removal of heavy metals, the mechanism of adsorption of carbon on heavy metals must be fully understood. In view of the good properties of carbon-based materials, a detailed study of their characteristics and synthesis, and modifications should be highlighted. Therefore, this article will discuss the properties, modifications, and use of carbon-based materials as adsorbents for various hazardous metal ions.

Impact of Weather Conditions on the Operation of Power Unit Cooling Towers 905 MWe

The paper presents the results of measurements and calculations concerning the influence of weather conditions on the operation of wet cooling towers of 905 MWe units of the Opole Power Plant (Poland). The research concerned the influence of temperature and relative humidity of air, wind and power unit load on the water temperature at the outlet from the cooling tower, the level of water cooling, cooling efficiency and cooling water losses. In the cooling water loss, the evaporation loss stream and the drift loss stream were distinguished. In the analyzed operating conditions of the power unit, for example, an increase in Tamb air by 5 °C (from 20–22˚C to 25-27˚C) causes an increase in temperature at the outlet of the cooling tower by 3-4˚C. The influence of air temperature and humidity on the level of water cooling ΔTw and cooling efficiency ε were also found. In the case of ΔTw, the effect is in the order of 0.1-0.2˚C and results from the change in cooling water temperature and the heat exchange in the condenser. The ε value is influenced by air temperature and humidity, which determine the wet bulb temperature value. Within the range of power changes of the unit from 400 to 900 MWe, the evaporated water stream mev, depending on the environmental conditions, increases from 400-600 tons/h to the value of 1000-1400 tons/h. It was determined that in the case of the average power of the unit at the level of 576.6 MWe, the average values of the evaporation and drift streams were respectively 0.78% and 0.15% of the cooling water stream. Using statistical methods, it was found that the influence of wind on the level of water cooling, cooling efficiency and cooling water losses was statistically significant.

Evaluation of the Total Dispersion and Distribution of Petroleum Hydrocarbons in the Aya Stream, Located in Niger Delta: Implications on the Quality and Health of Aya Water Stream

Globally, oil spills are known catastrophic events with harmful consequences that tend to endanger plant, animal and human life. The dispersion and distribution of petroleum hydrocarbons levels were investigated to evaluate its effect on the quality and health of Aya stream, located in the Niger Delta sub region, south east Nigeria. Water samples were collected from the stream, which is the most available source of water in Ikot Ada Udo local community, five years after an extensive oil spillage between the months of June and November 2012. These samples were analyzed to assess the level of total petroleum hydrocarbon (TPH) and physicochemical enrichment using Spectrophotometric with 1g of Bonny Light and Bonny Medium Crude Oils dissolved in 1000 ml of tetrachloromethane were used as standards as well as insitu measurements of water temperature and dissolved oxygen. TPH concentrations ranged from 0.21mg/l in dry season (September, October, November) to a maximum level of 0.33 mg/l in wet season (June, July, August) during the study. The mean concentrations found for physicochemical parameters during wet and dry seasons respectively were: temperature (27.67±0.29 & 27.83±0.290C), DO (3.47±0.65 & 3.44±0.67 mg/l), Cd (0.03±0.003 & 0.03±0.01mg/l), Pb (0.17±0.06 & 0.18±0.04 mg/l), Ni (0.08±0.01 & 0.08±0.005 mg/l), V (0.02±0.01 & 0.02±0.01 mg/l).The distribution pattern of trace heavy metals in the stream water followed the sequence: Pb>Ni> Cd>V. In all cases, Pb was the most abundant and V the least abundant metal. Elevated levels of some physicochemical parameters shown to correlate significantly (p=0.05) and associate with the oil spill infer that Aya stream has been severely polluted. Statistical analysis (t-test) of seasonal levels of TPH in water samples showed positive relationship (t=0.55, p=0.05). The implication of these results is that the concentrations of the studied parameters did not depend on seasonal influence but were connected with the incessant exposure of the site to oil seeps from the well-head. The high levels of lead above permissible limits in the studied samples poses a health threat, hence, the removal of the well-head and future situation of such structures away from the source of communal water source should be implemented to preserve the quality and health of the water source.