Unaccounted Losses Research Articles

Water Balance for a Tropical Lake in the Volcanic Highlands: Lake Tana, Ethiopia

Lakes hold most of the freshwater resources in the world. Safeguarding these in a changing environment is a major challenge. The 3000 km2 Lake Tana in the headwaters of the Blue Nile in Ethiopia is one of these lakes. It is situated in a zone destined for rapid development including hydropower and irrigation. Future lake management requires detailed knowledge of the water balance of Lake Tana. Since previous water balances varied greatly this paper takes a fresh look by calculating the inflow and losses of the lake. To improve the accuracy of the amount of precipitation falling on the lake, two new rainfall stations were installed in 2013. The Climate Hazards Group Infrared Precipitation Version two (CHIRPS-v2) dataset was used to extend the data. After reviewing all the previous studies and together with our measurements, it was found that the period of 1990–1995 likely had the most accurate gauged discharge data. During some months in this period, the lake water balance was negative. Since the river inflow to the lake cannot be negative, water was either lost from the lake via the subsurface through faults, or the outflow measurements were systematically underestimated. Based on the evaporation rate of 1650 mm, we found that unaccounted loss was 0.6 km3 a−1, equivalent to 20 cm of water over the lake area each year. This implies the need for reliable rainfall data and improved river discharge measurements over a greater portion of the basin both entering and exiting the lake. Also, integrated hydrological and geologic investigations are needed for a better understanding of the unaccounted water losses and quantifying the amount of subsurface flow leaving the lake.

Persistent collapse of biomass in Amazonian forest edges following deforestation leads to unaccounted carbon losses.

Deforestation is the primary driver of carbon losses in tropical forests, but it does not operate alone. Forest fragmentation, a resulting feature of the deforestation process, promotes indirect carbon losses induced by edge effect. This process is not implicitly considered by policies for reducing carbon emissions in the tropics. Here, we used a remote sensing approach to estimate carbon losses driven by edge effect in Amazonia over the 2001 to 2015 period. We found that carbon losses associated with edge effect (947 Tg C) corresponded to one-third of losses from deforestation (2592 Tg C). Despite a notable negative trend of 7 Tg C year-1 in carbon losses from deforestation, the carbon losses from edge effect remained unchanged, with an average of 63 ± 8 Tg C year-1 Carbon losses caused by edge effect is thus an additional unquantified flux that can counteract carbon emissions avoided by reducing deforestation, compromising the Paris Agreement's bold targets.

Thermodynamic analysis of gasoline-fueled electronic fuel injection digital three-spark ignition (EFI-DTSI) engine

Numerous researchers have devised various strategies to improve the combustion efficiency of the internal combustion engine. Despite continuous improvement during past decades, there is still scope for further development in engine performance. This paper analyzes the energy and exergy distribution of a single-cylinder 199.5 cc electronic fuel injected three-spark ignited high-speed petrol engine. The engine is operated at 25%, 50%, 75%, and 100% throttle positions for different speeds of 4000–10,000 rpm with an increment of 2000 rpm. From the detailed heat balance analysis, the best results obtained are: maximum brake thermal efficiency of 34.9% corresponding to 6000 rpm at 50% throttle opening, minimum heat carried away by exhaust gas of 18.5% at 4000 rpm and 25% throttle position, minimum heat carried by cooling water as 13% for 10,000 rpm and 25% throttle, and the minimum unaccounted energy loss of 26.6% under the condition 8000 rpm and 75% throttle position. However, the best results of exergy analysis are: second law efficiency of 51.93% corresponding to 4000 rpm and 25% throttle, maximum exergy transfer for useful work as 33.7% concerning 6000 rpm and 50% throttle, minimum exergy transfer for exhaust gas as 15.7% for 6000 rpm and 25% throttle, minimum exergy transfer associated with coolant of 4.6% at 4000 rpm and 25% throttle, and minimum exergy destruction of 39.4% corresponding to 8000 rpm and 50% throttle, respectively.

ESTIMATION OF THE SUITABILITY OF METHODS FOR DETERMINING LACTIC ACID CONTENT IN DIFFUSION JUICE FOR APPLICATION IN CHEMICAL AND TECHNICAL CONTROL OF SUGAR PRODUCTION

Development of microbiological infection in the process of production of diffusion juice is one of the most important factors affecting the quality of diffusion juice and sucrose loss. In this regard, it is important to promptly monitor the microbiological contamination of mixture from water and beet chips in the diffusion apparatus. Lactic acid is used as an indicator of the degree of microbiological contamination of the diffusion juice. Traditionally, when calculating unaccounted sucrose losses on diffusion, the titrimetric method is used to determine the concentration of lactic acid with preliminary isolation of acid anions from the diffusion juice on ionite columns. However, this method is time-consuming and labor-intensive and is not suiTable for operational control. The article suggests using a simpler and less time-consuming spectrophotometric method for operational control, based on measuring the optical density of the colored product of the reaction of lactate ions with iron(III) chloride at a wavelength 400 nm. The results of evaluating the consistency of data on the content of lactic acid in diffusion juices obtained using the traditional and spectrophotometric methods are presented in article. The results of data analysis using the Bland-Altman descriptive statistics method confirm that the data obtained by various methods are in good agreement with each other, and therefore the spectrophotometric method for determining the concentration of lactate ions can be used in production control in the sugar industry.

Compound parabolic solar collector – Performance evaluation as per standard test method and actual field conditions for industrial process heat application in Indian context

Industrial process heating has been identified as a potential field for solar thermal applications. In this paper, a comparative study was carried out on the performance of an individual solar collector under laboratory conditions and performance of the collector array under field condition. Compound Parabolic Concentrator (CPC) has been used as a solar collector for the application of boiler feed water preheating. The characterization of CPC has been done in liquid phase with water as a working fluid as per the standard, IS 16648 (Part-5):2017. The optical efficiency of the CPC is found to be 64.8% under standard test conditions. In the field, total 200 number of CPCs, each having 3 m2 area, were installed. The performance monitoring and evaluation of the actual installation was carried out over a period of 10 months. The system was designed to supply average 448,500 kWh- Thermal/year, saving the equivalent amount of fossil fuel. The comparative study of the performance of CPC collector under standard conditions and actual operating conditions in the field shows significant variation. The average variation in the performance was about 9% with a maximum variation of 14.7%. The major reasons behind the lower performance output than expected, attribute to the heat losses through the collector manifold and piping (3.9%), soiling of reflector and absorber of CPC (1.72%), uncertainties of instruments (1.49%) and other unaccounted losses like dislocation of the evacuated tubes from the original position, loss of vacuum through evacuated tubes, shadow effect, heat utilization pattern etc. (1.89%), which should be considered while designing the solar field to meet the required output.

Effect of altitude on thermal balance of a heavy-duty diesel engine

Diesel engines working at high altitudes are prone to thermal failure. In this paper, a series of experiments and simulations were conducted to analyze the thermal balance, in-cylinder heat transfer, and performance of diesel engines at various altitudes. A six-cylinder four-stroke diesel engine was used to conduct the thermal balance tests at altitudes from 0 m to 4500 m. The experiment results show that the engine thermal efficiency declines from 37.8% to 33.9% at the rated speed as altitude rises. The heat loss through cooling water has no significant change in trend and remains about 22%-24% in most conditions. The heat loss through exhaust decreases as altitude rises and accounts for 26.7%-39.8% of total energy. The unaccounted losses increase greatly as altitude rises but it makes up no more than 12.1% of total energy at all altitudes. To acquire more detailed in-cylinder heat transfer parameters, a one-dimensional in-cylinder simulation was conducted. The simulation results show that the in-cylinder heat transfer coefficient and heat fluxes increase first and then decrease as altitude rises. In addition, with the increase of altitude, the in-cylinder average gas temperature substantially increases. This study has practical significance for reducing thermal load of the engines working at high altitudes.

Effect of methane augmentations on engine performance and emissions

Automobile numbers are increasing day by day that demand more fuel and produce more emission. In addition, petroleum sources are limited in nature and emission norms are tightening day by day. Those scenarios are motivating the researcher to find non-petroleum clean energy source. Gaseous fuel supplementation is helpful in obtaining the above stated objective. In this study, methane gas supplementation has done to diesel engine. The investigation was carried out to analyze the performance and emission of CI engine using 0–75% substitution of diesel indicated power by methane energy in dual fuel mode at varying load (25%, 50% and 75%). The result shows that brake thermal efficiency (BTE) and relative air fuel ratio decreases with methane energy share (MES), while unaccounted heat loss increases. Here, a comparison of NO and NO2 emissions have been presented to investigate the non-thermal effect of CH4 on NOx emission. Combined reduction in nitrogen oxide and soot emission makes the outcomes of this study more suitable to implement for achieving the strict emission norms. Hence, CH4 augmentation is beneficial at mid and higher load conditions with lower emissions and energy consumption.

Towards Improving Experimental Learning- Exploring Bernoulli’s Equation

This study illustrates through the verification of Bernoulli’s equation (as a case study experiment) about how analysis of the gap in experimental results when compared to its theoretical value based on the fundamental principles underlying a hypothesis should become a part of the experimental learning approach which is being adopted in teaching a course. For this experiment, even after making a thorough analysis, it is found difficult to exactly answer the gap in the experimental and theoretical values. Particularly, it is seen that the unaccounted loss is about 10%. Various assumptions adopted in arriving at the conclusions are also elaborated to get a clear picture on carrying out the analysis. This investigation effectuated deep interest among student in the course and also engrossed them to discover the reason for any unaccountable losses in the experiment other than the well identified losses.

Nitrogen Flows a nd Sustainability o f Agrosystem

In the experiment through sod-podzolic soil, nitrogen flows were estimated in agrocoenosis when applied under spring wheat using 15N ammonium nitrate labeled with isotope and white mustard biomass as a siderate. It was established that the increase of grain yield from the use of N45 is 42%, the siderate – 58%, their joint introduction – 99%, from seed inoculation with the Rizoagrin biopreparation – 16%. 60 - 80% of spring wheat harvest is formed due to soil nitrogen, the share of "extra" nitrogen reaches 14%. Plants use 41% of ammonia nitrate nitrogen for crop formation, and 23% of the siderate. Seed inoculation with a biological product increases plant nitrogen intake of mineral fertilizer by 5 - 9%. 26% of ammonium nitrate nitrogen and 33% of siderate nitrogen are fixed in the soil, the biological product does not affect this process. Unaccounted losses of 15N mineral fertilizer make up 32% of the applied amount and reduced by 8% when adding ammonium nitrate and inoculating seeds. The loss of labeled siderate nitrogen is 25% of the amount deposited, the use of the biological product increases the nitrogen consumption of N-fertilizers and provides a positive tendency for green manure nitrogen to fix in the soil and reduces its loss by 4%. On sod-podzolic light loamy soil, agroecosystem functions in the homeostasis mode (norm) when using green manure, in the stress mode (permissible) – when sharing green manure and mineral nitrogen fertilizer. When using only ammonium nitrate, agroecosystem operates in resistance mode. Differences in the performance of agroecosystems among variants with the inoculation of spring wheat with Rizoagrin and without it have not been established.

Experimental investigation of the effects of CR, hydrogen addition strategies on performance, energy and exergy characteristics of a heavy-duty NGSI engine fueled with 99% methane content

In order to analyze and improve thermodynamic process of NGSI engine and achieve better energy utilization, a low CR (11.6) SI engine was modified by replacing pistons with different bowl volumes and an experimental investigation of the effects of CR (13.6 and 14.5), hydrogen addition strategies on performance, energy and exergy characteristics of a heavy-duty NGSI engine fueled with 99% methane content was conducted. The results showed that the PCP, maximum HRR and in-cylinder temperature increased obviously with the increase of hydrogen contents, CR and engine speed, and the locations of PCP and maximum HRR advanced towards TDC, which led to the advance of 50% combustion position, shorter combustion duration and more output work. Secondly, with the increase of hydrogen contents and CR, the proportions of indicated work and heat transfer energy to coolant turned larger but the unaccounted losses and combustion loss became smaller. In addition, with the increase of engine speed, both indicated work and friction loss were large, which caused the decrease of BTE, besides, the percentage of friction loss and pumping loss turned up. And the hydrogen contents and CR had little effect on exhaust energy and exergy. Finally, comparing the energy and exergy of NGSI engine under operated conditions, the change trends of exergy terms were similar to their corresponding energy, however, the exergy efficiency was 7.97–9.70% lower than BTE and the percentage of exhaust energy and heat transfer energy to coolant was 2.46–2.51 and 7.09–8.09 times larger than corresponding energy, respectively.

Voltage Cycling Degradation Dependence on O2 Pressure: A Comparative Voltage-Loss Analysis

Polymer-electrolyte-membrane fuel cells (PEMFCs) have proven their applicability as a clean energy conversion technology. At the same time, a clear understanding of their degradation under dynamic operation is critical to project and ultimately improve long-term durability. In order to mimic real-life operation stressors, accelerated stress tests (ASTs) are used to enhance a particular type of degradation mechanism. After the AST application, various physico- and electrochemical diagnostic tools aid to understand and catalogue the observed performance losses. Since the ultimate goal is to develop in situ mitigation and recovery strategies for automotive applications, a comprehensive voltage loss study describing the degradation effects on performance losses is desired. Particularly inside ASTs, voltage cycling tests reproduce conditions that mimic the dynamic operation of a fuel cell stack, and which are directly linked to the degradation of catalyst layers1 in a membrane electrode assembly (MEA). In a semi-empirical study, voltage cycling tests were applied by Kneer et al. 2 to promote electrochemical surface area (ECSA) losses of a carbon-supported platinum catalyst (Pt/C) for the oxygen reduction reaction (-ORR), establishing an ECSA loss semiempirical model for a wide range of voltage cycling conditions. Subsequently, this model was used to project performance losses in H2/air curves based on a theoretical relationship between ECSA evolution and the ORR observed kinetic and transport losses. However, the authors observed that their model prediction resulted in a substantial unaccounted voltage loss (compared to experimental data), suggesting that deeper analyses are required to understand voltage cycling induced performance losses, with the ultimate goal to develop in situ mitigation and recovery strategies. Therefore, our study will make use of voltage cycling ASTs, which will correlate voltage losses to degradation phenomena measured by various diagnostic tests3. These include the ORR mass activity (via H2/O2 measurements), proton transport resistance through the membrane and catalyst layer (via impedance analyses), and O2 transport resistance (via limiting current measurements). By performing a standardized protocol, the differences in MEA aging during voltage cycling tests conducted with H2/air vs. the more frequently used H2/N2 (anode and cathode, respectively) will be separately studied. Furthermore, as observed in Figure 1a, lowering the relative humidity (RH) of the reactants significantly reduces ECSA losses during voltage cycling tests, in comparison to the same protocol performed at 100% RH. More importantly, the H2/air performance losses are substantially lowered after low RH testing (in comparison to 100% RH) (Figure 1b). The unaccounted voltage losses vs. specific current density (ispec ) (the difference between the theoretical 70 mV/dec. line (black line in Figure 1c) and the corrected experimental cell voltages) are lowered, as well. Therefore, the effect of further operational stressors (e.g. cell temperature) on voltage cycling aging for H2/N2 vs. H2/air will be presented. Ultimately, we will seek to correlate the observed losses to those under automotive operating conditions. This insight leads to a better understanding of catalyst degradation and its subsequent suppression via appropriate mitigation strategies through the correct application of operating conditions as described by single cell experiments. Figure 1: a) ECSA losses vs. number of cycles. The insert depicts the used voltage profile (1 cycle equals to 8s at the lower voltage limit (LVL) followed by 8s at the higher voltage limit (HVL), voltage ramp >4V/s). Voltage cycling tests were performed as described by Harzer et. al. in a single-cell PEMFC with 5 cm2 active area (loading: 0.1 and 0.4 mgPt cm-2 in the anode and cathode, respectively; 100 kPaabs, 80°C and H2/N2 flows of 200 nccm/75 nccm on anode/cathode, respectively)3. b) H2/air performance curves (conditions: differential flow, 80°C, 170 kPaabs inlet-controlled pressure, anode: 2000 nccm of H2, cathode: 5000 nccm of air). c) Tafel representation of I-V curves after voltage cycling AST at 30% RH (20k cycles) and 100% RH (10k cycles). Ecell was corrected for HFR, H+ resistance through the catalyst layer, and O2 mass transport resistance; specific current density (ispec ) is corrected for cell shorting resistance and H2 crossover current. References Kneer, A.; Wagner, N.; Sadeler, C.; Scherzer, A. C.; Gerteisen, D., Effect of Dwell Time and Scan Rate during Voltage Cycling on Catalyst Degradation in PEM Fuel Cells. J Electrochem Soc 2018, 165 (10), F805-F812. Kneer, A.; Wagner, N., A Semi-Empirical Catalyst Degradation Model Based on Voltage Cycling under Automotive Operating Conditions in PEM Fuel Cells. J Electrochem Soc 2019, 166 (2), F120-F127. Harzer, G. S.; Schwämmlein, J. N.; Damjanovic, A. M.; Ghosh, S.; Gasteiger, H. A., Cathode Loading Impact on Voltage Cycling Induced PEMFC Degradation: A Voltage Loss Analysis. J Electrochem Soc 2018, 165 (6), F3118-F3131. Figure 1

Thermal analysis of paraboloid dish type solar cooker

This study presents thermal performance analysis of paraboloid dish type solar cooker under steady and unsteady state conditions. The performance is analyzed under two conditions: firstly steady state operation of cooker subjected to radiation and convection losses from vertical cylindrical surface & top cover of the cooker and secondly unsteady state operation of cooker associated with mass transfer from cooker to the surrounding when heat is supplied at a constant rate to the cooker after saturation pressure is reached.Under steady state condition, predicted value of average thermal efficiency of cooker is 54%, first and second figures of merit are respectively 1.7 and 3.4, time taken to raise the temperature to 95°c is 24 minutes and time for boiling is 26 minutes. The difference in predicted and experimental results can be attributed to unaccounted losses from the cooker surface and operational error. In the second case, energy leaves the cooker with steam at a rate of 0.91 kW, accompanied by heat losses by convection and radiation from the outer surface of the cooker.

Energy and exergy analyses of Al<SUB align="right">2O<SUB align="right">3-diesel-biodiesel blends in a diesel engine

The usage of nanoparticles as a fuel additive to improve fuel economy and reduce harmful exhaust emissions has been a popular research topic in recent years. The effects of biodiesel (5% in volume) and aluminium oxide (Al2O3) nanoparticles (50 ppm and 100 ppm) addition to pure diesel on the energy and exergy analysis of a diesel engine were investigated in this experimental study. The experiments were carried out at variable engine loads (25%, 50%, 75%, and 100%) and constant engine speed at 1,500 rpm. The results of this study showed that the biodiesel addition increased the brake specific fuel consumption (BSFC) while decreased slightly the brake thermal efficiency (BTE). As well as, the heat loss from cooling water increased, whereas the unaccounted heat loss, the engine brake power, and the heat loss by exhaust gases reduced. On the other hand, the addition of Al2O3 nanoparticles at a rate of 50 ppm and 100 ppm to biodiesel-pure diesel blend increased the BTE and the exergy efficiency by 8.15% and 7.28%, averagely. Further, BSFC, entropy generation, and unaccounted losses decreased by 7.57%, 13.49%, and 31.89% averagely.

Improvement of the Method for Calculating the Metal Temperature Loss on a Coilbox Unit at The Rolling on Hot Strip Mills

The paper improves the calculation methodology of metal temperature loss during hot rolling process at continuous mills. The proposed methodology can be implemented at hot strip mills with various in-line equipment arrangements within the temperature ranges appropriate for processes simulation of hot rolling, normalized rolling and Thermo-Mechanical Control Process of carbon and microalloyed steels. It provides engineering analysis of unaccounted temperature losses of feed by means of radiation and convection, which, in the first time, through the time factor, additionally accounts for strip motion speed factors, roller table length and feed length, and also length of rolls contact arc with metal. The accountability of the above mentioned factors in the various compositions depending on the rolling method increases the engineering simulation accuracy, ensures the versatility of the elaborated method with respect to different types of mills and makes the scientific novelty of the study. The equations were developed to calculate the metal temperature loss while coiling at the CoilBox unit. The equations accounts for the influence on the temperature of strip length, coiling and uncoiling speed, strip thickness, inside radius of the reeling coil, the time the feed rests being coiled. The improved model was verified based on actual data.

Laminated NbTi-on-Kapton Microstrip Cables for Flexible Sub-Kelvin RF Electronics

Large arrays of superconducting devices such as microwave kinetic inductance detectors require high density interconnects from higher temperatures with minimal heat load, low loss, and negligible crosstalk capable of carrying large and overlapping bandwidth signals. We report the fabrication of superconducting 53 wt% Nb-47 wt% Ti (Nb-47Ti) microstrip transmission lines laminated onto flexible polyimide substrates with lengths up to 40 cm and up to ten traces. The 50 Ω traces terminate in G3PO coaxial push-on connectors. We found transmission losses of 2.5 dB and a nearest-neighbor forward crosstalk of -25 dB at 8 GHz on a typical 5 trace, 1.8-cm-wide, 0.198-mm-thick, 22-cm-long flex cable at 30 mK. A simple two-port analytical model and subsequent Sonnet simulations indicate that this loss is mainly due to a complex impedance mismatch from wirebonds at the end connector without which the insertion loss would be <;2.7 dB/m. This is about six times worse than the transmission measured in Coax Company, Ltd.'s smallest (O 0.86 mm) Nb-47Ti coaxial cables, possibly from differences in the low temperature loss properties of polyimide laminates versus PTFE or from unaccounted resistive losses in the copper adapter coaxes of our tested device. Heat flow calculations from literature data show that the 0.198-mm-thick flex cables tested have roughly equivalent thermal conductance per trace below 4 K compared to the O 0.86 mm Nb-47Ti coaxial cables.

Energy-exergy analysis of biodiesel fuels produced from waste cooking oil and mustard oil

The present work includes the production of six blends of biodiesel using waste cooking oil/mustard oil with methanol (99% pure) having NaOH/KOH (91% pure) as the catalysts. The kinematic viscosity, density, calorific value, flash point, cloud point, pour point, and cetane number of prepared bio-fuels were determined. The comparative energy-exergy analyses for six biodiesel fuels were conducted using a 4 inline-4stroke diesel engine with 2392 cc at 0%, 25%, 50%, and 100% load for constant/varying speed. The break-power (BP), heat taken by cooling water (Qw), heat taken away by exhaust gases (Qex), and unaccountable losses were evaluated. It was found that the tested biodiesels offer competitive energetic performance to the diesel. The exergetic performance parameters followed similar trends with the corresponding energetic ones, but with increased brake specific fuel consumption and reduced exhaust emission due to higher oxygen content in biodiesel fuel. The results of analysis of variance clearly reflect that the B.P. is influenced most by the load, followed by the type of oil and speed has the least effect. It was also found that the biodiesels are having considerably lower CO emission than diesel. NOx emissions were least at higher load in diesel followed by waste cooking oils. Soot emissions were alike for diesel, waste cooking oils, and mustered oils at low load, but at higher load diesel has an exponential increment in soot emissions.

Evaluation of potassium thiosulfate as a nitrification inhibitor to reduce nitrous oxide emissions

Potassium thiosulfate (KTS, K2S2O3) has been shown to function as a nitrification inhibitor, thus has the potential to reduce nitrous oxide (N2O) emissions and play an important role in effective N management. The objective of this research was to determine the potential effects of KTS on N2O emissions and N transformation processes in comparison with commercial N transformation inhibitors (stabilizers). A laboratory incubation experiment was conducted using urea and ammonium nitrate (UAN) applied at 150mgNkg−1 in a Hanford sandy loam soil (coarse-loamy, mixed, superactive, nonacid, thermic Typic Xerorthents). Treatments included three rates of KTS (26, 51, and 102mgS2O32−-Skg−1), a urease and nitrification inhibitor (Agrotain® Plus), a nitrification inhibitor (N-Serve® 24), and an untreated control. Nitrous oxide emission, soil pH, and mineral N species were monitored for 35days. Total N2O emissions were reduced significantly by all KTS treatments as a function of KTS rate. At 102mgS2O32−-Skg−1, KTS reduced N2O emissions by 48% (0.18% of total inorganic N), which was statistically similar to the N-Serve® 24 treatment (60% reduction) although lower than Agrotain® Plus (78% reduction). The KTS resulted in significantly less unaccounted (total N) loss compared to the commercial inhibitors. If the N2O emissions reductions observed in this laboratory study are validated in the field, using KTS for this purpose can also provide a fertility benefit and may reduce total chemical inputs into agronomic systems. Future research needs to determine the effectiveness of thiosulfate for improving overall nutrient management while reducing N2O emissions under field conditions.

Pressure-driven water flow through hydrophilic alumina nanomembranes

We present an experimental study that focuses on pressure-driven flow of distilled water through γ alumina membranes with 5, 10 and 20 nm pore radii. The nanopore geometry, pore size and porosity are characterized using scanning electron microscopy images taken pre- and post-flow experiments. Comparisons of these images have shown reduction in the pore size, which is attributed to precipitation of hydroxyl groups on alumina surfaces. Measured flowrates compared with the Hagen–Poiseuille flow relations consistently predict 2.2 nm reductions in the pore size for three different membranes. This behavior can be explained by the formation of a thick stick layer of water molecules over hydroxylated alumina surfaces, evidenced by water droplet contact angle measurements that exhibit increased hydrophilicity of alumina surfaces. Other possible effects of the mismatch between theory and experiments such as unaccounted pressure losses in the system or the streaming potential effects were also considered, but shown to be negligible for current experimental conditions.

The effect of a novel hybrid nano-catalyst in diesel-biodiesel fuel blends on the energy balance of a diesel engine

In internal combustion engines, only about a third of the total fuel input energy is converted into useful work. If the energy rejected into the cooling system and the exhaust gases could be recovered instead and put into useful work, fuel economy would have been substantially improved. The main aim of this research paper was to evaluate the effects of the hybrid nano-catalyst containing cerium oxide and molybdenum oxide in amide-functionalized multiwall carbon nano-tubes (MWCNTs) on the thermal balance of a diesel engine using two types of diesel-biodiesel blends (B5 and B10) in three concentrations (30, 60, and 90 ppm). The research engine was a single-cylinder, four-stroke, direct-injection, and air-cooled diesel engine. The engine was run at two speeds (1,700 rpm and 2,500 rpm) in full load conditions. The thermal efficiency (useful work) resulting from the energy transferred into the cooling system, the exhaust gases, and the unaccounted losses, including the lubricating oil heat loss and the convection and radiation heat transfer, were computed using the first law of thermodynamics. The results showed that by increasing the amount of nano-catalysts (cerium oxide and molybdenum oxide) in fuel blends, the energy transferred to the cooling system and exhaust gases were decreased. The highest reduction in the energy transferred to the cooling system and the exhaust gases was 5.38% and 2.26% for B5, containing 90 ppm (B590ppm), and 5.61% and 2.62% for B10, containing 90 ppm (B1090ppm) respectively. Also, the thermal efficiency went up. Compared with the nano-catalyst-free fuel blends, the highest increase in thermal balance was observed as 6.75% and 5.41% for B590ppm and B1090ppm respectively.

Composition of primary kimberlite melt in a garnet lherzolite mantle source: constraints from melting phase relations in anhydrous Udachnaya-East kimberlite with variable CO2 content at 6.5 GPa

The critical issue in the study of kimberlites, known as principal host rocks of diamonds, is the reconstruction of their primary melt composition, which is poorly constrained due to contamination by xenogenic materials, significant loss of volatiles during eruption, and post-magmatic alteration. It is generally accepted that the last equilibration of primary kimberlite melt with surrounding mantle (garnet lherzolite) occurred beneath cratons at 5–7GPa (150–230km depths). However, the subliquidus mineral assemblages obtained in kimberlite melting experiments at mantle pressures differ from lherzolite, probably owing to unaccounted loss of CO2. Here we present experiments at 6.5GPa and 1200–1600°C on unaltered kimberlite with an addition of 2–22mol% CO2 over its natural abundance in the rock (13mol%), but keeping proportions of other components identical to those in an exceptionally fresh anhydrous kimberlite from Udachnaya-East pipe in Siberia. We found that the partial melt achieves equilibrium with garnet lherzolite at 1500°C and 19–23mol% CO2 in the system. Under these conditions this melt contains (mol%): SiO2=9, FeO=6–7, MgO=23–26, CaO=16, Na2O=4, K2O=1, and CO2=30–35. We propose, therefore, the alkali-rich carbonatitic composition of primary kimberlite melt and loss of 34–45mol% (34–46wt%) CO2 during ascent of the kimberlite magma to the surface.