ВОЗМОЖНЫЕ МЕРЫ ПОВЫШЕНИЯ СРОКА СЛУЖБЫ ОСНОВНЫХ ЭЛЕМЕНТОВ ТОПЛИВОВПРЫСКИВАЮЩЕГО НАСОСА ДИЗЕЛЯ

This article aims to study the impact of ribs on flow parameters and laminar heat transfer of water–aluminum oxide nanofluid with different nanoparticle volume fractions in a three-dimensional rectangular microchannel. To this aim, compulsory convection heat transfer of water–aluminum oxide nanofluid in a rib-roughened microchannel has been numerically studied. The results of this simulation for rib-roughened three-dimensional microchannel have been evaluated in contrast to the smooth (unribbed) three-dimensional microchannel with identical geometrical and heat–fluid boundary conditions. Numerical simulation is performed for different nanoparticle volume fractions for Reynolds numbers of 10 and 100. Cold fluid entering the microchannel is heated in order to apply constant flux to external surface of the microchannel walls and then leaves it. Given the results, the fluid has a higher heat transfer with a hot wall in surfaces with ribs rather than in smooth ones. As Reynolds number, number of ribs, and nanoparticle volume fractions increase, more temperature increase happens in fluid in exit intersection of the microchannel. By investigating Nusselt number and friction factor, it is observed that increase in nanoparticle volume fractions causes nanofluid heat transfer properties to have a higher heat transfer and friction factor compared to the base fluid used in cooling due to an increase in viscosity.

Process development of bottle gourd sweetmeat by microwave heating: Changes in rheological, textural, sensory and morphological parameters

The Air Force Research Laboratory’s Prop ulsion Directorate is developing higher energy density hydrocarbon fuels for application in reusable liquid rocket engines . For increased performance and operability, next generation engines will require better thermal stability understand ing of hydrocarbo n fuels under high heat fluxes . Of the existing thermal stability test rig s, none ha ve the ability to accurately simulate the high heat flux conditions that will exist in the cooling channels of these new high -pressure hydrocarbon engines . To design and te st fuels to meet the high reliability and reusability requirements proposed for these engines , the Air Force Research Laboratory (AFRL) at Edwards AFB has designed the High Heat Flux Facility (HHFF) using experience gained from past thermal stability test rig experiments . In order to design a facility capable of simulating the higher heat fluxes expected in the channels, CFD++, a Metacomp Technologies Inc. computational fluid dynamics software suite, was employed to optimize the design prior to manufacture . Conjugate heat transfer calculations were performed in a single computational domain containing the copper heater block and the fluid channel of the new test rig design . The parameters of interest during each experiment will be heat transfer coefficient, degree of coking and corrosion in the channel, and pressure drop as a function of heat flux, wall temperature, Reynolds number, channel material, fuel composition and pressure . AFRL’s HHFF will be an important tool for facilitat ing the development and tran sition of new advanced hydrocarbon fuels .

Experimental investigation and model development for effective viscosity of MgO–ethylene glycol nanofluids by using dimensional analysis, FCM-ANFIS and GA-PNN techniques

Silica nanoparticles (silica sols) based gels have increasingly been used as alternative grouting material for sealing the small fractures in the tunnel walls. Gelling of silica nanoparticles at room temperature has been investigated thoroughly but gelling at different temperatures scarcely investigated. At the same time temperature is one of major factor which can affect the long-term stability of grouted silica. In this work we have investigated the gelling of three different types of silica sols (Levasil CS40-213, Levasil CS40-222, and Levasil CS30-236) having different particle sizes, in 0.28 M NaCl at 10, 20 and 30 °C. Aggregation process, starting from the addition of salt to the gelling point, was monitored by measuring the time dependent particle size distribution. Electrospray scanning mobility particle sizer (ES-SMPS) was used to measure the aggregating. These measurements were complemented by rheological measurements in order to get a relationship between changes in aggregate structure and in the viscosity of silica suspension. Data from the temperature dependent gel time measurements were used to calculate the activation energy. At room temperature, silica sols with smallest average particle size showed the shortest gel times whereas the sols with the largest particle size showed the longest gel time. However, at increasing temperature shorter gel times were seen for all the sols. Temperature dependent rheological measurements showed similar trends in viscosity changes as seen for gel times i.e., increased temperature leads to quicker increase in the viscosity and a sharp increase in viscosity near the gelling point. Our calculations of fractal dimensions showed that in the gel network there are still many free particles which continuously incorporated into the gel network. Apparent activation energies calculated for CS40-213, CS40-222, CS30-236 were 13.40, 23.36 and 41.45 kJ/mol, respectively. These values are lower than values reported for silica in the literature. Moreover, temperature dependent zeta potential measurements show that zeta potential get less negative as temperature increase. The above mentioned measurements are at odd what has been reported in literature but we have provided plausible explanation of these results.

In the paper presented are the results of laboratory studies on roily oils purification from mechanical impurities and petroleum products using methods and devices designed at the JSC "SSC RF—IPPE." These studies were carried out within the framework of the Agreement on granting. These studies have demonstrated the effectiveness of nanostructured membranes for removal of mechanical impurities from water-oil emulsions and jet-film generator of air bubbles for floatation purification of emulsions from petroleum products. Nanostructured membranes are capable of completely removing mechanical impurities over 0.5 μm in size from model roily oils solutions resulting in neither impurities biofouling, nor pores plugging. Mechanical impurities are accumulated on the surface of the nanostructured membrane, and upon reaching their max permissible amount, regeneration of the membrane is carried out. As a result of regeneration, filtering element capacity is recovered up to 95–97% of its initial value. The possibility of production of finely divided air bubbles (less than 100 μm in size) by the jet-film generator was demonstrated and their high concentration in water was reached. Studies were carried out on the possibility of transport of finely divided air bubbles in the low speed (less than 2 m/min) water flow. The effectiveness of floatation purification method was tested under laboratory conditions by increasing amount of the air bubbles and decreasing their size. Taking into account the roily oils properties, the proposed methods of their purification seem quite promising.

Viscosity measurements at high temperature were made using a concentric cylinder viscometer. These measurements were conducted on a typical lead blast furnace slag, and this master slag doped with various amounts of SiO2, A12O3, CaO, MgO, and/or ZnO. It was found that additions of A12O2 and/or SiO2 increased the viscosity of the master slag over the entire temperature range of interest (1150 °C to 1350 °C). Additions of the basic oxides CaO, MgO, and/or ZnO decreased the viscosity at high temperatures but raised the slag liquidus temperature. The majority of the measured viscosities are accurate within ± 10 pct. The viscosity data of this study, along with that of several similar studies from the literature, were correlated with the weight parameter (WP), a composition-dependent function similar to a basicity ratio. Analytical expressions were developed relating viscosity and the WP at several temperatures between 1150 °C and 1350 °C. Viscosities calculated using these expressions have estimated accuracies of ±1 poise (within certain temperature and composition limits). PbO and ZnO activity coefficient data from the literature were collected and correlated with composition-dependent functions. The calculated activity coefficients are considered accurate within ±0.3 for γpbo and ±0.5 for γzn within certain composition and temperature limits.

This study presents an in-depth computational investigation of the thermohydraulic performance of water-based hybrid nanofluids containing graphene and aluminum oxide (Al₂O₃) nanoparticles. Using computational fluid dynamics (CFD) software, the research focused on understanding the behavior of these nanofluids under turbulent flow conditions in a circular tube. The analysis included examining how various parameters, including the Nusselt number, friction factor, and performance evaluation criteria, were influenced by the addition of nanoparticles. Five different nanoparticle volume concentrations, ranging from 0.1 to 1%, were analyzed. The simulation was conducted for turbulent flow regimes using Reynolds numbers between 20,000 and 80,000. A constant surface heat flux boundary condition was applied to the tube. The k-ε RNG (Renormalization Group) turbulence model was used as it is suitable for capturing turbulence effects in such flows. The thermophysical properties of the hybrid nanofluids were calculated using correlations available in the literature. The addition of graphene and Al₂O₃ nanoparticles significantly increased the Nusselt number, demonstrating enhanced heat transfer performance. The improvement in the Nusselt number was observed across all volume concentrations and Reynolds numbers. The maximum enhancement (28%) was recorded compared to pure water at 1% volume concentration. The friction factor increased with the addition of nanoparticles due to the higher viscosity of the hybrid nanofluids. The highest increase in the friction factor was 7.2% at the maximum volume concentration of 1%. The increase in viscosity contributed to an increased pressure drop in the system. However, the magnitude of this increase was relatively modest compared to the heat transfer benefits. The PEC (Performance Evaluation Criteria) value was found to be greater than 1 in most cases. The highest PEC value of 1.26 was achieved at the lowest Reynolds number (20,000) and the highest nanoparticle concentration (1%). This indicates that the use of the hybrid nanofluid is thermohydraulically advantageous under these conditions. The study concludes that water-based hybrid nanofluids containing graphene and Al₂O₃ nanoparticles enhance heat transfer performance significantly, making them suitable for applications requiring efficient thermal management. The slight increase in flow resistance was outweighed by the substantial heat transfer improvements, particularly at higher volume concentrations and lower Reynolds numbers, as reflected by the favorable PEC values.

The article highlights the urgency of the research of working processes of a self-cleaning filter designed to purify the engine oil in the internal combustion engines. There was carried out experimental modeling of countercurrent regeneration of self-cleaning filters used in fuel preparation and diesel lubrication systems on ships. The layout of the unit for modeling the working processes of self-regenerating filters includes a service tank, a hydraulic motor with a stirrer, a pump, a hydraulic cylinder, a receiver of compressed air, a waste tank, a filtering element, shut-off and pneumatic control equipment, a pollution gauge, a temperature sensor, and other elements. A planning matrix is formed, and the experiment results on evaluating the efficiency of the self-regenerating filters are illustrated. The main factors of the regeneration coefficient are considered. There are presented the dependencies of evaluating the process effectiveness and predicting the life of filters between dry cleanings. The methods of calculating the regeneration parameters of automated filters based on the SRF-60 and SRFD-120 modules have been presented, which allows choosing the hydrodynamic modes and backwash time of filter elements taking into account the operating conditions of oil filters. The influence of the filtering process regeneration efficiency identified by the specific intensity of the removal of the dispersed phase from the oil, hydrodynamics (Reynolds number) and the relative backwash time, the adhesive properties of sludge, the filter design, and dispersion of the pollution are analyzed. The evidence of the validation of the calculated experimental dependences obtained from the laboratory tests of the filter model and their compliance with the results of field tests of self-cleaning filters on ships are presented. The possibility of calculating and adjusting the off-line operation of the self-cleaning filter in the lubrication systems of marine diesel engines is presented subject to diesel forcing, fuel quality and lubricants used, oil aging, additives wear and contamination by coarse-grained mechanical impurities.

For practical testing and detection of electromigration (EM) induced failures in dual damascene copper interconnects in today's and future sub-10nm ICs, one critical issue is how to create stressing conditions so that the chip will fail exclusively under EM in a very short period of time so that EM signoff and validation can be carried out efficiently. In this work, we propose novel EM wearout-acceleration techniques for practical VLSI chips. We will first review the recently proposed three-phase physics-based EM models and discuss the important factors contributing to the EM aging process. Then we propose a new formula for fast estimation of the void's saturation volume for general multi-segment interconnect wires, which is important for EM mortality check. We then investigate two strategies to accelerate the EM failure process: reservoir-enhanced acceleration and temperature-based acceleration. First we show that multi-segment interconnects with reservoir structures and their stressing currents can be exploited to significantly speedup the EM wearout process. Such configurable reservoir-based wires are very flexible and can achieve various EM accelerations at the costs of some routing resources. Additionally, we show that further acceleration can be achieved by increasing temperature. On average, 10% increase in temperature yields about 10X wearout acceleration. However, purely temperature based acceleration is not possible since practical VLSI chips have temperature limitations which must be strictly enforced to ensure the chip only fails under EM, and not due to other reliability effects. In this study, we show that it is possible to achieve significantly high acceleration while staying within the feasible operating zones by combining the two acceleration techniques. Experimental results show that by combining temperature and reservoir accelerations, we can reduce the EM lifetime of a chip from 10 years down to a few hours (about 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> acceleration) under the 150°C temperature limit, which is sufficient for practical EM testing of typical nanometer CMOS ICs.

Homopolyribonucleotides and E. coli DNA wer spin labeled with an iodoacetamide-nitroxide compound. The extent of labeling is highly dependent upon the nature of the base and the secondary structure of the nucleic acid. This spin label-polymer linkage is unstable at high temperatures and in phosphate buffers. In order to determine the effect of changes in the environment of nucleic acids on the esr signals of their attached spin labels, the polynucleotides were subjected to temperature and viscosity perturbations. An increase in temperature (T) affects a linear decrease in the anisotropy factor of the esr signal. The log tau (tau = correlation time) versus (1/T) profile is linear with a positive slope when the spin label is attached to single stranded polynucleotides but exhibits discontinuities at certain critical temperatures when attached to the duplexes poly (As-U) and poly (I-Cs). These critical temperatures are lower than the optical Tm. Logarithmic increase in viscosity was found to produce a linear increase in tau in aqueous sucrose solutions.

The present study investigated the effect of processing on the nutritional, functional, organoleptic and rheological properties of millet and sprouted legumes beverage flavored with jaggery (B1) and buttermilk (B2) for its processing suitability. The millets, sprouted legumes, flavoured with jaggery (B1); and buttermilk and salt (B2), used influenced the suspension stability, nutritional, sensory quality and rheology of beverages. Millets imparted minerals and starch while sprouted legumes improved solubility and extractability of nutrients and also increased the levels of anti-oxidants and flavonoids. Buttermilk improved the stability, increased contents of proteins and minerals and imparted a light colour to the beverage. Jaggery was responsible for caramelized colour and flavor, improved consistency, psuedoplasticity and better organoleptic acceptability. The nutritional quality of B2 was higher in terms of iron (1.8mg/100g) and calcium (75mg/100g) with 90% antioxidant activity. Highest L* values were obtained for B2 indicating lighter color, whereas B1 was darker with lower L* values. Organoleptic evaluation showed higher acceptability (7.6) of B1 as compared to B2. Results of flow behavior indicated pseudo-plastic nature of beverages. Significant increase in viscosity was also observed with the increase in temperature (10, 25 and 45°C) of the beverages. The flow curves of B1 produced the best fit applying the Power law model and for B2, Casson model was the best fit. Results of this study could be used in improvement of the process for making millet-based beverage, design of packaging system and also to predict the flow behavior of beverages during storage.

Background Currently, gas control stations use the gas cleaning systems based on filter net, which is the most cost effective for cleaning purposes. Aims and Objectives Development of a mathematical model to substantiate the value of pressure drop in the mesh-type filter element, at which the filter must be cleaned from mechanical impurities Results In this paper it is proved that the value of the pressure drop at the gas net-type filter element inversely impact on the capital investment into the filter, on the one hand, and on the operating costs associated with the removal of solid particles, on the other hand. On this basis a mathematical model was developed to substantiate the maximum allowed pressure drop in the filter element, caused by gradual clogging of the filter net. The model includes a block diagram, the efficiency function of the integral costs, equations of the balance of expenditure, and limitations of the control parameter. Minimal integral cost of the filter is the taken as a criterion to determine optimum of the efficiency function of the mathematical model. The adopted efficiency function is featured by fractional powers, which makes necessary to solve a complex transcendental equation, and this is a rather time-consuming process of successive iterations. Therefore, to determine the optimal pressure drop across the filter element the numerical method of solving the problem was used, that is, a set of values of the pressure drop with known geometric filter parameters being given, we determine the integral costs. The optimal pressure drop on filter element corresponds to the option with minimal costs. The proposed mathematical model determines the optimal value of the maximum allowable pressure drop on the gas filter.

A laboratory approach on the improvement of oil recovery and carbon dioxide storage capacity improvement by cyclic carbon dioxide injection

Aggregation, viscosity measurements and direct observation of protein coated latex particles under shear