Optimum Inclination Angle Research Articles

The influence of the rake angle on the excavation energy in a sandstone

The inclination of the cutting bits has a strong influence on the excavation energy in rocks. As matter of fact, a correct prediction of the cutting forces acting on the bits is very important to geotechnical engineering. Several cutting tests at 1 m/s cutting velocity (with different rake angles and penetration values) were performed on a sandstone (Ruhrsandstein). The results were interpreted using the models of Evans and Nishimatsu. The optimum angle of inclination which reduces the horizontal cutting forces in this material with this cutting velocity was found to be 49°. The specific excavation energy was also calculated. It was found that it does not change with the penetration, but depends only on the rake angle and on the geotechnical properties of the sandstone.

Structural optimization of re-entrant negative Poisson's ratio structure fabricated by selective laser melting

In this paper, a quantitative optimization of a modified re-entrant negative Poisson's ratio (NPR) structure whose overhanging struts were replaced with inclined ones to avoid the support structures which were generally required in the selective laser melting (SLM) process was carried out using finite element analysis (FEA) method. Poisson's ratios of models with inclined links of different strut inclination angles were calculated. The optimal simulated inclination angle of struts was 9° and the corresponding optimum re-entrant angle was 79° while the thickness of the strut was 0.9mm. The influence of fillet radii on Poisson's ratio and stress concentration was also discussed and the Poisson's ratio decreased and the stress concentration phenomenon remitted to some extent with increased fillet radii. In order to verify the improvement of the manufacturability of structures with inclined links, AlSi10Mg specimens were fabricated by SLM process using different scanning speeds and compression tests were also developed. Experimentally obtained results and simulation predicted ones were in good agreement. Therefore, the custom-tailor service could be accomplished in this way and the modified NPR structure with better surface quality could be obtained.

Numerical study of heat and mass transfer optimization in a 3D inclined solar distiller

A numerical study of the 3-D double-diffusive natural convection in an inclined solar distiller was established. The flow is considered laminar and caused by the interaction of thermal energy and the chemical species diffusions. The governing equations of the problem, are formulated using vector potential-vorticity formalism in its 3-D form, then solved by the finite volumes method. The Rayleigh number is fixed at Ra = 105 and effects of the buoyancy ratio and inclination are studied for opposed temperature and concentration gradients. The main purpose of the study is to find the optimum inclination angle of the distiller which promotes the maximum mass and heat transfer.

Computational fluid dynamics analysis of sponge iron rotary kiln

2D CFD model of rotary kiln of sponge iron process is developed to study the effects of angle of inclination, number of rotation and mass flow rate of iron ore on output parameters. Based on grid independent test for temperature profile optimum mesh size is selected. The result shows that optimum angle of inclination, number of rotation and flow rate of iron ore are found as 2.7 degree, 4.8rpm and 10kg/s, respectively. At these optimum conditions the % metallization is predicted as 89.5%, which is 3.24% less in comparison to the existing system. The temperature profiles of gas and bed are also found within acceptable temperature limits. The results are compared well with the published work as well as industrial data.

Substantiation of installation angle of inclined wall of charging hopper of a root chopper

Tuberous roots obviously benefit in comparison with other feeds, due to the high level of specific volume energy, productivity and good digestibility. When they are mixed with other components, the palatability of finished mixtures for animals increases. The quantity of digestible nutrients in tuberous roots can reach up to 90%. To make the nutrients more fully digested by animals, the correct preparation for feeding is necessary, including chopping. One of the problems of roots cutting process is the increased exudation, which results in undue losses of vitamins. Therefore creation of choppers providing the required quality of finished product is a crucial task. The aim of the research is to determine the optimum angle of inclination of the wall of charging hopper depending on the size of tuberous roots and on the offset of horizontal knife of a chopper. Brief description of the developed chopper of tuberous roots is given, as well as the sources of information containing the detailed description of the installation and its operation principles. In the process of theoretical calculations, the scheme of all forces acting in the moment of tuber pinching between the wall of charging hopper and the horizontal knife is drawn; the chain of discourse and theoretical reasoning are shown in detail. As a result of calculations, the analytical dependences are obtained through which assigning the thickness of slices and sizes of chopped tubers, it is possible to calculate the desired inclination angle of wall of charging hopper. Under estimated values, the tuber does not roll over the cutting knife, and the deformation is minimal. Therefore the exudation decreases, and nutrients losses are minimal. On the basis of the derived dependence, the graphs and their analysis are given.

Experimental investigation of reinforced concrete beams with spiral reinforcement in shear

The use of continuous rectangular spiral shear reinforcement as transverse reinforcement is experimentally investigated by testing 28 reinforced concrete beams in a static four-point bending setup. In this paper two shear span-to-depth ratios (2.5 and 3.0), three spacing (125, 150 and 200mm) and five inclination angle of stirrups (62, 70, 75, 80 and 85°) are adopted. The behavior of the shear-critical beams is studied through monitoring the load–deflection curves, ultimate load values, vertical deflections measurements and crack propagation during static tests. The experimental shear capacity of the beams are compared with analytical values from the design shear formulas of ACI 318M-14 code. Test results clearly indicate that using rectangular spiral shear reinforcement improved the shear capacity and ductility of beams compared with traditional individual closed stirrup beams. Furthermore the results showed that the optimum inclination angle for spiral stirrups is 80°. Accordingly, using rectangular spiral shear reinforcement is recommended because it improves the shear capacity and ductility in beams and can reduce the total cost due to labor costs.

A modified solar desalination system using evacuated tube collector

Solar energy is turning to one of the important types of clean energies, due to its availability, and its potential for wide range of applications. In this work, a new passive solar desalination system is introduced, which benefits from excellences of twin-glass evacuated tube collectors. For the first time, the evacuated tube collector is not only used as the solar thermal collector, but also as a basin to heat the water. Hence, the thermal resistance between the collector and basin is virtually eliminated. Results show a considerable increase in the rate of desalinated water production and the maximum production reaches up to 0.83kg/(m2·h). It was observed that the maximum rate of the production occurs when the tube is in inclination angle of 35°, and filled 80% with water. Moreover, it is seen that filling the tube with a stainless steel wool can enhance the production rate up to 1.01kg/(m2·h). It was observed that optimum inclination angle is 35°, which is the latitude of location of the experiments. Moreover, a theoretical model is presented in order to evaluate the system's efficiency in quasi-steady state conditions.

Use of Oriented Spray Nozzles to Set the Vapor–Air Flow in Rotary Motion in the Superspray Space of the Evaporative Chimney-Type Tower

The present paper considers the problem of upgrading the thermal efficiency of chimney-type evaporative cooling towers due to the rotary motion of the vapor–air flow in the superspray space. To set the vapor–air flow in rotary motion, we propose to use the momentum of the sprayed water. It has been shown that the existing parameters of spray nozzles permit setting up to 30% of the water flow momentum in translatory motion, which is enough for changing considerably the aerodynamics of the vapor–air flow in the superspray space and improving the operation of the cooling tower. The optimal angle of axial inclination of the spray cone has been estimated. Recommendations are given and problems have been posed for engineering realization of the proposed technologies in a chimney-type cooling tower.

Optimizing the Inclination Angle of a Solar PV System for Installation in Slave Lake, Alberta, for Maximizing PV Power Generation

Increasing fossil fuel prices, electricity demand, and global concern for greenhouse gas emissions have generated an increase in research of novel renewable energy technologies for green power generation. Renewable solar-photovoltaic (PV) systems are known fosr their ability to directly convert the solar energy into electrical energy for locations where there is a desperate need and demand for electrical power, e.g. Communities and towns in remote locations, and solar energy is available. PV systems tend to generate more power if they are operated efficiently. The inclination (tilt) angle at which a solar photovoltaic (PV) module is sloped from the horizontal plane is one of the most influencing system parameters that affects the electrical power output from the PV system. This is due to the fact that the variation in the tilt angle affects the amount of incident solar radiation received on a PV system and utilized by the load once installed at a certain site. In this work, a mathematical model is used to estimate the total solar radiation incident on an inclined surface and to determine the optimum inclination angle for maximizing power generation from a solar PV system installed in Slave Lake, Alberta, Canada. The total solar energy received on the optimally inclined PV surface is computed for all months in a year. It was found that the monthly average optimum tilt angle of the PV system varied from a minimum value of 9o in the month of June to a maximum value of 78o in the months of January and December. The yearly average monthly optimum tilt angle for the fixed PV system in Slave Lake was estimated to be at 47o. It was also found that the highest maximum incident radiation of approximately 21.30 Mj/m2 for the whole year occurred in the month of June, where as approximately 30.4% of this value (the lowest in the year) occurred in the month of December. The minimum incident solar radiation for all months in the winter season occurred at almost zero tilt angle and that the variation of the monthly average daily sunlight hours varied from 6.9 hours in December to as high as 17.1 hours in June.

The Effect of Flat Panel Reflectors on Photovoltaic Energy Harvesting in Wireless Sensor Nodes Under Low Illumination Levels

This paper discusses the application of flat panel reflectors in conjunction with photovoltaic cell used to power wireless sensor node. The aim of the reflectors is to increase the indoor ambient light energy harvesting efficiency, especially under low illumination levels (<;200 lx). The benefit of the reflectors usage is in the reduction of the node cold boot time and increase of the data transmission frequency. In addition, the physical placement and orientation of nodes in a wireless sensor network is less dependent on the illumination conditions. This paper presents a simple theoretical model suitable for the calculation of the optimal inclination angle for the reflectors. Experimental data show that the cold boot time can be reduced up to 30% and data transmission frequency increased almost twice by using two reflectors of the same size as the photovoltaic cell. The reflectors are produced in the conventional printed circuit board technology, so they can be incorporated into the node design with negligible costs.

NUMERICAL SIMULATION OF METAL-PLASTIC COMPOSITE HEAT RADIATOR WITH HEMISPHERICAL MICROSTRUCTURE ARRAY

A new type of metal-plastic composite heat radiator with hemispherical microstructure array was proposed in this paper. The influence of the geometrical parameters of the microstructure array, including size of the hemisphere, configuration of hemisphere, tilt angle of the radiator, thermal conductivity and radiation emissivity of the plastic, on the process of heat transfer under natural convection were numerically simulated. It was concluded that the metal-plastic composite heat radiator with hemispherical microstructure array had comparable heat transfer behaviors with those of metal heat radiator. So it is possible to replace metal heat radiator by such a metal-plastic composite heat radiator in case of high moisture or corrosion applications. Under the same volume, the cooling capacity of the heat radiator made of metal-plastic was 20 times as the heat radiator made of metal. The heat flux of plastic plate with hemispherical microstructure was superior to the ordinary flat plastic plate. And the former heat flux was 2050 W/m 2 , about two times as the latter, 1272W/m 2 . The optimal inclination angle of the heat radiator with maximum heater flux was around 45°.

Optimal Photovoltaic Resources Harvesting in Grid-connected Residential Rooftop and in Commercial Buildings: Cases of Thailand

Photovoltaic (PV) has recently undergone impressive growth and substantial cost decreases. A single-crystal silicon (mono-Si) or polycrystalline (poly-Si) have been dominant for solar rooftop and in commercial buildings installation in the past years. However until recently thin-film PV modules both amorphous silicon (a-Si) and other non-silicon thin films technology have been advance efficiency developments with low cost. The competition of crystalline and thin film solar panel technologies drives the cost significantly decreased and helps the solar investors for a good financial profit return for a shorter time. This study by satellite-derived data, Solar GIS pvPlanner software shows that the highest output is in a-Si, CdTe and followed by CIS, and c-Si PV modules for the locations considered in this study. The average energy output of amorphous panels in residential solar rooftop installed in Bangkok has the highest values of 1,503 kWh/kWp. The average energy output of amorphous panels in commercial building installed in Chonburi province has the highest values of 1,601 kWh/kWp. The optimal inclination angle is 15° south direction in both areas. Finally, the economic assessment of solar panels is also investigated for the feasibility investment by RETscreen model.

A new folded plate membrane module for hydrodynamic characteristics improvement and flux enhancement

Abstract To intensify the air scouring efficiency and reduce the membrane fouling, a new folded plate membrane module (FPMM) was designed by modifying the configuration of conventional flat sheet membrane module (FSMM). The hydrodynamic characteristics near the folded plate membrane surface, and its filtration performance in different operating conditions were studied. The particle image velocimetry (PIV) measurement results showed that, the higher flow velocity, the stronger turbulence, and more vortices existed near the folded plate membrane surface. The stable flux of the FPMMs had an increase of 17.8–57.7% over that of the FSMM, and the optimal vertical inclination angle was 15°. Moreover, in the filtration process, the flux enhancement of the FPMM was affected by the aeration intensity, yeast suspension concentration and trans-membrane pressure (TMP).

An approach to optimization of double slope solar still geometry for maximum collected solar energy

This investigation represents the optimum inclination angles of the glass cover of the double slope solar still, and orientation for maximum collected solar energy that could be captured by the solar still glass cover. The results will be displayed for different latitudes (ϕ=24°, ϕ=27.2°, ϕ=30° and ϕ=31.2°) to cover Egypt geographically. The double slope solar still has two opposite inclined surface; so it has two surfaces azimuth angles (γ1 and γ2) according to |γ1|+|γ2|=180°, with opposite signs, these values are (γ1=0° and γ2=180°), (γ1=90° and γ2=−90°), (γ1=45° and γ2=−135°) which is equivalent to (γ1=−45° and γ2=135°); consequently, the total energy is the summation of the collected energy by the two surfaces represents the double slope solar still surface area. The inclination angle (β) is changed from 10° to 60° on both sides of the glass cover to get independently the optimum inclination angles for each side that not necessary to be the same.

Impact of speed, direction, and accuracy of diffractive optical element shift on efficiency of speckle suppression

The impact of the precision and direction of motion of a diffractive optical element (DOE) placed inside an optical system on the efficiency of speckle suppression is analyzed. A simple model for calculating the speckle suppression efficiency in systems having a moving DOE and a random diffuser is developed. Simulation results show that at the optimal inclination angles of a regular 2D DOE and at sufficiently rapid displacement (at least N DOE periods), the speckle contrast exhibits a broad minimum. At angles that differ significantly from the optimal values, the speckle contrast varies rapidly and has peaks that exceed the minimum value by several tens of percent. For certain DOE inclination angles, the speckle contrast is several times higher than the minimum value.

Froude number dominates condensation heat transfer of R245fa in tubes: Effect of inclination angles

Condensation heat transfer of R245fa in a tube with the diameter of 14.81mm and length of 1200mm was investigated. The R245fa mass fluxes, inlet vapor mass qualities and inclination angles covered the ranges of 191.3–705.4kg/m2s, 0.191–0.947 and −90° to 90°, respectively. The non-dimensional analysis yielded the importance of inertia force and gravity force to influence condensation heat transfer. Surface tension force played unimportant role. Condensation heat transfer coefficients (h) showed the general increase trend versus inclination angles (θ) and the non-monotonic behavior in the full inclination angle range. The maximum h occurred at θ=30° and −15°. The h values were sensitive to θ near the horizontal positions. The main flow patterns in the condenser tube were stratified-smooth flow, stratified-wavy flow and intermittent flow. For inclined upflow, the liquid layer thickness and interface wave competed with each other to influence heat transfer. An optimal inclination angle existed at which heat transfer coefficients reached maximum. For inclined downflow, condensation heat transfer was balanced by the liquid layer thickness and buoyancy force. The flow was more stable. Heat transfer coefficients were well correlated with the general increase term multiplied by the non-monotonic variation term. The parameters in the correlation depended on the Froude number and vapor mass qualities. The correlation successfully explained the effects of mass fluxes, vapor mass qualities and inclination angles on condensation heat transfer coefficients. Based on the present finding, the condenser is recommended to operate at the inclination angle of −15° or 30°, at which heat transfer coefficients are maximum and pressure drops are minimum. The exactly horizontal flow weakens the condenser performance.

Induced flow for ventilation and cooling by a solar chimney

An experimental and numerical model of a solar chimney was proposed in order to predict its performance under varying geometrical features in Iraqi environmental conditions. Steady, two dimensional, turbulent flow was developed by natural convection inside an inclined solar chimney. This flow was investigated numerically at inclination angles 15° to 60°, solar heat flux 150–750 W/m2 and chimney thickness (50, 100 and 150) mm. The experimental study was conducted using a single solar chimney installed on the roof of a single room with a volume of 12 m3. The chimney was 2 m long; 2 m wide has three gap thicknesses namely: 50, 100 and 150 mm. The performance of the solar chimney was evaluated by measuring the temperature of its glass cover, the absorbing wall and the temperature and velocity of induced air. The results of numerical model showed that; the optimum chimney inclination angle was 60° to obtain the maximum rate of ventilation. At this inclination angle, the rate of ventilation was about 20% higher than 45°. Highest rate of ventilation induced with the help of solar energy was found to be 30 air changes per hour in a room of 12 m3 volumes, at a solar radiation of 750 W/m2, inclined surface angle of 60°, aspect ratio of 13.3 and chimney length of 2 m. The maximum air velocity was 0.8 m/s for a radiation intensity of 750 W/m2 at an air gap of 50 mm thickness. No reverse air flow circulation was observed even at the largest gap of 150 mm. The induced air stream by solar chimney can be used for ventilation and cooling in a natural way (passive), without any mechanical assistance.

The effect of four flat plate reflectors on light energy-harvesting system characteristics

In this paper, the effect of four flat panel reflectors (bottom, top, left and right side reflectors) on the total light radiation on a small-size photovoltaic cell is analyzed. An analytical model for the determination of the optimum inclination angle of the reflectors with respect to the cell?s horizontal surface is presented. The optimal angle was calculated to be 66?. The calculated value was experimentally verified by measuring the short-circuit current of the cell. It was shown that the increase in the short-circuit current of the cell with reflectors in the optimal position was about 60% for the illumination levels between 10 lx and 1000 lx. The cell with reflectors was used to charge the primary capacitor in the energy harvesting circuitry of the wireless sensor node and it was demonstrated that the time needed for the cell to charge the primary capacitor could be reduced 35-40%.

Energy-Efficient Modernization of the Nobel’s Mansion in Saint Petersburg: Solar Energy Supply Potential

The mansion of the Nobel family is one of the most featured world recognized monuments of the city of Saint-Petersburg. The article deals with a reconstruction option of the Nobel’s mansion space aimed at gaining extra area to be used for the purpose of solar power generation. Photovoltaic systems are suggested to be used as an alternative energy resource to ensure in-house demand for heating. Inputs of solar radiation on the surfaces oriented in different directions have been estimated herein. A computation method and estimations for energy production of PV-modules placed under conditions of partial shading cased by the building’s wings have been presented herein as well. An optimal inclination angle of the modules with respect to the horizon, which can ensure maximum energy gains under weather conditions of Saint-Petersburg, has amounted to 35°.

On the natural convection heat transfer in a rectangular passage solar air heater

This paper presents and discusses the experimental measurements versus the results from the available correlations in the literature that are commonly used to predict the free convection heat transfer coefficient between the surfaces and the flowing air. The experimental investigations were accomplished using a rectangular duct comprising a flat plate-glass cover as the solar air heater with the following dimensions: 0.48-m width×0.07-m depth×2-m length. The absorber plate was made of 1-mm gauge of aluminium. The measurements were performed at inclination angles of 30°, 50°, and 70° to determine the optimum angle of the absorption-free convection mechanism in a solar air heater. The comparison is presented and discussed in terms of the Nusselt number. The optimum inclination angle to achieve the best collector performance was found to be 50°. The results of the present work can assist in resolving the issue of predicting the free convection in thermal passages.