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1.
The combustion and heat release of engines using diesel fuel and bio-diesel fuel have been investigated. The results illustrate that the combustion happens in advance and the ignition delay period is shortened. The initial heat release peak declines a little, the corresponding crankshaft angle changes in advance, and the combustion duration is prolonged. The economic performance and emission features of diesel engines using diesel fuel and bio-diesel fuel are compared. The results also show that the specific fuel consumption of bio-diesel increases by about 12% .The emissions, such as CO, HC, and particulate matter decrease remarkably whereas NO x increases a little. 相似文献
2.
One of the most important basic requirements of diesel-powered vehicles that they have lower pollutant emissions and fuel consumption. In diesel engines, combustion and engine performance are influenced by the physical and chemical properties of the used fuel. Engine design studies are not enough to increase engine performance and reduce exhaust emissions alone. By adding fuel additives in diesel fuel, the physical and chemical properties of the fuel can be improved. Fuel additives affect engine performance, combustion and emissions positively by exerting catalyst effect during combustion. In this study, n-hexane and n-hexadecane were added in diesel fuel (D0) by volume of 4, 12 % and 20 %. With respect to D0 fuel, in DHD20 and DHX20 fuels engine torque increased by 1.60 % and 1.32 %, respectively, while the brake specific fuel consumption decreased by 3.12 % and 1.98 %, respectively. Maximum cylinder pressures and heat release rate values of the ingredient added fuels increased. It was seen that NOx emissions increased while HC, CO and soot emissions decreased with increasing contribution ratio. 相似文献
3.
Due to the shortage of petroleum products and its increasing cost, efforts are on to develop alternate fuels, especially diesel oil, for partial or full replacement. Also, internal combustion engines generate undesirable emissions during combustion process. The emissions exhausted in to the surroundings pollute the atmosphere and causes several problems. The emissions of concern are: unburnt hydrocarbons, oxides of carbon, and oxides of nitrogen (NO X). Advanced diesel fuel formulations offer significant emission reductions to new and older in-use engines every time the fuel tank is filled. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation. The incorporation of water also reduces NO X emissions by lowering the peak combustion temperatures through high heat of vaporization. When using water blend diesel, the engine fuel system recognizes the liquid as diesel fuel because the water droplet is encapsulated within a diesel fuel. In this experiment, we have used single cylinder four-stroke engine and the water-blend diesel emulsion is used and the diesel emission test, emulsion emission test, and various gases has been analyzed; smoke meter test is also conducted for various rate of loads. The test results from the engine fuelled with water-blend diesel showed reduction in emissions as compared to that of engine fuelled with conventional diesel. The better emissions in the CI engine using water-blend diesel is due to the incorporation of water which reduces NO X emissions by lowering the peak combustion temperatures. Water-blend fuel enhances fuel atomization by micro-explosion. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation 相似文献
4.
The cutting heat dissipation in chips, workpiece, tool and surroundings during the high-speed machining of carbon steel is
quantitatively investigated based on the calorimetric method. Water is used as the medium to absorb the cutting heat; a self-designed
container suitable for the high-speed lathe is used to collect the chips, and two other containers are adopted to absorb the
cutting heat dissipated in the workpiece and tool, respectively. The temperature variations of the water, chips, workpiece,
tool and surroundings during the closed high-speed machining are then measured. Thus, the cutting heat dissipated in each
component of the cutting system, total cutting heat and heat flux are calculated. Moreover, the power resulting from the main
cutting force is obtained according to the measured cutting force and predetermined cutting speed. The accuracy of cutting
heat measurement by the calorimetric method is finally evaluated by comparing the total cutting heat flux with the power resulting
from the main cutting force.
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Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(11): 1–4 [译自: 华南理工大学学报(自然科学版)] 相似文献
5.
Owing to the increasing cost of petroleum products, fast depletion of fossil fuel, environmental consideration and stringent emission norms, it is necessary to search for alternative fuels for diesel engines. The alternative fuel can be produced from materials available within the country. Though the vegetable oils can be fuelled for diesel engines, their high viscosities and low volatilities have led to the investigation of its various derivatives such as monoesters, known as bio diesel. It is derived from triglycerides (vegetable oil and animal fates) by transesterification process. It is biodegradable and renewable in nature. Biodiesel can be used more efficiently in semi adiabatic engines (Semi LHR), in which the temperature of the combustion chamber is increased by thermal barrier coating on the piston crown. In this study, the piston crown was coated with ceramic material (TiO 2) of about 0.5 mm, by plasma spray method. In this present work, the experiments were carried out with of Pongamia oil methyl (PME) ester and diesel blends (B20 & B100) in a four stroke direct injection diesel engine with and without coated piston at different load conditions. The results revealed 100% bio diesel, an improvement in brake thermal efficiency (BTE) and the brake specific fuel consumption decreased by about 10 % at full load. The exhaust emissions like carbon monoxide (CO) and hydrocarbon (HC) were decreased and the nitrogen oxide (NO) emission increased by 15% with coated engine compared with the uncoated engine with diesel fuel. The peak pressure and heat release rate were increased for the coated engine compared with the standard engine. 相似文献
6.
The transient thermo-elastohydrodynamic (TEHL) lubrication simulation and isothermal elastohydrodynamic (EHL) simulation were
performed on the exhausting camtappet friction pair of an internal combustion engine. Although by employing the two models
the center pressure, the thickness of the lubricant film and friction coefficient obtained were similar in the changing trend
during a rotating cycle, the parameters make a great difference, especially for the thickness of the lubricant film; the TEHL
was four times thicker than the EHL. These results show that the temperature should not be neglected in the study of the lubrication
of cam-tappet pairs.
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Translated from Tribology, 2006, 26(4): 362–366 [译自: 摩擦学学报] 相似文献
7.
Ammonium aluminum carbonate hydroxide (AACH) was prepared by a precipitation-azeotropic distillation method, which uses aluminum
sulfate as the Al source and ammonium carbonate as the precipitant. Then, AACH was calcined into ultrafine α-Al 2O 3 powder. The factors that influence the dispersion property of ultrafine α-Al 2O 3 powder are discussed in this paper, such as the methods of adding materials, surfactant, and drying methods. The changes
of the structure and property of ultrafine alumina in the thermal treatment process are also studied. The morphological structure
and properties of AACH are characterized by DTA/TGA, SEM, XRD, and ICP measurements. The results show that ultrafine α-Al 2O 3 powder with a uniform particle size and well-distributed property can be synthesized only after aluminum sulfate atomizes
into ammonium carbonate, proper amount of PEG1000 is added as the dispersant, and the product is treated by azeotropic distillation.
The phase transformation of alumina during the calcination process can be described as amorphous Al 2O 3→γ-Al 2O 3→ϑ-Al 2O 3→α-Al 2O 3. The crystal grain size and density of ultrafine alumina powder increase with the increase of the calcination temperature.
After AACH has been calcined at 1200°C for 2 h, the ultrafine α-Al 2O 3 with uniform particle size, spherical shape, and more than 99.97% purity is obtained and its powder is well dispersed.
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Translated from Journal of Hunan University of Science & Technology (Natural Science Edition), 2007, 22(2): 35–39 [译自: 湖南科技大学学报(自然科学版)] 相似文献
8.
Based on the Darcy fluid model, by considering the effects of viscous dissipation due to the interaction between solid skeleton
and pore fluid flow and thermal conduction in the direction of the fluid flow, the thermally developing forced convection
of the local thermal equilibrium and the corresponding thermal stresses in a semi-infinite saturated porous plate channel
are investigated in this paper. The expressions of temperature, local Nusselt number and corresponding thermal stresses are
obtained by means of the Fourier series, and the distributions of the same are also shown. Furthermore, influences of the
Péclet number ( Pe) and Brinkman number ( Br) on temperature, Nusselt number ( Nu) and thermal stress are revealed numerically.
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Translated from Journal of Lanzhou University (Natural Science Edition), 2006, 42(2): 114–119 [译自: 兰州大学学报(自然科学版)] 相似文献
9.
A dynamical sliding-mode controller is devised to track the output of mobile manipulators. During the investigation, firstly
a reduced dynamic model considering the dynamics of the driving motor is developed for mobile manipulators. Then, the system
is decomposed into four lower-dimensional subsystems by means of diffeomorphism and nonlinear input transformation. Moreover,
a design method of the dynamical sliding-mode controller that is applied to the output tracking of mobile manipulators is
proposed. The simulation results indicate that the dynamical sliding-mode controller can not only track the given trajectory
correctly but also reduce the chattering of sliding-mode control system considerably.
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Translated from Journal of South China University of Technology ( Natural Science Edition), 2006, 34(6): 29–33 [译自: 华南理工大学学报 (自然科学版)] 相似文献
10.
An energy reclaiming suspension is proposed to reclaim vibration energy in the suspension. To study its riding performance
and reclaiming energy performance, a hydraulic energy reclaiming device prototype is produced and its mechanical behavior
is analyzed and tested according to the hydraulic theory. Theoretical analysis shows that mechanical behavior of the energy
reclaiming device is embodied by a viscidity damping parameter and an analogous coulomb damping parameter determined by its
structure; their expressions are obtained. Experimental investigation shows that theoretical predictions agree with test results.
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Translated from Journal of Jiangsu University (Natural Science Edition), 2006, 27(1): 35–39 [译自: 江苏大学学报(自然科学版)] 相似文献
11.
A blind identification method was developed for the threshold auto-regressive (TAR) model. The method had good identification
accuracy and rapid convergence, especially for higher order systems. The proposed method was then combined with the hidden
Markov model (HMM) to determine the auto-regressive (AR) coefficients for each interval used for feature extraction, with
the HMM as a classifier. The fault diagnoses during the speed-up and speed-down processes for rotating machinery have been
successfully completed. The result of the experiment shows that the proposed method is practical and effective.
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Translated from Journal of Tsinghua University (Science and Technology), 2005, 45(8): 1 036–1 039 [译自: 清华大学学报(自然科学版)] 相似文献
12.
It seems very difficult to comply with upcoming stringent emission standards in vehicles To develop low emission engines,
better quality of automotive fuels must be achieved Since sulfur contents in diesel fuels are transformed to sulfate—laden
particulate matters as a catalyst is applied, it is necessary to provide low sulfur fuels before any Pt-based oxidation catalysts
are applied In general, flash point, distillation 90% and cetane index are improved but viscosity can be worse in the process
of desulfunzation of diesel fuel Excessive reduction of sulfur may cause to degrade viscosity of fuels and engine performance
in fuel injection systems This research focused on the performance of an 11,000 cc diesel engine and emission characteristics
by the introduction of ULSD, bio-diesel and a diesel oxidation catalyst, where the bio—diesel was used to improve viscosity
of fuels in fuel injection systems as fuel additives or alternative fuels 相似文献
13.
This paper presents an optimization model for rotor blades of horizontal axis wind turbines. The model refers to the wind
speed distribution function on the specific wind site, with an objective to satisfy the maximum annual energy output. To speed
up the search process and guarantee a global optimal result, the extended compact genetic algorithm (ECGA) is used to carry
out the search process. Compared with the simple genetic algorithm, ECGA runs much faster and can get more accurate results
with a much smaller population size and fewer function evaluations. Using the developed optimization program, blades of a
1.3 MW stall-regulated wind turbine are designed. Compared with the existing blades, the designed blades have obviously better
aerodynamic performance.
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Translated from Journal of Shantou University ( Natural Science), 2006, 21(1): 44–49 [译自: 汕头大学学报 (自然科学版)] 相似文献
14.
The high-speed double wire pulse metal-gas arc (MAG) welding process possesses advantages of automation and high efficiency
and quality. Thus, it attracts much more attention nowadays. To meet the requirements of the double wire pulse MAG welding
process, a novel double wire pulse MAG welding inverter integrated with technologies, such as soft-switching, double closed
loop control, and synchronic control, is produced. A complete performance test was done for the pulsed MAG welding power supply
by using a computer testing platform. The results of the experiment indicate that the novel welding inverter has an excellent
performance both in the dynamic and the static characteristics. Also, the synchronic control between the master inverter and
the slave inverter is reliable.
Translated from Journal of South China University of Technology ( Natural Science Edition), 2006, 34(7): 31–34, 59 [译自: 华南理工大学学报 (自然科学版)] 相似文献
15.
To precisely implement the force control of robot manipulators in an unknown environment, a control strategy based on fuzzy
prediction of the reference trajectory in the impedance model is developed. The force tracking experiments are executed in
an open-architecture control system with different tracking velocities, different desired forces, different contact stiffnesses
and different surface figurations. The corresponding force control results are compared and analyzed. The influences of unknown
parameters of the environment on the contact force are analyzed based on experimental data, and the tunings of predictive
scale factors are illustrated. The experimental results show that the desired trajectory in the impedance model is predicted
exactly and rapidly in the cases that the contact surface is unknown, the contact stiffness changes, and the fuzzy force control
algorithm has high adaptability to the unknown environment.
Translated from Journal of Northeastern University ( Natural Science), 2005, 26(8): 766–769 [译自: 东北大学学报 (自然科学版)] 相似文献
16.
The volume of an in-tube micro robot is small and its interior space is very limited. However, conventional transmission methods
are unfit to drive in-tube micro robots. A novel micro drive mechanism called the micro-elastic-meshing-wheel is presented
in this paper. It can be used for transmitting power and locomotion between two shafts, which are upright and cross in a micro
space. The mechanical model of the novel drive mechanism is built, and the maximal transmission force is deduced. Then, sufficient
experiments are carried out to test maximal transmission force produced by the novel drive mechanism. The calculation and
experiment results show that the novel drive mechanism can transmit sufficient power to in-tube micro robots.
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Translated from Journal of South China University of Technology (Natural Science Edition), 2006, 34(7): 45–49 [译自: 华南理工大学学报 (自然科学版)] 相似文献
17.
Fracture is a common defect in sheet metal forming and it is essentially caused by tensile instability. This paper analyzes
some experiments and theories for building forming limit diagrams of sheet metal and points out the advantages and disadvantages
of current experiments and theories. According to this, a method that integrates the finite element simulation and experiment
was used to research the forming limit diagrams of the sheet metal under complex strain paths. Taking the rear hanger that
undergoes twice stamping as an example, the strain paths of the dangerous point of the rear hanger is investigated. Finally,
the forming method of the rear hanger is confirmed. Results indicate that finite element method (FEM) can achieve the complex
strain paths and different strain paths will have great impacts on the result of the sheet metal forming.
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Translated from Journal of Jiangsu University ( Natural Science Edition), 2005, 26(4): 289–293 [译自: 江苏大学学报 (自然科学版)] 相似文献
18.
To satisfy the needs of the high deep-width ratio and thickness of a planar micromotor’s stator windings, a process method
to produce an electromagnetic planar micromotor with AZ4903 is proposed. Optimum relationships, such as the desired rotation
speed vs. thickness of the coating process, and the temperature vs. time of pre-baking, are obtained. The appropriate time
of lithography and development are also achieved. The thickness of the produced windings is 40 μm with ideal perpendicularity.
Finally, stators and rotors are fabricated. The rotation speed and pull-out torque of the micromotor are tested. The experiment
proved that the micromotor worked with a steady speed and a low ripple of pull-out torque.
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Translated from J Tsinghua Univ (Sci & Tech) 2005, 45(8): 1062–1065 [译自: 清华大学学报(自然科学版)] 相似文献
19.
A two-degree-of-freedom (2-DOF) steering model of multi-axle vehicle was established. The steering center position, the relationship
between the steering angle and the vehicle velocity, and the minimum turn radius were deduced on the basis of the proportional
control with a zero sideslip angle. Results indicate that the system stability is decided by the vehicle barycenter position
and the lateral stiffness of a tire. Under this control, the steady value of the lateral acceleration is obviously diminished
and the yaw angular velocity changes little under any vehicle velocity. The system rapidly responds, the vehicle smoothly
steers, and its handling stability is prominently improved.
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Translated from Journal of Jilin University, 2006, 36(3): 321–326 [译自: 吉林大学学报] 相似文献
20.
A mathematical model for fuel optimal control and its corresponding dynamic programming (DP) recursive equation were established
for an existing parallel hybrid electric vehicle (HEV). Two augmented cost functions for gear shifting and engine stop-starting
were designed to limit their frequency. To overcome the problem of numerical DP dimensionality, an algorithm to restrict the
exploring region was proposed. The algorithm significantly reduced the computational complexity. The system model was converted
into real-time simulation code by using MATLAB/RTW to improve computation efficiency. Comparison between the results of a
chassis dynamometer test, simulation, and DP proves that the proposed method can compute the performance limitation of the
HEV within an acceptable time period and can be used to evaluate and optimize the control strategy.
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Translated from Journal of Shanghai Jiaotong University, 2006, 40(6): 947–951, 957 [译自: 上海交通大学学报] 相似文献
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