Effect of CO2 Laser on Glazed Zircon Surface Complemented by ZrO2 Oxide

In this paper, the effect of CO2 laser on glaze-dental Zirconia ceramics after adding ZrO2 nanoparticles to glaze is introduced, and its improvement methods are studied. Specimens have been prepared using CAD/CAM dental machines and sintered at 1530o-C. Then the surface was glazed with VITA glaze plus (5% and 10%) Nano ZrO2. A 15W continuous CO2 laser was used as the indicator power to irradiate the glaze layer. The main phase of the ceramic substrate is tetragonal Zirconia, and the alumina content in the corundum phase is a certain percentage. The appearance of the varnish on the ceramic substrate changes the X-ray diffraction pattern through the appearance of new phases, which changes the crystallite size and the percentage of lattice strain. The range of grain size measured by atomic force microscopy was 88.46 nm to 62.18nm. In addition, the surface roughness was changed due to the appearance of crystal cores and grain growth. In addition, the addition of ZrO2 and laser irradiation changed the residual stress on the surface, which was reflected in the hardness value increased from 575 kg/mm2 to 1215 kg/mm2 after the laser treatment with the addition of 5% ZrO2. Generally, in terms of the structure and hardness of the surface of the glaze layer, the addition of 5% ZrO2 is better than 10%. SEM tests also showed no cracks in the central part of the treated area. These characteristics increase hardness.

Experimental detection of mechanical efficiency of marine diesel engines

The article summarizes the results of heat engineering tests of diesels used in the educational process of Volga State University of Water Transport and its branches. Although the test goals were different in each case, the indicator diagrams of the working process in each cylinder were recorded in the course of the tests. Analysis of indicator diagrams helped to determine the indicator power of the engine in each case. By comparing the indicator parameters with the corresponding effective ones there was performed the estimation of the mechanical efficiency of each engine at different speeds of rotation of the crankshaft. The studies were carried out on engines of brands 6NVD48AU, 6L275RrII/PN, 8NVD36U, 6L160PNS. It was found that in almost all cases, mechanical losses included fan losses in load devices and friction losses in their bearings. The concept of a screw characteristic is considered. A graph of the propeller characteristics in relative units for various types of engines is built. It is noted that it is very difficult to set a specific value of the crankshaft speed required for testing, the actual points will be close to the theoretical ones, shifting along the helical characteristic. An algorithm for testing and processing the results is presented. There have been analyzed the dependences covered in literature (analytical and statistical) for determining the mechanical efficiency.

Efficiency Control Improvement Of Diesel Engines Conditions By Using The Method Of Analytical Synchronization Of Monitored Data

Improving the efficiency of the ship's diesel power plant is becoming increasingly important every year. This is primarily due to the restrictions on emissions of sulfur and nitrogen oxides into the atmosphere during the operation of the ship's diesel engines. Article is devoted to the problem of synchronization of data monitoring working process in transport diesel engines operation. The accuracy of data synchronization determines the error in determining power, control of the main engine systems operation and its diagnostics. The method of solving the synchronization problem must be analytical. The method of solving the synchronization problem must be analytical. In comparison the hardware methods used in most diagnostic systems of the working process of diesel engines have several disadvantages. It is impossible to conduct rapid diagnostic control in operation, non-stationary phase and amplitude errors in calculation the main parameters of the working process, the need for preparatory operations and related need for temporary withdrawal of diesel engine operation, complexity and high cost of diagnostic control. An analytical synchronization method is developed based on the top dead center coordinate determination algorithm, which uses three stages: linear, sinusoidal and model equal to zero the first derivative of the pressure under compression. The proposed method of analytical synchronization gives the obvious advantages for monitoring working process systems of diesel engines. The error in determining the main parameters of the working process and the indicator power does not exceed 2.5%.

An Analysis of Power Characteristics of Oil-Free Scroll Vacuum Pumps

This paper presents an analysis of the indicator power of an oil-free scroll vacuum pump based on the indicator diagrams obtained through high-speed pressure sensors. These values are compared with the results of calculations using a mathematical model of the pump working process. It is shown that the divergence of the calculated results and experimental values does not exceed 4%, which confirms the adequacy of the developed mathematical model. The total power of the scroll pump exceeds the indicator power by more than 2 times due to the friction losses between the face seals and disks of the reciprocal scroll elements, friction losses in the stuffing box seals and rolling bearings, as well as due to the coefficient of efficiency of the motor. The influence of the radial clearance between the scroll elements on the power consumption is considered. It is shown that at low pressures nearing the ultimate pressure, the power increases with the increased clearance, while at inlet pressures exceeding 40 kPa it decreases. The performed analysis can be used for selecting the optimal geometrical parameters of the scroll elements and increasing power efficiency of the pump depending on specific operating conditions.

PENGARUH TEKANAN POMPA BAHAN BAKAR TEKANAN TINGGI TERHADAP KINERJA MESIN

AbstrakPenelitian ini dilakukan untuk mengetahui pengaruh pompa injeksi bahan bakar tekanan tinggi terhadap kinerja sebuah mesin pada mesin penggerak utama MV. ALAM JAYA II yang menggunakan mesin diesel YANMAR type M22-EN. Berdasarkan data-data yang diperoleh dilapangan, setelah dilakukan pembahasan bahwa tekanan pompa injeksi berpengaruh pada kinerja mesin diesel. Untuk tekanan pompa injeksi sebesar 820 kgf/cm2, kinerja yang dihasilkan mesin adalah : Daya Indikator 1204 kgf/cm2, Daya Efektif 1016 kgf/cm2, Efisiensi Thermal Efektif 32,0% dan konsumsi bahan bakar spesifik sebesar 192 g/hp.h. Sedangkan setelah dilakukan perbaikan pompa injeksi, tekanan pompa menjadi 1120 kgf/cm2, kinerja yang dihasilkan oleh mesin adalah : Daya efektif 1399 hp, Daya Efektif 1195 hp, Efisiensi Thermal Efektif : 37.32%, dan Konsumsi Bahan Bakar Spesifik sebesar 165.7 g/hp.h Dengan adanya perbaikan pompa injeksi sehingga dapat menaikkan tekanan injeksi dari 880 kgf/cm2 menjadi 1120 kgf/cm2, maka kinerja mesin dapat ditingkatkan Kata kunci: mesin diesel,pompa injeksi, kinerja mesin AbstractThis research was conducted to determine the effect of high pressure fuel injection pump on the performance of a machine on the MV main drive engine. ALAM JAYA II which uses the YANMAR type M22-EN diesel engine. Based on the data obtained in the field, after discussion that the injection pump pressure affects the performance of the diesel engine. For injection pump pressure of 820 kgf /cm2, the engine performance is: Indicator Power 1204 kgf /cm2, Effective Power of 1016 kgf /cm2, Effective Thermal Efficiency of 32.0% and specific fuel consumption of 192 g / hp.h. Whereas after the injection pump repairs, the pump pressure becomes 1120 kgf / cm2, the performance produced by the engine is: Effective 1399 hp, Effective 1195 hp, Effective Thermal Efficiency: 37.32%, and Specific Fuel Consumption of 165.7 g / hp. H With the improvement of the injection pump so that it can increase the injection pressure from 880 kgf / cm2 to 1120 kgf /cm2, the engine performance can be improvedKeywords: diesel engine, injection pump, engine performance

WORKING PROCESS OF INTERNAL COMBUSTION ENGINE RUNNING ON ENRICHED HYDROGEN GASOLINE-AIR MIXTURE

The effect of hydrogen additives on the working process of a piston-type gasoline engine is studied. The indicator diagram has been built, and the operation of the piston engine on gasoline-air mixtures enriched with hydrogen in the amount of 0…20 % of the volume of air entering the engine has been analyzed. The possibility of obtaining satisfactory parameters when the engine works on gasoline with hydrogen additives is shown. The dynamics of the engine performance is studied depending on the oxidant excess coefficient. It has been established that the oxidizer excess ratio at which the maximum indicator pressure is reached is moved to the zone of poor mixtures. When the mixture is enriched with hydrogen in the amount of 20 % of the air volume, the maximum of indicator pressure pimax = 5.3...5.8 MPa is reached at α = 1.15...1.25, while for 10 % hydrogen addition the maximum pimax = 4.9...5.2 MPa takes place at α = 1.05...1.10 against pimax = 4.7...5.1 MPa at α = 0.90...0.95 for pure gasoline. According to the indicator diagram, the dynamics of intra-cylinder parameters is studied when the mixture is enriched with hydrogen. Thus, with a 20 % hydrogen addition the mean indicator pressure decreases by 12...19 %, despite a slight increase in the maximum cycle pressure (3...18 %), compared with gasoline operation, which leads to a proportional decrease in both the engine indicator power, and the indicator efficiency.