ملخص البحث :

In centrifugal pumps, the flow physics and dynamic performances are generally affected by any modification in blades shape and design layout. The investigations of estimating the optimum impeller geometry and the appropriate number of blades with a fitting angle need to find a better insight. At the present time, the dominant verification method used for investigation these characteristics are numerical simulation. Commercial code Fluent (CFD) under ANSYS software has been used for investigation the working characteristics of pump impeller under different conditions by using two different geometrical models. For these purposes, two different impellers with different blades number in 3D configuration are designed by using single arc curved blades design method and submitted for analysis and simulation to determine the best characteristics through comparison procedure. Conventional impeller case used as a base for comparison purposes during recording any changes associated with each individual case such as heads, flow rates and efficiency. The solution of dynamic analysis is carried out to approve that impeller structure can resist and withstand many variable loads and turbulent conditions. Results approved that, the static pressure, total head and efficiency are proportional with blades numbers and blades geometry. Even more, it is found that there are some important parameters have some effects on centrifugal pump performance such as inlet diameter of impeller and blades angle. It can be concluded from this works that suitable predicted results are estimated, and these analyzed results can used and adopted for this type of centrifugal pumps. 

ملخص البحث :

Biodiesel fuels are used as an alternative fuel in internal combustion engines. In this study, the damaged vegetable oil (the vegetable oil after using in cooking) was mixing with methanol to produce biodiesel fuels and tested in a single cylinder 4- stroke engine. Gases emission and engine performance were recorded at constant speed and five load conditions. This experimental study measured NOx, CO, CO2 and O2 at the different biodiesel concentration. The emissions of gases and the performance of engine measured at five blending biofuels and five load conditions and at constant speed. The blending ratios of biodiesel with diesel fuel based by volume were set at 0% (pure fuel), 5%, 10%, 20% and 30%, throughout this work denoted as 0S, 5S, 10S, 20S and 30S. The results show that, at higher content of biodiesel fuel, biodiesel exhibited better emission CO and CO2, the reduction percent of these emission gases reach to 46% and 22% respectively. Also, the exhaust temperature gases reduction reach to 20%. Also, the obtained results found that the decrease values of break power and thermal efficiency. Furthermore, NOx increased when the content of biodiesel increases.

ملخص البحث :

Transferring thermal energy efficiently necessitates utilizing a heat exchanger capable of producing the full thermal power of the energy supply at lowest possible cost and time. Therefore, in the present investigation, the impact of corrugated helical coil concentric tube-in-tube heat exchanger on the thermal performance is investigated experimentally. As a continuous in our issue of heat exchanger, the corrugated helical tube-in-tube is carried out and compared with smooth helical tube-in-tube for free convection heat transfer. The set-up of the experimental apparatus are designed and utilized to be appropriate for the cooling and heating systems of working fluid. The impacts of geometry and operating conditions on the thermal and hydraulic characteristics such as the thermal effectiveness, whole coefficient of heating-transfer, number of thermal unit, pressure drop, Number of Dean and Number of Nusselt are taken into consideration of this investigation. The steady state flow condition and the counter flow direction are assumed in this investigation. The experimental results demonstrated that the whole coefficient of heating-transfer, effectiveness, number of thermal units, and Number of Nusselt were improved significantly due to the adoption of the corrugated helical coil tube-in-tube heat exchanger. This is happened because of the impact of geometrical configuration of corrugated tube in comparison with that of smooth tube, which is affected on increasing of the coefficient of heating-transfer. The maximum enhancement magnitude of the whole coefficient of heating-transfer was 33% for water flow rate of 16 L/min. For the latter water flow rate, effectiveness found that the maximum enhancement was 35%. The high magnitudes of NTU and Number of Nusselt were 3.37 and 218.5, respectively at the corrugated coil tube-in-tube for 16 L/min of hot water flow rate. The pressure drop for the corrugated tube was higher than that of smooth tube due to the swirl flow of hot water inner tube.

ملخص البحث :

In this study, experimental investigations and exergy analysis on shell and helically coiled tube heat exchanger are carried out for free convection heat transfer. The measured data are totally optimised utilizing thermodynamics rules in which exergy study is performed to investigate the thermal performance of the helical system under different operating conditions. The experimental set-up of apparatus are designed and made for cold water and hot water as a working fluid of both the shell side and helical coil side, respectively. The effects of several parameters such as geometry and operational conditions on the exergy destruction and dimensionless exergy destruction are investigated. The counter flow direction is considered under the steady state flow condition, and the critical Reynolds number wasmore than 4000 in this study. The main objective of this work was to clarify the effect of the volume flow rates and inlet temperatures of hot water and cold water in the shell and helical coil on exergy efficiency and pressure drop. Results showed that the exergy destruction and dimensionless exergy destruction decrease with the increase of coil pitch and Dean number. In contrast, the exergy destruction and dimensionless exergy destruction are obviously increased with the hot water flow rates or cold water flow rates. These exergy characteristics are also augmented with the values of hot water inlet temperatures and cold water inlet temperatures. The pressure drop is considerably increased with the increase of Dean number and reduced with the increase of coil diameter. While, the exergy efficiency steadily increases with the decrease of the cold water flow rates and with the increase of Dean number.

ملخص البحث :

Nowadays, the rapid developments in the automobile industry generate a high challenges on the manufacturing companies to find suitable solutions to decrease the amount of fuel consumption and the percentage of pollutants emissions. Bioethanol has greater oxygen content and smaller carbon content comparing with gasoline. Ethanol-gasoline is used as blend fuel for indicating the performance of 1.5 L turbocharged spark ignition engines. The measurements are recorded for several engine equivalence ratios, namely (0.9), (1) and (1.2), respectively. Moreover, it’s very important to make comparative analyses between the gasoline proprieties and bioethanol to find the implications on the operation of (SI) engine. It’s also a remarkable idea to develop a mathematical model and simulate this thermo-gas-dynamic process inside engine cylinder to enhance the findings through comparison between theoretical and empirical results. The main objective of this research is to improve the thermal efficiency of the supercharged ignition engine and decrease the emission level by using bioethanol fuel. The experimental part includes filling the turbocharged (SI) engine by bioethanol in blend with gasoline. In this research work, an actual state and complex analysis in bioethanol by using a supercharged spark ignition engine was carried out. Also, the commercial software (Unichip Dastek) was used for the analysis and simulation of the electronic control system. The results showed that there’s a good improvement in the engine efficiency due to the nature of bioethanol combustion proprieties, and this is considered an important advantage step which leads to improve the total efficiency. Also, the emissions level of (HC) and (CO) decreased with the improvement in the combustion process. Furthermore, the level of (NOX) emissions decreased (50%) at the same engine power at [E20]. It’s concluded that the combustion variability will improve by using (E20) fuel, due to the higher limit of in flammability of bioethanol comparing with gasoline, especially at the specific air excess coefficient. Accordingly, bioethanol can be considered as a good alternative fuel.