Department of Chemical Engineering

Design and implementation of 200 kV Van de graff generator with improved insulation characteristics /

2018-01-01T00:00:00Z

Design and implementation of 200 kV Van de graff generator with improved insulation characteristics / Bilal Anwar, Muhammad The Vann De Gra is very famous in the electrical industry, high-voltage X-rays, nuclear physics, and dielectric testing. It has gained its importance because of its unconventional design and high voltage capacity with an extremely low current. However, the sensitivity to the environment and over insulation requirements restrict its use immensely and thus it becomes a major reason of ignorance for quite sometimes. Also, the unavailability of an empirical model lacks its proper designing which ultimately fails to deliver e cient performance. This problem has been analyzed sensitively and its solution has been implemented in this research. The designing in this research is critically analyzed and especially the problem in some critical parts like Designing of Dome is solved by selecting the aluminum material dome with perfect sizing by using the sphere vs charge calculation to get desired voltages. The Te on Belt material is selected instead of rubber belt for the better performance because Te on material is more close to "capture" electrons. The Belt is also stretched for more charges to liberate out. But it may cause the breakage of belt, to avoid this we use soft starting of motors using SCR Controlled voltage regulator. While designing the generator we cannot ignore the insulation of this generator because it possesses very high voltage with a small current that's why the insulation of internal and external part of the generator focused on this research, some parts of the generator must be highly insulated otherwise the charge failed to establish. The functionality of this generator is mainly dependent on weather conditions. The electrostatic charges leak very rapidly in moisture. The insulation is the prime factor for improvement in every Van de Gra generator. The irregularities at the dome surface cause a leakage of charges. So to remove this issue we polished a dome with zinc material. Further we introduce silica gel at the outer side to remove moisture of inner region and for inside part the generator is insulated through a vacuum pump and a bulb which generates the heat to avoid humidity e ect. The rate of discharge is a superior parameter of the execution of the machine than the ideal voltage. Thus we perform two di erent tests to verify the performance of generator one of the test is conventional voltage test using electrostatic generator and other is gap spark tests. The results with proper testing provide a 200 kV generator with better e ciency than the one commercially available.

Design and modling of portable & safe chaff cutter machine /

2019-01-01T00:00:00Z

Design and modling of portable & safe chaff cutter machine / Hammad, Muhammad Agriculture is consider to be backbone of Pakistani economy, it is estimated that 19.5% of Gross Development Product employing a large quantity of the workforce to provide raw materials for many regions of value-added. Hence it plays a tremendous role in national development, security of food and shortage alleviation. Instantaneous progress in city areas in Pakistan depicts that the need for important fresh products such as fruits, vegetables, dairy products, and the meat is increasing. In this research work, the utility model reveals a portable and safe chaff cutter machine which consists of a feed channel, a pair of feed roller, one shear blade, three cutting blades, a discharge channel, an electric motor, power transmission unit, an idler frame and a casing. Electric motor transmits power to the shaft of cutting blades and these blades act tangentially to the shear blade. The upper feed roller shaft transmits power to lower feed roller shaft through spur gears. These spur gears mesh and generate opposite rotation to each other and this rotation helps the chaff to move forward. The utility model has the advantage of good automatic feed effect, reduces the number of workers, lightens labor intensity, improves the efficiency, avoids personal injuries, and short crops and long crops can be all fed simultaneously.

Two-Phase frictional pressure drop with pure refrigerant vertical mini/micro channels /

2020-01-01T00:00:00Z

Two-Phase frictional pressure drop with pure refrigerant vertical mini/micro channels / Shujaat Ali, Muhammad Conventionally used synthetic refrigerants (Chlorofluorocarbons, Hydro chlorofluorocarbons etc.) are considered to have significant impact on environmental degradation owing due to their high ozone depletion potential and global warming potential. Global treaties (Kyoto protocol) are now coming into force and asks for ban on utilization of potential harmful fluids. Refrigeration and air conditioning industry is therefore in search of environmental benign alternatives. With growing quest on optimum utilization of energy sources devices used for exchange of thermal energy are now becoming more compact while required thermal duty is increasing day by day. Phase change heat transfer process in compact channels is now becoming increasing popular due to its capability to withstand high heating/cooling loads. Pressure drop is an important parameter and in case of phase change process this may affect system’s thermal performance. Accurate estimation of pressure drop and its proper consideration in the design process is crucial to assure functionality of any thermofluid system involving phase change heat transfer process. The current research is therefore emphasized on frictional pressure drop during flow boiling of environmental benign refrigerants (GWP<150), isobutane, HFC-152a, HFO-1234yf were tested against commonly deployed HFC-134a. The data presented here was collected under heat flux controlled conditions, the test piece was a round tube (Lheated=245 mm) while experimentation was performed at 27 and 32°C with mass velocity in 50-500 kg/m²s range. The effects of key parameters like heat flux, mass velocity, exit quality, operating medium were critically analyzed. It was observed that pressure drop increases as mass velocity increases in the test piece, increases with increase in exit vapor quality while the same was noticed to decrease with an increase in operating saturation temperature. Parametric effects and prediction assessment of correlations is reported.

DOE based response surface regression methodology of the study of PVD coated cemented carbide tool performance on surface roughness /

2019-01-01T00:00:00Z

DOE based response surface regression methodology of the study of PVD coated cemented carbide tool performance on surface roughness / Farooq Mustafa Now days PVD and CVD coated tools are widely used in different industries to ensure cost effectiveness in terms of tool life and work piece quality. Selection of tool geometry, its material and cutting parameters are very important in machining processes. These stake holders can affect production quality as well as time.. In this research uncoated cemented carbide tools and PVD coated cemented carbide tools are used for the dry machining of aluminum alloy 2024 to evaluate surface roughness and tool wear. Purpose of this research is to compare the performance of two tools. Experiments were conducted on full factorial design of experiments in which three levels of depth of cut, feed rate and cutting speed were taken as input variables and surface roughness and tool wear were the response for both tools. Machining time was taken as 30 minutes. Tool wear is measured by CMM and surface roughness by Surftonic. For the analysis of data response surface regression technique are used. Pareto coefficient and marginal mean plot shows the effectiveness of this approach. It is observed that depth of cut has great dominance on tool wear and surface roughness followed by cutting speed. Optimum levels are investigated to gain minimum tool wear and surface roughness for both coated and uncoated tools.