http://172.22.28.37:8080/xmlui/handle/1/343 2026-03-23T09:14:59Z 2026-03-23T09:14:59Z Kumbhar, Vishal Sharad http://172.22.28.37:8080/xmlui/handle/1/470 2018-11-03T06:30:27Z 2017-01-01T00:00:00Z

Title: Analysis of Flow and Heat Transfer Enhancement of Internally Corrugated Tubes Using MgO/Water Nanofluid Authors: Kumbhar, Vishal Sharad Abstract: The heat exchange between the two mediums is typically low due to formation of static boundary layer of fluid over the tube wall which offers higher convective resistance in the path of hat transfer. Also conventional heat transfer fluids are inherently poor heat transfer fluids and although various techniques are applied to enhance the heat transfer, the low heat transfer performance of these conventional fluids obstructs the performance enhancement of heat exchanging devices. Nanofluids are envisioned to describe a fluid in which nanometer-sized particles are suspended in conventional heat transfer basic fluid. Therefore by combining the effect of the both i.e. corrugation and nanofluids the heat transfer characteristics can be dramatically increased and thus can be used for the development of efficient heat exchanger device. In the view of the above discussions, the report presents numerical and experimental investigation of heat transfer and pressure drop in internally corrugated tubes. The corrugation is in the form of ribs orientated at angle of attacks of 0º, 30º, 45º, 60º, and 90º to the main flow direction. Numerical analysis is carried out to find optimum rib angle of attack, rib diameter and pitch of the. Based on the optimization data flow domain is manufactured. Experimental investigations using MgO/Water is carried out on smooth tube with Reynolds number ranging from 4500-11500, Four different concentrations namely, 0.005%, 0.01%, 0.05% and 0.1% are used to find most optimum concentration amongst them. Experimental trials are conducted on optimized corrugated flow domain using optimum nanofluid concentrations. Numerical analysis is performed to find the optimized flow domain. On the basis of thermo-hydraulic performance factor it is found that tube with 30º rib angle of attack, v 1.5 mm rib diameter and 40 mm rib pitch provided the maximum thermal and hydraulic performance. MgO nanoparticles were selected to prepare the nanofluid using base fluid as distilled water. Actual measurement of thermo-physical properties such as density, viscosity ad thermal conductivity was carried out. Relative viscosity is seen to increase with increase in nanoparticle concentrations. Thermal conductivity is observed to increase for 0.005% and 0.01 % concentration and then decrease for 0.05% and 0.01% due to particle agglomeration phenomenon. Experimental trials conducted on smooth tube using nanofluid showed that 0.01% concentration provided about 46% increment in heat transfer compared to distilled water. Pressure drop was observed to increase with increasing the nanoparticle concentration. Correlations are developed in the form of Nusselt number and friction factor. It was observed that in the optimized corrugated tube there was about 41% increase in heat transfer coefficient compared to distilled water under similar flow conditions by using 0.01% MgO/Water nanofluid. Comparison between numerical results and experimental results show good agreement. Heat transfer results for nanofluid are compared with existing correlations and are in good agreement with Maiga correlation Description: Under the Supervision of Prof. Sanjay V. Kadam

2017-01-01T00:00:00Z Khanase, Rahul Shivaji http://172.22.28.37:8080/xmlui/handle/1/469 2018-11-03T06:26:22Z 2017-01-01T00:00:00Z

Title: Performance, Combustion and Emission Analysis of Biodiesel Derived from Acidic Oil (By-product of soybean oil refining process Authors: Khanase, Rahul Shivaji Abstract: Biodiesel appear to be one of the most energy efficient, environmental friendly alternatives in the recent edge of technology. The present work deals with the Performance, Emission and Combustion characteristics of Biodiesel derived from Acidic oil, which is a by-product of soybean oil refining process. Biodiesel was extracted using two- step esterification and transesterification process from the raw acidic oil. Different blends were prepared on the volume basis and one separate blend was prepared using 2% Antigel Additives in one of the combination. Tests were conducted with diesel and prepared blends on single cylinder, four stroke, multi-fuel, water cooled engine at compression ratio of 17.5:1 with different loading conditions. Present investigation indicates reduction in performance parameter as the engine is fuelled with biodiesel, but significant changes are observed in combustion parameters in case of biodiesel fuelled engine. On the other hand, reduction in CO, HC and increase in NOx, CO2 is observed with the use of biodiesel. It is further seen that, when 2% Antigel Additives are added, significant reduction in BSFC, exhaust gas temperature, NOx percentage and integrated heat release rate is observed. Simultaneously it is associated with increase in brake thermal efficiency, HC and CO percentage and peak in cylinder pressure. Description: Under the Supervision of Dr. Abhijeet P. Shah

2017-01-01T00:00:00Z Wangdare, Sagar Changdev http://172.22.28.37:8080/xmlui/handle/1/468 2018-11-03T06:05:43Z 2017-01-01T00:00:00Z

Title: Numerical Investigation on Effect of Geometrical Variations of Microchannel Heat Sink in LED Cooling Authors: Wangdare, Sagar Changdev Abstract: The heat sink is the last and most influential part of the thermal stack, and is needed to first conduct heat away from the LEDs and then to convect and radiate heat to the ambient air. In some cases, heat sinks are coupled to other heat dissipating devices such as housings, enclosures, etc. For this document, we group these devices under the general term “heat sink”, but this should not be overlooked in system design as it can contribute significantly to the performance of the entire LED system. Microchannel provides the more surface area to volume ratio i.e. compactness, so it preferred in compact electronic devices as a heat sink. Before analysis of Micro-Channel Heat Sink (MCHS), heat transfer phenomena in LED are studied. Mathematical modeling is also done to represent physical system in the form of mathematical equations. Plain microchannel heat sink is analyzed and validated with the published experimental data by comparing Nusselt number and Fanning friction factor at various inlet velocities ranging from 1.54 m/s to 6.17 m/s. In validation it has found that numerical results are in good agreement with experimental results with deviation of 10% to 13%. In plain MCHS six different types of offset ribs are added on sidewall which are rectangular, backward triangular, forward triangular, mix of forward and backward triangular, isosceles and semicircular in shapes. All these geometries are analyzed at Reynolds (Re) number ranging from 200 to 800. The heat flux at the bottom of channel is given as 106 W/m2. All these microchannels are analyzed based on different thermal parameters such as Nu, fe, pressure drop and temperature at the bottom face. From the observation it shows that mix of forward and backward offset ribs MCHS gives better results (At Re 500 and q 106, Nu 15.01, Pressure drop 245.738 KPa, Tb 304.25 K) as compared to other types of channels. So this geometry is selected as best geometry and again simulated with higher heat fluxes. Finally at q 500 W/cm2, Re 500 and selected thickness and thermal conductivity of TIM and PCB temperatures obtained at bottom face of heat flux 73.94 after TIM 78.94 and after PCB i.e. at junction 112.27 . As junction temperature is less than 120 oC which is safe working temperature of LED so, given model of heat sink can be selected for LED. Description: Under the supervision of Dr. Sharad D. Patil (Associate Professor, Department of Mechanical Engineering)

2017-01-01T00:00:00Z Gudaghe, Sujay Bhausaheb http://172.22.28.37:8080/xmlui/handle/1/467 2018-11-03T06:00:56Z 2017-01-01T00:00:00Z

Title: Design, Fabrication and Performance Testing of Air to Air Heat Exchanger for Telecom Panels Authors: Gudaghe, Sujay Bhausaheb Abstract: In today’s competitive world, the customer expects better products than the existing one with qualities like reliable with long life, low power consumption, maintenance free and efficient performance. The telecom panel that encloses electric components need to be protected from dust, ingredients and cooled by limiting the temperature rise near to ambient temperature. The design, development, testing and analysis of flat plate, single-phase and single pass, air as the working fluid heat exchanger is put forth within this thesis. To explore the use of plate heat exchanger was the aim of this study, for boosting performance of flat plate heat exchanger for lower heat flux and coupled wall application which has operating system in counter flow configuration. The design of the heat exchanger is enclosed in the thesis, followed by the testing, numerical simulations and analysis results. The balancing of experimental and empirical tests reveals capability of the heat exchanger for delivering an cooling capacity of 200 W/K for overall heat transfer coefficient close to 14.99 W/m2K at flow rates around 5-6 m/s (corresponding to air flow domains Reynolds’s number of 5357) and around 100-200Pa pressure drop. The verification of heat load around 1400W is obtained by experimentation. The results obtained by established contrary flow heat exchanger and numerical analysis by LMTD method are compared to verify its effective working. Further, numerical simulation results for a single flow channel of the similar geometry are described in this paper showing reasonable agreement of the results. The present work conveys the successful use of heat exchanger plate type for boosting performance in industrial applications of electric panel sectors Description: Under the Supervision of Dr. Suresh M. Sawant (Professor, Mechanical Engineering Department, RIT, Rajaramnagar) & Mr. Vishwjit Patil (R&D Engineer, Sunbeam Appliances, Yelur)

2017-01-01T00:00:00Z