Pusat Pengajian Kejuruteraan Mekanikal - Tesis

Browse

Now showing 1 - 5 of 237

Numerical study of heat transfer and flow characteristics of microchannel heat sink with staggered water droplet geometries using water and nanofluids
(2024-02)
Soo, Yan Hao
The rapid transition of electronic devices from low performing, low-speed systems to high performance systems with high computational speeds has led to the exponential hike in power density which poses a challenge for effective heat dissipation. To prevent thermal-induced damages in miniaturized electronic devices, the heat dissipation rate must be increased by incorporating heat exchangers with large surface area to volume ratio such as the microchannel heat sink (MCHS). This research sought to augment the thermohydraulic performance of a conventional MCHS using two different approaches: geometrical modification and flow parameter modification. Three-dimensional conjugate heat transfer analyses were conducted using state of the art computational fluid dynamics (CFD) software, ANSYS Fluent 2022, to assess the hydrothermal attributes of water and water-based nanofluids on an MCHS, employing staggered water-droplet geometries. The research focused on single phase laminar flow (Re<1000) through microchannels with hydraulic diameter (D_h) of 750 μm and aspect ratio of 1.5. The thermohydraulic performances of the MCHS were evaluated against different geometric parameters including groove aspect ratio, groove pitch, groove size, and geometry type. Apart from that, the impacts of the nanofluid properties (i.e., nanoparticle type and nanoparticle concentration) on the heat dissipation performance were also examined in the study. The geometrical modifications were found to induce a substantial enhancement in the thermal performance of the MCHS through the promotion of fluid mixing which intensified the thermal exchange between the solid and fluid domains. However, the pumping cost associated with such modifications were higher because of a higher pressure drop penalty. The employment of nanoparticles as fluid additives led to a substantial heat transfer increment, albeit with a higher pumping power requirement. With that being said, the implementation of nanofluids is preferable in comparison to plain water as the advantages greatly outweigh the disadvantages.
Study On The Effect Of Tool Nose Wear On Surface Roughness And Dimensional Deviation Of Workpiece In Finish Turning Using Machine Vision
(2009-02)
Haghighi, Hamidreza Shahabi
The aim of this research is to study the effect of tool nose wear, which is in contact with the surface profile of workpiece directly, on Ra using a developed machine vision in finish turning operation.
Tar Removal From Biomass Producer Gas By Absorption And Adsorption Methods
(2014-12)
Ahmad, Nor Azlina
Tar in biomass producer gas should be removed to avoid blocking of the pipe lines and to allow producer gas utilization in internal combustion engines (ICE) and turbines for power generation. Among the physical tar removal methods, scrubbing technique are more attractive to remove tar from biomass producer gas. This technique aims to use reusable material for tar removal. Tar removal system was conducted by two methods: absorption method (collected waste palm cooking oil (CWPCO), laboratory waste palm cooking oil (LWPCO), diesel oil and water) and combination of absorption method (optimum absorption medium are selected) with adsorption method (commercial activated carbon (CAC), empty fruit bunch char (EFBC) and oil palm shell char (OPSC». Tar species and oil-based mediums (CWPCO, LWPCO and diesel oil) were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). Whilst, adsorption medium properties were determined using Thermogravimetric Analyzer (TGA), Microstructure Analysis (BEn and Scanning Electron Microscope (SEM).
Analysis Of Piston Secondary Motion
(2014-04)
April 2014
In an internal combustion engme, the piston performs secondary motion besides the primary reciprocating motion. The clearance between the piston skirt and cylinder liner allows the piston to move in the lateral direction and rotational motion about the piston pin axis. The piston secondary motion created impact between the piston skirt and the cylinder liner that radiates unwanted engine noise and increases friction loss. A measurement system consists of three laser displacements sensors are developed to capture the instantaneous piston motion and posture directly from the piston assembly under motorized condition. The laser spots aimed at the piston crown with machined profile in order to obtain the rotational and lateral motion of the piston. The instantaneous piston motion showed that the likelihood of contact between the piston skirt and the cylinder liner increases with the occurrence of the piston secondary motion. In addition, a non-linear model of the piston with reciprocating, lateral and rotational degree of freedom is developed to investigate the piston secondary motion and the piston slap induced vibration behavior of the single cylinder engine.
Mampatan beban paksi keatas tiub segienam
(2000-01-01)
Azam, Mohd Azizul
Pengujian hentaman untuk rekabentuk sesebuah kenderaan secara tradisional adalah berdasarkan ujian pemusnahan prototaip. Oleh itu pakar-pakar dalam bidang unsur terhingga (finite element) telah membangunkan sofwer yang dapat membantu jurutera merekabentuk dengan lebih effisien dan juga mendapatkan maklumat tentang sistem serapan tenaga pada tiub yang di uji. Antara sofwer yang di bangunkan adalah DYNA-3D, ABAQUS, I-DEAS dan lain-lain. Rekabentuk sesuatu komponen yang berupaya menahan hentaman secara menegak atau melintang memerlukan pengetahuan dan pemahaman dalam bidang struktur dinamik dan juga ciri-siri mekanisme perubahan setiap bahan atau komponen yang diperlukan. Kebanyakan aplikasi terkini yang melibatkan hentaman serapan tenaga tertumpu kepada sifat sesuatu struktur atau komponen logam yang mana mekanisme pelepasan tenaga utama melibatkan perubahan plastik, patah atau koyakan pada logam. Kajian ini melibatkan perbincangan mengenai suatu tiub segienam berdinding nipis yang dikenakan mampatan secara menegak. Perubahan lengkokan secara menegak ini akan menumpukan bagaimana untuk menentukan beban purata operasi (mean operating load) dan had-had kemampuan serapan tenaga dapat diperolehi. Seterusnya ramalan mengenai kekuatan hentaman untuk tiub berdinding nipis ini adalah berdasarkan mekanisme lipatan yang berlaku. Terdapat dua jenis lipatan yang biasanya berlaku iaitu perubahan mod secara quasi-inextensional dan extensional seperti yang dinyatakan oleh Wierzbicki dan Abramowicz(1983).

Browse

Recent Submissions