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| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | Ishak Hashim, Prof. Dr. | |
| dc.contributor.author | Mat Salim Selamat (P52174) | |
| dc.date.accessioned | 2023-10-13T09:33:03Z | - |
| dc.date.available | 2023-10-13T09:33:03Z | - |
| dc.date.issued | 2014-06-16 | |
| dc.identifier.other | ukmvital:80307 | |
| dc.identifier.uri | https://ptsldigital.ukm.my/jspui/handle/123456789/499598 | - |
| dc.description | Dalam dekad kebelakangan ini, kajian pemindahan haba secara olakan tabii di dalam bahantara berliang menjadi tumpuan utama kerana penggunaannya yang meluas dalam bidang sains persekitaran dan kejuruteraan. Kajian fundamental kadar pemindahan haba yang optimum amat penting dalam proses industri dan kejuruteraan. Oleh kerana itu dalam tesis ini, beberapa masalah berkaitan pemindahan haba secara olakan tabii di dalam rongga yang ditepukan dengan bahantara berliang dikaji secara berangka. Persamaan-persamaan menakluk pemindahan haba olakan tabii tersebut dijelmakan kepada satu sistem persaman terbitan separa (PTS) tak linear. Kaedah beza terhingga (KBT) digunakan untuk menganggarkan PTS tersebut dalam rongga segi empat sama dan trapezium yang ditepukan dengan bahantara berliang. Sistem persamaan aljabar yang terhasil diselesai menggunakan kaedah lelaran pengenduran berlebihan berturut-turut (LPBB) dan kaedah tersirat langsung selang seli (TLSS) dengan algoritma matriks tiga pepenjuru (AMTP). Kaedah LPBB digunakan untuk menyelesaikan masalah pemindahan haba olakan tabii di dalam rongga segi empat sama yang dipanaskan dengan suhu tidak seragam, rongga trapezium yang diisikan dengan bahantara berliang anisotropik dan rongga trapezium yang mengandungi plat pemanas dalaman. Manakala kaedah TLSS dengan AMTP digunakan untuk mengkaji pemindahan haba di dalam rongga segiempat sama yang dipanaskan dan disejukkan pada dinding bersebelahan dan rongga segiempat sama berpenyekat yang dikenakan medan magnet serta mengandungi panjana haba dalaman. Teknik pseudofana digunakan bagi mengubahsuai persamaan fungsi strim dan fungsi haba menjadi bersandar dengan masa. Dalam semua model yang dikaji, aliran diandaikan Newtonan, bermatra dua dan tak termampatkan. Penghampiran Boussinesq diguna pakai dalam variasi ketumpatan. Kesemua skim berangka diaturcarakan dalam MATLAB. Kajian pengesahan dilakukan dengan membandingkannya dengan kajian-kajian terdahulu bagi memastikan ketepatan dan kejituan pengiraan dalam tesis ini. Kejituan juga ditentukan dengan memastikan kadar pemindahan haba pada dinding yang dipanaskan adalah seimbang dengan kadar pemindahan haba pada dinding yang disejukkan. Keputusankeputusan pengiraan berangka dipaparkan dalam bentuk kontor medan garis strim dan isoterma. Kadar pemindahan haba ditunjukkan melalui nilai nombor Nusselt tempatan dan nombor Nusselt purata. Pemindahan haba juga ditunjukkan melalui fungsi dan garis haba. Nilai maksimum fungsi haba turut digunakan bagi mendapatkan kadar pemindahan haba. Keputusan berangka menunjukkan bahawa sudut condong dinding rongga segi empat dan trapezium mempengaruhi corak aliran dan kadar pemindahan haba. Bagi bahantara anisotropik, nisbah ketelapan dan nisbah kekonduksian terma memberikan kesan yang berlawanan terhadap kadar pemindahan haba. Manakala arah medan magnet yang selari dengan dinding tegak dan penjana haba akan memberikan kadar pemindahan haba optimum. Proses pemindahan haba olakan juga akan mencapai keadaan mantap dengan lebih cepat apabila dikenakan penyerapan haba dalaman.,In recent decades, the study of heat transfer by natural convection in porous media is a major concern because of its wide usage in the field of environmental sciences and engineering. Fundamental studied on optimum heat transfer rate are very important in industrial processes and engineering. Therefore in this thesis, several problems related to heat transfer by natural convection in a cavity with a saturated porous media were studied numerically. The governing equations of natural convection heat transfer were transformed to a system of partial differential equations (PDEs). The finite difference method (FDM) was employed to approximate the PDEs in a square and trapezoidal cavities which were impregnated with porous media. The resulting systems of algebraic equations were solved by the successive over-relaxation (SOR) and alternating direct implicit method with tri-diagonal matrix algorithm (TDMA) scheme. The SOR method was employed to solve the problem of natural convection heat transfer in a square cavity non-uniformly heated, the trapezoidal cavity filled with anisotropic porous media and trapezoidal cavity containing an internal heater. The ADI method was used to study the heat transfer in a square cavity heated and cooled on adjacent walls and a partitioned square cavity subject to a magnetic field and internal heat generation. A pseudo-transient technique was used to modify the stream function equation and the heat function to become independent of time. In all models studied, the flow was assumed to be Newtonian, two-dimensional and incompressible. In addition, the Boussinesq approximation was used for the density variations. All numerical schemes were programmed in MATLAB. Validation studies were carried out by comparing with previous studies to ensure the accuracy and precision of calculations in this thesis. The validation was also done by ensuring that the heat transfer rate on the hot wall was balanced with heat transfer rate on the cooled wall. The numerical results were shown in contour form of streamlines and isotherms. Heat transfer rate was shown by the local Nusselt numbers and average Nusselt numbers. Heat transfer was also reflected in the heat function and heatlines. Maximum value of heat function was also used to obtain the heat transfer rate. Numerical results show that the tilt wall of the square and trapezoidal cavities affected the flow patterns and heat transfer rate. For anisotropic media, the permeability ratio and thermal conductivity ratio show the opposite effect on the rate of heat transfer. While the direction of the magnetic field parallel to the vertical wall and the heat generation will provide an optimal heat transfer rate. In addition, the convective heat transfer process will reach a steady state more quickly when subjected to an internal heat absorption.,PhD | |
| dc.language.iso | may | |
| dc.publisher | UKM, Bangi | |
| dc.relation | Faculty of Science and Technology / Fakulti Sains dan Teknologi | |
| dc.rights | UKM | |
| dc.subject | Pemindahan haba | |
| dc.subject | Olakan tabii | |
| dc.subject | Bahantara berliang | |
| dc.subject | Heat - Convection | |
| dc.subject | Natural | |
| dc.title | Penyelesaian berangka pemindahan haba olakan tabii dalam rongga yang ditepukan dengan bahantara berliang | |
| dc.type | Theses | |
| dc.format.pages | 146 | |
| dc.identifier.callno | QC330.M396 2014 tesis | |
| dc.identifier.barcode | 001168 | |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi | |
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| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_80307+SOURCE1+SOURCE1.0.PDF Restricted Access | 3.98 MB | Adobe PDF |  View/Open |
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