Browsing by Author "RAHMAN, MD. MAHBUBUR"

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    NUMERICAL STUDY OF CONVECTIVE HEAT TRANSFER FOR A TURBULENT FLOW IN A CORRUGATED TUBE USING NANO FLUID
    (DEPARTMENT OF MECHANICAL ENGINEERING MILITARY INSTITUTE OF SCIENCE AND TECHNOLOGY MIRPUR CANTONMENT, DHAKA - 1216, BANGLADESH, 2018-12) RAHMAN, MD. MAHBUBUR
    Heat transfer enhancement can be done in different ways, but the use of nanofluid is one of the latest approaches. A numerical investigation of turbulent forced convection through a right-angled triangular-shaped corrugated tube is presented by using commercial computational fluid dynamics software, ANSYS Fluent. The length and diameter of the tube which is considered for the study are 200 mm and 8 mm respectively and a uniform constant heat flux of 5,000 W/m2 is applied at the corrugated wall boundary. A 2D simulation with the axisymmetric model is considered for analyzing different parameters. The corrugation has an amplitude of 1.60 mm and a wavelength of 6 mm. Realizable k-ε turbulent model is employed with enhanced wall treatment for the analysis. Nanofluid is allowed to flow with uniform velocity and uniform temperature of 300 K at the inlet of the pipe with an assumption of a no-slip condition. Heat transfer parameter like convective heat transfer coefficient and fluid dynamics parameter like friction factor and pumping power are calculated using three different nanofluids, namely Al2O3-water, TiO2-water, and CuO-water of different volume fraction (1%, 2%, 3%, 4% and 5%) for a range of Reynolds number 5000 to 25000. The result shows that the heat transfer coefficient increases with the increase in volume fraction of the nanofluid as well as with the Reynolds number. That is 44.66% for Al2O3-water, 27.35% for TiO2-water and 25.74% CuO-water nanofluid at Reynolds number of 25000 and 5% volume fraction.
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    VARIABILITY STUDY IN SOME INDIGENOUS AND EXOTIC PROMISING CLONES OF SUGARCANE (Saccharum officinarum L.)
    (DEPARTMENT OF GENETICS AND PLANT BREEDING, SHER-E-BANGLA AGRICULTURAL UNIVERSITY, DHAKA, BANGLADESH, 2006-12) RAHMAN, MD. MAHBUBUR
    Variability, heritability, genetic advance, characters association and path coefficient analysis for the characters number of tillers per heetare, number of millable canes per hectare, number of millable canes per dump, stalk height, stalk girth, single stalk weight, number of green leaf, leaf length, leaf breadth, sucrose percentage and cane yield per hectare were studied with 25 (twenty five) indigenous and exotic promising clones and two standard check varieties of sugarcane. The experiment was conducted at the Bangladesh Sugarcane Research Institute, Ishurdi, Pabna during the cropping season of 2005-2006. The genotypes were found to differ significantly for all the characters studied. The genotype 1 27-02 produced the maximum number of tillers, millable canes and cane yield. The maximum number of millable cane per clump was found in 1 65-02 and I 85-02, respectively. The minimum number of millable cane per clump were 154-02 and K 88-65, respectively. The tallest genotype was 1 191-02 (3.21m) and shortest genotype was K 84-69 (1.57m). The genotypes! 81-02 and! 87- 02 produced the highest stalk girth and single stalk weight, respectively. The highest number of green leaf was found in the clones 1 20-02 and I 85-02, respectively. The lowest number of green leaf which produced in 113-02, 1 87-02, K 88-65 and K 88-87 respectively. The highest leaf length v,-as found in VMC 84-549 (2.11 m) and the shortest leaf length was found in 1 85-02 (0.4m). The widest leaf breadth was found in the genotype K 88-65 (7.16 cm). The study showed that the K 88-87 had the highest potentiality for sucrose percentage (9.45) among the genotypes studied. Number of tillers per hectare, cane yield per hectare and single stalk weight had high genotypic coefficient of variation. Other characters had low to moderate genotypic coefficients of variation. High heritability with high genetic advanced in percentage of mean was obsen'ed for number of tiller and stalk height. Other characters showed either high, moderate or low heritability with variable magniwde of genetic advance in percentage of mean. Cane yield per hectare was positively correlated with number of tillers per hectare. number of millable canes per hectare, stalk height and single stalk weight. The direct contribution of the number of millable canes per hectare was highest followed by single stalk weight. These results suggest that there is a scope of improving canes yield in sugarcane through selection of number of millable canes per hectare and single stalk weight.