Nur Irmawati Om

Influence of sinusoidal flow on the thermal and hydraulic performance of microchannel heat sink

In this paper, the effect of sinusoidal flow on the thermal and hydraulic performance of microchannel heat sink (MCHS) is numerically investigated. This investigation covers Reynolds number in the range of 100 ≤ Re ≤ 1000 and pure water is used as a working fluid. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using finite volume method (FVM). The water flow field and heat transfer performance inside the sinusoidal microchannels is simulated and the results are compared with the straight microchannels. The effect of using sinusoidal microchannels on temperature distribution, Nusselt number, friction factor and thermal resistance is presented in this paper. It is found that with same rectangular cross-section, sinusoidal microchannels have a better heat transfer performance compared to the straight microchannels.

Effectiveness of Computerized Homework Implementation in Thermodynamics: Correlation Between Doing the Homework and the Grade

The objective of the implementation is to gauge the effectiveness of computerized homework in improving students’ understandings of Thermodynamics, and to investigate the correlation between the scores attained in computerized homework and the overall grade achieved by the students in Thermodynamics. There were two sections of MEHB213 Thermodynamics I offered during Special Semester 2013/2014. Section 1 with 63 students used the computerized homework while the other section (Section 2, 60 students) continued with the normal manual homework. The computerized homework did not utilize the commercial software available in the market, instead it was developed at College of Engineering, UNITEN. The computerized homework system is a MATLAB and PHP based program and resides on Apache Web server. MATLAB generates the questions and randomize the variables, while PHP displays the contents on the web. The database used for the system is MySQL. The manual homework assigned for the subject had been replaced by the computerized homework in order to give a fast feedback to the students and to reduce the time engaged by lecturers to mark the homework. The answers submitted by students in computerized homework were automatically graded by the system, and they would be immediately notified whether the answers given were correct or not. The students could access the computerized homework at anytime throughout the semester. The questions were arranged according to chapters and the time to release each question could be set in the system. The result from this study shows there is a direct correlation between doing the computerized homework and the improved grades in Thermodynamics I. 90.4 % of students from Section 1 who used the computerized homework passed the subject while the section which did not use the system had 56.7 % passing grade.

Numerical Study of Mixed Convection through Horizontal Duct Utilizing Al2O3

In the present study, mixed convection in a horizontal rectangular duct using Al2O3 is numerically investigated. The effects of different Rayleigh number, Reynolds number and radiation on flow and heat transfer characteristics were studied in detail. This study covers Rayleigh number in the range of 2 106 ≤ Ra ≤ 2 107 and Reynolds number in the range of 100 ≤ Re ≤ 1100. Results reveal that the Nusselt number increases as Reynolds and Rayleigh numbers increase. It was also found that the dimensionless temperature distribution increases as Rayleigh number increases.

Preliminary CFD Investigation of Syngas Combustion at Different Operating Pressures

Study on the flow and combustion behavior inside gas turbine combustor used in thermal power plant is described in this paper. The combustion process takes place using synthetic gas and emphasis is given to the effect of pressure variation on flame profile, temperature distribution and emissions as compared to the conventional combustion using methane. The operating pressure of the can-type combustor varies in the range of 1-10 atm. while the syngas composition is assumed to have fixed values of 10% CH4, 55% CO, 30% H2 and 5% N2. Preliminary result shows that the flow inside the can-combustor is highly swirling which indicates good mixing of fuel and air prior to the entrance of the mixture to the main combustion zone. The temperature distribution at combustor mid plane show identical pattern for pressure range between 1-10 atm for both maximum and average temperature magnitude.

Effect of Inclination Angle on Three-Dimensional Combined Convective Heat Transfer of Nanofluids in Rectangular Channels

Combined convective nanofluids flow and heat transfer in an inclined rectangular duct is numerically investigated. Three dimensional, laminar Navier-Stokes and energy equations were solved using the finite volume method. Pure water and four types of nanofluids such as Au, CuO, SiO2 and TiO2with volume fractions range of 2% φ 7% are used. This investigation covers the following ranges: 2 × 106 Ra 2 × 107, 100 Re 1000 and 30° Θ 60°. The results revealed that the Nusselt number increased as Rayleigh number increased.SiO2nanofluid has the highest Nusselt number while Au nanofluid has the lowest Nusselt number. An increasing of the duct inclination angle decreases the heat transfer.