With development and advancement of notebook, at the same time it brings its cooling problem, it is very important that use outside surface cooling except inside. The main in study is simulate of electronic cooling in Notebook outside surface, design force convection models and placed them under the Notebook, force convection has immediate effect on the surface and produce heat dissipation. The simulation uses software FLUENT 6.0 to analysis the result of heat dissipation, the models are constructed and described by use turbulent field of three dimensions. The study has two main parameters¡GThe form of force convection models and controlled airflow. The result of numerical analysis use Nusselt number to determine the effect of heat dissipation. According to the result of numerical analysis to increase effect of heat dissipation for the following methods¡G1. Increase airflow across the designed models, 2. Decrease the angle of elevation when using notebook, 3. Airflow enter the designed models by one entrance and leave by the side exports, 4. When airflow pass through the designed models smoothly, 5. Airflow can influence the notebook surface immediately.

This thesis uses aluminum porous board (AP board) to study the noise reduction for cooling tower. It sets the barrier to isolate the sound propagation. But it will happen diffracted phenomenon when sound wave impinging at the edge of barrier. So the mathematical model of acoustic diffraction on the barriers, which is set up by Hayek, is applied in this thesis. Base on this theorem, the AP board and the paths of sound propagation are analyzed. In experiment, it uses the sound intensity method to measure the cooling tower for determining the major source first. The major source is determined by ranking the sound power. And the suitable insulation material is selected by analysis the frequency band of major source. After analyzing, the major source of cooling tower is the region of fans by motor driven that is located upper the cooling tower. And its frequency range is between 25 Hz to 2500 Hz. So the AP board is a candidate since it has broadband characteristic on noise insulation. After aim of the major source, the noise barrier is studied for noise reduction. In this thesis, the U profile of barrier (looking down from above), which considers the situation in the field, is designed to surround the cooling tower. This barrier is made of aluminum board, and the aluminum porous board is applied to add on the upper barrier for noise reduction. To study the acoustic diffraction on the boundary of barrier, the thick of porous board is added on the upper barrier. The insulation effect is compared in the different condition after measuring the transmission loss. The T shape barrier is also designed for noise reduction evaluating in this thesis. Finally, the best-insulated effect is obtained when the complex board is added on the upper barrier. And the noise level is down to 59 dB around the environment. This result is matched the EPA noise standards.

Abstract Spray cooling is frequently encountered in a number of engineering applications. An experimental study was made to investigate the effect of liquid sprays used to cool a hot surface. Both pure water and R-134a were served as a working medium sprayed from a single circular nozzle onto a Pt plated surface of an electrically heated surface. Spray cooling tests were performed for steady state and transient experiment. Cooling characteristics curves were obtained over a range of Weber number(Water¡G80¡B148¡B231¡AR-134a¡G50¡B96¡B152),pressure drop of liquid(0.1Mpa¡B0.15Mpa¡B0.2Mpa),degree of subcooling (Water¡G55¢J¡B60¢J¡AR-134a¡G2¢J¡B4¢J) and initial temperature(Water¡G240¢J¡AR-134a¡G60¢J). Thermal design data of high performance as well as more and further physical insight of the above-stated spray cooling heat transfer can be acquired. The results will hopefully be helpful not only for the academia but for the industry.

An investigation was conducted to determine the feasibility of using the technique of ultrasonic nebulization of water into the anode gas stream for evaporative cooling of a Proton Exchange Membrane (PEM) fuel cell. The basic concept of this form of internal evaporative cooling of the PEM fuel cell is to introduce finely atomized liquid water into the anode gas stream, so that the finely atomized liquid water adsorbs onto the anode and then moves to the cathode via electro-osmotic drag, where this water then evaporates into the relatively dry cathode gas stream, carrying with it the waste thermal energy generated within the fuel cell. The thermal and electrical performance of a 50 cm2 PEM fuel cell utilizing this technique was compared to the performance obtained with conventional water management. Both techniques were compared over a range of humidification chamber temperatures for both the anode and cathode gas streams so as to determine the robustness of the proposed method. The proposed method produced only meager levels of evaporative cooling (at best 2 watts, for which a minimum of 30 watts was required for adequate cooling), but the average cell voltage increased considerably (as much as a 10% gain), and the technique increased the fault tolerance of the fuel cell (the Nafion™ membrane did not dry out even if cell temperature went well in excess of 70° C despite both anode and cathode humidification temperatures of 55° C). An interesting phenomena was also observed wherein the fuel cell voltage oscillated regularly with a period of tens of seconds, and that the amplitude of this oscillation corresponded inversely with the level of humidification received by the fuel cell.

A computational study of three-dimensional turbulent flow and heat transfer was performed in four types of rotating channels. The first type is a rotating rectangular channel with V-shaped ribs. The channel aspect ratio (AR) is 4:1, the rib height-to-hydraulic diameter ratio (e/Dh) is 0.078 and the rib pitch-to-height ratio (P/e) is 10. The rotation number and inlet coolant-to-wall density ratio were varied from 0.0 to 0.28 and from 0.122 to 0.40, respectively, while the Reynolds number was varied from 10,000 to 500,000. Three channel orientations (90 degrees, -135 degrees, and 135 degrees from the rotation direction) were also investigated. The second type is a rotating rectangular channel with staggered arrays of pinfins. The channel aspect ratio (AR) is 4:1, the pin length-to-diameter ratio is 2.0, and the pin spacing-to-diameter ratio is 2.0 in both the stream-wise and span-wise directions. The rotation number and inlet coolant-to-wall density ratio varied from 0.0 to 0.28 and from 0.122 to 0.20, respectively, while the Reynolds number varied from 10,000 to 100,000. For the rotating cases, the rectangular channel was oriented at 150 degrees with respect to the plane of rotation. In the rotating two-pass rectangular channel with 45-degree rib turbulators, three channels with different aspect ratios (AR=1:1; AR=1:2; AR=1:4) were investigated. Detailed predictions of mean velocity, mean temperature, and Nusselt number for two Reynolds numbers (Re=10,000 and Re=100,000) were carried out. The rib height is fixed as constant and the rib-pitch-to-height ratio (P/e) is 10, but the rib height-to-hydraulic diameter ratios (e/Dh) are 0.125, 0.094, and 0.078, for AR=1:1, AR=1:2, and AR=1:4 channels, respectively. The channel orientations are set as 90 degrees, the rotation number and inlet coolant-to-wall density ratio varied from 0.0 to 0.28 and from 0.13 to 0.40, respectively. The last type is the rotating two-pass smooth channel with three aspect ratios (AR=1:1; AR=1:2; AR=1:4). Detailed predictions of mean velocity, mean temperature and Nusselt number for two Reynolds numbers (Re=10,000 and Re=100,000) were carried out. The rotation number and inlet coolant-to-wall density ratio varied from 0.0 to 0.28 and from 0.13 to 0.40, respectively. A multi-block Reynolds-averaged Navier-Stokes (RANS) method was employed in conjunction with a near-wall second-moment turbulence closure.

In considering the global power generation industry, fossil fuel power plants still dominates where LNG presents one of the major clean fuel source. Although Taiwan remains as one of the main importers of LNG in the world, the cold energy was not utilized effectively which only accounts for 8% of total. Especially, the hot and humid local climates caused the Gas turbines to work under low efficiency which presents significant room for improvement when inlet cooling technology was imposed. In this research, the inlet cooling process using mechanical chillers, absorption chillers, and LNG cold reclaim technology were simulated using the Thermoflex software in a tpical combined cycle environment. The waste heat from the power plant was further utilized for Sea water desalination purposes under MED process. Simulation result indicated that , in using 2% of the waste heat from the plant, and produce 60 tons per hour of fresh water , at the cost of power output reduction of 1 %. Further simulation result also validated the economic feasibility which warranted engineering application potentials.

Thesis (Ph.D.)--University of Texas at Arlington, 2008.

Thesis (Ph. D.)--School of Mechanical Engineering, Georgia Institute of Technology, 2004. Directed by Sheldon M. Jeter. / Vita. Includes bibliographical references (leaves 195-201).

Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Garimella, Srinivas; Committee Member: Allen, Mark; Committee Member: Fuller, Tom; Committee Member: Jeter, Sheldon; Committee Member: Wepfer, William. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Mississippi State University. Department of Mechanical Engineering. / Title from title screen. Includes bibliographical references.