This article presents a numerical study on forced convection of nanofluid flow in a two-dimensional channel with trapezoidal baffles. One baffle mounted on the top wall of channel and another mounted on the bottom wall of channel. The governing continuity, momentum and energy equations in body-fitted coordinates are iteratively solved using finite volume method and SIMPLE technique. In the current study, SiO2-water nanofluid with nanoparticles volume fraction range of 0- 0.04 and nanoparticles diameters of 30 nm is considered for Reynolds number ranging from 100 to 1000. The effect of baffles height and location, nanopar-ticles volume fraction and Reynolds number on the flow and thermal fields are investigated. It is found that the average Nusselt number as well as thermal hydraulic performance increases with increasing nanopartiles volume fraction and baffle height but accompanied by increases the pressure drop. The results also show that the best thermal- hydraulic performance is obtained at baffle height of 0.3 mm, locations of baffles at upper and lower walls of 10 and 15 mm, respectively, and nanoparticles volume fraction of 0.04 over the ranges of Reynolds number.
In this study, thermal-hydraulic performance of a confined slot jet impingement with Al2O3-water nanofluid has been numerically investigated over Reynolds number ranges of 100-1000. Two triangular ribs are mounted at a heated target wall; one rib located on the right side of the stagnation point and another one located on left side of the stagnation point. The governing momentum, continuity and energy equations in the body-fitted coordinates terms are solved using the finite volume method and determined iteratively based on SIMPLE algorithm. In this study, effects of Reynolds number, rib height and rib location on the thermal and flow characteristics have been displayed and discussed. Numerical results show an increase in the average Nusselt number and pressure drop when Reynolds number and rib height increases. In addition, the pressure drop and average Nusselt number increases with decrease the space between the stagnation point and rib. The maximum enhancement of the average Nusselt number is up to 39 % at Reynolds number of 1000, the rib height of 0.3, rib location of 2 and nanoparticles volume fraction of 4%. The best thermal-hydraulic performance of the impinging jet can be obtained when the rib height of 0.2 and rib location of 2 from the stagnation point with 4% nanoparticles volume fraction.
In this paper, turbulent forced convection of nanofluid flow in channel with isoscelestriangularbaffles is numerically investigated over Reynolds number ranges of 5000-10000.One baffle mounted on the bottom wall of channel and another mounted on the top wall.Al2O3-water nanofluid with nanoparticles volume fraction of 4% and nanoparticles diametersof 25 nm is used. The governing continuity, momentum and energy equations as well as thelow Reynolds number k-ε model of Launder and Sharma have been solved using finitevolume method. The effect of baffle height, baffle distance as well as Reynolds number onthe flow and thermal characteristics have been presented and discussed. It is found that theenhancement ratio of the average Nusselt number as well as the fraction factor increase withincreasing in the baffles height. It is also found that the enhancement ratio of the averageNusselt number increases as the distance of top baffle decrease. Furthermore, the bestthermal-hydraulic performance of channel with triangular baffles using nanofluid can beobtained at baffle height of 2.5 mm, distance of the top baffle of 40 mm and Reynoldsnumber of 5000.
In this paper, turbulent convective heat transfer in a triangular-ribbed chan-nel has been numerically investigated. SiO2-water with nanoparticles volume fraction of 4% and nanoparticles diameters of 30 nm is employed with Reyn-olds number ranging from 2000 to 8000. The governing continuity, momen-tum and energy equations in addition to low Reynolds number k-ε model have been transformed into body-fitted coordinates system and then solved using finite volume method. The effects of Reynolds number and rib heights on Nusselt number, pressure drop, thermal-hydraulic performance factor and entropy generation are presented and discussed. It is observed that the Nusselt number, pressure drop and thermal performance increase with in-creasing of Reynolds number and rib height. In addition, the highest perfor-mance factor can be obtained at Reynolds number of 6500 and rib height of 1.5 mm.
This paper contributes to the field of improving the performance of heat exchangers using metal foam (MF) full-filled and partially/periodically-filled within the gap between the two pipes. The effect of configuration and arrangement of copper MF (15PPI and porosity of 0.95) installed on the outer surface of the inner pipe of a counter-flow double-pipe heat exchanger on the thermal and hydraulic performance was studied experimentally. The test section consisted of concentric two pipes; the inner pipe which was made of copper while the outer pipe was a Polyvinyl chlo-ride. Air was used as a working fluid in both hot and cold sides. A wide cold air flow rate range was covered from 3 to 36 m3/h which corresponds to Reynolds number (Re) range from 2811 to 31,335. The hot air flow rate was kept constant at 3m3/h. The temperature difference (ΔT) be-tween the inlet hot air and inlet cold air was adopted to be (20°C, 30°C, 40°C, and 50°C). The re-sults revealed that the higher Nusselt number (Nu) was at ΔT= 50°C and the thermal performance of the heat exchanger with the MF for all the arrangements was greater than the smooth heat exchanger. The highest and lowest friction factor was 1.033 and 0.0833 for the case 1 and 8, re-spectively, and the optimal performance evaluation criteria (PEC) was 1.62 for case 7 at Re = 2800. The Nu would be increased with a moderate increase in the friction factor by optimizing the arrangement of the MF. The two essential parameters that played an important role for in-creasing the PEC were the MF diameter and the MF arrangement along the axial length of the cold air stream.
In this study, a numerical investigation on the thermo-hydraulic performance of thedouble pipe heat exchanger into heat transfer by different shapes of fins on the outersurface for the inner tube as extended surfaces. The inner and outer diameters of theinner pipe were (16.05 mm), (19.05 mm) respectively, and (34.1 mm), (38.1 mm) for theouter tube. The length of the heat exchanger was (1000 mm). Hot and cold water wereused as the working fluid, where the hot water flows inside of the inner one in counterflow with the cold water which flows in the annulus. The inlet temperature for the hotwater is (75 OC) while it is (30 OC) for the cold. The hot fluid flows at constant ratewhich is (0.1kg/s) while the cold is varied from (0.1 kg/s to 0.2 kg/s).The study wasperform using the known commercial CFD package (ANSYS – FLUNET 15) .Theresults shows that both (rectangular and triangular) fins enhances the heat transfercoefficient compare with the conventional plain tube .The rectangular fins presents anheat transfer enhancement ratio of (61% to 74%). Using of extended surfaces present agood result in saving energy by enhancing the performance of the double pipe heatexchangers used in petroleum industry.
Enhancing the hydrothermal performance of plate-fin microchannels heat sink (PFMCHS) promises smaller size and lighter weight, and then improve the heat removal in consequently increase the speed of electronic devices. In this numerical study, an innovative hydrothermal design of PFMCHS is suggested by inserting elliptic pins inside microchannels in different; aspect ratio (AR) of pin, pin number ratio (ψ) in order to optimize the hydrothermal design of this kind of heat sinks. The main objectives of this study are; investigating the effect of pins on the performance of PFMCHS by investigating the best geometry in the pinned-fin MCHS and which is higher, thermal or hydraulic performance of this kind of heat sinks and what is the optimal number of pins numerically and what about the pressure drop penalty in the proposed design, little, modest or high increase. It is seen that the thermal resistance of the pinned fin MCHS is about 50% lower, and pressure drop of it is much higher than that of the (PFMCHS) under the condition of equal wind velocity. Maximum mechanical fan power reduction obtained is about 57% for the pinned fin MCHS with ψ = 1 and Dh = 1 ×10-3 m compared to the corresponding original channel heat sink. To show the overall performance of the two parameters; aspect ratio (AR), pin number ratio (ψ), the overall JF factor is estimated and the concrete findings shows that the best hydrothermal performance is obtained at the greater aspect ratio which is around overall JF = 1.2. In addition, the trend of overall JF is going down with the pin number ratio, starting from 1.2 to 1.15. And the concrete findings show that pinned fin MCHS provides thermal performance of 1.42 times greater than the smooth one under the corresponding conditions when one pin is used in each channel