Determination of Heat and Flow Characteristics in Spray Cooling with Rectangular Finned Heat Sink

Abstract

Spray cooling process has many parameters such as extended surface, angle of inclination, effect of gravity, diameter of nozzle, angle of spray, mass flux, geometry of cooled surface, thermal performance and critical heat flux of spray etc. Many effective parameters to carry out the experiments with conventional test methods are both expensive and time consuming. As a solution in these circumstances, Taguchi method, which is one of the modern experimental design and optimization methods and very effective in solving such problems, was used in this study. Taguchi method, as well as being in effective to improve the quality of products, also gives the opportunity to achieve better results with much less experiment. Using Taguchi method, as well as to reach the target value exactly, the sensitivity of the design against uncontrollable factors is reduced to a minimum. Thus, the optimum tolerance range in cost and quality factors is determined. When compared to conventional experimental design methods, Taguchi method has many advantages. In these experiments with using rectangular pin fin heat sinks, the effects of the longitudinal and lateral distances of the consecutively arranged nozzle or diffuser-like fin pairs, widths of the fins, angle of fins, heights of fins, spraying time, air flow rate, liquid flow rate (ALR, the ratio of air-liquid flow rate) and the ratio of the nozzle-heat sink distance to the nozzle diameter (h/d) on heat and flow characteristics have been investigated by using Taguchi experimental design method. For this reason, characteristics of flow and heat transfer are considered separately. Nusselt number considered as performance statistic, L27(3 11 ) orthogonal array has been selected as an experimental design plan for the eleven parameters mentioned above. The Nusselt number was calculated by taking into account the characteristic length of heat sink and the optimized results were found to be fin width of 45 mm, fin angle of 45 IntroductionAtomization is used to transfer energy from wide surface areas in low temperatures throughout cooling applications. From the outlet of an atomizer, an unsteady liquid mass performs a fragmentation process respectively in the order of layer formation, ligament formation, and droplet formation. The velocity and diameter rates of the droplets to compose spray are important. When the droplets with a certain speed and diameter range are grouped, the droplet speed and diameter range occur, and these two ranges are fundamental to characterizing the spray. Effective energy transfer is ensured with spray cooling, a technology characterized by high heat transfer, heat convection homogeneity, and a low droplet impact speed, which are explored for engineering applications today. Having gained momentum especially in the last 20 years, studies on the atomization of liquids have been used widely in industry. The cooling of metal surfaces and electronic components, drying operations, humidification, washing, watering and fire extinguishing operations, pulverized f...

Numerical Determination Of Cooling Performance On Heat Sink Using Impingement Jet

“…The distance between nozzle and heat sink is also a very important parameter. However, h/d=1 distance was used in previous experimental studies and it was observed that the best heat transfer was achieved with h/d=1 [14,24,25]. Therefore, numerical analyses were performed for optimum rectangular pinfin heat sink at four different impingement jet velocities (10, 12, 14, and 16 m/s), three different nozzle diameters (D=50, 63, and 75 mm), and three different heat fluxes (Q=2222, 3333, and 4444 W/m 2 ) at fixed dimensionless nozzle-heat sink distance (h/d=1).…”

“…The heat sink optimized in the previous studies was used in the numerical analyses [24]. The heat sinks were optimized using Taguchi experimental design method.…”