The Behavior of Variable Zone for Concave Arcs -Fin of Heat Sink with Multi Air Jet Impingement

Novel array arcs- fin heat sink 7×2 with 6×2 multi air jet impingement are presented in this paper by using numerical simulation. Temperature distribution of jets diameter of 5mm and arcs- fin heat sink with variety shapes at constant radius of 45mm are evaluated. Reynolds number ranges from 7000 – 11000. The study has been done at constant Z/d= 6 and constant heat flux =8333.33 W/m2. The best shapes of fins has an effective role in improving the rate of heat transfer .In this paper, the design concerned in arcs ships to construct fin geometry. Four concave arcs constricted the shape of fins heat sink for model A. This model has been changed to construct models (B-C-D-E) by reflect two concave arc from it to be convex arc. All five models at the same radius. The five configurations were comparative between each other and the best model comparative with flat plate heat sink. It is observed that model D of heat sink showed best temperature dissipation than the others. The results of this paper can help to select heat sink that meets a design's thermal, Power, packaging and cost requirements (specialized in arcs fins) with array of impingement jet, which is a popular used in cooling electronic devices. Keywords: arcs –fin heat sink; array of impingement jet; CFD. DOI: 10.7176/CMR/13-2-02 Publication date:May 31st 202

The effect of polluted samples on Bayesian Estimators of Burr type –XII distribution

Bayesian estimators may be affected by the polluted samples, because these samples can lead to the influence of the estimation methods in general and the Bayesian methods in particular, and thus the deviation of the values of the distribution parameter from their real values, and this leads to the divergence of the capabilities of the Bayes survival estimators from the real values. The results showed that the estimators of the parameters were affected by many factors (sample size, distribution parameter, number of outliers and the estimation method). Simulation experiment results also showed a difference in Mean Square Error (MSE) of the Bayes survival estimators for each different experiment. Bayesian methods can be compared with other estimation methods (Maximum likelihood Estimation (MLE), Moment estimation (MOM) and shrinkage method (SH)). Also, Bayesian methods can be used to estimate the survival function of other distributions (exponential, Gamma and mixed) to observe the estimation results with the presence of extreme values

THE BEHAVIOR OF HEAT SINK-IMPINGEMENT COOLING WITH FLAT PLATE AND ARCED FINS MODELS

In this paper, a statistical analysis was applied to the numerical predictions of temperature distribution for the heat sinks. There are two types of heat sink with an array of impingement. The first type is a flat plate heat sink, and the second type is arcs-fins heat sinks. The second type category considers five models (A, B, C, D, and E). The shapes of fins were changed, but the thickness, distance between fins, and radius were held fixed for comparing and analyzing them depending upon the improvement of the fin geometry of heat sink. The heat sinks of the two types are subjected to multi impinging flow at different Reynolds numbers (7000- 11000). Thermodynamic and hydraulic results were collected. The best model was calculated through a statistical analysis. The efficiency of an arcs-fin heat sink was superior to that of the flat plate heat sink. The findings of Model D were more appropriate than those of the other models. The concave arc near the heat sink's exit (model D) created better effect than the convex arc (model E), despite the fact that the (model D) shape fins being identical to (model E) shape fins (only rotated 180° at the same location). However, Descriptive Statistics manifested that in all situations, the mean temperature for (model D) is better than (model E). The results of comparison between the flat plate heat sink and models (D and E) evinced that the average heat sink temperature in the suggested design reduced via 12%, 8%, while the (model E) decreased by 12%, 7% for Re (7000, 9000), respectively. In addition, the two models maintained the same percentage of (8% and 7%) improvement at Re (11000). The correlation coefficient between the flat plate and the arcs-fins heat sink for model B has the highest value (0.809), while model A has the lowest value of correlation (0.673)