This paper focuses on investigating and analyzing the effects of geometric parameters on the performance of interrupted flying-wing fins (IFWF). The incorporation of interruptions in the flying-wing fins (FWF) effectively enhances heat transfer efficiency, and increases flow resistance. Moreover, when the number of interruptions exceeds 3, the comprehensive performance of the heat exchanger is diminished. Numerical simulations are employed to thoroughly investigate the effects of geometric parameters individually, within the Reynolds number range of 600-1600, and correlations for the j and f-factor of the interrupted flying-wing fins (IFWF) are proposed using the responses surface method. The parametric study of the contribution ratio on the j-factor, f-factor, and JF-factor is obtained by the Taguchi method, including 18 cases with different combinations of key parameters. At a Reynolds number of 1000, it becomes evident that parameter A exerts the most substantial influence on the j-factor, f-factor, and JF-factor. Consequently, in the design of IFWF, prioritizing amplitude A is imperative.

The present study proposes a model to predict the heat transfer coefficient in R134a liquid–vapor two-phase pulsating flow boiling in an evaporator using the experimental data and response surface methodology (RSM). The model is based on the current existing empirical correlation for R134a liquid–vapor two-phase continuous flow with an imposed modification factor. The model for the imposed modification factor is the function of the pulsating period and inlet/outlet vapor quality, which is obtained using the limited experimental data. An analysis of variance (ANOVA) is carried out to test the significance of the model and normal probability of residuals is analyzed as well. Results show that the regression model produces a mean error of −4.3% and a standard deviation of 15.4%, compared to experimental results. Of the data 95.1% is contained inside a ±50% error window, which indicates that the proposed model could predict the heat transfer coefficient of R134a liquid–vapor two-phase pulsating flow boiling well.

Efficient ventilation and heat dissipation in indoor substations are crucial for the stable operation of transformers. This study investigates the impact of inlet and outlet positions on ventilation and heat dissipation performance in a 110 kV indoor substation using CFD. A model of the 110 kV main transformer chamber is developed. Twelve combinations of inlet and outlet positions are analysed. Inlet positions include side walls parallel to radiators, side walls perpendicular to radi?ators and both side walls perpendicular to radiators. Outlet positions include the top of the chamber, the side of the inlet, adjacent to the inlet, and opposite inlet. Results demonstrate that locating outlets at the top of the chamber reduces transformer temperature by 0.5-1.6? and increases energy utilization by 8.6%-24.8% regardless of inlet position. Two opposite inlets perpendicular to radiators allows even air distribution between radiators. This configuration reduces transformer temperature by 3.4?C when the outlet is located at the top of the chamber. Overall, the optimal ventilation design involves top chamber outlets and inlets on opposite walls perpendicular to radiators.

Refrigerator, as an indispensable electrical appliance in various families at home and abroad, consumes 7% of the total electric energy. Modern researches in refrigeration focus on affordability an...