Condenser is a type of heat exchanger that serves as condensation for turbine output steam. In general, a steam power plant uses a surface condenser. This type of condenser is a type of shell and tube. Condensers have a phenomenon of convection heat transfer. The change in distance between condenser tubes is one way to increase the rate of heat transfer. To produce maximum heat transfer, it can be determined by the variety of distances between tubes. The research was conducted by analyzing the flow characteristic and heat transfer around condenser tube banks with gap ratio variation (s/d), which compares transverse distance (ST ) and tube diameter (d) with variations of 3.2, 2.7, 2, and 1.7. 2-dimensional simulation with Computational Fluid Dynamics (CFD) is a numerical method and algorithm for solving and analyzing problems that occur in fluid flows. Based on the results obtained, the smaller the Gap Ratio, the lower the outlet temperature produced and the maximum heat transfer, but the pressure drop value obtained the bigger. Also, the smaller Gap ratio, the bigger v max produced. The lowest outlet temperature value at the variation of 1.7 is 310.66 K, and the coefficient of heat transfer is 103.34 W/m2K. Pressure drop produced at variation 1.7 is 515.99 Pa. Variation 2 is the best gap ratio variation, seen from the heat transfer result and the pressure drop value is not too large. The coefficient heat transfer and pressure drop in variation 2 are 76.95 W/m2K and 119.17 Pa.

The primary air fan functions as a primary air producer which is used as air to transport coal powder from the pulverizer to the burner to be burned in the boiler furnace. This study aims to obtain the effect of the rotation variation of fan to  fluid flow characteristics such as the distribution of total pressure, the dynamic pressure, the pressure static contours, velocity distribution, and the fan optimal efficiency. This study was numerical study with simulated a backward impeller type centrifugal fan in a two-dimension model using Fluid Computational software with the multiple reference frame method with the variation of fan rotation. Based on the visualization of the pressure contour and velocity distribution, it could be concluded that there was a volute phenomenon, this was indicated that the greater the volume area in the volute is the greater the total pressure value too. Based on the visualization of the outlet velocity distribution at the position of -0,8531m to -1,01301m, it was found that the velocity is close to the value of 0 m/s2. It showed that the minimum velocity in the area due to the volute tongue radius occurs a flow collision and it impacted the velocity in the area decreased up to V=0. From the simulation results, it was found that the greater the fan rotation value was the greater the efficiency value too. It would be verified by the actual operating data of the centrifugal fan with a minimum rotation range value of 1194 rpm to a maximum of 1468 rpm

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