One type of boiler is a boiler with tangential combustion. Tangential combustion is combusted with a burner arrangement located at each corner (corner) of the boiler, where each burner forms a certain angle to the boiler wall. Most of the tangential boilers are equipped with a tilting burner facility. An inclined burner is a facility to direct the burner to face up or down a certain angle to a horizontal line. Changes in the direction of the burner tilt angle will move to the fireball position in the furnace so that there can be changes in temperature, velocity, also species. This study was conducted to determine setting the burner tilt angle by varying the angle simulated using CFD. The data to be obtained are qualitative data in the form of contours and vectors from the distribution of temperature and velocity and quantitative data in graphs and tables. In this study, it is hoped that the ideal angle for the boiler will be obtained so that combustion in the boiler occurs efficiently.

Abstract. Along with the increasing number of vehicles, the consumption of fuel oil also increases. It can be seen from the data that the contribution of fuel oil in 2015 was quite high, that was about 42% of the amount of oil supplied, and the most fuel oil was used in the transportation sector. The efforts to energy conservation are needed to support the achievement of sustainable development in the energy field. One solution that can be used is adding H2 gas on four 120 cc stroke engines. It can be obtained from electrolysis process using Wet Cell HHO Generator Type. The Wet Cell HHO Generator Type is a device for decomposition of water (H2O) into hydrogen (H2) and oxygen (O2) due to an electric current being passed through the water with electrodes immersed in an electrolyte liquid. Hydrogen gas can be added with gasoline fuel in combustion process on four 120 cc stroke engines. The size of HHO's generator reservoir is 20 x 10 x 20 cm, using Ba(OH)2 catalyst in variation of concentration were 1, 3, 5, 7, and 9 g/l and the throttle-opening are 1,2,3,4,5. The effects of adding hydrogen gas to know performance and exhaust gaseous emissions of four 120 cc stroke engines. The performance of four 120 cc stroke engines which is measured are torque, effective power, thermal efficiency, and specific fuel consumption. The content of exhaust gaseous which is measured are concentrations of carbon monoxide, nitrogen oxide and hydrocarbons. The results of this research shows that the addition of Ba (OH)2 catalyst in HHO's generator can improve the performance and reduce exhaust emissions on four 120 cc stroke engines.

Pressure drop is one of the problems that can occur due to bend components in the piping system. To minimize the pressure drop, modification of the bend pipe component was made at the bend outlet of the main steam line. In this study, an analysis of the effect of the bend angle on the pressure drop was carried out on the pressure and velocity steam distribution. The angle variations used are 30°, 45°, and 60° with the Computational Fluid Dynamics (CFD) method simulated by CFD software. The simulation results show that the lower the angle of curvature of the pipe, the lower the pressure drop and the lowest pressure drop is obtained in the 30° bend domain of 26.2 kPa. The pressure distribution pattern shows that the pressure value will increase from the inner wall to the outer wall. The greater the bend pipe angle, the greater the possibility of flow separation and pressure drop value. The velocity distribution pattern shows that the flow velocity becomes non-uniform after passing through the bend pipe. The greater the bend angle, the sharper the flow direction so that the time taken is longer. In addition, the greater the bend pipe angle, the greater the flow stagnation.

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