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Centrifugal compressors are the most commonly used types of compressors in industry. Performance of compressor is one significant parameter to be first determined prior to its design and operation. Centrifugal compressor's is usually expressed in terms of flow, head, speed and efficiency. Determining centrifugal compressor's performance operation is however very costly, due to it requirement for testing after fabricating and manufacturing of the compressor. This research is addressed to predict the centrifugal compressor performance cheaply through a numerical simulation. The study was conducted at a specific off design parameter for designed mass flow rate of 0,98 kg/s of centrifugal compressor. It is a single stage centrifugal compressor with an impeller diameter of 236.24 mm and a diffuser outer diameter of 349.83 mm. The number of impeller blades is 18 and the number of diffuser blades is 6 with a diffuser inlet angle of 15⁰. The numerical simulation was established and validated with experimental study. The simulation was then carried at the range of operating mass flow representing varies operation condition. The results revealed that simulation model has been built to simulate the performance of the centrifugal compressor. The simulation results were validated and accepted at deviation below 5%. In addition, the simulation is enabling to generate performance curve in term of pressure ratio and efficiency with respect mass flow rate. Maximum efficiency of the designed centrifugal compressor occurs at a mass flow rate of 1 kg/s with a value of 80.83%. This numerical method is very promisingly to be further incorporated for industrial application for predicting the centrifugal compressor performance. [ABSTRACT FROM AUTHOR]

Impeller is a part of centrifugal compressor that has an important role in the pressure generation process. Differences in the shape and size of this component greatly affect the overall ability of the compressor to generate pressure. This research is focused on prediction of centrifugal compressor performance by varying the impeller outlet blade angle. The study was conducted at off design parameter of a single stage centrifugal compressor with an impeller diameter of 236.24 mm and a diffuser outer diameter of 349.83 mm. The number of impeller blades is 18 and the number of diffuser blades is 6 with impeller inlet blade angle (β1) of 42°, and impeller outlet blade angle (β2) of 50°. The maximum efficiency of the designed centrifugal compressor occurs at a mass flow rate of 0.993 kg/s with a value of 83.71%. Result of the numerical simulation shows that the higher value of β2, the higher pressure-ratio that can be produced under all mass flow rate condition. Compressor overall efficiency also increases with the increase of β2 value. However, higher value of β2 results in an increase of instability level of gas flow at impeller outlet and eventually backflow began to occur in the β2 value of 90° that would reduce the volumetric efficiency of the compressor. [ABSTRACT FROM AUTHOR]

Heat Recovery Steam Generator (HRSG) is one of the vital units in various industries in order to improve energy efficiency. Uniform distribution of gas turbine exhaust gas that enters the HRSG becomes one of the important parameters of the HRSG design to minimize corrosion and hot spots that cause the tube to burst. The characterization of the effect offlow diverter was carried out to observe the velocity distribution as a parameter of flow uniformity, the distribution of pressure and temperature of the gas flow that passes through each heat exchanger module as a parameter of HRSG performance. CFD simulation was conducted on the HRSG model which included the inlet duct, the heat exchanger module section which is assumed to be the porous media, and the stack as the flue gas output. Flow diverter configuration consisted of the number of plates 1, 3 and 5 with angles of 30°, 45°, and 60°, respectively. The numerical simulation was establishedand validated with experimental study. The dimensionless numbers, swirl number and Euler number, were considered as the dynamic similarities between the experimental model and the numerical simulation. Flow uniformity from the configuration of 3 plates with angle of 45° was 86.3%, which was 3.522% higher than HRSG without a flow diverter. Other configurations caused flow uniformity decreased. Installation of flow diverter had no significant effect on HRSG performance. [ABSTRACT FROM AUTHOR]