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Bambang Teguh T.,Agency for the Assessment an Application of Technology BPPT | Bambang Teguh T.,National Institute of science and Technology ISTN | Komara R.J.,Agency for the Assessment an Application of Technology BPPT
International Journal of Mechanical and Mechatronics Engineering | Year: 2014

A number of tubes in the Ortho-Dichlorobenzene (ODCB) condenser have been damaged. ODCB condenser is vertical shell and tube exchangers, BEM type, with the expansion joint on the shell. ODCB flows in the tube side with the mass flow rate of 0.5778 kg/s at a pressure of 1 baia and a temperature of 180oC. Cooling water (CW) flows in the shell side with the mass flow rate 0.4615 kg s at a pressure of 2 baia and a temperature of 30oC. Both fluid flows in parallel from top to bottom. Tube made of stainless steel pipe SS 316 L, 26.67 mm outside diameter, schedule 40, and a total is 106 pieces. The test of material concluded that the damage in the form of stress corrosion cracking caused by bending stress due to longitudinal expansion of tube cannot be accommodated by the fixed tube sheet type (M type). One indicator is a crack occurs in a transverse position and starting from the outer surface of the tube. However, in reality cracks were not occurred in the middle of a tube length, but at a distance of about 450-500 mm from the tube sheet, not far from the shell inlet nozzle. This study focused on the simulation of the heat transfer process and Computational Fluid Dynamics. The purpose of this study was to determine the local phenomena that occur which is related to damage of tubes. Simulation results show at a range of about 450-500 mm from the tube sheet, CW in the shell side begins to boil and ODCB began condensed in the tube side. Water vapor fill the space of the upper shell. In this zone, ODCB in the tube still in the gas phase. The combination of these two circumstances cause convection heat transfer in this zone is very bad and lead to the tube wall temperature gradient is high enough at longitudinal direction. High temperature gradient causes the tube wall strength decreases, so that when the tube expansion on hold, the tube will be bent in the zone. © February 2014 IJENS. Source

Cholis N.,National Institute of science and Technology ISTN | Ariyono S.,Semarang State Polytechnic Polines | Priyandoko G.,Universiti Malaysia Pahang
Energy Procedia | Year: 2015

The design of Single Acting Pulley Actuator (SAPA) Continuously Variable Transmission (CVT) utilizes combinations of DC motor system, gear reducers and power cam mechanisms to actuate primary movable pulley sheaves on the transmission shaft. The secondary pulley supported by spring provides a belt clamping force to prevent slips, while the secondary controls the rubber v-belt from slipping. Since the methods of controlling these are similar, this paper only discusses the primary part. The servomotor regulates the axial movement of primary movable pulley sheaves to shift the rubber v-belt placed between the sheaves, and change the belt-pulley contact radius. Changing this contact radius means changing the CVT ratio. Computer simulation results are presented to demonstrate the effectiveness of the proposed PD controller. The research outcome gives a significant result to complete 75.08° rotation of the CAM from lower gear ratio to top gear ratio is less than 6.79 sec, with minimum error and less overshoot with a manual PD tuning contribution to the field of DC motor based electro-mechanical CVT control system. © 2015 The Authors. Published by Elsevier Ltd. Source

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