Wang H.-N.,China Municipal Engineering North China Design and Research Institute Co. |
Su X.-C.,China Municipal Engineering North China Design and Research Institute Co.
Reneng Dongli Gongcheng/Journal of Engineering for Thermal Energy and Power | Year: 2015
A three-dimensional model for shell-and-tube heat exchangers for use in the coal gasification process in the environment of supercritical water was established and a numerical simulation study was made of the heat exchange and phase-change process of materials in both tube and shell side by making use of the software CFX (computational fluid dynamics analytic software). The IAPWS IF97 database was successfully used to numerically simulate the physical property and state of the supercritical water and the phase-change process of the material in the tube side from its subcritical state to supercritical one was expounded. By making use of the available test results, the model in question was verified. The simulation results show that the pressure drop and heat transfer coefficient in the shell side will increase with an increase in the flow rate in the shell side. The growth rate of the temperature at the outlet of the shell side will first become big and then small. To increase the interval of the baffles in the heat exchanger from 117 mm 150 mm will be not conspicuous in enhancing the heat transfer effectiveness, however, the flow resistance in the shell side will increase greatly. At a pressure of 23 MPa, under the operating condition of the temperature changing from 400 ℃ to 600 ℃, the influence of the radiative heat transfer in the heat exchanger is relatively big. When a numerical simulation is made, the amount of heat transferred in the form of radiation cannot be ignored. The actual structure of the heat exchange will be finalized by comprehensively considering the influence of the heat transferred and coal particle deposition. The above-mentioned numerical simulation results can offer a certain theoretical significance and practical value in engineering projects in the design and study of the heat exchangers for use in supercritical water coal gasification process. © 2015, Harbin Research Institute. All right reserved. Source