摘要
针对在超临界水环境下进行煤气化过程所使用的管壳式换热器,建立了在管程和壳程内同时存在物料流动和换热的三维管壳式换热器模型,利用CFX软件(计算流体力学分析软件)对管程和壳程中物料的换热和相变过程进行了模拟研究,成功应用IAPWS IF97(国际通用工业用水和水蒸气热力性质计算公式)数据库模拟了超临界水的物性状态,阐述了管程内物料从亚临界相到超临界相的转变过程。利用已有的实验结果对模型进行了验证。模拟结果表明,随着壳程内物料流量增大,壳程压降和传热系数随之增大;壳程出口温度增大的速率渐趋平缓;当换热器板间距从117 mm增大到150 mm时强化传热效果并不明显,同时大大增加了壳程的流动阻力;在压力为23 MPa,温度达400-600℃的操作条件下,换热器中辐射传热影响较大,进行数值模拟时不应忽略这部分的影响。研究指出:换热器结构设计时需要综合考虑传热和煤颗粒沉积的影响。
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.
出处
《热能动力工程》
CAS
CSCD
北大核心
2015年第6期837-841,965-966,共5页
Journal of Engineering for Thermal Energy and Power
关键词
管壳式换热器
数值模拟
超临界水
煤气化
shell and tube type heat exchanger,numerical simulation,supercritical water,coal gasification
