The refrigerant flow distribution in the parallel flow microchannel evaporators is experimentally investigated to study the effect of header configuration.Six different configurations are tested in the same evaporator...The refrigerant flow distribution in the parallel flow microchannel evaporators is experimentally investigated to study the effect of header configuration.Six different configurations are tested in the same evaporator by installing insertion device and partition plate in the header to ensure the consistency of the other structure parameters.The results show that the uniformity of refrigerant flow distribution and the heat transfer rate are greatly improved by reducing the sectional area of header.The heat transfer rate can increase by 67.93%by reducing the sectional area of both inlet and outlet headers.The uniformity of refrigerant flow distribution and the heat transfer rate become worse after installing the partition plate in the insertion devices and changing the inner structure of the header further.展开更多
The mechanical stress distribution and the stress concentrations of the superheater outlet header of a 600MW supercritical boiler were analyzed by the finite element method. The results showed that the stress concentr...The mechanical stress distribution and the stress concentrations of the superheater outlet header of a 600MW supercritical boiler were analyzed by the finite element method. The results showed that the stress concentrated at the inside conjunction area between the pipe and the header cylinder , and the value of the maximum mechanical stress concentration factor is 2.51.展开更多
At present, the main attention of researchers is paid to the deterioration of heat transfer when heating the outer surface of the pipe with the liquid or steam, flowing inside it, in the presence of films or deposits ...At present, the main attention of researchers is paid to the deterioration of heat transfer when heating the outer surface of the pipe with the liquid or steam, flowing inside it, in the presence of films or deposits on its inner surface. However, when pipe is heating by heat carrier medium, flowing inside it, film on the inner pipe surface serve a dual protective function, protecting the pipe from corrosion and reducing its thermal stress. The article represents the results of the computational analysis of protective films influence on the thermal stressed state of headers and steam pipelines of combined-cycle power plants (CCPP) heat-recovery steam generators at different transient operating conditions particularly at startups from different initial temperature states and thermal shock. It is shown that protective films have a significant influence on the stresses magnitude and damage accumulation mainly for great temperature disturbances (for thermal shock). Calculations were carried out at various thicknesses of films and assuming that their thermal conductivity less than thermal conductivity of the steam pipelines metal.展开更多
基金the Key Industry Common Key-Technology Innovation Project of Chongqing Municipal Science and Committee(No.cstc2015zdcy-ztzx60001)
文摘The refrigerant flow distribution in the parallel flow microchannel evaporators is experimentally investigated to study the effect of header configuration.Six different configurations are tested in the same evaporator by installing insertion device and partition plate in the header to ensure the consistency of the other structure parameters.The results show that the uniformity of refrigerant flow distribution and the heat transfer rate are greatly improved by reducing the sectional area of header.The heat transfer rate can increase by 67.93%by reducing the sectional area of both inlet and outlet headers.The uniformity of refrigerant flow distribution and the heat transfer rate become worse after installing the partition plate in the insertion devices and changing the inner structure of the header further.
文摘The mechanical stress distribution and the stress concentrations of the superheater outlet header of a 600MW supercritical boiler were analyzed by the finite element method. The results showed that the stress concentrated at the inside conjunction area between the pipe and the header cylinder , and the value of the maximum mechanical stress concentration factor is 2.51.
文摘At present, the main attention of researchers is paid to the deterioration of heat transfer when heating the outer surface of the pipe with the liquid or steam, flowing inside it, in the presence of films or deposits on its inner surface. However, when pipe is heating by heat carrier medium, flowing inside it, film on the inner pipe surface serve a dual protective function, protecting the pipe from corrosion and reducing its thermal stress. The article represents the results of the computational analysis of protective films influence on the thermal stressed state of headers and steam pipelines of combined-cycle power plants (CCPP) heat-recovery steam generators at different transient operating conditions particularly at startups from different initial temperature states and thermal shock. It is shown that protective films have a significant influence on the stresses magnitude and damage accumulation mainly for great temperature disturbances (for thermal shock). Calculations were carried out at various thicknesses of films and assuming that their thermal conductivity less than thermal conductivity of the steam pipelines metal.
