目的应用衰减全反射傅里叶变换红外(attenuated total reflection-Fourier transform infrared,ATRFTIR)光谱技术分析长白猪死后肋软骨和肋骨组织随死亡时间推移的化学降解过程,为死后较长时间段内推断死亡时间提供可行的新途径和方法...目的应用衰减全反射傅里叶变换红外(attenuated total reflection-Fourier transform infrared,ATRFTIR)光谱技术分析长白猪死后肋软骨和肋骨组织随死亡时间推移的化学降解过程,为死后较长时间段内推断死亡时间提供可行的新途径和方法。方法猪放血处死后取肋软骨和肋骨离体置于20℃环境,后每72 h提取部分组织样本,进行ATR-FTIR光谱分析,并与对应死亡时间点进行相关性分析。结果随死亡时间的延长,肋软骨与肋骨FTIR的主要吸收峰峰位没有发生明显变化,而其部分峰强比出现了不同时序性的变化趋势,并与死亡时间存在良好的相关性,肋软骨较肋骨组织有更好的时序性。结论应用ATRFTIR光谱技术发现死后猪肋软骨和肋骨组织光谱学变化存在一定的规律性,有望成为基于光谱学推断死亡时间的一种新途径。展开更多
The conventional straight microchannel heat sinks have been reported to inadequately remove the increasing power density of electronics.In recent years,an effective heat transfer enhancement method,flow disruptions ha...The conventional straight microchannel heat sinks have been reported to inadequately remove the increasing power density of electronics.In recent years,an effective heat transfer enhancement method,flow disruptions have attracted the attention of researchers,where interrupted structures are arranged in the microchannel to enhance flow mixing and heat transfer.However,previous numerical studies of interrupted microchannel heat sinks(I MCHS)mainly focus on single-phase flow condition,and the characteristics of the boiling heat transfer of I MCHS in two-phase flow condition have been rarely explored.Thus,the flow and heat transfer characteristics of two I MCHS based on rectangular microchannel heat sink(R MCHS)are investigated by modeling both single-phase and two-phase flow conditions.These two interrupts consist of a combination of cavities and ribs,namely elliptical cavities and elliptical side ribs(EC-ESR),and elliptical cavities and elliptical central ribs(EC-ECR).The results show that for single-phase flow condition,the maximum Nusselt number is increased by 187%in the EC-ESR design and150%in the EC-ECR design compared with the R MCHS.For subcooled boiling(i.e.,two-phase flow)condition,the EC-ECR design is a promising structure to enhance boiling heat transfer with 6.7 K reduction of average wall temperature and 29%increment of local heat transfer coefficient when compared with those of R MCHS.However,the local heat transfer coefficient in the EC-ESR design is decreased by 22%compared with the R MCHS due to the formation of a rare flow pattern(i.e.,inverted annular flow with vapor film separation)in the microchannel.This flow pattern can induce departure from nucleate boiling(DNB),thereby deteriorating the heat transfer on the channel walls.展开更多
基金supported by the National MCF Energy R&D Program(Grant No.2018YFE0312300)the National Natural Science Foundation of China(Grant No.51706100)+1 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK20180477)the Fundamental Research Funds for the Central Universities(Grant No.30918011205)。
文摘The conventional straight microchannel heat sinks have been reported to inadequately remove the increasing power density of electronics.In recent years,an effective heat transfer enhancement method,flow disruptions have attracted the attention of researchers,where interrupted structures are arranged in the microchannel to enhance flow mixing and heat transfer.However,previous numerical studies of interrupted microchannel heat sinks(I MCHS)mainly focus on single-phase flow condition,and the characteristics of the boiling heat transfer of I MCHS in two-phase flow condition have been rarely explored.Thus,the flow and heat transfer characteristics of two I MCHS based on rectangular microchannel heat sink(R MCHS)are investigated by modeling both single-phase and two-phase flow conditions.These two interrupts consist of a combination of cavities and ribs,namely elliptical cavities and elliptical side ribs(EC-ESR),and elliptical cavities and elliptical central ribs(EC-ECR).The results show that for single-phase flow condition,the maximum Nusselt number is increased by 187%in the EC-ESR design and150%in the EC-ECR design compared with the R MCHS.For subcooled boiling(i.e.,two-phase flow)condition,the EC-ECR design is a promising structure to enhance boiling heat transfer with 6.7 K reduction of average wall temperature and 29%increment of local heat transfer coefficient when compared with those of R MCHS.However,the local heat transfer coefficient in the EC-ESR design is decreased by 22%compared with the R MCHS due to the formation of a rare flow pattern(i.e.,inverted annular flow with vapor film separation)in the microchannel.This flow pattern can induce departure from nucleate boiling(DNB),thereby deteriorating the heat transfer on the channel walls.
