变热容工质不可逆布雷顿热机的优化分析

研究以变热容气体为工质的不可逆布雷顿热机循环的优化性能,导出循环的输出功率和效率的表达式,通过数值计算获得循环的一些重要优化特性曲线。结果表明,当布雷顿热机运行在压强比、热机效率、输出功率、工质的最低和最高温度的优化区间时,热机的性能最佳。变热容工质对上述优化区间的影响是显著的。     

Towards the primary target of chloroacetamides –new findings pave the way

This review reports on research of the last ten years to find the primary target enzyme for chloroacetamides. As could be shown first with the green alga Scenedesmus, the formation of very‐long‐chain fatty acids (VLCFAs) is severely impaired. Subsequently, in short‐term experiments, labelled malonate or stearate could be incorporated into leaf discs of cucumber, barley or leek seedlings. While the formation of ‘normal’ long‐chain fatty acids (up to C18) was not influenced, phytotoxic chloroacetamides strongly inhibited the synthesis of VLCFAs of C20, 22 and 24, with I₅₀ values of 10–100 nM . Inhibition depends on the amide structure and on stereospecificity. Also cafenstrole or recently developed tetrazolinones and phosphosulfonates were found active to inhibit fatty‐acid elongation. Subsequently, a cell‐free elongase assay was developed using a microsomal preparation from leek seedlings (Allium porrum L), [¹⁴C]malonyl‐CoA and C18, 20, or C22 acyl‐CoA primer substrates. All elongation steps were strongly affected by those phytotoxic herbicides which were also active in vivo. The inhibitors form a tight‐binding complex with the condensing elongase enzyme system which develops with time and lowers the I₅₀ values markedly. Apparently, a nucleophilic attack of the inhibitor takes place at the specific target enzyme. Acyl‐CoA elongation inhibition is correlated with growth inhibition of the intact cell. Due to the low I₅₀ values and the specific inhibition, we assume that impaired VLCFA‐formation is the primary phytotoxic impact of chloroacetamides and functionally related structures. © 2000 Society of Chemical Industry     

两有限热源间的不可逆斯特林热机的优化性能

建立不可逆气体斯特林热机循环新模型,研究有限热源、热阻、回热损失和工质内不可逆性等对热机性能的影响,应用有限时间热力学方法,导出输出功率与效率间的优化关系解析表式,进而获得最大输出功率及其它优化性能参数。所得结论比现有文献的相关结论更为普遍,对实际斯特林热机的研制和优化设计提供新的理论指导。