The uniformity principle of temperature difference field is very useful in heat exchanger analyses and optimizations.In this paper, we analyze some other heat transfer optimization problems in the thermal management s...The uniformity principle of temperature difference field is very useful in heat exchanger analyses and optimizations.In this paper, we analyze some other heat transfer optimization problems in the thermal management system of spacecrafts,including the cooling of thermal components, the one-stream series-wound heat exchanger network, the volume-to-point heat conduction problem, and the radiative heat transfer optimization problem, and have found that the uniformity principle of temperature difference field also holds. When the design objectives under the given constraints are achieved, the distributions of the temperature difference fields are uniform. The principle reflects the characteristic of the distribution of potential in the heat transfer optimization problems. It is also shown that the principle is consistent with the entransy theory. Therefore, although the principle is intuitive and phenomenological, the entransy theory can be the physical basis of the principle.展开更多
A novel method has been designed and exploited to determine the thermal junction potential difference(TJPD) between two acids or alkalies of the same composition but with different temperature. The absolute value of m...A novel method has been designed and exploited to determine the thermal junction potential difference(TJPD) between two acids or alkalies of the same composition but with different temperature. The absolute value of measured TJPD between two strong acids(or alkalies) maintained at different temperatures increases with increasing of the temperature difference between the two electrolytes over the range from 0 to 40 °C. In strong acids, the hot end always has the lower potential while in strong alkalies, the cold end has the lower potential. This is because the ions of fast diffusion rate contribute most to the TJPD. Our results demonstrate the importance of the correction for TJPD in deriving the kinetic parameters when studying the temperature effect on reaction kinetics.展开更多
为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理...为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理冠层温度(T c)受土壤水分影响明显,处理间冠气温差(ΔT)差异极显著。叶水势(LW P)与ΔT、作物水分胁迫指数(CW S I)相关显著。LW P=-1.8M Pa,CW S I=0.40是指示冬小麦发生水分胁迫的关键性指标。综合各指标,为了达到节水目的,使ΔT维持在0^-4℃,可获得冬小麦产量最优值,此时冬小麦灌溉量下限应使土壤相对含水量达到58.7%。展开更多
基金Project supported by the Science Fund for Creative Research Groups of National Natural Science Foundation of China(Grant No.51621062)
文摘The uniformity principle of temperature difference field is very useful in heat exchanger analyses and optimizations.In this paper, we analyze some other heat transfer optimization problems in the thermal management system of spacecrafts,including the cooling of thermal components, the one-stream series-wound heat exchanger network, the volume-to-point heat conduction problem, and the radiative heat transfer optimization problem, and have found that the uniformity principle of temperature difference field also holds. When the design objectives under the given constraints are achieved, the distributions of the temperature difference fields are uniform. The principle reflects the characteristic of the distribution of potential in the heat transfer optimization problems. It is also shown that the principle is consistent with the entransy theory. Therefore, although the principle is intuitive and phenomenological, the entransy theory can be the physical basis of the principle.
基金supported by the National Basic Research Program of China (2015CB932301)National Natural Science Foundation of China (21273215, 91545124)
文摘A novel method has been designed and exploited to determine the thermal junction potential difference(TJPD) between two acids or alkalies of the same composition but with different temperature. The absolute value of measured TJPD between two strong acids(or alkalies) maintained at different temperatures increases with increasing of the temperature difference between the two electrolytes over the range from 0 to 40 °C. In strong acids, the hot end always has the lower potential while in strong alkalies, the cold end has the lower potential. This is because the ions of fast diffusion rate contribute most to the TJPD. Our results demonstrate the importance of the correction for TJPD in deriving the kinetic parameters when studying the temperature effect on reaction kinetics.
文摘为了给以作物高效灌溉制度提供理论依据,对不同供水条件下冬小麦冠层温度进行了多年田间观测,模拟了以土壤水分条件为主导的冠气温差、叶水势、水分亏缺指数等的变化规律及其对影响因素的响应。结果表明,冬小麦各生育阶段不同供水处理冠层温度(T c)受土壤水分影响明显,处理间冠气温差(ΔT)差异极显著。叶水势(LW P)与ΔT、作物水分胁迫指数(CW S I)相关显著。LW P=-1.8M Pa,CW S I=0.40是指示冬小麦发生水分胁迫的关键性指标。综合各指标,为了达到节水目的,使ΔT维持在0^-4℃,可获得冬小麦产量最优值,此时冬小麦灌溉量下限应使土壤相对含水量达到58.7%。
