Determining the optimal pinch point temperature difference of evaporator for waste heat recovery

From the perspective of exergy recovery, the pinch point temperature difference (PPTD) of evaporator for waste heat recovery has been optimized by exergo-economic principle using the annual net profit per transferred heat load as objective function. And for comparison, another criterion, the annual total cost per transferred heat load from the view of exergy destruction, is introduced. Taking organic fluid R600a as an example, the effects of thermodynamic and economic parameters on the optimal PPTD are examined. It is found that the optimal PPTD is closely related to the total investment costs of evaporator. Different trends on the optimal PPTD are provided with the variations of thermodynamic and economic parameters. And the flow exergy loss has little impact on the optimal PPTD of evaporator. The optimal PPTD from the perspective of exergy recovery is larger than that from the view of exergy destruction.     

脉冲光热偏转测量大的光学吸收系数

本文叙述了脉冲光热偏转方法测量介质的光学吸收系数的基本原理和理论依据。实验测量了几种不同浓度的ＫＭｎＯ４溶液在５３２ｎｍ波长的光学吸收系数并与分光光度法测量值直接比较，两者完全符合。实验还测量了６３２．８ｎｍ波长滤光片在５３２ｎｍ波长的光学吸收系数。