The transpiration characteristics and heat dissipation analysis of natural leaves grown in different climatic environments

Abstract

Because vegetation is one of the typical backgrounds on land, it is necessary to investigate the transpiration characteristics and heat dissipation processes of the leaves grown in different natural environments to optimize the thermal infrared camouflage performance of the bionic materials for countering the thermal infrared detection. Considering ambient temperature and relative air humidity as the dominant environmental factors, daily transpiration rates of various kinds of leaves grown in Wuxi (summer and winter, moderate relative air humidity) and Xishuangbanna (summer, high relative air humidity) were measured respectively, and a thermophysical model was established to investigate the heat dissipation processes of the leaves. Results show that the average daily transpiration rates of the leaves are 1.42, 0.42 and 0.92 kg/m2∙day in Wuxi summer, Wuxi winter and Xishuangbanna summer respectively, indicating that the daily transpiration rates vary significantly with different environments. In Wuxi summer and winter, the daily transpirative heat flow accounts for approximately 55.8% and 24.3% of the total heat dissipation of the Cinnamomum camphora leaves respectively, revealing the significant effect of the transpirative heat transfer on the temperature of the leaves grown in the environment of high ambient temperature and the weakened effect in the environment of low ambient temperature. In Xishuangbanna summer, the daily transpirative heat flow accounts for approximately 37.3% of the total heat dissipation of the Ailanthus leaf, which is significantly lower than that in Wuxi summer, indicating that relative air humidity also dominates the effect of transpirative heat transfer on the temperature of the leaves.