【摘要】 茶叶传热特性的基础是其热物理特性,即茶叶的比热、导热系统和导温系数,它们都随茶叶的加工方法、形状、容重、揉捻紧度和含水量而变化。试验测得,茶叶的比热为1.59—1.66千焦耳/公斤·开,加工1公斤干茶所需的热量理论值为1750大卡。茶叶的导热系数为0.0362—0.0486瓦/米·开,是一种热的不良导体。茶叶的导温系数随容重和含水量的变化而变化。茶叶的含水量增加,导温性能提高,温度变化快,茶叶的容重增大时,导温性能下降,温度变化慢。研究茶叶的传热特性有助于品质管理及提高热效率,也为茶叶加工实现定向控制提供有利条件。更多还原

【Abstract】 The basis of heat transfer in tea processing is the physical properties of tea,i.e,the specific heat,thermal conductivity and thermal diffusivity of tea leaves.They arenecessary for calculating heat transfer velocity,temperature profile and the temperatureat certain spot,they are different due to the processing method,shape,bulk density,rolling tightness and the moisture content.The specific heat of tea leaves is 1.59-1.66kj/kg.K,the total amount of heat needed for making 1 kg made tea is 1750 kcal.The thermal conductivity of tea leaves is 0.0362-0.0486 W/m·K,thus indicates thetea leaves are one of the insulating materials.Thermal diffusivity of tea leaves varieswith the bulk density and moisture content.As the moisture content increases,thethermal diffusivity of tea leaves becomes higher,and the change of temperature will begetting faster;on the contrary,as the bulk density of tea leaves increases,the thermaldiffusivity becomes lower,and the change of temperature will be getting slower.Teaprocessing is not only of a dehydration process,but also of a great mass transferprocess which occured with the moisture loss,resulting in the development of thespecific color,flavour and taste of tea.Studies on the heat transfer characteristics oftea leaves is the technical basis of improving the quality,thermal efficiency and will beuseful for developing the directional processing of tea.更多还原