dsc测量比热容实用教案.ppt

ABSTRACT
This study presents a methodology to determine the specific heat capacity (Cp) of materials for thermal energy storage (TES) by different DSC methods are considered to be applied in the methodology, and are explained and compared in this study in order to select the most proper one for Cp determination.
To perform this study, the Cp of three materials commonly used in sensible TES systems, slate, water, and potassium nitrate (KNO3), is determined.
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一、INTRODUCTION
lack of fossil energetic resources
its price
need to decrease CO2 emissions
lead to dedevelop new energy systems able to take profit of renewable energy and be environmentally friendly and less expensive
TES systems are a possible solution
Solar energy abundant clean and easy accessible.
problem:as the hours of maximum energy demand match with the hours of no solar irradiation
with the aim to fill this existing energy supply gap, TES systems are presented as the solution to store the energy and use it anytime
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TES technologies
sensible heat storage
the process by which the heat is accumulated due to the increase of the material temperature without experimenting structural changes, no phase change
latent heat storage
phase change , thermochemical energy
material selection
A high storage capacity
Therefore,need a high specific heat capacity.
(1)
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定义：在程序控制温度下，测量物质与参比物之间的能量差随温度变化关系的一种技术。
DSC曲线峰包围的面积正比于热焓的变化
可以测定多种热力学和动力学参数，例如比热容、反应热、转变热、相图、反应速率、结晶速率、高聚物结晶度、样品(yàngpǐn)纯度等。该法使用温度范围宽（-175~725℃）、分辨率高、试样用量少。适用于无机物、有机化合物及药物分析。
差示扫描(sǎomiáo)量热法（DSC） （Differential Scanning Calorimetry）
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采用试样和一标准物质在相同条件下进行扫描，然后量出二者的纵坐标进行计算。要求标准物质在所测温度范围内没有发生物理化学变化，且比热容已知。常用的标准物质是蓝宝石。具体作法是在DSC内先用两个空样品皿，以一定的升温速度作一条基线，然后放入蓝宝石样品在相同条件下作一条DSC曲线，最后(zuìhòu)在同样条件下作未知试样的DSC曲线，如图
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three DSC methods for Cp measurement
The dynamic method has traditionally been used to measure PCM lat