The Design And The Development Of The Calorimeter For Measuring Thermal Conductivity Of Liquids

The design and the development of the calorimeter for measuring the thermal conductivity of liquids is dissertated in this disquisition. Thermal conductivity is one of the important thermal-physical property of matters, and is very important in both practical application and theoretical research. At present, lots of thermal conductivities are obtained from experiments, so it is practicability to construct the calorimeter. In this disquisition, the apparatus is disserted in several aspects such as blue print, arithmetic model, unitary structure, hardware, software, etc.At first, based on the comparative method of transient point heat source, the mathematic model of transient point heat source is established, and the theoretic basis of apparatus that the thermal conductivity is linear with the rate of temperature change of the point heat source is brought forward.Then, the design of the unitary structure and unit combination is dissertated. This apparatus is a totally automatic instrument utilizing computer control, combining with the automation technology, the testing technology, the computing technology and the communication technology. It is made of data collection unit, LCD display unit, pushbutton scanning unit and upper PC. And it is through the serial port that the data communication is realized.This disquisition emphasizes on designing software and hardware of all units in detail, and dissertates the method of communication between PC and Atmega8. At the same time, This disquisition introduces the software design of upper computer. In additional, some methods of anti-jamming that adopt in this apparatus are also dissertated.The apparatus is rapid and convenient. And it can be applied to measure the thermal conductivity of the solution of both electrolyte and nonelectrolyte. Thisapparatus can reduce the effect of convection with methods of shorter heating-time and lower temperature-rise. Through analyzing the results of several experiments, we conclude that the average error of the apparatus is less than 2%, and its accuracy reach class A.