Study On Characteristics Of The Paraffin Used In Thermostatic Valve

The thermostatic valves, one kind of self-acting temperature regulator which can automatic control temperature of fluid, are widely used in metallurgy , chemical industry and civil-used device. The valve in this article has characteristics of high efficiency and working smoothly because of paraffin's physical properties.There are no reported articles about how to allocate needed paraffin used in thermostatic valve. Thermal expansion properties of paraffin is important to the function of thermostatic valve, so plenty of experiment are made to research how to mix paraffin with needed expansion properties for thermostatic valve.First, this article introduced the main achievement, the characteristic and appliance of thermostatic valves. Second, characteristics of physical properties and appliance of some sensitive material used wildly are analyzed. Finely, the structure,principal and the main component are analyzed, and heat transfer analysis of paraffin in sensitive wrap is made.The melting point of samples were measured by digital instrument of melting point and microscopic instrument of melting point, and expansion ratio of samples were determined by self-made devices. DTA analysis and measure of expansion ratio for different types of sensitive paraffin on market are made in this article firstly. Then a discussion has been made on the regulation of connection between the melting point and the expansion ratio of sensitive paraffin. To study the law of preparing paraffin which be used in the phase-change thermostatic valve, the expansion ratio experiment and measurement of melting point were performed by mixtures of eicosane and octadecane with different proportion. After comprehensive analysis of experimental results, the melting point of samples was not the simple proportional adduction of melting point of each elementary substance, then a research has be made on the optimization law of preparing paraffin based on expansion ratio.Because of the function of spectrogram of DTA that can describe the heat change of phase transition for material, the samples which were made by mixtures of eicosane and octadecane with different proportion were investigated by DTA analysis. After comprehensive analysis of results of properties testing,peak differential heating and peak area, it has further verified how to optimize the mixture of paraffin.