The Effect Of Temperature On The Specific Heat Capacity Of Heat Transfer Oil Based On Nanofluids

As an excellent heat transfer medium,heat-conducting oil,how to effectively improve the thermal conductivity and other basic thermal properties of heat transfer oil has also become a question worthy of discussion.Nanofluid has the advantages of strong stability,good compatibility,and excellent thermal conductivity.It provides a new idea for improving the basic thermal properties of heat transfer oil,such as heat transfer efficiency.Nanofluid refers to a solid-liquid two-phase fluid prepared by adding different kinds of nanoparticles into a base liquid.The basic thermophysical properties of heat transfer oil will change with the addition of nanofluid,which can strengthen its heat exchange and heat transfer capabilities.In this thesis,TiO₂-heat-transfer-oil based nanofluids and SiO₂-heat-transfer oil based nanofluids are the research objects,and the relationship between the specific heat capacity and temperature of the heat-conducting oil-based fluid and two heat transfer oil based nanofluids is studied,and the mass concentration of nanoparticles is explored.The influence of particle size and type of base fluid on the specific heat capacity of heat transfer oil based nanofluids and their laws,especially the research on the specific heat capacity of heat transfer oil based nanofluids at high temperature,provides a reference for the engineering application of heat transfer oil based nanofluids.The main research contents are as follows:Based on the HC2100 fluid specific heat test system,the law of specific heat capacity changes with temperature in the temperature range of 30～290℃of four heat transfer oils,Lontherm-50,Lontherm-80,SKX310 and LQ320 are experimentally studied.The research results show that the specific heat capacity of heat transfer oil increases with the increase of temperature,and the change law satisfies the quadratic equation of one element.By adding TiO₂ nanoparticles and SiO₂ nanoparticles,respectively,the specific heat capacity of 12 kinds of heat transfer oil based nanofluids was experimentally studied.The experimental results show that,in contrast to the water-based nanofluid,the addition of nanoparticles can effectively increase the specific heat capacity of the heat transfer oil,and the specific heat capacity of the nanofluid will increase with the increase of temperature.Experimental studies have found that the mass concentration,nanoparticle size and type of base fluid will also affect the specific heat capacity of the nanofluid.The specific heat capacity of the nanofluid will first increase and then decrease with the increase of the mass concentration,showing a parabolic change.The smaller the particle size of the nanoparticle,the greater its specific heat capacity under the same mass concentration.The greater the specific heat capacity of the base fluid,the greater the specific heat capacity under the same conditions.Through the existing experimental data,the accuracy of the P-C model and the S-S model in calculating the heat transfer oil-based nanofluid was verified.The P-C model can be used to predict the specific heat capacity of TiO₂ heat transfer oil based nanofluid and SiO₂ heat transfer oil based nanofluid with a mass fraction of less than 0.5%.The S-S model is not suitable for the calculation of the specific heat capacity of the thermal oil-based nanofluid.Based on the least square method,the specific heat capacity of TiO₂heat transfer oil based nanofluid and SiO₂ heat transfer oil based nanofluid at different temperatures and different mass fractions was regression analyzed using MATLAB.The linear relationship between the specific heat capacity of the two heat-conducting oil-based nanofluids,temperature and mass fraction is obtainedc_p=A+BT+Cψ,and the calculation error of the relationship is less than 5%,which has high accuracy.