| Hydroenergy,as a kind of green energy with huge storage,can be converted to electric energy.Hydroenergy comprises two types of energies: mechanical energy and transformation energy,while the transformation energy contains tremendous amounts of energy.However,the most widespread form of transformation energy is evaporation energy.Due to the deficient conversion method,evaporation energy has been difficult to use for a long time.This thesis is dedicated to explore the energy conversion of water droplet in evaporation,investigate the conversion method of evaporation energy,and develop a micro-nano spherical thermocouple.Using this micro-nano spherical thermocouple,the temperature change of water droplet during evaporation can be measured accurately,and the relationship between the loss volume of water droplet and the conversion of energy can be explored.Meanwhile,this micro-nano spherical thermocouple can provide a powerful tool for single-cell temperature measurement.The research contents of this paper mainly include:1.Preparation and calibration of micro-nano spherical thermocouple: A coaxial four-layer micro-nano spherical thermocouple was designed,which consists of the base layer(tungsten),dielectric layer(polyurethane),outer electrode(platinum)and hydrophobic layer(teflon).Firstly,the base electrode was prepared by a micro-nano spherical thermocouple preparation system.Secondly,the dielectric layer was fabricated by the double wrapping and electroporation methods.Thirdly,an ion sputtering instrument is used to prepare the outer electrode.Finally,the hydrophobic layer is enwrapped by a soaking method.With the support of automatic calibration system,the W-Pt micro-nano spherical thermocouple prepared under different humidifies were calibrated.Therefore,the W-Pt micro-nano spherical thermocouple with high linearity and consistency was obtained,which can be applied to suspend droplet and measure the temperature inside the droplet.2.A droplet evaporation device and the corresponding imaging program: Environmental monitoring system,droplet suspension device,temperature acquisition system,and image acquisition system have been established to simultaneously collect the change of temperature and volume.The environmental monitoring system can monitor the environment temperature and humidity changes.The C# based droplet evaporation imaging program can obtain the outer coordinates of the droplet in each frame of the images,and then acquire the morphological parameters by the analysis and calculation system.3.Systematic error analysis: A calculation method of uncertainty was given,and the accuracy of measurement values was obtained.The uncertainty of the square of diameter generated in the preparation and imaging process were obtained,respectively,by this calculation method.When the volume of water droplet is 0.8~2.5 μL,the uncertainty of the square of diameter is 0.553%~1.667%.In the early of evaporation,the uncertainty of the square of diameter is about 2%.In briefly,the normalized droplet diameter can reduce the influence of binomial errors.4.The real-time evaporation rate and temperature change were measured by the water droplet evaporation experiments.We found that the evaporation rate and temperature change had a nonlinear relationship with time as the droplets became smaller. |
