Experiment Study Of Supercritical CO₂ Cleaning For Remanufacturing

With the peoples' environmental protection consciousness gradually improved, remanufacturing as a resource-conserving and environmentally friendly circulation mode of production becomes the focus. Remanufacturing includes dismantling, cleaning, test, repair and assembly process, and remanufacturing cleaning is an extremely important role in these processes. Traditional remanufacturing cleaning methods are varied and widely applied, but they still faces many challenges in implementing green cleaning, therefore, some environmental protection cleaning technologies developed quickly. As a green cleaning solvent, supercritical CO2 fluid possess excellent features such as low viscosity, low surface tension, strong penetration and strong mass transfer ability, which becomes the ideal solvent for remanufacturing cleaning. In this paper, supercritical CO2 fluid was used to remove the lubricant oil on the surface of the parts in engine, and this cleaning method has overcome the problem and insufficiency of traditional cleaning methods.We systematically analyzed the kinds of contaminants in discarded engine and used optical microscope, Fourier transform infrared spectrometer and element analyzer to analyze the contaminants. We summarized the kinds and sizes of adhesion forces in contaminants and proved the important role of supercritical CO2 cleaning as a pre-cleaning method by cleaning experiment.Based on solubility parameter theory, we obtained the solubility parameter of supercritical CO2 by computer simulation and found the effect of temperature, pressure and co-solvent on the solubility parameter of supercritical CO2 system. We revealed the law of lubricant oil dissolved in supercritical CO2 and verified it by solubility test experiments and cleaning experiments. We used orthogonal experiment to explore the temperature, pressure, and concentration of ethanol on the influence of supercritical CO2 cleaning lubricant oil, and obtained the best technological parameters under the laboratory scale. The cleaning force of supercritical CO2 cleaning carbon deposit was analyzed and tested by supercritical CO2 cleaning experiments. We successfully removed oil sludge and carbon deposit on the surface of metal parts by supercritical CO2 cleaning and abrasive water jet cleaning.In order to improve the effect of supercritical CO2 cleaning the complex structure parts, we studied supercritical CO2 pressure pulse cleaning method. We studied the effect of pressure pulse frequency, pressure amplitude and pressure release rate on the cleaning rate of lubricant oil in small gap, obtained better cleaning process parameters under laboratory scale. At last, we studied the effect of supercritical CO2 pressure pulse cleaning on the metal parts in discarded engine.