The Heat And Mass Transfer Mechanism Of The Rising Liquid Film On The Microscale Fluted Surface Of Horizontal Tubes And Its Application In Desalination Device On The Offshore Platform

Space microscale effect appears when the object is under the micro-size space. In microscale time or microscale space, a lot of physical phenomena appear which are different from phenomena in the conventional scale. Investigating the nature of these physical phenomena, such as mechanism of heat and mass transfer and laws of fluid flow in microscale time and space, looking for the research methods and testing technology of these laws, and applying the results of research in engineering to develop new products of heat and mass transfer in microscale is an urgent scientific and technical issue which has become a research hotspot at the forefront of the international heat transfer.The so-called rising liquid film means that, when the bottom surface of the horizontal tubes is tangent with the surface of the liquid or slightly submerged the liquid, the liquid will cover the surface of the tubes uniformly from the bottom to the top, which is droved by the wetting force and temperature gradient. VHX-500 3D microscope System has been used to observe the formation and flow state of the rising liquid film on the microscale fluted surface of a horizontal tube. The circumferential temperature of the surface has been measured by 0.5mm armored thermocouple laid in the wall of the tubes. Based on the results of measure, the influencing factors of the formation of the rising liquid film, the driving forces of the flow and the coupling effects of them has been analyzed by unbalanced thermodynamic theory. The expression of the quantity of heat of the rising liquid film on the microscale fluted surface of a horizontal tube under the orthogonal curvilinear coordinates has been achieved after the numerical simulation of the distribution of the velocity and the film thickness. The circumferential distribution of the heat transfer coefficient has been achieved by establishing heat transfer experiment table of rising liquid film on the microscale fluted surface of horizontal tubes. And compare and analyzed different heat flux and strengthen measures of the microscale fluted surface of horizontal tubes. Analyze the formation of the rising multi-component liquid film and heat transfer, and compare the rising film heat transfer of different concentrations of multi-component fluid with ethanol-water mixture and solution of Nacl as working fluid, which provide theoretical support for the project application.Design the more efficient and compact device of multi-effect desalination process and make the numerical analysis on the basis of the experimental parameters of the single-effect rising film desalination on the microscale fluted surface of horizontal tubes. Compare every-effect temperature difference of heat transter and the water output of the rising film desalination using the microscale fluted surface of horizontal tubes with the parameters of the falling liquid film desalination using vertical tubes under the same work conditions. Analyze the adaptability of the device of rising film desalination on the fluted surface of horizontal tubes in the marine environment (offshore platforms, ships, etc.).Through the study above, it has been found that the rising liquid film on the fluted surface of horizontal tubes is influenced by micro-capillary pressure, wetting force, circumferential temperature difference, bubbles, and other combined factors. The coupling effects of the forces referred appears in the process of mass and heat transfer of the rising liquid film. Circulating pump is not needed in the process of the liquid film rising on the fluted surface of horizontal tubes. Subcooled boiling can be realized in the fluted surface and the coefficient of heat transfer can be achieved through the experiment. The formation and heat transfer of multi-component fluid film rising on the fluted surface of horizontal tubes has been initially analyzed, which provides a basis for the design of the device and process of desalination using in the marine environment. Parameters of multi-effect of nine rising film desalination on the fluted surface of horizontal tubes has been calculated, which has been compared with the falling liquid film desalination on vertical tubes under the same work conditions. The advantage of rising film desalination on the fluted surface of horizontal tubes rests with it decreasing evaporation temperature and steam pressure, which is good for the application of maritime work. The rising liquid film on the fluted surface of a horizontal tube can adapt to the wobble marine environment, which has been approved by the simulation of flow under the oscillation situation. Besides, the effect of parameters (salinity, temperature, etc.) of different sea areas to the rising film desalination on the fluted surface of horizontal tubes has been analyzed.