Research On The Key Technology Of Refrigeration Dryer

As an important device of post-processing compressed air,refrigeration air dryers are widely used in pneumatic systems.They works by heat exchange between compressed air and cryogen.But refrigeration dryers still has several defects:low heat exchange efficiency,dead zones of compressed air.It is of great significance to study the heat exchange situation of refrigeration dryers,and explore the influence of structures and parameters on heat exchange effects.This thesis focuses on the heat exchange characteristics and flow characteristic of the refrigeration dryer by simulations and experiments.The heat exchange characteristic and flow characteristic of pre-cooler and evaporator is analyzed by numerical simulations,and the simulation and experiment on heat exchange characteristics of plate-fin heat exchanger is conducted.The main works are below:Firstly,the influence of different structures of baffles on heat transfer characteristics and flow characteristics of pre-cooler is studied in this thesis.The study shows that segmental baffles has the maximum heat exchange and pressure loss,while flower baffles has the minimum heat exchange,and improved flower baffles shows the minimum pressure loss.If the comprehensive performance index is the heat exchange coefficient of per unit pressure loss(k/?p),then the improved flower baffles show the best comprehensive performance.The effect of different condition of inlet is analyzed.By analyzing the relationships between heat transfer and flow characteristics with inlet velocity and diameter,the distribution disciplinarian of evaporator's internal flow in different working condition is confirmed.And the effect of heat exchange is valued through k/?p.The effect of different distance between baffles is studied by setting three different distances between each baffles.The research found that:with the distance decreased,heat transfer gets better and the total heat exchange increases;for the pressure loss,it increases too.But The values of k/?p are decreases.The model of plate-fin heat exchanger is built to conduct the simulation with different inlet velocity and air pressure,and the situation of heat exchange and flow of the compressed air between fins is analyzed.In addition,A test platform is set up to measure the temperature at the outlet of the plate fin heat exchanger.The heat transfer effect of the plate fin heat exchanger was verified by comparing the experimental results with the numerical results.The research found:with the inlet pressure,inlet velocity increases,the total heat exchange,the average heat exchange coefficient and pressure loss increases;the value of k/?p increases with the increase of inlet velocity,but the inlet pressure has little effect on the value of k/?p.