Study On Cleaning Mechanism Design And Enhanced Heat Transfer Performance Of Falling Film Evaporator

Falling film evaporation has many advantages,such as high heat transfer coefficient,small temperature difference,and so on.It has been widely used in chemical,energy and other fields.However,the fouling problem in evaporation tubes directly reduces the heat transfer efficiency of falling film evaporators.Based on this,this paper proposes an online cleaning mechanism for tubes.The problem of online fouling prevention and fouling and heat transfer enhancement of falling film evaporator was studied by means of simulation and experiment.The main contents of the paper are as follows:Ⅰ.In view of the scaling problem of falling film evaporator,the research status on anti-scaling and heat transfer enhancement technology at home and abroad is investigated.And a new kind of online cleaning mechanism,including the new film distributor and the tube inserting spiral,can be used to solve the problems of the dry wall,the wall scaling and the clogging of the film distributor in the process of falling film evaporation.Ⅱ.The influence of the structural parameters of the new type film distributor on the flow and uniformity of the liquid film,as well as the relationship between the thickness and the velocity of the liquid film with the length of the tube,can be studied by the numerical simulation method,which can provide reference for the design of a new dynamic film distributor..Ⅲ.A single tube falling film evaporation heat transfer experimental platform was built.Firstly,the feasibility of reciprocating motion in the condition of cold and hot mold was analyzed from the perspective of equivalent driving force.Secondly,the influence law of tube inserting cleaning spiral and coupling spring on the heat transfer coefficient of falling film evaporation is analyzed,and a better combination working condition is obtained.Finally,the heat transfer performance of the cleaning mechanism under different process parameters is analyzed,which provides the application basis for scaling prevention and heat transfer enhancement in the falling film evaporation tube.The results of heat transfer experiments show that the experimental device has high feasibility and technical superiority in the field of falling film evaporation.When the spiral diameter 30mm,the pitch 45mm,the wire diameter 1.8mm,and the reciprocating stroke 100mm,the heat transfer performance of the equipment is the most ideal when the equipment is stable.The heat transfer coefficient can be as high as 1543.67W/(M2K),which is 100.85%higher than the heat transfer efficiency of the smooth tube.A theoretical formula for the heat transfer coefficient of falling film evaporation is established in the experimental conditions.