Study On Flow Characteristic Of Fluid And Heat Transfer Experiment Of The Corrugated-plate Evaporative Condenser

With the rapid development of national economy and progress of the society, the energyissue has become increasingly prominent, Chinese government proposed the developmentstrategy of constructing a resource-saving society, in this year's two meeting, Low-carboneconomy become the focus of question and the direction of social development .Energyconversation and water-saving have become the long-term aim and significant demand in theplanning of the energy development of our country. Energy conversation is a long-termstrategic policy in the national economic development and the primary approach to solveenergy problem. The principal means of saving water is to improve the efficiency in recyclingwater. Evaporative condenser is a kind of new highly effective heat exchange equipment,which has the advantages of saving energy and water. At present, we face a serious situationconcerning energy and water resources in China. And such equipment has being greatlyimproved and widely applied under such a circumstance. In view of this, this paper carriedout the research on corrugated plate evaporative condenser in the following aspects.1. optimization of the corrugated plate internal structure corrugated plate, and theinvestigation of the air-liquid two phase flow characteristic of falling film. two-dimensionalcomputed model of fluid flow in plate and three dimensional computed model of air-liquidtwo-phase falling film was set up,which were simulated by computational fluid dynamic(CFD) software Fluent. Effects of plate structure, spraying water, velocity and direction of thewind on the characteristics of water film flow was studied and the influence mechanicsconcerning heat transfer was analyzed. The results show that The water film thicknessincreases when the volume of water increases; The advantages of air-liquid co-currentoperation over counter-current operation in making use of the characteristics of heat transferof fluid film are obvious. Structures and sizes of the corrugation have great impact on thedistribution of the liquid film.Smaller h/λcan help the formation of continuous liquid film.2. Numerical simulation of gas-liquid heat transfer between corrugated plates. two-dimensional computed model of gas-liquid heat transfer was set up, effects of heat flux, spraying densityof cooling water, gas inlet velocity,plate spacing on heat transfer of falling film wereresearched. The results show that effects of heat flux on the wall temperature, gas-liquidinterface temperature is linear; In the same heat flux, the interface temperature be reducedaccordingly with the spray density increases; Increasing gas flow rate or reducing the platespace can play the role of enhancing heat transfer.3. Heat transfer experiment of corrugated plate evaporative condenser. Heat transfer performance test platform of the condenser was established. Effects of operation of differentwind direction (gas-liquid two phase co-current, counter- current, cross-flow), spray density,wind velocity on heat transfer performance of the evaporative condenser. The result show thatu was fixed a value, with gas-liquid two-phase co-current , qfmax is 13.82 kW/m2 whenΓis0.072 kg/m·s, with two-phase cross-flow, qf increasing is not obvious, optimalΓis0.053kg/m·s, with two-phase counter- current, qf increasing is not obvious whenΓ>0.062kg/m·s, qfmax is 11.89kW/m2 whenΓis 0.072kg/m·s;Γwas fixed a value, with two-phaseco-current, qf increasing is not obvious when u>2.5m/s, qfmax is 14.15 kW/m2; withtwo-phase cross-flow, qfmax is 12.6 kW/m2 when u is 2.0m/s, with two-phase counter-current,qfmax is 11.71 kW/m2 when u is 2.0m/s. The effect of heat transfer is co-current>counter-current>cross flow. The advantages and disadvantages of three kinds of plate (corrugatedplate, plate- tube, harmonica plate) were compared.The visual analysis of the corrugated plate evaporative condenser has been performed, bymeans of the infrared video camera. Comparing the CFD simulation, the experiment with thevisual analysis, the results show that three conclusions were very consistent.The study on flow characteristic of fluid and heat transfer experiment in this subjectenriched theoretical research system of the evaporative condenser and supplied reference forfurther study of the performance and optimal design of the corrugated plate evaporativecondenser.