Experimental Study On The Performance And Optimization Of Packing

With the increasing awareness of energy crisis, the efficiency of cooling tower has been receiving more attention to study. Packing, as a core component in the open cooling tower, whose thermal and resistance performance will make a great impact on the tower operating efficiency. Nowadays, thousands of packing with different structure have emerged in the cooling industry. The packing performance tests, however, are always carried at the outside with instable temperature, and the part of packing in the tower is not tested independently, which may cause large deviation in the practical projects. Whether the optimization of packing can improve the performance is also unknown for lacking the test data.According to this background, a packing performance test laboratory has been set up and detailed testing technique has been given in this dissertation. Packings before and after optimization and packings with different patterns are tested to analysis their performance.First, this dissertation analyzes the process of heat and mass transfer in the packing. According to some references and on the basis of Merkel equation and Simpson integral method, a mathematical model is established. Using the MATLAB software, this model can calculate the temperature of outlet water and the cooling efficiency of the packing by entering the parameters of original variables. The maximum deviation between the measured value of outlet water temperature and the calculated one is0.75%, while the maximum deviation between the measured value of cooling efficiency and the calculated one is7.7%, which means that the mathematical model is reasonable and meets the requirements of practical project.The dissertation tests four kinds of oblique cross packings with the height of600mm:two of which are packings using conventional adhesion technology with the sheet pitch of15mm and12mm, and the other two are packings using embedding points adhesion technology with the sheet pitch of12mm and19mm. Results show that the embedding points adhesion technology can improve the performance significantly. On the condition of6～10m3/(m2·h) spray water density and1～2.6m/s face velocity, athe air resistance of embedding points pcking with12mm sheet pitch is93.2%～98.14%of the counterpart of conventional adhesion packing with12mm sheet pitch, and the cooling value of the former is22.0%～29.2%higher. Besides, embedding points packing with small sheet pitch can also improve the cooling efficiency. The air resistance of conventional adhesion packing with12mm sheet pitch is higher than the counterpart with15mm sheet pitch, but the cooling value of which is not obviously higher. However the cooling value of embedding points packing with19mm sheet pitch will increase by45%～53%through narrowing the sheet pitch to12mm. Packings in the height of1000mm and with patterns of S wave, herringbone wave and ANCS are also tested. Results show that air resistance of S wave packing is highest, followed by herringbone wave and the ANCS is the last. On the condition of6～10m3/(m2·h) spray water density and normal air-water ratio, the cooling value of ANCS is1.08～1.34times of the herringbone wave and1.06～1.1times of S wave packing.LDCM cooling tower with a capacity of20t/h, as a project case, is also discussed in the dissertation to get its reasonable air-water ratio and to calculate air resistance when it installs different packing types. Conclusion has been made that air resistance of embedding points packing with12mm sheet pitch is the lowest, which is14.76Pa, while the one of conventional adhesion packing with the sheet pitch of15mm is the highest, with the value of24.93Pa. Fan power of the tower installed embedding points packing with19mm sheet pitch is the largest, which amount to1.1kw, while the power of tower installing embedding points packing with12mm sheet pitch is0.37kw, which is the lowest.