Research On Key Technology Of Counterflow Cooling Tower Noise Reduction And Heat Dissipation

As the core of industrial refrigeration equipment and large air-conditioning systems,cooling towers are applied increasingly and extensively. Meanwhile, the noise pollutionproblems of cooling towers have increasingly brought public attention. Currently, the existingcooling tower noise control theory and technology, although able to control the cooling towernoise, but often worsen the thermal performance of the cooling tower itself, even make theequipment unable to work properly. To solve this problem, noise control and key thermaltechnologies of countercurrent cooling tower is studied in this paper, through theoreticalanalysis and numerical, combined with field experimental research method. Hence coolingtowers muffler structure optimization theory is brought up, in order to achieve a balancebetween cooling tower noise control performance and thermal performance.In terms of sound field characteristics of cooling towers, the sources of cooling towernoise are studied first in the paper, including fan noise, drowning noise, mechanical noise,tower radiated noise and so on, followed by the study of propagation characteristics of thecooling tower noise. Secondly, based on the analysis of the frequency characteristics of themain sound sources, cooling tower noise control strategy is proposed. Finally, with field dataas a reference, a cooling tower sound field model is built through boundary element theory.Then the curve of cooling tower noise level and muffler structure has been drew out basedon the simulation of the effects of cooling tower mufflers with various parameters on thesound field.In terms of cooling tower outlet temperature field characteristics, the cooling tower heatand mass transfer principles have been studied first in this part, with analysis of cooling towerheat exchange process from two angles of convective heat transfer and convective mass.Secondly, the finite element model of the cooling tower has been built through the finiteelement theory, and the cooling tower outlet cross-sectional temperature field analyzed.Finally, the curve of cooling tower section temperature field and muffler structure size hasbeen drew out, based on the simulation of influence of different structure size muffler oncooling tower section outlet temperature field. To solve the difficulties to balance cooling tower noise control effect and thermalperformance, on the basis of previous studies, a wide-band composite acoustic boardtechnology-based, hybrid impedance type muffler theory and technology is brought upaccording to the characteristics of cooling tower noise frequency. Secondly, the design methodof size and structure of the muffler is put forward. Finally, according to the muffler structuralcharacteristics, PSO algorithm is improved. Global adaptive particle swarm is proposed andintroduced to muffler design. Algorithm steps and processes are given to optimize thestructure and size of the muffler, and to achieve the balance of cooling tower noise controleffect and thermal performance.Based on the analysis above, in a cooling tower noise reduction project in a residentialarea in Shenyang, Several theories and key technologies of cooling tower noise control andheat dissipation presented in this paper is applied to the engineering project. Firstly, afterpreliminary test of each measuring points and getting the noise data, noise sources areanalyzed. From the sound signal collected, the real and effective noise source signals areseparated based on which the main noise source of cooling tower is distinguished. Secondly,after analysis and calculation of Cooling tower sound field and temperature field, and thecalculation of the noise spectrum structure of the cooling tower, the design of structure andsize of the mufflers is optimized based on the field measurement. Finally, each measuringpoint is tested after the completion of noise reduction project, including analyzing coolingtower sound field and outlet temperature field, as well as the noise spectral characteristics. Theresults show that the proposed cooling tower noise control theory is able to meet therequirements of thermal performance, and meanwhile effectively control the noise of thecooling tower.