UtilizaÃÃo de materiais alternativos como Enchimento de Torres de Resfriamento

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This work studies the behavior of alternative materials as packing for cooling towers. The following materials had been evaluated: vegetal sponge ( Luffa Cylindrica), coconut ( Cocos nucifera Linnaeus) fiber, curlers for hair and necks of PET bottles. In order to investigate the performance of those materials, a prototype of a cooling tower with forced circulation in counter flow was built, consisting of a skeleton formed by aluminum profiles in âLâ shape, covered by acrylic, with a container in brass. The water distribution was done through PVC pipes. The system also counted with diffusers, axial fan of multiple shovels and centrifugal pump for water circulation. The prototype was constructed in reduced dimensions, in the laboratories of GET/DEMEC/UFPE (Group of Thermal Engineering, Mechanical Engineering Department, at the Federal University of Pernambuco, Brazil). For simulations, the tower makes use a dimmer for variation of the speed of the fan and a by-pass for control of the outflow of the pump, besides two resistances of 4400W each, to act as thermal load for the tower. The temperatures had been indicated by thermocouples type T and K, AWG â 26. A system of data acquisition based in the Labview was used, with industrial computer PXI 1002 and interface NI 4351 for data acquisition of the National instruments. The effects of water outflow had been analyzed, as well as the variation of air outflow and thermal load, in comparison to a standard cooling pack of trapezoidal polypropylene grid, used in the industry for heavy waters. Results of the effect of the pad on the cooling capacity (ΔT) and the approach of the tower for each pad were presented. The cooling pad of trapezoidal grid presented the best performance with a 46,40% effectiveness, followed of the curlers for hair with 40,30% and the PET with 33,61%. The Coconut Fiber achieved 27,8% and the vegetal sponge achieved 20,97%, for air outflow of 0,49mÂ/s and water of 0,11 l/s. A program in Matlab, was used to calculate the NUT for each cooling pack. In agreement with experimental results, the cooling pads that achieved the highest NUT were the pads that reached the highest efficiency. Through the evaluated NUT the program to simulates different situations as variation of the relative humidity, variation of the temperature of the water getting in the tower and variation of the humid bulb temperature. To validate the program, a comparison between the experimental and numerical results was carried out, indicating an error less than 0,01. Thus, this program revealed to a valuable tool in the project and simulation of towers of reverse flow cooling using the used alternative materials in this project

ASSUNTO(S)

resfriamento evaporativo cooling tower enchimento torre de resfriamento engenharia mecanica packing evaporative cooling

ACESSO AO ARTIGO

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