| In the thermal power generation, the water consumption of air cooling unitsonly accounts for15%～25%proportion of that in the water cooling unit, hence, theapplication of air cooling system becomes an effective way to solve thecontradiction of coal rich and water shortage. As the main cooling end equipment inthermodynamic cycle, the air cooling tower constitutes one of the most importantparts in indirect air cooling system. Therefore, research on the internal and externalflow field in indirect air cooling tower makes great theoretical significance andengineering value. The main parts of thesis are as follows:(1) For the SCAL indirect air cooling tower, based on the actual size of bundlesand the arrangement mode of cooling triangles, the geometrical models of heatexchanger and air cooling tower are established via Gambit, and mesh and boundaryconditions are generated.(2) Based on RNG k-ε turbulence model, adopting Boussinesq approximationand porous media model,3D numerical simulations on internal and external flowfield in SCAL indirect air cooling tower are carried out at different ambient windspeed and ambient temperature. The influence of ambient wind speed and theambient temperature on the operation performance are studied.(3) Under variable operating conditions, the variation of circulating coolingwater flow rate will lead to the change of heat sink thermal load. According to theactual operating conditions, the numerical simulations on the air cooling tower arecarried out at different ambient wind speed and heat sink thermal load. The effect ofheat sink thermal load on the operation performance is explored.(4) For the non-full-load operating conditions of air-cooled heat sink, changingthe circulating cooling water flow rate, as well as the heat sink thermal load, willimprove the ventilation of cooling tower and optimize the heat transfer properties ofheat sink. Based on the conclusion, taking the ambient temperature at34℃andthermal load at0.7Q0(Q0is the designed heat dissipation) as reference conditions,different heat sink heat load distribution plans are proposed. Results indicate that,when the heat load is distributed unevenly according to the optimization plan, theheat exchange between the cooling air and heat sink is enhanced, and the operatingperformance of air cooling tower is improved. |
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