Yuan-bin Zhao

THREE-DIMENSIONAL REGULARITIES OF DISTRIBUTION OF AIR- INLET CHARACTERISTIC VELOCITY IN NATURAL-DRAFT WET COOLING TOWER

A model for heat and mass transfer in a natural-draft wet cooling tower was established. Numerical simulation with the k-ε turbulent model was conducted. Distribution rules of air inlet aerodynamic field were studied. Field experiments were done in a cooling tower in power plant, and the test data was compared with the related results. The definition of characteristic air velocity was proposed and its influencing factors, such as the cross-wind velocity and circumferential angle, were quantitatively studied. It can be used to evaluate the performance of cooling tower and to calculate the ventilation quantity and resistance of air inlet. It is also a theoretical basis for cooling tower design and performance optimization.

Research on the Effect of Cross-wind to Temperature Difference and Efficiency of Natural Draft Counter flow Wet Cooling Tower

The experiment in terms of heat transfer performance of natural draft counter-flow wet cooling Tower (NDCWCT) is done for cases with cross-wind conditions. The variation of circulating-water temperature difference (Δt) and cooling coefficient of efficiency (η) with cross-wind velocity, circulating water inlet temperature and flow rate, are shown under cross-wind conditions, compared with cases without wind. According to experimental results, it is found that Δtand η are influenced by the cross-wind, Δt and η can decrease mostly by 9.2% and 9.6%, respectively. When the critical Fr l number is less than 0.153, Δtand η decrease with increasing cross-wind velocity, however, when it is greater than 0.153, Δt and η increase with increasing cross-wind velocity.

Three-dimensional numerical analysis of wet cooling tower

A mathematical model for water evaporation and water droplet movement is established to describe the air-water interaction in natural draft wet cooling tower (NDWCT).The standard k e − model is used to close the Reynolds average Navier-Stokes equations. The three-dimensional heat and mass transfer process in NDWCT is simulated to analyze the crosswind effect on wet cooling tower performance. It is found that the heat and mass transfer in fill zone is seriously affected by crosswind, while the wet cooling tower performance is improved when crosswind velocity is higher than 5 . Conditions and locations for good cooling performance are pointed out. -1 ms ⋅

Performance Deterioration Mechanism Analysis of Natural Draft Cooling Towers Under Crosswind Conditions

Based on the developed three-dimensional computation model of natural draft wet cooling towers, the effect of crosswind on circumferential distribution of air radial pressure gradient and velocity at tower air inlet was studied, and the effect of crosswind on total air inflow rate, transverse mass flow rate, vertical mass flow rate and water temperature drops of the three zones (i.e. spray zone, filling zone and rain zone) were also analyzed. Analysis of crosswind effect on air flow field in heat and mass transfer zone indicates that the induced longitudinal eddy causes reduction of effective ventilation area in filling zone. Results showed that crosswind destroys the uniform air inflow, reducing the total air inflow mass rate and the effective ventilation area of filling zone, resulting in cooling performance deterioration of natural draft wet cooling towers.Copyright