Performance Of Natural Draft Dry Cooling Tower Research Articles

The effect of crosswind and installation of wind-break deflector on the performance of natural draft dry cooling tower (NDDCT)

Natural draft dry cooling tower (NDDCT) is one of the most important components of combined power plant cycles in arid regions. Studies illustrate that being subjected to the wind blowing has negative effects on NDDCT's thermal performance. These adverse effects mostly inflict on the outlet port of the tower and the installation platform of the radiators at the bottom of the tower. In this study, the influence of installing wind-break deflectors at the outlet port of the tower and addressing the negative impacts of the wind is investigated. Considering the buoyancy effect for a 3-D incompressible flow, the flow field inside and outside the tower as well as the heat transfer from the radiators is modeled through simultaneously solving the Navier-Stokes and energy equations via computational fluid dynamics method (CFD). The performance of NDDCT is compared with and without the presence of deflectors where considered variables are height of the deflector and wind velocity. The improvement in the rate of the heat released to the atmosphere from the radiators will be estimated. Generally, in the presence of deflector walls the thermal performance of the tower enhances. With the increase in the height of deflectors, the thermal performance will further improve. For instance, the enhancement in the tower's performance with a 12-m deflector at wind velocities of 5 and 20 m/s is 57 and 44 percent, respectively.

Entransy analysis optimization of cooling water flow distribution in a dry cooling tower of power plant under summer crosswinds

The performance of natural draft dry cooling tower (NDDCT) of a coal-fired power generating unit is susceptible to ambient conditions, such as natural wind and temperature. An approach was proposed to relieve the adverse effects of ambient wind, which was the optimization of waterside flow re-distribution among heat exchangers of NDDCT under natural wind. With the help of entransy balance equations that described the heat transfer processes in each heat exchanger sector and condenser, all 20 influencing factors were considered to establish the optimization mathematical model of whole system, including both of the steam turbine subsystem and dry cooling system. A practical 660 MW dry cooling supercritical power generating unit was selected as object. The flow and heat transfer of NDDCT by natural wind effect were obtained numerically with verification. The results indicated that the performance of NDDCT could be improved by optimal distribution of waterside flow rate among the heat exchangers at any wind speed, especially at high wind speed. The comprehensive saving of power output coal consumption could be acquired although the pump power would raise by optimal water flow distribution. The decrease of coal consumption could reach 0.74 g/kWh at the natural wind speed of 12 m/s.

Economic Analyses of Natural Draft Dry Cooling Towers Pre-cooled Using Wetted Media

Evaporative pre-cooling with wetted-medium can improve heat exchange of natural draft dry cooling towers (NDDCTs) in hot days (usually in summer). However, the media introduce extra pressure drop which reduces the air flow of a NDDCT, and as a result, impairs the tower performance. Scholars studied the effect of evaporative pre-cooling on performance of cooling tower through experiments or simulations by taking into account both the benefit of evaporative pre-cooling and the disadvantage of extra pressure loss. They found that the performance of NDDCTs can be improved by wetted-medium evaporative pre-cooling when the ambient air is hot and dry. Nevertheless, whether the pre-cooling proposal will bring potential increase in the revenue for the owner of the power plants employing NDDCTs requires further study. To this end, the current study investigates the benefit of NDDCT with wetted-medium pre-cooling through calculating the electricity production and water consumption.