The Study Of The Effect Of Related Parameters On Solar Enhanced Natural Draft Dry Cooling Tower

In this paper,based on the solar chimney working principle,we introduce a new cooling system,named the Solar Enhanced Natural Draft Dry Cooling Tower(SENDDCT)to improve the low cooling efficiency of natural draft dry cooling tower(NDDCT).In the SENDDCT system,a solar collector is added to a conventional NDDCT system,which improves the air velocity inside the system.Therefor the air mass flow rate increased,so the heat transfer rate increased.With the SENDDCT system as object,this paper established the physical model of SENDDCT system.Based on the theory of Heat Transfer and Fluid Dynamics,a mathematic model of the SENDDCT system is modeled.According to the above physical model and mathematical model,the numerical model of SENDDCT system is established by fluent software.A numerical stimulation is developed to investigate the SENDDCT performance under different solar collector diameter,heat exchanger layout,ambient temperature and relative humidity.The air mass flow rate and the heat transfer rate are obtained.We study the spray cooling effect on the improvement of the system.This study shows that: for the structure parameters of the SENDDCT,tower height has less effect on the heat transfer rate,however the solar collector diameter has a great influence on the heat transfer rate.With the increase of the solar collector diameter,the air mass flow rate and heat transfer rate increased significantly.With the increase of the coverage rate and the unit coverage rate of heat exchanger decreases,the heat transfer rate decreased.And the optimal layout of heat exchangers is that the coverage ratio is 93% without blockage between heat exchangers under the situation that heat exchangers are divided evenly and small.For the environmental parameters of the SENDDCT,under the condition of other parameters constant,the heat transfer rate increases a little with ambient humidity increase,but falls steeply with ambient temperature increase.Although the spray cooling reduces the air mass flow rate,it reduces the inlet air temperature,humidity,thus significantly higher heat transfer rate of the system.In this article,compared to no spray cooling,the heat transfer rate increased by 13.91%.