The Numerical Simulation Of The Effect Of Environmental Parameters On Solar Enhanced Natural Draft Dry Cooling Tower

In order to solve the problem of low efficiency of natural draft cooling tower in arid regions,the solar enhanced cooling tower is put forward on the basis of the natural draft cooling tower and the solar chimney power generation technology.the solar enhanced cooling tower is a new Kind of cooling tower and it use solar energy to improve the air flow rate,air mass flow and heat transfer rate.In the papers,a detailed mathematical model of of air flow and heat transfer in solar enhanced cooling tower system was established by mathematical analysis.The mathematical model is the theoretical foundation for choosing the more reasonable numerical model and setting the boundary conditions for numerical simulation.The three-dimensional structure model is established by Gambit,and be correctly divided the grid.The physical structure size of the solar enhanced cooling tower and the physical properties of different materials was choosed for the three-dimensional structure model.CFD software Fluent was used to numerical simulation calculation,and choosing the rational calculation according to the mathematical analysis method.The independence of the grid was verified and the validity of numerical model was proved by comparing with the results of Matlab programming under the same conditions.In the same working conditions,through comparison and analysis the two numerical results obtained by the numerical model adopts to simulate the solar energy transfer process in collector,and the numerical model in which setting the solar radiation as the internal heat surface stored in the a thin layer of accumulation,found that the heat transfer rate computed by the numerical model in which setting the solar radiation as the internal heat surface stored in the a thin layer of accumulation is higher 1.15%than the result from numerical model with radiation,because that the effects of the radiation heat transfer is ignored in the numerical model without the radiation model.So the radiation model can more objectively and accurately simulate the solar energy heat transfer process in collector.Different environmental parameters was set as variables for solar enhanced cooling tower to numerically simulate,found that the intensity of solar radiation or environmental pressure increasing can improve the the air mass flow rate and heat transfer rate,solar radiation increases by 900 w/m~2,heat transfer rate can be increased by 1.1%;And environmental temperature increasing cause a decline on air mass flow,and heat transfer rate can be greatly reduced,especially.the environment temperature increases 1.5℃,the heat exchange rate reduced by 5.77%.When a number of environmental parameters change at the same time,solar radiation and the environment pressure increase a certain amount,which can make up the reduced air mass flow rate due to environment temperature rise slightly,but only can make up a part of the reduced heat transfer rate due to environment temperature change.Under the condition of lower environment pressure,growth rate of air mass flow rate with the intensity of solar radiation tends to increase,but the growth rate of heat exchange rate along with solar radiation increasing will increases in the condition that the environmental pressure is bigger.