Influence Of High-salinity Circulating Water On The Thermal Characteristics Of Cooling Towers

Water shortage has become one of the bottlenecks restricting the sustainable development of economy and society.Seawater is rich in water resources and chemical resources.It has become a common understanding of human society to ask for water from the sea.In order to solve the problem of the lack of fresh water resources,the development of seawater for industrial water,especially for industrial cooling water,can greatly reduce the use of freshwater,which is a strong force to promote the sustainable economic development of our country and other countries in the world,can effectively alleviate the shortage of freshwater resources.It is of great significance and imperative.The application and development of seawater cooling towers that use seawater as the cooling medium can greatly save freshwater resources and reduce ocean thermal pollution.It is one of the important ways to solve the problem of fresh water resources crisis in China and the world.It is the main development direction of cooling tower in coastal areas in the future.In view of this background,this paper takes the countercurrent seawater cooling tower with mechanical ventilation as the research object,and studies the influence of high-salinity circulating water on the thermal characteristics of the cooling tower.Firstly,based on the principle of heat and mass transfer and the properties of wet air,two calculation models of wet cooling tower,namely,Merkel model and Poppe model,are presented and compared.Secondly,based on the physical characteristics of seawater,an improved thermal calculation model of seawater cooling tower is given.At the same time,fully considering the characteristics of seawater,the changes of seawater specific heat,seawater vapor pressure,seawater density,seawater vaporization latent heat.etc.with salt content and seawater temperature are analyzed separately.The theoretical calculation formula of the cooling task number of seawater cooling tower is derived,and the difference between the cooling task number of seawater cooling tower and the existing cooling task number of seawater cooling tower based on fresh water calculation is obtained.Thirdly,the influence of circulating water with high salt content on the outlet water temperature,the air volume of the fan,the total pressure of the fan and the power of the motor are studied with the help of MATLAB software.At the same time,the variation of cooling water temperature difference and cooling tower efficiency with seawater salt content,air-water ratio and inlet water temperature were also studied.In order to further understand the influence of seawater on the formation of plume,with the aid of Matlab software,the influence of seawater salinity on cooling tower outlet air parameters under constant working conditions was studied.Finally,the influence of seawater salinity on the evaporation rate and water saving of cooling towers under variable working conditions was studied,the influence of seawater salinity and environmental meteorological conditions on concentration rate were studied.In summary,this paper gives a more accurate thermal calculation method of seawater cooling tower from the direct start of seawater physical properties,fully consider the characteristics of seawater.The influence of circulating water with high salt content on thermal characteristics,outlet air parameters,water saving and concentration ratio of cooling tower are obtained,which can provide reference and basis for engineering design and application of seawater cooling tower.