مقاله انگلیسی رایگان در مورد جریان آب در سیستم های خنک کننده نیروگاه – الزویر 2018

In all types of power plants, cooling installations play a significant role in the electricity production process. They are utilized to remove waste heat (e.g. a cooling system including condensers and cooling towers) or protect a boiler’s auxiliary equipment against overheating. Regardless of the intended use, the cooling installation can always be divided into two parts: a series-parallel system (consisting of pipelines and pumps) which transports the cooling medium and heat exchangers responsible for heat transfer processes. Hydraulic systems with cooling water are designed according to optimization criteria in order to achieve maximum flow rates for the nominal thermal output of the power unit if it is operating under standard thermodynamic conditions (Malek 2007). However, a gradual decrease of the overall efficiency of coal-fired power plants with time is observed (Campbell 2013). Among others, working parameters of hydraulic installations are subject to deterioration due to, for example, reconstruction of the system, deterioration of the circulating pumps’ characteristics or deposition of mineral sediments inside pipelines. The above-mentioned changes cause a gradual decrease in flow rates in the cooling systems which cannot then achieve their design flow parameters. This situation is reflected in lower heat fluxes achieved in the heat exchangers (e.g. condensers, ash coolers) or higher outlet temperatures of the cooling medium. These negative changes also have an influence on the increase in the combustion of fossil fuels, which leads to an increase of the emission of greenhouse gases (GHG) and other pollutants to the atmosphere (Blog 2016). In order to stop (or at least slow down) this trend, Ryabchikov et al. suggested a number of specific actions, among which the retrofit of cooling water installations is one of the most important (Ryabchikov 2012). Nichols et al. estimated that the modernization of cooling system performance in American power plants could lead to an improvement in the overall efficiency of the unit by about 0.2  1.0% (Nichols 2008). Similar estimations, made for APEC countries, indicate that the improvement of feed water heaters and condensers could enhance the overall power unit efficiency by a value of approximately 0.8% (Boncimino 2005).