Heat Balance Analysis to Validate the Heat Dissipation Rate of a Man-Made Lake as a Heat Rejection Device in a Power Plant

Power plants were originally designed to use convenient bodies of water such as lakes and rivers and cooling towers where the natural sources of water bodies are not available to dissipate heat. Though the Environment Protection Agency (EPA) has been pushing regulation that requires all new generation created to incorporate cooling towers, existing plants can still use the bodies of water they are built on at this point. Lakes are typically less efficient than cooling towers in that they cannot usually get the temperatures as cooling towers could get, so the condensers on lakes and rivers are usually designed with a high design inlet temperature. However, there typically would be energy saving by using a lake for no need for cooling tower fans operation. In this paper, through a case study, a thermal balance analysis was conducted to investigate heat dissipation rate of the lake and thus to determine the outlet temperature of the water from the lake to feed into the generator's condenser, which is a critical factor to influence the generator's efficiency. In addition, the analysis is to identify the most dominant variables for enhancing the lake dissipation rate and hence provide cost-effective measures to enhance the power plant efficiency. The case study power plant has 900 MW of power capacity with five power generator and a man-made lake with an approximately 330 acres. Two of generators depend on the lake as a method of heat rejection from the condensers.