Effect of Fouling on the Thermal Performance of Condensers and on the Water Consumption in Cooling Tower Systems

摘要

Circulating water in cooling tower systems contains an excess of amount of mineral ions. When this hard water is heated inside condensers, these minerals precipitate and the deposition of unwanted material on the heat transfer surface reduces the overall heat transfer performance and increases the pressure drop. Fresh water is often used to mitigate fouling but then water conservation might become a concern. This paper focuses on fouling effects on the thermal and hydraulic performance of refrigerant condensers and on the water consumption of cooling tower systems. Two brazed plate heat exchangers and a smooth tube-in-tube heat exchanger were experimentally investigated under fouling operating conditions. A model for the mineral species dissociation and mineral precipitation on the heat transfer surfaces was developed. A new semiempirical correlation for the fouling deposition strength factor was also developed and the simulation results predicted the fouling thermal resistance with an error of 30%. The daily ions concentration in the water stream is a key input to the model, but unfortunately this information is not always readily available for long periods of operation with water in fouling conditions. The fouling model limitations and potential improvements are discussed.