In this paper, solutions for improving chiller energy efficiency by reducing fouling of shell and tube heat exchangers are discussed. Sponge-ball type automatic tube cleaning system technology is introduced and discussed as a solution for improving chiller energy efficiency and tube cleaning system operating principles are presented.Multiple case studies are provided demonstrating the positive impacts of tube cleaning system technology implementation
Shell and tube condensers and heat exchangers are core to a wide range of processes including power generation, oil refining, industrial processing, and HVAC comfort cooling. Unfortunately, this means that 'fouling' of these heat exchangers (the accumulation of efficiency-killing deposits) is also pervasive—at extremely high economic and social costs.
The expenses associated with fouled heat exchangers and condensers are significant, and include increased power consumption, increased fossil fuel consumption, reduced production, and frequent condenser cleaning costs. Heat exchanger fouling costs have been estimated at 0.25% of the gross domestic product (GDP) of highly industrialized countries in several studies, which, based on estimated U.S. GDP of $15 trillion, translates to fouling-related costs of $37 billion a year. HVAC applications, fouling of the chiller condenser tubes has substantial impact on the power consumption of the compressor. Even with good water treatment programs, it's not uncommon to find chillers that appear to be in good working order operating at a fouling factor of 0.0025 hr-ft2-F/Btu or higher — causing compressor power consumption to increase by 25% or more.
Fouling occurs because cooling water contains minerals, such as calcium and magnesium that precipitate to form deposits on heat transfer surfaces. Cooling water systems are also commonly plagued by biological growth that forms slime or algae on heat transfer areas. Additional foulants include mud, silt, corrosion products, petroleum products, etc. All of these foulants reduce the heat transfer efficiency of even the best-designed heat exchangers, induce localized corrosion leading to early equipment failure, and force shut downs of the power generation, refining, or cooling process. Several methodologies are commonly used to mitigate or reduce fouling in various plants and industries. Typically these include off-line mechanical or chemical cleaning, or on-line mechanical cleaning systems.