Keeping evaporator and condenser tubes as clean as possible is one of the most important factors of maintaining chiller efficiency. If interior tube surfaces become fouled with scale, mud, algae, sludge, or other contaminants, thermal resistance causes the chiller to work harder and energy efficiency plummets.
Manufacturers typically recommend cleaning condenser tubes annually. Evaporator tubes should be cleaned about once every three years for closed systems, more often for open systems. There are two basic methods of cleaning chiller tubes: chemical and mechanical. Chemical cleaning entails circulating an acid solution through tube bundles to break down or soften scale deposits. It should always be followed by a thorough mechanical cleaning. While chemical cleaning can be quite effective in many cases, it can be costly and time consuming.
Mechanical cleaning is effective for removing accumulate materials such as mud, sand, and algae from smooth-bore tubes, and there are several means with which to do it. The old-fashioned rod and brush method is sometimes still used, but is time and labor intensive and is only moderately effective. Chiller tube cleaning machines are a better alternative in which brushes, rubber bullets, or scrapers are propelled through tubes using compressed air and water, or high-pressure water alone, to remove deposits. New internally-enhanced chiller tubes, which employ spiral grooves to provide better heat transfer, are more difficult to clean and require more specially-adapted equipment.
Many new chillers come equipped with online tube cleaning systems, which can also be retrofit onto existing chillers. One type utilizes brushes that are trapped in plastic baskets attached to both ends of each tube. The direction of water flow is periodically reversed, causing the brush to travel to the opposite end of the tube. Another type of system features sponge balls that circulate through the tubes and keep surfaces clean. With proper water treatment, automatic systems can be extremely effective and eliminate the need for tube cleaning. Though retrofits can be expensive to purchase and install, payback periods are typically less than two years.
PJM Mechanical Contractors, Inc. is a multi-faceted mechanical contractor providing construction and installation, service and maintenance, and design/build services in a comprehensive range of mechanical disciplines that include HVAC, plumbing, controls, refrigeration, custom metal fabrication, piping, fire protection, and backflow preventer testing. PJM primarily serves clients in pharmaceuticals, manufacturing, healthcare, institutional, and other various commercial and industrial sectors. pharmaceuticals, manufacturing, healthcare, institutional, and commercial sectors.