One inch of sludge can reduce heat transfer by more than 25 percent.

Energy efficiency in heating, cooling and heat recovery systems depends on how well the heat and cold transfer systems work.

These must be regularly maintained and cleaned to function properly so that energy efficiency can be attained. This may sound obvious, but improper maintenance, mix of old and new components, and lack of instruction can create a variety of problems.

“In order for a heating or cooling system to be energy efficient, it is important that it is clean and corrosion-resistant,” says Rafael Ospino, Marketing Director at Chemiclean.

“Poor water quality in combination with high oxygen content enhances the corrosion process which leads to poor heat transfer. The system becomes clogged and fouled, resulting in decreased efficiency and increased operating and energy costs. One problem area is the fluid in the system. For example, the condition of glycol, used as protection against freezing and corrosion, should be regularly checked. Part of our program is to prevent risks and analyze fluid composition. Customers who review their cooling and heating systems will recover their investment very quickly in terms of reduced energy costs and less downtime.”

Corrosion is the villain

The liquid in cooling and heating systems consist of water or water-based solutions such as glycols or salts. Corrosion in such systems is often oxygen-related and problems have increased in recent years. Oxygen remains bound in the liquid because of higher pressures and temperatures. This results in corrosion on the pipe walls and on other metal parts.

This chemical reaction between iron and oxygen forms different types of rust. The rust then flows downstream damaging valves, impellers, shafts and seals through abrasion. It also binds with minerals to form sediment or sludge.

In systems containing antifreeze liquids, the risk is that the presence of oxygen leads to a degradation of various chemical substances that give rise to an aggressive liquid and crystal formation. The crystals can be deposited on surfaces, which in turn reduce the heat exchange. This also diminishes the anti-freeze protection. And this risk increases dramatically if one accidentally mixes antifreeze fluids with different properties.

Chemiclean’s model for preventing corrosion and other problems includes the inspection of the cooling or heating system, analysis of the liquid, and control of the heat and air exchangers. The result is a risk analysis and proposals for action. The measures usually include cleaning the system and processing system fluid with oxygen-reducing and anti-corrosion agents. Additionally, Chemiclean can install a degasser and a filter to ensure the continuation of a clean and energy efficient system.

Cleaning of heat exchangers

It is common for heat transfer surfaces in a heat exchanger to be coated with lime, corrosion products, microorganisms and oil. A one-inch coating can reduce heat transfer by more than 25 percent. Chemiclean has developed a method called CIP (Cleaning-In-Place) that does not require the heat exchanger to be disassembled.

Chemiclean’s method pumps a heated wash fluid (about 50 ° C) through the heat exchanger’s primary and secondary side. The cleaning effect is created using biodegradable chemicals and is amplified by means of air bubbles from an air compressor. The liquid is heated rapidly by the electric heater and circulated through the pump assembly. For optimal effect, the directional flow of the wash fluid is changed several times.

In addition to the specially developed cleaning fluids, this unique cleaning process includes an air compressor to create a vortex effect with micro-bubbles. This provides efficient cleaning that shatters the coatings on the pipe walls. After the cleaning the heat exchanger is flushed clean before it is reconnected to the system. The whole process takes about eight hours.

Learn more about heat exchangers in the article “Biofuels opening new markets for heat exchangers.”

The article was published in August 2011