INTRODUCTION – THE PROBLEM
HVAC systems rely on a compressor to convert the refrigerant from a low-temperature, low-pressure, saturated vapour to a high temperature, high pressure, superheated vapour as a first step in the vapour compression cycle, that is used for air conditioning. Like most mechanical devices, compressors require a lubricant oil to reduce friction and heat buildup in the moving parts. During the normal course of the refrigeration process, the refrigerant comes into contact with these moving parts and 0.5% to 8% of the compressor’s lubricating oil is circulated throughout the system along with the refrigerant according to the ASHRAE Handbook on HVACs. This oil then builds up on the inside walls of the coil tubing through which the refrigerant flows. This buildup is known as oil fouling.
Oil fouling creates a permanent insulating barrier of compressor oil inside the walls of the coil tubing in the air conditioner that impedes the refrigerant’s ability to transfer heat.
This results in:
- Compressor having to run longer to achieve the same effect
- Increased energy costs
- Decreased thermal conductivity of the metal and therefore, lower heat transfer coefficient
- Increased wear and tear on the equipment due to reduced lubrication of compressor crankcase
- Increased maintenance costs
According to ASHRAE, The American Society of Heating, Refrigerating and Air-Conditioning Engineers, performance is degraded by as much as 30% due to the build-up of lubricants on internal surfaces (click here).
Mechanical solutions like skimmers and suction risers are some proposed solutions. However, they only reduce the problems of restricted or clogged capillary tubes or sticky expansion valves. They do not resolve the boundary layer oil fouling over time.
The best solution in this case is to use a fouling Inhibitor additive that increases refrigerant side heat transfer efficiency in HVAC systems.
This additive is an intermetallic compound technology that, when introduced into the refrigerant oil of a system, forms a permanent bond to metal surfaces. This action:
- eliminates oil fouling by replacing the oil molecules and debris
- restores the thermal nature of the metal. Oil diminishes the thermal conductivity of the coil tubing. With the additive, the thermal conductivity of the metal is restored to like new.
- lowers the boiling point of the refrigerant gas, which is increased due to fouling. The presence of oil and debris results in a higher heat coefficient of the gas. Removing these results in restoring the boiling point of the refrigerant gas to its natural levels.
Once added, the polarized molecules of the fouling inhibitor permanently bond to the metal surface through covalent bonding (since the additive is negatively charged), after dislodging built-up oil and debris. Essentially, it creates a new film, one molecular in thickness on the inside of the coils. This film repels oil and debris and restores the ability of the system to efficiently transfer the heat load. More efficient heat transfer results in lower head pressure and less work required by the compressor. More efficient heat transfer also results in colder evaporator coils, which allows for the set point to be reached quicker. This can allow the compressor to cycle off more often, thereby running less and saving more energy and reducing electrical operating costs.
The result is a more efficient operating system with 10-30% savings in energy costs. This additive has consistently shown 3 times the oxidation and corrosion protection than untreated oil.The Fouling Inhibitor is a one-time application that restores like-new performance. It can be used at temperatures ranging from -50 °C to 210 °C and has several other benefits:
- Reduces humidity up to 50%
- Extends equipment life
- Less downtime & maintenance costs
- Rapidly improves operating conditions
- Significant CO2 emission reduction
Considering the fact that this product is an additive, there might be questions on the risks associated with it.
This fouling inhibitor is napthenic-based and compatible and readily mixes with standard refrigeration oils and some synthetic oils. It forms a protective molecular layer. It is independently and third party tested and approved (including Intertek and SGS). It meets the U.S. OSHA hazards standard and determined NOT to be hazardous.
It does NOT:
- change mechanical tolerances
- contain elements of the Halogen group like Chlorine, Fluorine, nor Sulphur or Phosphorus
- contain PTFE (Teflon®) or any other particulate
- contaminate waste oil
- void manufacturer warranty
- require filter changes in a hermetically sealed system
Moreover, if the additive causes any equipment failure, the equipment will be replaced or repaired, backed by an insurance policy for liability. In more than 12,000 installations however, there has never been an equipment failure or a claim.
The water content of refrigeration oil is an important variable in refrigeration systems because water can hydrolyze with refrigerant and form strong corrosive acids. If the water content of refrigeration oil is greater than 200 ppm there are serious system problems that this Fouling Inhibitor cannot fix.
Also, this additive does not operate in Brine chillers.
This Fouling Inhibitor has to be added just once, lasts through the life of the equipment and does not disrupt the flow of business. It offers:
- Payback in as low as 4-6 months
- Reduced energy consumption by 10-30%
This technology has been installed in several units across industries successfully. The Ohio Department of Transportation, Wipro, Schneider Electric, Franklin Templeton, Apollo Hospitals, Titan Industries, Godrej Industries, Aurobindo Pharma, Hyatt Hotels, Genpact, among others, are using this product with significant savings.
Energyhive can help you realise similar success for your HVAC systems. Contact us today to know more.