It is well known that pollution of refrigeration systems cause a reduction in performance of the system, both in actual cooling/heating capacity and in energy efficency (COP).
However many contractors and/or end users do not address these problems, causing several side effects to be a common occurance in refrigeration systems:
- Increased condensing pressure
- Lower than necessary evaporating temperature
- Increased oil consumption
- Degradation of oil
Visiting plants we often find that end users are focused on getting the required amount of cooling for their process, which in itself is natural. But ignoring the pollution problems as long as the system is cooling results in one thing that should be very important to every end user: An increase in cost from higher than necessary compressor power consumption and/or higher service cost.
On the vast majority of systems we visit we suggest changes that can save the end user in excess of 30% reduction in power consumption. These reductions have been verified. On top of that the systems deliver a higher cooling capacity.
The main sources of pollution are:
- Air (or other non-condensible gasses) – Air is transported by the system to the high pressure side where they are unable to condense at the given temperatures. As a result they collect and block out surface area of the condenser, resulting in a higher condensing temperature. Usually it is thought that positive pressure systems does not have air problems but in reality all systems suffer from this. In some cases it is not atmospheric air, but rather gases from chemical reactions between refrigerant, oil and materials in the system.
- Water – Water can enter either during service or through leaks to the atmosphere or in heat exchangers and even the highest quality new refrigerant contain some water. Water usually reside on the low pressure side where it doesn’t leave with the refrigerant as is evaporate. Water will degrade oil in the system and in R717 systems cause a shift in the saturation pressure/temperature curve, throwing control systems off
- Oil – Oil is (usually) required in compressors, but in the rest of the system it will foul heat exchanger surfaces resulting in a reduction of heat transfer/increase in temperature difference.
Usually refrigerant, oil and materials are matched to remain chemically stable, but in the presence of water and air (oxygen) this changes. Depending on the mix a large number of chemical reactions can take place, always resulting in unwanted
Cool Partners have developed a number of components that can be used to remove or control the pollutants in the systems. These are: