Energy technologies: RefrigerationRefrigeration has many large energy saving options. With Emsol, you should be able to achieve savings of between 10% to 50%.
There are often some quick and low cost energy saving options with refrigeration, as well as a vast number of more complex or longer payback options. With some refrigerants being phased out (such as R22), some of the easy-to-change alternatives (such as R303a) actually increase energy costs. This may be a time to change to a more efficient refrigeration system.
With refrigeration, the aim is to reduce compressor discharge pressure, increase suction pressure and reduce unnecessary heat loads. All refrigeration efficiency improvements should result in one or more of these, which will save energy while obtaining required temperatures.
A common and large energy saving option is to increase the size of condensers or cooling towers. However, before doing this, they should be cleaned, which can save up to 10% in energy use alone. Increasing condenser or cooling towers size will reduce discharge pressure, as long as there are no design constraints in the compressor system. If there are constraints, such as in DX designs or for oil cooling needs, then other changes can be made to the design to overcome these limitations.
Another large energy saving option is to increase the size of evaporators. Similar to condensers, they should first be cleaned (and kept free of ice) and any damage fixed. These will allow suction pressure to be increased. A rule of thumb is 2-3% energy savings with every 1oC decrease in discharge pressure, and 3-5% energy savings with every 1oC increase in suction pressure. These savings can be calculated more accurately and they depend on current set points.
Unnecessary heat loads include cool room fans operating too often and/or too fast, trace heating, oil heating or lights left on unnecessarily. Also, cool room doors left open or poor/wet insulation and gaps in cool room envelope will result in the same.
Some of the more effective tips for saving energy with refrigeration include:
- Decrease discharge pressure during winter months.
- Increase suction pressure during winter months.
- Float discharge pressure to reduce at cold times of the day.
- If bore/river water available, use this for condensing.
- Clean condensers/cooling tower.
- Keep cold store doors closed at all times/install rapid roll doors.
- Analyse and clean impurities from refrigerant, particularly in ammonia.
- Use VSD on one screw compressor for part loads.
- Otherwise, use reciprocating compressor for part loads.
- Use fixed speed screw compressors only for 80%-100% full load.
- Automate defrost length to match ice build-up; avoid defrosting too often.
- Make changes until ammonia systems can be 700 kPA discharge pressure.
- Change from solenoid valves to modulating control valves and increase suction pressure.