Practical steps to improve refrigeration efficiency
There is a common misconception that there is little you can do to improve the efficiency of your refrigeration system. Many think that once a system is installed and running, it simply performs in a set or given way over time, with little difference between one system and the next.
But refrigeration efficiency is as variable as the efficiency of a family car, which changes from one car to the next, and depends on the design of the engine, operational conditions and how well it is looked after.
Refrigeration efficiency is measured in terms of the Coefficient of Performance (COP) — the ratio of cooling energy supplied, to the amount of electrical energy used. The COP varies according to:
- System type and design, for example refrigerant gas and compressor type
- Operational parameters and control settings
- Cooling temperature
- Ambient temperature
- Cleanliness of system
- Refrigerant quantity
- Lubricant quantity
In a Potato Council-funded project*, refrigeration systems were tested to establish their efficiency and to determine what could be done to improve them. The range of efficiencies, as stated by their COP, was 1.6 to 4 — in other words, a variation of 2.5 times from best to worst.
So, there is great potential to improve the efficiency of some refrigeration systems, and it pays to have your system checked out to assess its current performance. Often, you can make positive changes with some simple, low-cost ‘re-tuning’.
There is also more than just sound economic and environmental reasons to carry out an inspection — it is in fact a legal requirement.
The Energy Performance of Buildings Directive (EPBD), January 2003, requires that all air conditioning systems greater than 12 kilowatt cooling output be inspected for safety and performance by January 2011, and thereafter every five years. Also, the Fluorinated Greenhouse Gases Regulations 2009 (FGG Regulations 2009) state how refrigeration systems containing these gases should be maintained and inspected to reduce their greenhouse gas emissions.
Both sets of regulations place importance on ensuring equipment is as efficient and well maintained as possible. Most of their requirements can be met by ensuring your system is kept in good condition and annually checked for leaks, energy efficiency and correct operation.
So, an inspection every year or two will both ensure legislative compliance and show what you can do to keep your refrigeration system working efficiently; saving both energy and money.
Practical improvements for packhouse refrigeration efficiency
Here is our checklist to help you understand the range of possible improvements, their likely effect and level of cost involved.
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* The project was carried out in collaboration with Sutton Bridge Crop Storage Research