Refrigeration
Refrigeration systems contribute both directly and indirectly to global warming. Greenhouse Gases are emitted directly through the leakage of chlorofluorocarbon (CFC) and hydro-fluorocarbon (HFC) refrigerants and indirectly through the consumption of electricity. The release of one unit of these refrigerants is equivalent to the release of at least 1500 units of CO2, the most common Greenhouse Gas. A major UK supermarket group has stated that 25% of its carbon footprint is a direct result of refrigerant leakage.
A refrigeration system that uses CO2 as a refrigerant has the potential to significantly reduce Greenhouse Gas emissions. CO2 has a low global warming potential as well as favourable heat transfer properties that make it more attractive than HFC based refrigerants. In recent years systems have been installed across Northern Europe in a variety of formats including: cascaded low temperature direct expansion (DX) with HFCs, cascaded medium temperature pumped liquid with HFCs and transcritical DX. Systems vary depending on country, but due to the relatively low ambient temperatures and simplicity of design and service the transcritical DX system has emerged as the most popular option. |
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Due to the high operating pressures of transcritical CO2 systems, greater care must be taken in their design, manufacture and operation to minimise energy consumption. The favourable properties of CO2 as a refrigerant allow a system to be run at different set-points than an HFC based system. A major UK supermarket group has recently installed CO2 refrigeration packs at 30+ locations and by utilising innovative design and operation techniques observed a 5% drop in energy consumption.
Energyexcel has proven expertise in this developing field and can provide the following services:
- Feasibility studies
- System design and analysis
- Performance modelling
- Verification of claimed performance or carbon savings
- Integration with other utilities such as tri-generation systems
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