Brunel University unveiled its carbon dioxide based ‘integrated energy system’ for retail, food and manufacturing facilities
It claims the system has the potential to produce 30 per cent energy savings and 40 per cent greenhouse gas savings over conventional systems.
Brunel has been working with 14 commercial refrigeration partners on the system, which integrates CO2 and trigeneration technologies and can be tailored to a variety of local power generation and sorption refrigeration technologies.
It uses the energy released by a combined heat and power system to drive a sorption refrigeration system which in turn is used in a cascade arrangement to condense the CO2 refrigerant of a subcritical refrigeration system. Brunel says this ensures operation of the CO2 refrigeration system in the subcritical region all the time and at a constant condensing temperature, ensuring high energy efficiency throughout the year.
The system can employ any type of sorption machine (absorption or adsorption) depending on the temperature of the heat available from the CHP plant and the desired condensing temperature for the CO2 refrigeration plant.
Tests in the Brunel laboratory have shown the LT system can deliver a steady state COP of 4.0 at an evaporating temperature of – 32 deg C and condensing temperature of -7 deg C. The COP of the MT system is very high – over 50 - due to the low power requirement of the pump. On a 5,000m2 supermarket, the team calculate a 30 per cent energy saving over an equivalent R404a system.