The introduction of new F-Gas measures in the EU as of 2015, and in particular the bans on HFCs in certain sectors, have opened up new market opportunities for a wider uptake of climate friendly natural refrigerants.
World premiere of CO2 trailer prototype by Carrier Transicold
Lionel Pourcheresse of Carrier Transicold made a presentation about the new E-Drive Natural Refrigerant Trailer prototype launched in 2014. This world premiere prototype is a refrigeration unit dedicated to road transport using CO2 in a closed loop system, which is fully autonomous and driven by an independent diesel engine.
The prototype aims to demonstrate the future for refrigerated transportation systems in compliance with the EU F-Gas Regulation. The trailer is charged at the factory with a defined amount of CO2 refrigerant. This quantity of CO2 inside the refrigeration circuit is compressed then expanded, and compressed again in a closed loop system.
The benefit for the user is that there no need to recharge the system everyday and no need for heavy infrastructure to store the natural refrigerant,” said Pourcheresse. “This new design reduces potentially harmful effects on the environment, without compromising reliability or performance, creating a desirable balance between efficiency and sustainability.”
The cost of the system, initially higher than current or partially improved systems, is countered by the elimination of leakage check costs, taxes on refrigerant and refrigerant price versatility, which emphasises the competitiveness and viability of using natural refrigerants.
First CO2 transcritical ice rink in Europe by Green & Cool
Another first in Europe in 2014 was the implementation of the first CO2 transcritical ice rink installed in Gimo, Sweden. Kent Hofmann of Green & Cool and Jörgen Rogstam of Energi & Kylanalys, presented a case study on the initial efficiency results since the project’s implementation in September 2014.
After the system upgrade, the daily average energy usage is down to 1500 kWh, from 4200 kWh, which suggests that the seasonal energy usage will be about 350,000 kWh. This is an energy savings for the municipality of about 600,000 kWh a year; corresponding to an over 60% reduction in energy cost.
The project stemmed from the collapse of the ice-rink’s roof in 2013, which was replaced, less than a year later, with a new roof and innovative upgrade of the energy systems. At the heart of the energy management system is a transcritical CO2 unit, with a 250 kW nominal cooling capacity. The system is able to recover a large portion of the waste heat from the cooling process to use for site heating and hot water. Any excess heat is transferred to a geothermal energy storage enabling subcooling of the CO2 process and saving heat for use during colder periods, thus providing both a “warm climate” and “cold climate” solution. No supplementary heating such as gas, electricity or district heating is used.
In addition, the low pumping power suits the vast distribution system in the rink floor and CO2 can be used directly (i.e. no secondary fluids are required) on both the cold and the warm side, which cuts losses in heat exchangers and reduces parasitic energy usage by pumps and fans. Reduced energy usage, mainly due to heat reclaim, will be the dominating saving factor for the ice rink owner together with lower service costs.
A first for CO2 in food-service refrigeration in the UK
Garry Broadbent and Dave Blinkhorn of Green Cooling presented a case study about a CO2 food-service refrigeration system provided and installed for KPMG at Canary Wharf, London- a project which encompassed a restaurant with seating capacity of 1,500 people. This installation is important to the UK market for delivering a substantial CO2 installation within a HORECA (hotel, restaurant, café) application, providing chilled/ cold storage and also kitchen/ display refrigeration. The project highlights the practical nature of utilising CO2 refrigeration within a centralised system as an alternative to conventional designs, whilst satisfying the UK BREEAM sustainable building standard.
The system features a twin refrigeration Enex CO2 pack design with 6 Dorin compressors. A 4,500 litre hot water production system was incorporated within the CO2 system design, in order to reuse the waste heat and provide more overall system efficiency. The catering facility benefits from higher efficiency and a sustainable cooling system that matches the flexible and variable load conditions that are found within a busy restaurant environment. This CO2 system represents a step forward within the HORECA market in the UK, which is no longer only reserved to the large capacity retail sector.
First retailer equipped with Thermo King CryoTech technology in trailers
On the topic of transport refrigeration, Thermo King’s Anthony Bour presented a case study on CO2 sustainable delivery operations with CryoTech temperature controlled solutions. There are nearly 1000 CryoTech equipped trailers running on European roads everyday, including 10 in Delhaize Belgium’s fleet, the first retailer to equip themselves with the technology in an effort to help reduce its greenhouse gas emissions by 20% by 2020 (as compared to 2008). Estimations show that during delivery the CryoTech-equipped Delhaize trailers only use 25% of the total energy and generate 75% fewer emissions than an equal-sized domestic refrigerator.
Principles of CryoTech:
- Heat is absorbed by passing liquid CO2 through an evaporator
- CO2 does not enter the load compartment
- Max noise level 58dBA
Thermo King CryoTech technology uses liquid CO2 (R744) in an innovative open-loop system. The recovered R744 used for cooling is obtained as a by-product from industrial processes, which would otherwise have been released into the atmosphere. As such, there is no new CO2 emissions during operation of the CryoTech system.
These units feature faster recovery temperature compared to conventional diesel driven refrigeration and allow for faster temperature pull-downs. This is crucial where the cooling unit is often interrupted as drivers deliver goods at multiple locations,” said Bour.
CO2 transcritical freezing factory in France
AF Consulting’s Paul Rivet presented about a CO2 transcritical system in a frozen fish factory in France. The systems is made up of 2 continuous freezers with capacities of 350 kW at -40°C, as well as frozen storage rooms with a 100 kW capacity at -25°C, and working areas of 150 kW at +8/+10°C. Usually, a project of this nature would use ammonia refrigerant, but in this case a complete CO2 transcritical system was installed, after having been compared to direct pumped NH3, direct pumped HFC, hybrid CO2/NH3, and also due to the strict constraints on ammonia refrigeration in France. The aspects taken into account were: investment costs, running costs, safety, service and heat recovery possibility.
The freezing equipment included:
- 8 semi-hermetic compressors on HT and 5 on LT (2 with inverter)
- 2 continuous freezers fed with CO2 pump with variable flow
- CO2 charge of 13000 kg
Even if the performance of using air to remove discharge heat is not as effective as ammonia, with the evaporative condenser during hot periods, an individual running room programme for day/nigh operation, the reduction of distribution piping at -40°C, and heat recovery, this CO2 transcritical system has proven to be a good potential alternative to ammonia which provides an excellent compromise on investment and running costs.