CO2 refrigeration in reefer containers and heat recovery reducing cost and TEWI

By Past Member, Nov 19, 2012, 11:24 3 minute reading

Data from more than 23,000 operating hours of CO2 refrigeration of reefer containers, open cycle R744 system and CO2 compressors for MAC were the topics highlighting the opportunity for CO2 refrigerant in the transport sector. Also presented at the ATMOsphere Europe conference were: heat recovery in commercial and industrial CO2 transcritical systems saving more than 1,000 tons of CO2-eq per year or reducing running cost by 20% in comparison

Efficient sustainable container reefer applications using CO2
J Michael Griffin from Carrier presented results from extensive sea trials of refrigerated reefer containers for the transport of perishable and frozen cargo.
Based on new CO2 technology with optimised efficiency for different modes of operation, the system consists of purpose built multi-stage compressor, gas cooler heat exchanger, two speed gas cooler fan, flash tank, variable speed drive and advance controls. The CO2 transcritical system has been successfully tested during more than 23,000 operating hours, resulting in an average energy use equal to R134a.

Transport refrigeration system using CO2
A new technology trend in the transport refrigeration sector brought to the ATMOsphere conference by Bart W. Ezendam from Thermo King is the open cycle CO2 refrigeration. Liquid CO2 obtained as a by-product from industrial production is stored in a tank mounted to a truck and when released cools air through an evaporator coil located in a refrigerated space.

CO2 Compressors for mobile air conditioning and light commercial refrigeration
A presentation by Jan Hinrichs from Ixetic introducing a heat pump system using CO2 for thermal management in battery electric vehicles and for passenger air-conditioning brought a lively discussion among participants in the market innovation session. The electric driven CO2 compressor with a gas cooler in the heating/ cooling unit with a heating power of 3.2kW at -7°C ambient temperature had a COP of about 3.0. With the recent development in the mobile air conditioning (MAC) sector pointing to a renewed interest in natural refrigerants, it is likely that CO2 MAC systems will be in the spotlight at next year’s ATMOsphere event.

Transcritical CO2 cooling and freezing system for Norwegian ice cream manufacturer
Torben M. Hansen from Advansor introduced a case study with performance analysis of the 220kW (at -38°C) industrial transcritial CO2 system with 150kW of heat recovery and hot gas defrost. According to the simulation of energy consumption, the R744 system with heat recovery achieves reductions of 1,000 tons of CO2 equivalent per year (direct and indirect emissions) in comparison with a similar R404A system.

Refrigeration and heat recovery with CO2 in food retail stores
Torben Funder-Kristensen from Danfoss showed the advantage of a R744 commercial system with heat recovery on a case study from Denmark. The CO2 booster system of 160kW cooling capacity (5 MT and 4 LT compressors) with heat recovery has a 34% lower TEWI than a conventional R404A system with high direct emission. With a potential running cost reduction of 20%, CO2 systems with heat recovery are suitable for supermarket applications.

Development of a high temperature CO2 heat pump for space heating
Georges Khoury from Sanden Europe in his presentation introduced a high temperature CO2 air/water heat pump with a new cascade and control. The newly developed R744 heat pump is targeting space heating applications. The heat pump supplies hot water of up to 80°C, the temperature required by heating systems in older buildings. The patented technology - the new cascade - is based on the upper stage recovery of the excess heat in the first stage through an intermediate heat exchanger. A maximum heating capacity of 8.6kW with a COP of 2.6 makes it an attractive alternative to fuel and gas boilers. According to laboratory tests, in combined mode (space heating & DHW), R744 would be more efficient than HFC.

More information can be found in the presentations attached at the end of this article.


By Past Member

Nov 19, 2012, 11:24

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