Innovative waste heat recovery with combined adsorption and transcritical system

By team, Mar 22, 2011, 17:49 2 minute reading

A new way of reducing energy use of transcritical CO2 systems at high ambient temperatures has been implemented for field-testing by Frigo-Consulting AG. An adsorption chiller that is integrated into the overall design allows the conversion of waste heat from the transcritical CO2 system into useful energy for cooling. This is expected to reduce the electrical energy consumption by 6-8%.

The Swiss engineering company Frigo-Consulting AG has successfully developed and implemented the worlds first transcritical CO2 refrigeration system with an integrated adsorption system. Since February 2011, the field test is running in Switzerland at a prodega cash & carry market run by transGourmet Schweiz AG.

Using the waste heat efficiently - not only in winter

Transcritical CO2 refrigeration systems release considerable amounts of waste heat depending on the operating conditions. In winter this can be used for heating the building, however, in summer this energy usually gets lost. With the pioneering design of Frigo-Consulting AG, the waste heat is now used to drive an adsorption chiller that generates additional cooling and thus supporting the R744 refrigeration system. The two systems are expected to complement one another perfectly, as high ambient temperatures lead to higher unused waste heat in the refrigeration system and this is when additional cooling from the adsorption chiller is especially effective.

fig. 1: Integration of adsorption refrigeration system into transcritical CO2 refrigeration system

Reducing cost, energy consumption and emissions

The adsorption chiller powered by the waste heat can reach a cooling capacity of up to 10 kW at high ambient temperatures. This energy is used for additional cooling of the refrigerant after it has passed the gas cooler. The cooling capacity of the conventional CO2 refrigeration system can this way be increased by that same amount of cooling capacity from the adsorption system. Furthermore, the additional cooling after the gas cooler leads to a lower head pressure of the CO2 system, reducing the compression work. Both effects combined will reduce the total energy consumption by about 6-8%.

By using standard components for the adsorption chiller and its integration into the refrigeration system, the costs can be reduced to a minimum, while ensuring high operating reliability.

fig. 2: Energy flow of CO2 system with integrated adsorption system 

About Frigo-Consulting AG

Founded in 1987 the Frigo-Consulting AG headquarters are situated in Bern, Switzerland. The well-trained and experienced engineers and specialists working for the company are mainly active in the field of commercial and industrial refrigeration systems. Frigo-Consulting AG has special expertise in sustainable engineering and is supporting the realisation of subcritical and transcritical R744 systems with great success.


By team (@r744)

Mar 22, 2011, 17:49

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