Technologies

Carbon dioxide (CO2 or R744) is a naturally occurring gas, and as such, part of our atmosphere. From birth, we inhale and exhale it and ingest it daily in the form of carbonic acid, e.g. in mineral water.
 

It first appeared as a refrigerant in the 19th century, as the benefits of CO2 as a refrigerant were already known at that time. In the 20th century, synthetic refrigerants replaced CO2, and it was not until the 21st century, when the serious consequences of synthetic refrigerants for the environment became known, that carbon dioxide experienced an immediate renaissance as a naturally available refrigerant. Modern CO2 refrigeration systems are characterised by their energy-efficient and highly environmentally-friendly operation, and ever-growing demand confirms their acceptance.

On the other hand, the CO2 used in refrigeration systems and heat pumps is a waste product from industrial processes that can be reused in such systems. If the CO2 enters the environment in the event of a leak, it has a negligible impact compared to synthetic refrigerants.

Ammonia (NH₃ or R717) is a true all-rounder. While synthetic refrigerants became increasingly important in the 20^th century for small and medium-sized refrigeration capacities, ammonia remained the undisputed leader in industrial refrigeration – and continues to do so today. Its excellent thermodynamic properties, which are natural and environmentally friendly among other things, make it a particularly economical solution, especially for large systems and heat pumps.
 

Ammonia is used in compression chillers such as reciprocating and screw compressors and in absorption chillers. Thanks to its efficiency and versatility, NH₃ has been a reliable standard in industrial refrigeration for decades.

Hydrocarbons have proven themselves for years as refrigerants in small and medium-sized refrigeration systems and heat pumps. Due to the ban on refrigerants with ozone-depleting potential and the gradual implementation of the F-gas Regulation, they are becoming increasingly important. With a negligible greenhouse effect (GWP), no ozone depletion potential (ODP) and no corrosive effect on the common materials used in refrigeration technology, they offer a sustainable and efficient alternative.

Of the family of hydrocarbons, iso-butane (R600a), propane (R290) and propene (R1270) are primarily used. Iso-butane is mainly found in household appliances, while propane is mainly used in refrigeration technology and heat pumps. Propene, on the other hand, is particularly suitable for industrial freezing applications.

Frigo-Consulting uses hydrocarbons selectively, depending on the specific requirements and application, while taking their individual properties into account. Possible applications include process cooling or the subcooling of cascaded refrigeration systems to increase efficiency or cooling capacity.

Back in 2008, we implemented the first transcritical CO2 refrigeration system with parallel compression – a milestone in the development of energy-efficient refrigeration technology. Thanks to the innovative technology, which does not require all compressors to fully increase the pressure, the system’s power consumption has been significantly reduced.

The increase in efficiency using ejectors can essentially be attributed to two effects:


1. The refrigeration system is designed in such a way that the medium and low temperature evaporators are ‘partially flooded,’ i.e. the refrigerant is still partly liquid at the outlet of the evaporator. This ‘partially flooded’ operation allows evaporation temperatures to be raised by up to 8 K compared to conventional systems.

2. Driven by the pressure difference during relief, the ejectors foreward liquid or gaseous refrigerant. The liquid refrigerant in the suction accumulator of the medium temperature system is fed back to the ‘partially flooded’ medium and low temperature evaporators . The gaseous refrigerant is compressed to high pressure by the parallel compressors.

Buildings can be heated and air-conditioned and food refrigerated with just one system – a solution that is not only versatile but also highly efficient. There are practically no limits to the individual design of such integrated systems. They significantly reduce the interfaces between different trades by not requiring an additional heat pump or air conditioning system. This ensures optimum use of available resources.