Customised CO₂ Refrigeration Systems

These are applications in which medium and low temperature refrigerating parts of the system are connected to each other in a single cooling circuit. There are also heat exchangers for gas cooling, before and after the liquid receiver, to improve the performance of the whole machine.

These refrigerating systems have a cooling circuit in which the low pressure and medium pressure machines are physically separated. It involves one or more units at medium temperature MT , with a certain number of compressors on board, and one or more units working at low temperature LT. The refrigerant circuit is designed in a way that the same heat exchanger is the condenser of the low temperature unit LT, and the evaporator of the medium temperature MT.

This kind of control unit combines the functionalities described above with the possibility of providing HVAC air conditioning in indoor environments. From the primary receiver, supply and return refrigeration lines are installed, and the CO₂ liquid goes to feed an evaporator that cools glycoled water, as in a standard chiller. In this case, therefore, it is possible to obtain low-temperature refrigeration (food storage cells), medium temperature (cells and refrigerated counters) and air-conditioning of civil ambient.

TRANSCRITICAL SYSTEMS WITH MT AND LT UTILITIES AND AIR CONDITIONING (CDZ) – IN CASCADE SYSTEM:

This kind of refrigerating system combines the characteristics of the previous 3 refrigerating systems in a single system. This type of unit, in addition to having higher COPs, the system also guarantees the continuity of operation of the entire machine even in the event of failure of one of the MT control panels, thanks to the presence of the MT control unit. The MT system disposed in parallel allows the LT in low temperature to be able to continue in any case its function.

The refrigeration systems with pumped liquid receiver are able to combine optimal performances of the heat exchangers with a high simple installation, with a more simple maintenance. The pumped receiver systems consist of a liquid refrigerant accumulation tank that feeds the refrigerant fluid distribution pumps. The pumps, installed downstream of this receiver, send the refrigerant to the evaporators.

These refrigerating systems use ejectors. They are components that are able to transfer liquid and refrigerant gas from a lower pressure to an higher pressure. In this type of refrigeration systems, the evaporators are completely wetted by the cooling liquid, which evaporates without generating overheating and reach a the suction accumulator with suitable volume downstream of the evaporators.

Transcritical systems with ejectors and pumped liquid receiver

This kind of refrigeration unit combines the action of the ejectors with the benefits provided by the use of the pumped liquid receiver. The combination of these 2 technologies means that a refrigeration plant has very high cooling capacities in all seasons of the year, and is particularly suitable when the climatic conditions in which the refrigeration system is operating are very hard (for ex, with air temperatures higher than 42°C).

Refrigerating systems with total heat recovery and backup on gas cooler

These refrigerating systems, in which can be applied different solutions for MT and LT lines, are designed for the complete recovery the heat available in the discharge lines, leading it into hot water tanks.

CO₂ systems with adsorber

A CO₂ refrigerating system equipped with an adsorber, uses the heat in the discharge line to produce the subcooling of the CO₂ gas at the gas cooler outlet. The adsorber is a component that uses zeolite and silica gel. The driving force of the process is the discharge line compressors heat, and so the adsorber creates a cold source adsorbing the heat.