6 horizontal air flow turbo line condensers and 4 industrial unit coolers
ThermoKey for an innovative warehouse at -20°C with new R449A
Aim: Cooling of low-temperature (-20°C) compactable storage warehouse in Reggio Emilia.
One of the first installations ever, operating in direct expansion with the new refrigerant with low GWP OPTEON XP40 ® R449A R449A (replacing R404A and R507) controlled by a computerized system and managed though sensors and drives, aimed at completely automating operation.
The installation realized by Mafferi Refrigerazione is composed by:
A refrigerating central with two semi-hermetic Bitzer screw compressors 125 Hp each, served by 6 horizontal airflow ThermoKey remote condensers model HK for a thermal power of 1860 kW Delta T 10° C.
• Two internal installations serving as many Low Temperature coldrooms (compactable warehouses) each including
nr. 2 ThermoKey industrial cubic unit coolers for low temperatures, model IMT463.78D5GS.
• Hot gas defrosting installations, 4-tube centralized technology, in order to obtain an optimal defrosting of the unit coolers, with high energy saving and direct control on pressure and actual defrosting temperature.
The energy saving aspect of this installation, obtained by the specific technical solutions chosen, deserves particular attention:
• The handling of refrigerant injection in the evaporators through electric thermostatic valves:
this system allows the optimization of the overheating of gas coming from the unit coolers therefore maximizing their thermic performance, thanks to closed ring control, based on temperature and pressure data detected by the sensors situated at the exit of the heat exchange coils.
Furthermore, it allows a proper supply to the evaporators, both with low or high condensation temperatures,
thus maintaining an optimal supply of the thermic exchange coils, even at low condensation temperatures
and consequently low refrigerant supply to the coil.
• Total energy saving of electricity for the defrosting of evaporating coils:
by using hot gas to defrost, the following benefits are obtained:
- The thermal load (and therefore the energy costs) of condensation is reduced.
- Defrosting is obtained at zero energy cost.
- Defrosting occurs quickly and – most importantly – in a more complete way (compared to the electrical solution).
- Steam production time is reduced and consequently the risk of ice forming on the walls and ceiling
of the cold-rooms is reduced as well.