Waterloop System / Aqualoop system

In the last few years, a new system has been gaining ground in the commercial refrigeration market, involving a water loop with variable speed compressors. This system represents a change in approach compared to traditional systems.
Traditional systems are centralised, with compressor racks - generally installed in equipment rooms or on the roof of the building - that supply refrigerant to the evaporating units (showcases and cold rooms inside the store) via long copper pipes.
The water loop solution, on the other hand, is a distributed system: the refrigeration units feature small water-cooled condensing units fitted with variable-speed compressors. A simple water circuit is used to carry away the heat or transfer it to the outside via a drycooler.

1. Firstly, the supermarkets that have started using this solution have seen considerable energy savings. The three key elements are the plugin unit concept, the efficiency of DC compressors with permanent magnet motors, and the effect of variable-speed. In a centralised system, a line of refrigerated showcases operates so as to meet the needs of the unit with the highest demand; this forces work the compressor racks to work in generally worse conditions. The use of plugin showcases means the operating conditions of each unit are independent and the board on each can consequently operate in more favourable conditions than the compressor racks in a traditional system. Permanent magnet DC motors are more compact than corresponding AC motors, require less energy to magnetise the rotor and thus in general consume around 5% less power in the same conditions. On a showcase, load varies depending on the time of day, the season, following defrosting or when loading the goods. The possibility to change compressor speed means that unit cooling capacity can be adapted based on actual demand. In this way, the compressor works most of the time in conditions that maximise COP, without affecting temperature control.

2. Another interesting aspect and feature of this technology is product preservation quality. In a traditional centralised system or a system of plugin showcases that uses on-off compressors, temperature is controlled discontinuously: when control (solenoid valve or compressor) is active, the temperature is lowered until reaching the set point; the control devices are then switched off and the temperature rises again - typically by a couple of degrees °C - before the controller reactivates the devices. The result of this type of control is that showcase temperature is not constant and indeed the average is higher than the set point. In a plugin system with variable-speed compressors, the possibility to modulate operating speed and refrigerant flow-rate according to load ensures more precise and stable temperature control, with average deviations from the set point in just the tenths of a degree. This means the temperature set point can be higher, with benefits in terms of energy savings and improved quality of the stored foodstuffs, meaning the goods on display last longer
3. Other important benefits are fast installation and lower maintenance costs. The plugin solution shifts system optimisation from the field to the manufacturer. Each showcase can be tested on the production lineas concerns construction, wiring and performance. Optimised parameters can be identified and pre-installed for every type of unit or use. Refrigerant can be charged during production, with the units delivered pre-charged. By perfecting this process, commissioning times can be slashed, with just a couple of days needed to commission systems with more than 100 showcases. Showcase industrialisation and standardisation and less commissioning operations required in the field also mean increased system reliability and lower maintenance costs, with savings of up to 30%.
4. There is also a reduction in refrigerant charge and less leaks. The water loop solution eliminates the need for the long lines that in traditional systems carry refrigerant from the compressor racks to the units. In a centralised system, these pipes are always welded in the field - with the probability of leaks in the medium-long term - and contain large amounts of liquid refrigerant. In systems with plugin units, the refrigerant is pre-charged in the factory, meaning not only an 80% reduction in total system charge, but also - due to the quality and standardisation of the welding processes - the almost total elimination of leaks. Indeed, estimates indicate that annual system leaks can be reduced by 96%. Moreover, in accordance with F-gas regulations the use of systems with a low refrigerant charge means periodical leak checking is not required.

5. One of the market trends in commercial refrigeration is a shift in investments from large hypermarkets to local stores, which are smaller, less standardised and easier to setup in old town centreswhere space and noise problems may prevent the opening of traditional stores. Not using compressor racks solves the problem of both space (moreover allowing a larger selling area) and noise.