05 July 2018
Andrew Slater, Senior Engineering Manager, LG Electronics, UK & Nordic, outlines the technical advances and wider benefits of its R32 range.
With the recent introduction of its R32 product range, LG’s commitment to technological innovation continues apace, from the introduction of new and exciting mechanical components to function and feature, delivering the environmental and efficiency factors that are expected of an industry leading brand.
Traditional system control and regulation is based around sensing changes in the environment by using temperature sensing. When specifying equipment, we use two design temperature dynamics, both measured in different ways: dry bulb and wet bulb.
We have introduced the industry’s first Dual Sensing control system, offering the ability to sense humidity along with temperature. Both sensible and latent loads can be monitored and reacted upon, moving from design considerations to real time adjustment for dry and wet bulb temperatures.
By utilising ‘smart cooling’ – an automatic refrigerant temperature control logic along with dual sensing capabilities – not only energy savings of up to 15% can be achieved compared to traditional control methods, but the comfort levels within a space can be maintained at optimum conditions. During periods of low humidity, raised evaporative temperature reduces moisture removal rates, but meet load conditions, and during high latent loads, the high humidity levels resultant load can be met, whilst removing moisture and self adjusting accordingly, to create a more comfortable environment.
Combining energy savings, comfort and wellbeing, LG’s new cassette accessory – the Human Detection Sensor – will switch an air conditioning product on or off in relation to human presence. Energy features allow periodic staged set back control to regulate, depending on occupancy, selectable to a range of between 5 and 60 minutes after no movement is detected, raising the set point temperature whilst in cooling mode and lowering it in heating mode.
That’s where the real differences in LG’s new R32 motion technologies become apparent. Instead of a traditional PIR based detector, that just senses occupancy, a motion tracker can detect exactly where the occupants are in the room, providing the user with the choice of directing air towards them, or away from, removing the possibility of draughts and improving the occupants thermal experience.
To achieve the market’s high expectations, two different styles of compressor have been developed to span the R32 range of both residential and commercial products, each lending themselves specifically to different capacity ranges.
With a discharge pipe redesign to reduce oil egress, the twin rotary compressor of a 2.5 to 7kW model includes an upper and lower rotor, offset to stabilise any imbalance that a single rotor would cause during shaft rotation. Vibration is reduced by up to 80% and noise levels reduce by up to 50% compared to single rotor models. This increases reliability, efficiency and control at high speed, with a maximum load torque reducing by 45% in comparison.
With a redesign of a concentrated winding motor, the resultant increase in stator cavity allows increased oil and refrigerant flow paths, regulating motor temperature at increased speeds, to a maximum of 130C.
Being able to operate with a compressor turn down to 15Hz, allows more efficient operation during low load conditions, whilst providing oil circulation reliability, because of differential pressure flow, rather than being ‘shaft rotational speed’ related.
Applied to larger capacity commercial models of 7kW and above, the new R Scroll compressor provides a complete redesign to a traditional scroll compressor layout and includes features such as the LG high-sided shell compressor design that has been applied to VRF models. This new design moves away from a traditional operating structure and uses high pressure, high temperature refrigerant to regulate a concentrated motor, instead of the traditional low pressure. Oil viscosity is kept low and reliability is increased. Amongst the modifications that have been applied are the repositioning of the scroll below the compressor motor with the shaft passing through the orbiting scroll rather than just supporting from underneath. As a result, efficiency has improved by 5% through a 54% reduction in orbiting scroll movement, leading to a 34% reduction in friction force.
The reduced movement of the orbiting scroll and its lower position within the compressor body, has allowed for a shell dimensional reduction, removing the lower supporting trusses and in turn, creating a lighter weight shell with a reduction of 4.5Kg in comparison to equivalent previous rotary compressors.
With the transition to scroll compressors within models of R32 products, increased cooling and heating performances are provided due to a 50Hz upper operational compressor range, realising a 20% increase in SEER due to efficiency increases at low load, providing improved comfort options. Using LG’s engineering approach maximises the benefits of an enforced environmental change to R32.
With the industry focus on R32 product ranges being on the wider environmental issues, LG has expanded that vision into the local environment, concentrating on design with wellbeing in mind. Thermal experience, noise, environment and control opportunities all play an important role in an occupant’s wellbeing. The combination of local and wider spread concerns in product innovation, is a direction LG is proud to be working towards.
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