City Multi uses aluminium heat exchangers

A close-up of the profile of the new Mitsubishi Electric aluminium heat exchanger (right) compared to standard copper

EUROPE: Mitsubishi Electric has become the first air conditioning manufacturer to adopt super-efficient aluminium heat exchangers in its VRF products.

The new City Multi YLM to be launched across Europe at Chillventa next week, includes a world-first aluminium heat exchanger amongst a number of improvements which is said to make the new range 27% more efficient compared to the previous equivalent City Multi systems.

Already available in Japan, the launch of the YLM in Europe and the first inclusion of an aluminium heat exchanger is seen as a pivotal step-change in VRF air conditioning technology. In addition, the new models, which will be available in Europe from January, offer greater evaporating temperature controls, new defrost options, reduced refrigerant and an induction-heated compressor to reduce standby power by 50%

While aluminium heat exchangers are common in the car industry and are seeing greater use in commercial air conditioning and refrigeration systems, this is thought to be the first use of flat tube aluminium micro-channel heat exchanger in a VRF system.

City-Multi-YLMThe unique design of the Mitsubishi heat exchanger is said to offer 30% more piping, deliver 17% greater contact with the fins and 26% more contact with the refrigerant.  At the same time, it reduces both weight and footprint and offers 10% less system refrigerant volume than previous models.

“The use of aluminium is an important step-change in refrigerant distribution and heat exchange,” commented Mitsubishi Electric’s air conditioning product manager Mark Grayston at the UK press launch.

To alleviate corrosion concerns, the heat exchanger has a zinc coating acting as a sacrificial anode and has been tested to Japanese standards for the equivalent of 30 years.

Units are available in capacities from 22-101kW in both heat pump and heat recovery variants, with up to 50 indoor units connectable to the largest model. 

The smallest unit in the range, the PUHY-EP200YLM-A model is just 740 x 920 x 1710mm in size, making it transportable in a standard building lift.

The design changes include a new compressor optimised specifically to maximise efficiency during part load, therefore offering high seasonal efficiencies and helping to reduce standby power consumption by 50% by using an induction-heated compressor.

The YLM range also includes a redesigned bellmouth grille to aid airflow, reduce static pressure and lower the energy consumption of the new DC fan motor.

In addition to standard reverse defrost, the new YLM also offers hot gas defrost. Available across the entire YLM range, in heat pump, heat recovery, single and multiple modules, this can provide 30-50% capacity to indoor units during the defrost cycle.

YLM is also said to offer an improved air-off temperature that delivers better control in three high sensible modes and an automated dynamic control mode.

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