Mitsubishi Electric enters UK chiller market
Mitsubishi Electric in the UK is not known for chillers, but that is about to change with the introduction of a modular range that bears closer comparison to modular boilers than it does to traditional chillers. Ken Sharpe has the story.
For nearly 25 years, Mitsubishi Electric has been one of the major players in the UK air-conditioning market. The company commands major market shares for split systems and VRF systems, which between them account for 55% by value of the UK market.
|Mitsubishi Electric’s e-series chiller and a schematic of how units are connected to a common header.|
The next largest section is air-handling units, at nearly 25% by value. Chillers (for air conditioning) are 16% and fan coil units 4%.
It was early last year that Mitsubishi Electric launched a range of air-handling units — the Lossnay Kanzen range. Five standard sizes enabled the company to cover just over 40% of the office sector. Throughputs range from 3500 to 15 000 m3/h, and the heat exchanger can recover sensible and latent heat.
The latest stage in Mitsubishi’s offering to the UK market is a range of chillers — but they are very different in approach to other chillers on the market.
Let’s put the launch into a market context first. Sebastien Desmottes, product marketing manager, explains that about half of the company’s customers already install chillers.
He further explains that the size of chiller they install corresponds to BSRIA’s figures — with 41% having cooling capacities from 50 to 100 kW, 24% in the range 100 to 200 kW and 20% covering 200 to 500 kW. These are all sizes using scroll compressors. Another attractive feature of the chiller market is its stability compared with construction as a whole, at just under 3000 units a year.
Elsewhere in the world Mitsubishi offers chillers made in its factory at Wakayama in Japan, and it is these chillers that are now being offered in the UK. This factory also makes City Multi units, and a common philosophy and common technologies are used in both products — such as the compressor and inverter. ‘The benefit,’ explains Sebastian Desmottes, ‘is that what we and our installers understand about City Multi can be applied to these chillers.’
One word summarises the important characteristic of the e-series of chillers — modular. The basic unit has a cooling capacity of 90 kW, which can be modulated down to 8%. Just as VRF outdoor units and many boilers can be connected to deliver larger outputs, so too can e-series units. Up to six units can be connected to deliver a total cooling capacity of 540 kW, which covers a lot of the market.For larger buildings, multiple banks of modular arrangements can be installed in rows with just 900 mm service space between the rows.
The principal features of e-series chillers
• High efficiency inverter compressors. Two advanced DC inverter-driven scroll compressors are incorporated within each 90 kW module, giving a capacity range of 8% to 100% for each module.
• 2-stage cooling circuit. Both compressors serve separate plate heat exchangers in the centre of the unit. By modulating the evaporating temperature individually, overall system efficiency can increase by an additional 3.9% compared to single evaporating refrigeration cycles.
• Fan inverter control. Each of the two refrigerant circuits has three separately controlled, inverter-driven DC fans, allowing for more precise control to save energy and optimise system efficiency.
• Front service. Access for the control box and other service parts is at the front of the unit to ease service and maintenance regimes.
• U-shaped high performance compact air heat exchanger. The use of U-shaped heat exchangers allows for a greater surface area whilst also keeping the units much narrower than conventional chillers. Weather-resistant coating on the heat transfer plate is standard.
• Fans. The e-series fan blades have improved ventilation characteristics and a newly designed rear edge that suppresses wind turbulence to increase efficiency.
• Internal header pipe. The in-built internal header pipes simplify design, installation and maintenance and make the e-series range modular and suitable for almost any situation.
• Digital indicator. A dedicated digital indicator inside the PCB displays high pressure, low pressure, water inlet temperature, water outlet temperature, error codes etc., aiding service and maintenance
There are heat-pump versions and cooling-only versions.
The modular capability of e-series means that a small range of units can cover a wide range of applications and that they can be held in stock rather than manufactured to order.
The chillers in a modular installation operate as an entity with a reverse-return header linking the chillers and making the connection to the chilled-water distribution system. The pipework is built into each unit, and they are connected using grooved pipe couplings.
Jason Tinsley is product manager for central plant, and he has the answers to the technical questions.
The refrigerant is R410A, and there are two inverter-driven scroll compressors in each module —enabling output to be modulated down to 8% of full capacity.
High operating efficiencies are achieved. The EER for an e-series unit, not including the pump, is 3.2, compared with 2.8 for a ‘leading competitor’. the more important seasonal figure (ESEER based on Eurovent conditions) is 5.5, compared to 4 for a ‘leading competitor’.
There is a series of figures for cooling EER at a range of output capacities and flow temperature. The peak performance is about 9 with a flow temperature of 7°C, ambient of 15°C and 25% output.
In heating mode a COP of 3.8 is achieved at 7°C ambient, 45°C flow and 60% load.
These units are expected to qualify for Enhanced Capital Allowances and are currently going through the procedure.
And since may chillers are installed in noise-sensitive areas, a bit about noise levels. The highest noise level is at the back of a unit — 65 dB(A) at a distance of 1 m and 1.5 m above the base of the unit.
Jason Tinsley summarises, ‘We are bringing these chillers to the UK chiller market because we believe the time is right for a high-performing low-carbon solution that can also help reduce space requirements.’