HOT|COOL NO.1/2021 - "Fuel, Flexibility & Green Transition"

As no oil is used to lubricate the compression process or bearing system, there’s no chance of oil fouling within the heat exchangers. And with contact-free operation, there’s no metal-to-metal contact degradation. This means there’s zero performance degradation over time – and no efficiency loss. Oil-free compressors are also small and quiet – making them perfect for district heating pants or any other location where noise levels are a concern. Magnetic bearings and centrifugal compression ensure that the compressor works at extremely low noise levels – on average, around 8dB(A) lower than an equivalent capacity screw compressor. The medium- and high- lift compressor models used in the Ringsted DHC heat pumps also ensure no direct global warming potential, as they utilize the ultra low-GWP HFO refrigerant R1234ze. And the hermetic factory pre-packaged heat pump design helps ensure the refrigerant can’t leak into the environment. The future of district heating: are you ready? Efficient district heating shouldn’t impact the environment – and with oil-free heat pumps, it doesn’t have to. Introducing electric water-to-water heat pumps, and other heat recovery components allowed Ringsted DHC to capture every last kilowatt of surplus heat – and use it to boost the district heating system capacity and efficiency. Not only does this allow the plant to hit key decarbonization goals, minimize dependence on fossil fuels, and improve plant efficiency, it also minimizes the price of heat for local residents. More importantly, it highlights the opportunities oil-free heat pumps can offer to other district utility providers and municipalities. And shows how, as environmental regulations get stricter, you can meet them head-on.

Another challenge Geoclima and Unicool faced was the size of the equipment room where the heat pumps are installed – like many district heating plants, it’s particularly narrow. This required Geoclima to design a dedicated pipeline and layout, to enable easy maintenance, modular usage, and quick parts replacement. Unlike traditional technologies, which are received in parts, assembled onsite, and filled with refrigerant, the new electric heat pumps, because they are built and charged at the factory, took less than a week to install, start, and commission. Meanwhile, the compressor’s compact size made it easier to achieve the required 2.7m x 1.2m footprint for the heat pumps 2 and 3. The variable high-speed centrifugal compression enables heat pumps to be smaller, as oil-free compressors like the TTH and TGH have roughly 30% of the cubic footprint of an equivalent capacity screw compressor. Additionally, the other components developed and optimized for oil-free applications and ultra-low-GWP refrigerant HFO1234ze helped ensure reliable and efficient Geoclima heat pump operation. How oil-free technology is heralding a new era of district heating Although relatively new to the district heating heat pump market, the oil-free technology – like the TTH and TGH models used at Ringsted – are an increasingly popular choice, because they offer a wealth of benefits that traditional oiled screw compressors can’t match: • Low maintenance: The oil-free action enables the design of a simplified system, reducing the time and cost of maintenance significantly. • Consistent high performance: Two-stage oil-free magnetic bearing-based centrifugal compression, and built- in variable speed, ensure extremely efficient, oil-free operation.

For further information please contact: Drew Turner, drew.turner@danfoss.com

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