ATMOsphere Asia 2014: Eco Cute continues reign as leading Japanese CO2 technology thanks to new innovations

By Klara Skačanová, Feb 12, 2014, 17:50 5 minute reading

The ATMOsphere Asia 2014 conference on natural refrigerants held in Tokyo on 3-4 February saw presentations on the latest CO2 heat pump (Eco Cute) technologies available for commercial and residential applications including Mayekawa’s unimo, Denso’s solar hybrid model, Itomic’s commercial Eco Cute models as well as the Q-Ton from Mitsubishi Heavy Industries.

The first Eco Cute CO2 hot water heat pumps were introduced to the Japanese market in the early 2000s, with Panasonic launching their first CO2 water heater in 2001, and Sanden launching their CO2 heat pump water system in 2006. Since then the technology has become an established and mainstream CO2 transcritical technology throughout Japan.

Solar-hybrid Eco Cute unit for residential use developed by Denso

Residential hot water consumption accounts for one third of Japan’s total hot water consumption. In order to provide a solution to reduce the impact on Japan’s energy supply, CO2 was selected as the refrigerant for use in a heat pump on the basis of calculated Life Cycle Climate Performance (LCCP), explained Naruhide Kimura, Manager of the Climate, Cooling and Heating Engineering Division 2 at Denso Corporation.

In addition to the company’s range of CO2 heat pump units that cover a wide range of household sizes and regions, with a capacity range from 4.5kW to 7.0kW, and a multi-functional model with combined floor heating, together with Sharp, Denso has developed a solar hybrid model. It features:
  • Integrated controller for PV system and Eco Cute
  • “Solar power assist” function that enables operation of Eco Cute with stored energy prior to solar power generation in the morning
  • “Summer mode” function allows for day time savings without a concern of running out of hot water

Another solar heat collector hybrid model with an Annual Performance Factor of 5.0, has been available since 2010, and is a result of Denso’s cooperation with Yazaki.

Mayekawa’s ‘unimo’ achieves 62% CO2 emissions reduction

Fujio Komatsu, Chief Engineer at Mayekawa Manufacturing’s Energy Department, presented Mayekawa’s Eco Cute ‘unimo’. The air and water source CO2 heat pump suitable for industrial and commercial installations in hospitals, hotels, sport and other facilities, can achieve a 62% reduction in CO2 emissions compared to conventional hot water boilers. Designed to provide constant supply of hot water, the output temperatures reach up to 90˚C.

Komatsu’s presentation also highlighted Mayekawa’s CO2 hot air heat pump, the ‘Eco Sirocco’, which can achieve close to a 50% emissions reduction compared to conventional systems. Suitable for material drying and heating, paint drying and similar applications, the heat pump provides a high level of safety and avoids the risk of possible damage due to combustion.

Watch our exclusive interview with Kuniaki Kawamura at ATMOsphere Asia 2014 

MHI’s Q-Ton with two-stage CO2 compressor maintains 30kW capacity in temperatures as low as -7°C

Hiroshi Takigawa, Sales Manager at Mistubishi Heavy Industries (MHI) Air Conditioning & Refrigeration System Solutions Division, introduced the company’s new CO2 heat pump, the Q-Ton. With a rated heating capacity of 30kW, maintained in ambient air temperatures as low as -7°C, the air source heat pump is probably the first to use a two-stage CO2 compressor. The scroll and rotary compressor was developed to avoid the significant reduction in heating capacity that occurs with a drop in ambient temperature to below 7°C for CO2 heat pumps. The average measured COP of the heat pump is measured at 3.04.

Field-testing in severe winter conditions in Hokkaido with temperatures as low as -20°C proved the performance of the Q-Ton, while reducing energy costs to 43-54% compared to conventional boilers. Takigawa pointed out that in intermediary and summer seasons heat pump’s performance improves, further bringing the energy costs down. As a result, annual running costs can be cut by 61% with an overall 29% CO2 emissions reduction compared to a conventional boiler.

Examples of Q-Ton installations can be found in the Japanese hot spring inn in Matsumoto and Kanazawa, where the Q-Ton was combined with the existing boiler and tank system and used to supply hot water. Other installations can be found in schools and food factories that require large amounts of hot water for cleaning.

Over 2,000 Eco Cute units sold by Nihon Itomic

Nihon Itomic first introduced an industrial Eco Cute in 2002 and at the end of 2013 more than 2,000 had been sold domestically and internationally, according to Itomic’s Manging Director, Kazuyuki Ochiai. With over ten years experience in the heat pump market, Nihon Itomic has developed unique expertise, enabling them to optimise the operation of their Eco Cute line up:
  • Small sized Eco cute with a Panasonic compressor (9kW/12kW)
  • Medium sized Eco Cute with a Dorin compressor (26kW/30kW)
  • Large Eco Cute with an inverter and a Bitzer compressor (50/80kW)

“CO2 has proven to be highly efficient, low GWP and energy saving,” noted Ochiai. He outlined several examples of Itomic’s Eco Cute installations including a Taiwanese leather-processing factory, where the heat pump ensures a constant supply of high temperature hot water (90°C) with a stable COP whilst reducing the operating costs of the steam boilers. The payback of such an installation is estimated to be about 2-3 years. Other installations can be found in Northern Japanese nursing home, where the storage tanks have been designed to withstand the harsh winter conditions.

Swedish CO2 transcritical heat pump project achieves €1.1 million in annual savings

Alfa Laval’s Rolf Christensen also presented a CO2 transcritical heat pump project in Lund, project inspired by the success of the Japanese Eco Cute heat pump, using Alfa Laval heat exchangers. To provide domestic hot water and heating for 24 apartment buildings with more the 400 apartments two different capacity heat pump units were developed: 54 and 68 kW.

The system features two storage tanks, a high temperature hot water tank (65°C) that also provides hot water for the radiators, and a low temperature water tank (38°C), used to cool down the CO2 condensate. By combining hot tap water and radiator hot water, it is possible to lower the return temperature from the radiators, helping to reduce energy consumption. The heat recovery unit is located on the roof, and takes in all the air from the apartments in a common exhaust duct.

According to Christensen the total annual energy savings for this project are about €1.1 million, and the pay back period is expected to be around 5 years.


By Klara Skačanová

Feb 12, 2014, 17:50

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