Mayekawa develops high temperature hydrocarbon steam heat pump

By Jan Dusek, Nov 08, 2013, 10:54 3 minute reading

At the 2013 JSRAE Annual Conference in Japan, Mayekawa presented a novel hydrocarbon (HC) refrigerant heat pump capable of supplying steam at 150°C. Testing has verified prototype compressor performance and confirmed a system COP of 3. The developed system is a suitable alternative to fossil-fuel-fired boilers in the food processing industry, and would reduce emissions by more than 550 tonnes of CO2eq per year in comparison to a fossil fuel boiler with 50% efficiency.

More than 580 participants attended the 2013 JSRAE Annual Conference that took place in Tokyo, 10-12 September. Organised by the Japan Society of Refrigerating and Air Conditioning Engineers, the event had a total of 189 technical presentations divided into specialised sessions dedicated to basic components, complete systems or fundamentals of refrigeration and air-conditioning. A number of presentations centred around natural working fluids CO2, ammonia, hydrocarbons and water. Hideki Fuchikami from Mayekawa’s R&D Center introduced the company’s latest research on a high temperature heat pump (HP) using hydrocarbon refrigerant.

Efficient supply of 150°C steam with hydrocarbon HP

Industrial processes such as food processing have a high demand for steam in the temperature range 100 - 150°C. Traditionally, fossil fuel fired boilers have been used to supply the heating needs of the industrial sector.

To provide a more efficient and environmentally friendly solution, since 2009 researchers at Mayekawa have been developing a heat pump using hydrocarbon as the refrigerant to generate high temperature steam above 150°C, as and alternative to fossil fuel using boilers.

According to Hideki Fuchikami, 39% of boiler use in the industrial sector is associated with temperatures under 100°C and 61% with temperatures above 100°C. While the sub 100°C heat demand can be efficiently provided by an industrial Eco Cute HP, new research was required to develop a natural refrigerant HP for high temperatures which could help to reduce CO2 emissions and energy consumption in the industry.

Achieved and verified goal of COP 3 for system with 245kW heat capacity

The aim of the research project was to develop a heat pump providing more than 150°C of heat with a COP of 3. Natural refrigerant normal pentane (n-pentane) with a GWP 3 was chosen as the most suitable refrigerant. PAG (Polyalkylene Glycol) lubricating oil was tested and selected for its thermal stability and for having a sufficient viscosity at up to 180°C. High operating temperatures required the development and design of a new compressor.

The newly designed HP system with a heating capacity of 245kW underwent a series of tests to verify its performance. Tests were carried out at condensing temperatures of Tc = 150 - 160°C and evaporation temperatures of Te = 70 - 80°C and a COP of 3 was confirmed. A high COP is expected by adjusting the system for optimal operation.

Next steps toward commercialisation

The prototype system performance was verified with promising results. The commercialisation is however still a few years away. Utilisation of n-pentan as a refrigerant will require changes to current regulation. The PAG lubricant, prototype compressor and its newly designed parts, will need to be tested and evaluated for long term durability and performance. According to Fuchikami’s presentation, with testing, evaluation and optimisation of the system in the next 3 years, the first commercial high temperature steam HP could be made commercially available around 2016. After 2020, a HP system with COP of 4 will be mass produced.

According to the presentation, if commercialised one such HP unit would lead to an emissions reduction of 560 t-CO2eq (1,468 t-CO2eq for COP of 4) per year compared to traditional fossil fuel boiler with 50% efficiency.

This research was sponsored by New Energy and Industrial Technology Development Organization (NEDO).


By Jan Dusek

Nov 08, 2013, 10:54

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