MHI-MME introduces ORC-based waste heat recovery system

The solution, which is expected to be particularly suitable for sulphur-free fuel burning engines, has been developed for use on a wide range of vessel types. It consists of a lineup of three models that cover rated outputs of between 200kW and 700kW.

In addition to offering high thermal efficiency, the fully-sealed solution is oil-free and maintenance-free. It was developed by combining MHI-MME’s marine waste heat recovery system – which includes a waste gas economiser, steam turbine, and a gas turbine – with the superior centrifugal chilling technology possessed by MHI Group company Mitsubishi Heavy Industries Thermal Systems, Ltd.

MHI-MME previously confirmed to The Motorship that it was developing a solution based on a hybrid Mitsubishi steam turbine and advanced organic Rankine cycle hybrid system targeted at LNG-fuelled vessels in an article in November 2020.

At the time, the company noted that the recovery of waste heat from LNG-fuelled engine waste gases did not create the same issues around sulphuric acid formation compared with higher sulphur fuels. As a result, the temperature range of recovered heat can be extended and exploited with greater efficiency by the two sub-systems in the hybrid configuration. The steam Rankine cycle can be optimised to boost efficiency at high engine loads, and the organic Rankine cycle system could be optimised to boost efficiency at lower loads. 

MHI-MME concluded by noting that the future introduction of carbon-free fuels, such as hydrogen and ammonia, as well as carbon-neutral fuels, including biomethane and bio-methanol, into the fuel mix would create additional demand for high efficiency and energy-saving in engines powered by such fuels.