Technologies

Waste heat recovery

Maximises the conversion of fuel into useful power by converting waste heat from the engine process, which is low-temperature heat into useful electricity

Waste heat recovery in maritime applications

Waste heat recovery systems (WHRS) have the potential to reduce fuel consumption and emissions by converting waste heat from the ship’s main engines into usable electric power for the ship’s electrical demand, reducing the load on the ship’s generators. There are several technical solutions for the utilisation of waste heat, however in this report we will focus on the organic Rankine cycle (ORC) system.

Organic Rankine Cycle systems

An ORC system operates as a Rankine cycle using an organic compound as the working fluid, making it possible to recover waste heat in the lower temperature ranges, in a sustainable manner. Today, ORC technologies are mainly used for the conversion of thermal power from industrial and geothermal sources. Developing ORC technology, cost-efficient production and the availability of environmentally friendly and effective working fluids makes the use of ORC systems a viable option for the maritime market, at a crucial time for the industry regarding their need to minimize environmental impact and find a carbon neutral way forward. Today, there are limited uses for the low-temperature jacket water heat from the main engine. In some cases, it is discharged into the ocean as waste heat. At the same time, diesel generators are used to provide electricity for the main electrical grid on board the vessel. Instead, an ORC-system can be used to convert the low-temperature heat into electricity to be used on board, as illustrated in below.

Simple layout of an ORC system
Simple layout of an ORC system

Deliverables

Engine operation and industrial processes produce large amounts of waste heat energy, which can be costly in certain environments. Waste-Heat Recovery technology in CHEK project converts low-temperature waste heat into clean, carbon-free electricity that can be used on site, distributed or sold back to the grid. The purpose of this work is to document the tests of relevant operating points, such as available thermal heat, temperatures and flows of hot and cold water, for a Waste-Heat Recovery system in a full- scale lab prototype of such a system. These tests were made to ensure the veracity of the Digital Organic Rankine Cycle (ORC) model of the Waste-Heat Recovery system of the CHECK vessels for the identified operating points and to understand the implications of the operating points on component degradation and performance. The tests were aiming to measure the performance at the fixed flow conditions of the Digital ORC model, i.e. at hot side flow and cold side flow. The Digital ORC model provides a good agreement with real product performance. Further, the first version of ORC prototype is suitable for marine historical operational conditions. However, based on experience heat exchanger fouling and rotating components wear have been noticed in real-life tests. These component degradations can be minimized by regular maintenance and an avoidance of unnecessary starts and stops of the ORC prototype. When the operational conditions for the future-proof vessel are set, continued testing, development and optimization of the Organic Rankine Cycle prototype will be planned. Continued testing is planned to investigate system performance where the temperature is fixed and the hot and cold side flow varies. Further development and testing will be documented and reported in the Waste-Heat Recovery testing work.

Engine operation produces large amounts of low-temperature waste heat, which can be converted into electricity with the help of Organic Rankine Cycle technology. The purpose of this work is to investigate the feasibility of implementing a solution based upon ORC-technology as a waste heat recovery solution in the two selected future-proof CHECK-vessels, Kamsarmax bulker and Meraviglia cruise vessel. This is done by evaluating the performance of a modelled ORC-product under operating points identified within the project in the digital model of the respective CHEK-vessel. Furthermore, the tests of relevant operating points, such as available thermal heat, temperatures and flows of hot and cold water, for a Waste-Heat Recovery system in a full- scale lab prototype of such a system are documented. These tests were made to ensure the veracity of the Digital Organic Rankine Cycle (ORC) model of the Waste-Heat Recovery system of the CHEK vessels for the identified operating points and to understand the implications of the operating points on component degradation and performance. The tests were aiming to measure the performance at the fixed flow conditions of the Digital ORC model, i.e. at hot side flow and cold side flow. The Digital ORC model provides a good agreement with real product performance. Further, the first version of ORC prototype is suitable for marine historical operational conditions. When the operational conditions for the future-proof vessel are set, continued testing, development and optimization of the Organic Rankine Cycle prototype will be planned. Continued testing is planned to investigate system performance where the temperature is fixed and the hot and cold side flow varies. Further development and testing will be documented and reported in the Waste-Heat Recovery testing work.

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