- Author: Nikolaos Matthaios Kakalis
- Keywords: Maritime, Maritime
LNGreen investigated the improvement of efficiency and performance of LNG carriers by considering actual operational conditions and optimisation in terms of hydrodynamics, machinery and system configuration. These developments were based on DNV GL’s integrated systems engineering approach COSSMOS, state-of-the-art computational fluid dynamics calculations (CFD), and a containment system design, tailored to a specific operational profile and anticipated trades. Martin Davies, the Project Manager at DNV GL stated that “using enabling computer tools we managed to develop a vessel which is approximately 8% more energy efficient and has increased its cargo volume capacity by 5%. The design is future compliant with new IGC code, Panama requirements as well as significant advances in a range of features, including the speed-range flexibility, hull form and boil-off rate”.
The total efficiency was assessed using an integrated systems approach. LNG carrier machinery systems are highly complex featuring tightly integrated sub-systems and components, like the BOG compression trains, gas management system, reliquefaction (if any), propulsion and/or generating engines, exhaust gas economisers and boilers. The primary fuel, i.e. boil-off gas, has variable properties depending on LNG cargo type and in-voyage boil-off rate conditions. In addition, the ships usually operate on a number of trading routes. Their operating profiles vary in terms of speed, propulsion, electrical and heat demand. The above features require a rigorous model-based approach, using DNV GL COSSMOS, to assess the integrated machinery system under realistic operating conditions as experienced by GasLog.
HHI and DNV GL carried out the hydrodynamic performance evaluation by comparing CFD simulations. Different CFD codes were applied for the comparison of resistance and self-propulsion performance but different scale effects were also considered. In addition, added resistance caused by wind and waves was investigated in order to ensure that the required power is sufficient for operation in the targeted environmental conditions.
Cargo containment optimisation was investigated by GTT and HHI. The tank shape, necessary reinforcements and boil off rate calculations, were examined to develop alternative cargo tank designs that could yield additional cargo capacity. With a starting design point of 174,000m3 cargo capacity, cargo tank optimisation by GTT and HHI allowed for a cargo capacity increase to 182,800m3, while maintaining the same main dimensions (length overall, breadth, draft) and taking into consideration newly introduced regulations and compatibility restrictions.
Nikolaos Kakalis, Manager of DNV GL Research & Development in Greece and responsible for COSSMOS development commented that “fusing unique competencies of key experts from across the industry, like HHI, GTT, and GasLog, with advanced tools like the COSSMOS machinery systems simulation and optimisation computer platform as well as state-of-the-art hull optimisation software, we bring innovation in practice that can generate tangible added value. As LNGreen utilizes existing technology it is important to stress that this concept design could be ordered today”.
About DNV GL
Driven by its purpose of safeguarding life, property and the environment, DNV GL enables organisations to advance the safety and sustainability of their business. We provide classification and technical assurance services along with software and independent expert advisory services to the maritime, oil & gas and energy industries. We also provide certification services to customers across a wide range of industries. Operating in more than 100 countries, our 16,000 professionals are dedicated to helping our customers make the world safer, smarter and greener.
GTT (Gaztransport & Technigaz) is the world leader in cryogenic membrane containment systems used for the transport and the storage of LNG (Liquefied Natural Gas). For over 50 years, GTT has offered to its customers technologies which allow them to optimize storage space and reduce the construction and operation costs of ships or tanks equipped with these systems. GTT operates in several sectors: LNGCs (Liquefied Natural Gas Carriers) and VLECs (Very Large Ethane Carriers), Multi-gas carriers, FLNGs (Floating Liquefied Natural Gas units), FSRUs (Floating Storage and Regasification units), onshore storage tanks and the use of LNG as a fuel.
GTT is listed on Euronext Paris, Compartment A (ISIN FR0011726835 Euronext Paris: GTT) and is included in SBF 120 and MSCI Small Cap indices.
Hyundai Heavy Industries, Co. Ltd. the world’s biggest shipbuilder and a leading integrated heavy industry company, is building a global network in the heavy industries arena that includes businesses in shipbuilding, offshore and engineering, industrial plant and engineering, engine and machinery, electro electric systems, construction equipment, and green energy. As the world’s leading shipyard since the 1980s, HHI can deliver about 80 ships or 7 million GT annually from 10 dry docks. HHI becomes the first shipbuilder in the world to reach 100 million GT in ship production in March 2012 and to deliver its 2,000th ship in May 2015. HHI has been playing a leading role in developing new ship designs, advancing shipbuilding technology, and enhancing ship performance.
GasLog is an international owner, operator and manager of LNG carriers, providing support to international energy companies as part of their LNG logistics chain. GasLog’s owned fleet consists of nineteen two wholly-owned LNG carriers, including eleven ships on the water and eight ships to be delivered. GasLog Partners LP a master limited partnership formed by GasLog owns a further eight LNG carriers. Through the wholly owned subsidiary GasLog LNG Services operate twenty-two LNG carriers, which include owned ships as well as three ships owned or leased by BG Group, and one additional LNG carrier in which GasLog has a 25% interest.