DNV GL Partners in New LPG and LNG Designs
Consolidated Marine Management, Hyundai Heavy Industries, Wärtsilä Oil & Gas and DNV GL have developed a new LPG-fuelled carrier design – LPGreen.
Compared to the high-quality, 2016 reference vessel, the new design offers an overall improvement of six to nine percent in energy efficiency, depending on machinery configuration and fuel used. A redesign of the tank allows for a filling limit of 99 percent – a one percent increase in overall carrying capacity. Loading duration has been decreased by 30 percent, while the newly designed cargo handling system concept results in a five percent reduction in energy demand.
LPGreen has also demonstrated the technical feasibility of a LPG-fuelled propulsion concept, which, depending on fuel prices and the development of a commercial and chartering framework, could result in a cut of up to 30 percent in fuel expenses.
To realize these gains, the development partners used advanced computer analysis tools. Hull form optimization both in calm water and waves was conducted using HHI’s and DNV GL’s CFD hydrodynamic optimization codes. The overall concept system evaluation and optimization was conducted using DNV GL’s COSSMOS modelling framework, which allowed for an integrated analytical approach to the evaluation of all machinery technology options and design improvements considered.
New LNG Carrier Design
DNV GL has also released a design of an innovative, efficient LNG carrier based on existing technology as a result of a development project with DSME. The project focused on delivering a design which an owner can take straight to the yard and is ready for upcoming market trends and incoming regulations, with an optimal size, hull form and machinery and electrical systems.
“We predict that in the years to come we will see the rise of post-Panamax LNG carrier designs which are dimensioned to fit of the new Panama Canal. Capacities of over 175,000 m3 are feasible,” says Johan Petter Tutturen, DNV GL – Maritime Business Director Gas Carriers.
An important aspect of the design is a shift towards lower, more energy-efficient transit speeds. The hull and propulsion system have been optimized for three different operating profiles on a standard transpacific route (19.5, 16 and 12 knots). Calm water optimization resulted in gains of six, two and five percent over the reference design at each of the three operating profiles. The optimization calculations were performed using the DNV GL hydrodynamic analysis software Wasim as well as statistics and Reynolds-averaged Navier-Stokes (RANS) simulations for determining wave resistance.
The design uses direct-coupled, two-stroke dual-fuel (DF) main engines and DF auxiliary engines, with LNG as the primary fuel. A combined gas turbine, electric and steam (COGES) propulsion system was chosen for the optimized machinery.
For the portion of the boil-off gas used as LNG fuel a “High Manganese Steel Cargo Tank Independent Type B” was chosen and underwent closed mock-up testing using liquid nitrogen (LN2). This was selected for its excellent tensile properties, high performance and product capacity at low cost, and allows flexible tank shapes while being slosh-free without imposing any filling limitations.
The design also incorporates DSME’s SloT (Ship Internet of Things) technology and their wireless computer network and integration system Smartship 4.0. The entire onboard computer environment underwent thorough testing to improve its cybersecurity.