|Bubbles under the vessel bottom of the new bulk carrier with MALS. Click to enlarge.|
Mitsubishi Heavy Industries, Ltd. (MHI) has designed a new bulk carrier equipped with the proprietary Mitsubishi Air Lubrication System (MALS), which reduces frictional resistance between the vessel hull and seawater using air bubbles produced at the vessel bottom, along with high-efficiency hull form and enhanced propulsion system. The new MALS carriers will enable reductions in CO2 emissions by about 25% compared with conventional averaged bulk carriers.
As the first commercial application of the new design, MHI will provide its conceptual design and green technologies to three grain carriers to be built for Archer Daniels Midland Company (ADM). The three bulk carriers, which mark the first new shipbuilding order placed by ADM, are designed to accommodate new post-Panamax needs.
[“Post-Panamax” class refers to the ships that are unable to travel through the Panama Canal and “new post-Panamax” refers to the size limit of ships that will be able to travel through the Panama Canal after its planned expansion is completed in 2014: 366m in length overall (LOA), 49m in width and 15.2m in tropical freshwater (TFW) draft. Panamax parameters are 295.0 m in LOA, 32.2 m in width and 12.0 m in draft.]
|MHI researchers first reported work on the use of microbubbles to reduce vessel skin friction in a paper published in the International Journal of Heat and Fluid Flow in 2000.|
|Kodama et al. later demonstrated an energy-saving effect of 5% in an actual ship test using a cement carrier.|
|In April 2010, MHI’s Nagasaki Shipyard & Machinery Works completed the Yamatai, a module carrier belonging to the NYK-Hinode Line, Ltd. The Yamatai was equipped with MALS; the ship achieved an energy-saving effect of more than 10% at sea trials prior to delivery.|
|In October 2010, MHI announced that it had completed the conceptual design of a new Panamax size container vessel equipped with the MALS system, along with a high-efficiency ship hull design and propulsion system.|
|Projected reductions of CO2 with the design of this type of vessel was 35% compared with container carriers of conventional design.|
Sumitomo Corporation of Japan has received the order for the ship construction from ADM, and Oshima Shipbuilding Co., Ltd. of Nagasaki was selected to build the ships. ADM’s ships will be the first case in which MHI provides the system to another shipbuilder.
Besides the MALS, which uses blowers to create air bubbles under the vessel bottom, the three grain carriers will also feature a newly designed bow shape that will reduce wave-making resistances. For propulsion, the ship adopts a system to effectively convert the main engine power into propulsion power by positioning fins forward of the propellers and placing particular grooves in the propeller boss cap.
The three grain carriers will be 95,000 deadweight tonnage (DWT) vessels: 237 meters (m) in length, 40m in width, and 12.5m in designed draught. The shallow draught of the ships facilitates the pursuit of energy savings and CO2 emission reduction efficiency by MALS. Oshima Shipbuilding will perform from the basic design work through construction based on the conceptual design and green technologies provided by MHI. Delivery of equipment related to MALS system from MHI is slated for 2014.
The talks to build the three dry bulk carriers began between ADM and MHI. MHI’s Shipbuilding & Ocean Development segment has been implementing a policy to promote engineering business, including technological support to other shipbuilders. Under this policy, the company decided to collaborate for this time with Oshima Shipbuilding, a firm that has earned a solid reputation in bulk carrier design and construction through delivery/order receipt of about 60 post-Panamax class ships. The collaboration has enabled the two companies to provide enhanced cost effectiveness to the customer.
CFD Predictions of Bubbly Flow around an Energy-saving Ship with Mitsubishi Air Lubrication System (MHI Technical Review, Volume 48 Number 1, 2011)
Experimental Study of Air Lubrication Method and Verification of Effects on Actual Hull by Means of Sea Trial (MHI Technical Review, Vol. 47 No. 3, 2010)