DK Group Improving efficiency by retrofitting of an existing vessel with a ACS/SMBG air lubrication system.

DK Group Marine Innovators at a glance

● Established in 2000, DK Group develops and markets fuel saving technologies to the global shipping industry

● DK Group has developed a unique and patented technology for the commercial shipping industry, the Air Cavity System Super Micro Bubble Generator ACS/SMBG

● Numerous tank tests support bunker consumption reduction of 5% to 10% from applying the ACS/SMBG technology on different vessel types

● Tests are carried out together with leading market participants and potential customers

● Savings translate directly into financial benefits as well as a cleaner environment from reduced CO2 emission and other greenhouse gasses

Introducing DK Group

Two methods of reducing frictional resistance by air lubrication, both DK Group patent● Super Micro Bubble Generator ACS-

SMBG● Air bubbles inside the boundary layer of

the vessel.● Expected efficiency improvement 5-10%

Air lubrication - ACS/SMBG

● Air Cavity System (ACS)● Long cavities in the bottom for reducing

the wetted surface of the vessel.● Expected efficiency improvement 5-15%

ACS Demonstrator

ACS Demonstrator the first vessel with ACS

ACS trials

● Build in 1975 at Sietas Schiffswerft, B.No. 697● Converted in 2008 with ACS at Gryfia Repair yard● 2800 DWT Mini Bulker ● Length 81.0m and Breadth 13.40 m● Draft 5.80 m /speed 12 kn

Full scale trials of the vesselPurpose:

● Demonstration of the concept● Confidence of scaling method

for the model tests● Making test at a high

Reinoldsnumber.● Real life test of the Automation

system for the cavities.● ACS Demonstrator is a model

for VLCC.

ACS trials - results

Results of full scale tests of ACS Demonstrator

● The measured savings from the full scale trials confirms results from model tests.

● The effect from the ACS is scalable from model to ships.

● The cavities are behaving more stable on the ship than on the model.

● The automation system which controls the cavities are acting as planed.

● ACS Demonstrator can sail with the ACS system without any limitation.

● The cavities produce super micro bobbles

ACS trials

Automation of the Air Cavity System● The ACS system is a part

of the vessel and should not increase the complexity in the vessels operation

● Development of suitable sensors

● Development of automation strategy

● Reliability of the automation system.

Drag reduction by Kelvin-Helmholtz Instability

Super Micro Bubble Generator

Super Micro Bubbles generated by the cavities

Stationary air above fast flowing water leads to Kelvin-Helmholtz instability, resulting in microscopic bubbles trapped in and carried on by fast flowing water.

Series of tests made at different institutes have proven that small bubbles inside the boundary layer reduces frictional resistance, super micro bobbles (10-40µm) are superior to larger bubbles (0.5-4mm).

Surface tension of water makes micro bubbles smaller and smaller resulting very high inner pressure.

Micro bubbles float in water and have very slow rise rate

Super Micro Bubbles in water

Billions of Micro Bubbles are generated and filling the water tank quickly, resulting in milky water.

Super Micro Bubble Generator

Cavity geometry

Super Micro Bubble Generator ACS-SMBG Cavity

Typical geometry of the cavity for producing Super Micro Bubbles

Size and positing of the cavities are adjusted for each vessel type

Number of cavities varies from 4 – 12Length ranging from 5m to 10m and the Breath 1-2m

Super Micro Bubble Generator ACS-SMBG

Typical installation

Other efficiency opportunities● More efficient propeller (Kappel or NBS)● Twisted Rudder● Wake equalising ducts ● Hull Cleaning, algae growing on the hull

increases ship resistance. Hull coating● Grids at bow thruster openings ● Autopilot adjustment, minimizing rudder

movements (self tuning, adaptive autopilot)● Cooling water pumps, speed control.

Optimizing flow according to actual needs. Both on salt water side and fresh water.

● Ventilators speed control.● Voyage planning● Scrubber● Other efficiency opportunities● By combining the above technologies a

efficiency gain of 20-30% can be expected.

Efficiency by DK Group

Fine tuning of the SMBG system:Test in Cavitation tank

Test with ACS Demonstrator

Preparation of installing SMBG on Aframax:Feasibility Study

Design of the SMBG system for the vessel

Approval

Selection of the yard and contract

Yard planning and purchase

Conversion of the vessel and tests

Timeline for the 1st installation of the ACS-SMBG system

2 months

1 2 3 4 75 6

2 months

1 month

1 month

1 month

2 months

Timeline