SLIPS Mechanisms and Design Principles for Marine Biofouling Prevention
Abstract
We propose to investigate the application of metal-based SLIPS to surfaces with awide range of temperature and geometry, and flow c"onditions. We will study thefundamental science of biofouling and its effect on the heat transfer for developing efficiencyenhancedmarine heat exchangers. We believe that our bio-inspired breakthrough technologyinspired by pitcher plant-inspired slippery surfaces will offer dramatic efficiency improvement ofmarine heat exchange systems (Fig. 21) The main objectives of the proposed effort a"re (i) to testthe effect of surface temperature, velocity of water stream, and surface geometry onmicrobiofouling, (ii) to model a""nd characterize heat transfer performance of SLIPS and othercontrols based on the experimental data, (iii) to investigate the longe""vity of SLIPS in thedifferent surface temperature and flow conditions, by checking two aspects ~ mechanicaldurability of surface t""exture and thickness of lubricant, and iv) to estimate energy and cost savingpotential for marine heat exchangers. To date, we have" fabricated small lab-scale SLIPS-coatedflat and curved stainless steel surfaces and demonstrated biofouling prevention performance"[5],commensurate with a starting level of proof of potential. Other metallic surfaces will be tested ina model marine organism tes"t setup systematically as explained below.3.3.1 Effect of surface temperature and velocity of water flow onmicrofoulingWe will first examine the effect of surface temperature and water flow on themicrofouling and build a characteristic biofouling curve. We will identify the critical surface20temperatures above which meaningful changes of microfouling pattern are observed for a certainamount of time. We will also check the effect of water flow on growth and release ofmicrofouling using flat surfaces at different angles of attack. We expect that the change oflubricant viscosity and micro-organism transport mechanism depending on the surface temperaturecould lead to a different result of microfouling in terms of initial or short term microfouling.3.3.2 Effect of surface geom"etry onmicrofoulingBased on the results obtained from the flat surface experiments, we will further study theeffect of the widely-""used curved geometry ~ pipes. First, we will investigate the effect of localflow characteristics (e.g., stagnation point, vortex) o""f a single pipe. Then, we will also examinethe effect of the diameter of the pipe and flow conditions that can be captured by the R""eynoldsnumber at a constant surface temperature. Further, we will study two pipes or even multi-pipestructures that can model the"" bundle of pipes used in the design of marine heat exchangers (e.g.,a box cooler). We anticipate that design parameters can be not" only the pipe diameter but also thespacing between the neighboring pipes and arrangement of pipes relative to the direction ofwater flow. We will also check the temporal change of flow characteristics due to the change ofeffective spacing by the growth of bio-"organisms, which can provide a predictive model ofblockage of the cooling water flow.3.3.3 Modeling and characterization of heat t"ransferperformanceWe will first develop a simple and systematic model that can predict the thermal resistanceof the bio-fouling la"yers at different fouling stages (e.g., biofilm formation, microfouling,macrofouling). We will also quantitatively characterize the"" overall heat transfer performanceof our metal-based SLIPS (Al, Ti, Stainless Steel) by measuring the temperature of a constantvol""ume of water that is under either natural or forced convection, and compare the resultswith conventional metallicsurfaces.3.3.4 Lo"ngevity of metal-based SLIPS underwaterThe change of mechanical durability and lubricant thickness in time under differentsurface temperatures and flow conditions is also a fundamentally and practically important issuein this research project. We will visualize the surface texture and test the change of slipperypropert
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 29, 2017
- Source ID
- N000141712913
Entities
People
- Joanna Aizenberg
Organizations
- Office of Naval Research
- President and Fellows of Harvard College
- United States Navy