Coatings for Drop-wise Condensation. Dr. Kevan Elsby

Transcription

1 Coatings for Drop-wise Condensation Dr. Kevan Elsby

2 Contents 1. Alkemy Coatings 2. Drop-wise Condensation Experiments The University of Birmingham Alkemy Ltd 1. Next Steps 2. Appendix

3 1. Alkemy Coatings

4 1. Alkemy Coatings In collaboration with a number of European suppliers, at Alkemy Ltd we have developed a range of affordable nano-scale coatings. Details have been included in the appendix. For a long time we have understood the very hydrophobic nature of many of our coatings. In collaboration with The University of Birmingham, we started earlier this year to look at the potential benefits of drop-wise condensation using Alkemy coatings. We then constructed our own test rig to test a wider range of coatings under a wider range of conditions.

5 1. Alkemy Coatings

6 Alkemy Gold Coated Aluminium Plate

7 2. Drop-wise Condensation Experiments

8 Birmingham University conducted condensation experiments against a gold-plated test standard. Pressure gauge Gold plated condenser New coated condenser Thermocouple reader Water flow meters Steam generator Dr Raya Al-Dadah The University of Birmingham

9 Gold Plated Alkemy Gold Coated Dr Raya Al-Dadah The University of Birmingham

10 Alkemy Gold performed as well as the gold plated condenser. Dr Raya Al-Dadah The University of Birmingham

11 Enhancement versus pure copper was better at lower degrees of sub-cooling, rising to a factor of over 4 in enhancement of surface heat transfer coefficient. Dr Raya Al-Dadah The University of Birmingham

12 Alkemy Ltd Condensation Heat Transfer Rig To Vacuum Pump Float Valve Vacuum Controller 200 Cold Water Out Condenser In/Out Temperature 20 Temperature Steam Temperature TC TC TC Mains Cold Water In Controller Coated Condenser Volumetric Water Flow Measurement Point Optional Cooling Coil Thermostatically Controlled Hot Plate Water To Drain Return Pump

13 In our second rig we tested a wider range of surfaces under a wider range of conditions including steam temperatures from 35 C to 85 C We identified two of our coatings to be As Good As Gold. - Alkemy Black Gold - Alkemy Gold uncoated new copper

14 uncoated new copper 14

15 Thanks to: 1. The University of Birmingham. Prof. Bott Dr. Raya al Dadah Dr. Ahmed Elsayed 1. Birmingham University Innovation Award. 2. BRDL

16 3. Next Steps

17 Next Steps 1. At Alkemy we want to: Continue our collaboration with The University of Birmingham. Reach out to industrial collaborators to develop applications in dropwise heat transfer for our coatings. 1. We found some surprising results for all surfaces. Condensation heat transfer is limited by the surface renewal of the condensed water and is not affected by the degree of sub-cooling. Whilst this is not a priority for us, we wish to explore this finding / hypothesis from a more academic perspective to enhance our understanding of the benefits of Alkemy coatings for condensation heat transfer. Contact: allenchasteauneuf@alkemy-gold.co.uk

18 4. Appendix

19 Alkemy Coatings In collaboration with a number of European suppliers, Alkemy Ltd has developed a range of affordable nano-scale coatings. Thin (typically 10 microns). Completely dense. Silicate bonds with metals that tend to oxidize or tarnish such as Aluminium. Retain a large degree of elasticity. Thermal expansion coefficients similar to metal. Formulated to be hydrophilic or hydrophobic. Can include actively anti-microbial ingredients to produce coatings that actively kill e-coli and MRSA, for example. Very smooth surfaces to the point of being anti-fingerprint. Provide a complete barrier that prevents corrosion such as saltwater on Aluminium or sulphides on Silver.

20 Alkemy Coatings Coating Metal

21 Alkemy Coatings Alkemy Gold modifies surface topography Smooth, low friction surface inhibits deposition of organic & inorganic material

22 Alkemy Coatings Electron microscopy for uncoated and coated copper surfaces.

23 Alkemy Coatings Coated Heat Exchanger made of aluminium after 18 month exposure without filter; o No Corrosion o No Dirt Adherence o No Blockage of Lamellae.

24 Alkemy Coatings

25 Alkemy Coatings Alkemy Gold coated Nickel-Plated Comparison of heat exchangers after 500h Salt Spray Fog Test

26 Coatings for Drop-wise Condensation Dr. Kevan Elsby