News from our Sponsor Solvay Fluor:

NOCOLOK® goes Smartphone!

NOCOLOK is a name synonymous with innovative products and solutions. No surprise then that Solvay Fluor is the first to provide a smartphone App for aluminium brazing. Comprehensive knowledge in a pocket-size format for all users in the aluminium industry is coming shortly. An absolute must-have for all smartphone users. The NOCOLOK App will be available for iOS and Android, providing a wealth of useful information all about brazing with NOCOLOK.

The App features a full listing of NOCOLOK products sorted according to application, comprehensive key data and the new GHS classifications. All NOCOLOK packaging units are clearly indicated with sizes and weights. The App comes complete with handy items, like a calculator for NOCOLOK quantities in various slurry concentrations and a tool to calculate heat exchanger surface areas with details of the required quantity of NOCOLOK in kg. And for those seeking more specifics, the NOCOLOK Encyclopedia presents information about aluminium brazing technology.

The NOCOLOK App is currently undergoing beta testing and will be presented soon.

We will inform you as soon as the App is available as a free download.

Calculator for Fluxload

A special program can calculate the surface area of aluminium heat exchangers.

7 replies
  1. shyam Gopal
    shyam Gopal says:

    Wonderful application will be a great tool for the brazing industry.

    We would like to have information on the benefits/ brazing adhesion and suitable application choice for fins used in tractors and agricultural applications.
    Dust and application waste are a major issue and hence manufacturers are providing a U shape/rectangle shaped fins in place of V shaped fins in wavy design for the above applications.
    Are there any major advantages of using the U /rectangular shape fin in place of the V shaped fins other than the less choking of the core matrix in the rectangle fin design..
    Thank you

    Reply
  2. Dr. Leszek Orman
    Dr. Leszek Orman says:

    Yes, one advantage of the square fins is their lower fouling in dusty or poluted (i.e. full of small debris) working environment. Other aspects are: lower pressure drop with the same performance, and higher resistance to fin crash.
    Therefore, the square fins have been used predominantly in heavy duty and agricultural applications. For the most severe cases – like fork trucks that would operate in paper mills – this is the fin design of choice.

    There are however some shortcomings: the square fins have less elasticity than the standard V shape fins. This can potentially increase fin drop – or even fall-out; and it is going to be more difficult to obtain a perfect square shape of the part after brazing. It is thus recommended to use elastic frames (jigs) and also it is very important to use good quality fin making machine which would produce fins with minimal variations in height.

    Reply
  3. Manos Eliades
    Manos Eliades says:

    V fins have more tolerance for more compression variation and spring back because the contact geometry at the tube is a radius, The larger the radius the more spring back. The tip radius also provides an area where the material can exhibit deformation , and yield, before effecting or collapsing the straight leg of the fin. In a SW fin, the contact are is a flat and the radius is half contact. This means that the compressive tolerance is much less than that of a v fin. It is very common that during over compression you can buckle the straight leg of the fin. It is more common to use braze fixturing that incorporate some means to accommodate the loss of elastic deformation in the core like ss banding straps, or a fixtures with springs build into them.

    Because there is less tolerance for compression variation in the SW core, the fin can enter plastic deformation sooner compared to V fins. It is very common for a braze line that process through a hot-cold-hot cycle to exhibit more fin drop than a cold-hot cycle. In some cases the thermo cycle alone can create enough plastic deformation that you will lose compression if you use a static design fixture. To address the fin drop issue, a solution is to use anti-drop feature in the design of the fin in addition to above mentioned braze fixturing methods.

    Reply
  4. Ahsan Riaz
    Ahsan Riaz says:

    I think one more advantage of square wave fin is its higher thermal performance due to extra ordinary contact area with tube, but on the other hand the heat dissipating area will be reduced. So, still don’t know about the net benefit.

    Reply
  5. Dr. Leszek Orman
    Dr. Leszek Orman says:

    Gents,
    One of the biggest advantage of the square fins over the standard ones is their lower pressure drop which I think is particular important when we have an assembly of heat exchangers in front of the car. Also there is lesser tendency for clogging with debris which plays an important positive role.

    The point about the bigger contact area, in my opinion, is not valid, because heat flows first through the contact area and then through very thin sheet of the fin, so it is the thickness of the fin which limits the flux of heat from the tube to the fin not the contact area. As a rule of thumb it is required the contact to be minimum 2 times longer then the fin sheet thickness. Generally this condition is easily achieved in standard fin design. Therefore I would say that due to lower turbulence and indeed slightly smaller “active” surface of the square fin the heat dissipation might be lower; however after a certain time of service it can be counterbalanced by less clogging.
    I believe that the aspect of clogging is one of the major reasons why this type of fins is preferred for heavy duty machinery.

    Another important aspect is elasticity of the fins, which is required for assembling and for prevention of fin drop. Elasticity of the square fins is very low therefore they are not really suitable for stiff tubes (extruded profiles). In case of welded tubes which are always made in an oval shape later on squeezed into rectangle, the square fins are OK because the tubes provide the required elasticity.
    I imagine that even with B-type tube square fins would be possible to assemble, but I cannot recall such design.

    Reply
  6. Manos Eliades
    Manos Eliades says:

    Heat transfer is directly proportional to the cross sectional area of the conductive area. The SQ wave is not any different at the cross section of the fin. The thickness of the fin will have more impact. The additional surface area of the flat of the Sq wave fin is of no value. Square wave was developed in the late 30’s and early 40’s’s to resist clogging. The company was Laegerer & Reich in Bernhausen Germany. The parallel legs offered a uniform channel for debris to pass through. You find this used in heavy duty applications in inducsries like agriculture and paper mills. Over the years it found its way into assemblies where high fin crush resistance was necessary, like plate fin evaporators.

    U=kA/Delat x’ (U = conductance, A= cross secdtional area, k= thermal conductivity, Delta x’ = distance between ends)
    U= W(m^2 K)

    Reply

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