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immersion wort chiller efficiency

Discussion in 'Homebrewing' started by dublthink, Mar 6, 2012.

  1. dublthink

    dublthink Initiate (0) Feb 22, 2012

    having a jet ski freestyle background riding/building skis cooling lines and efficiency has come up a few times in conversations...

    Anyway, I was thinking about wort chillers and getting the largest amount of cooling w/ the most efficiency. My mindset was always that higher pressure and increased flow does not always equate to more cooling, because the water travels too fast to properly exchange the heat therefore the pressure and flow need to be regulated in order to get the most efficiency. I picked up the quote below from a website and it seems to back up my way of thinking, yet I have seen other sites that say more pressure and flow will increase efficiency. What I do now is adjust the cooling till the water that is coming out is the hottest I can get it, which usually a very low flow. Is this the most efficient way to cool or just turn it up and don't sweat it?

    Anyone know the facts on this?

  2. Utawana

    Utawana Aficionado (120) New York Nov 7, 2007

    Faster flow through your chiller results in more water used, so maybe that is less efficient. However the fact remains that the faster you move water through your chiller, the faster you will cool down your wort.
    In other words, you will use more water in the final analysis, but you will get the job done faster.
  3. inchrisin

    inchrisin Savant (425) Indiana Sep 25, 2008

    The heat exchange will not be significant when comparing 3GPM to 15GPM. Will it chill faster with 15GPM? A bit. This will also be quite wasteful. Two bigger factors are chiller size and water temperature in the system.
  4. This thread (as in the past) is going to blow up...and destroy the thermal boundary layer : )
  5. I had this conversation with my son the mechanical engineer and putting cold water through the lines fast cool the wort faster. Efficiency in terms of time which is why you have a wort chiller is faster flow. if you water is coming out warm then you coils are warm in the wort and that is not cooling the wort. I'm making a chiller with a pump that I'll run through a bucket with baggies of ice. More GPM's the better.
  6. Utawana

    Utawana Aficionado (120) New York Nov 7, 2007

    Can't/won't get deep into this - the point has been argued by folks far more fluent in thermodynamics than I - but certainly a drastic difference will be noticed between 3 and 15 gpm. Just measure the temp of the water exiting the chiller. 3 gpm will feel almost like boiling. 15 will feel far cooler. Does this mean that 15 gpm is removing less heat? No. By maintaining a larger temperature gradient between the copper tubing and the wort along the entire length of the immersed coil, the faster flow allows more heat exchange to occur along the entire length of immersed coil. In the 3gph model, the water in the coil rises in temp much faster, and therefore earlier in the coil, making the last part of the chiller far less able to cool wort. In an extreme, the coil becomes so inefficient that you might as well use a shorter length of copper, as the last bit is doing no work for you.
    I'm finding I'm unable to resource the old posts about this - probably because I'm unfamiliar with the new system - but there have been some great discussions about this and every old pro who probably majored in fluid thermodynamics agreed that faster flow equals more heat transfer.
    If you live in an area with low water resource, this can be an issue for sure. Recirculating water from an ice bath reportedly works well.
  7. Faster uses the most water . Maximizes the Delta-T across the heat exchanger. This is the right answer.

    Your car's engine makes more waste heat as you drive faster. The water pump will pump more coolant at higher RPM. The radiator will disapate more heat at faster speeds.
  8. A solution I employ that's probably unsupported by physics. I run the chiller at full bore for the first few minutes until the wort's down to under 110 f. Then cut it way back as the cooling water temp is gets closer to the wort temp for the final degrees of cooling. BTW, I run the chiller water into the garden and bucket for cleanup.
  9. charlesw

    charlesw Savant (410) New York May 14, 2003

    Um. What?

    The quote you have is pretty logical - what's your question? They are trying to balance output and cooling only they're not telling you their criteria for optimality.

    Fact: faster flow => faster cooling
    Fact: faster flow => more water used
  10. leedorham

    leedorham Champion (835) Washington Apr 27, 2006

    Recirculate & reuse your chilling water in the winter. Water your lawn with it in the summer. Go as fast as you like.

    Now, can we get back to the jet skiing?
  11. dublthink

    dublthink Initiate (0) Feb 22, 2012

    ha ha... thanks guys... I guess my thinking on this was wrong. Thanks for all the good info. I have a pump and gonna do the recirc. through ice deal...

    flip a jet skiing anyone???

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