Pintodave
Well-Known Member
I hope this is the right forum - not a "chemical" question, but definitely scientific in nature...
I see a lot of people adding motorized devices to agitate the water in some of their brew vessels, which sounds like a really good idea. But then I started thinking about it and reading about the heat transfer properties of water and thermal equilibrium and all that stuff.
From what I know and can understand about it, as you heat a container of water, the heat will immediately start to flow to the cooler areas. This means even though you may not notice it in the kettle, the water should already be "mixing and flowing" and it will keep doing that as it seeks equilibrium. If you watch a pot of water on the stove, it is more noticable. This should also be further enhanced by placement of the heating element as close to the bottom as possible to the tank, as the heat source is at the lowest possible point.
If this is true (I am no thermal engineer, but these are pretty standard theories), then why bother adding a device to mix the water? Is it to further speed up the mixing? Does it need additional speeding up?
If you are recirculating through a heat exchanger with a HERMS type set up, you shouldnt have to agitate the heat exchanger water either because not only will the water have this natural "mixing" action, once the mash temp comes up, you will also have a coil of hot liquid circulating through the heat exchanger.
In the HLT, if the thermo probe is located close to the point of exit, that should be the area of critical temp you are worried about. Same with the recirc in the HERMS, as long as the temp probe is measuring the temp at the point where the mash water is re-entering the tun, that is the critical location (as I have read and what makes sense).
Again, I am speaking "in theory" - never done an all grain batch nor have I brewed on a rig with digital temp controls (thus why I am building one) so I guess I am looking for feedback from both ends of the spectrum. If you do use a device to mix anything in your brewing, why? If you don't, why not?
Thanks
I see a lot of people adding motorized devices to agitate the water in some of their brew vessels, which sounds like a really good idea. But then I started thinking about it and reading about the heat transfer properties of water and thermal equilibrium and all that stuff.
From what I know and can understand about it, as you heat a container of water, the heat will immediately start to flow to the cooler areas. This means even though you may not notice it in the kettle, the water should already be "mixing and flowing" and it will keep doing that as it seeks equilibrium. If you watch a pot of water on the stove, it is more noticable. This should also be further enhanced by placement of the heating element as close to the bottom as possible to the tank, as the heat source is at the lowest possible point.
If this is true (I am no thermal engineer, but these are pretty standard theories), then why bother adding a device to mix the water? Is it to further speed up the mixing? Does it need additional speeding up?
If you are recirculating through a heat exchanger with a HERMS type set up, you shouldnt have to agitate the heat exchanger water either because not only will the water have this natural "mixing" action, once the mash temp comes up, you will also have a coil of hot liquid circulating through the heat exchanger.
In the HLT, if the thermo probe is located close to the point of exit, that should be the area of critical temp you are worried about. Same with the recirc in the HERMS, as long as the temp probe is measuring the temp at the point where the mash water is re-entering the tun, that is the critical location (as I have read and what makes sense).
Again, I am speaking "in theory" - never done an all grain batch nor have I brewed on a rig with digital temp controls (thus why I am building one) so I guess I am looking for feedback from both ends of the spectrum. If you do use a device to mix anything in your brewing, why? If you don't, why not?
Thanks