Cooling ferrofluid by strong magnets

[andreas_varesi]

Using strong Neodym magnets to attract a ferrofluid should slow down the Brownian movement of the nanomagnets. The result must be a cooling of the liquid. As the energy must not get lost the magnet should get warmer. Maybe there is a possibility to collect ambient warmth from ferrofluid to heat up a magnet. So it should be possible to generate a thermic potential difference from ambient temperature. A classical case of 2nd "law" violation.

What do you think about this? I will try this and let you know whether it works.

Regards Andreas

[betajim]

Using strong Neodym magnets to attract a ferrofluid should slow down the Brownian movement of the nanomagnets. The result must be a cooling of the liquid. As the energy must not get lost the magnet should get warmer. Maybe there is a possibility to collect ambient warmth from ferrofluid to heat up a magnet. So it should be possible to generate a thermic potential difference from ambient temperature. A classical case of 2nd "law" violation.

Even with neodymium magnets the magnetocaloric is very small for iron based materials. Gadolinium
based materials have twice the magnetocaloric effect, but even then superconducting magnets are
used. With the small amount of cooling that occures with iron, why would the magnet heat up (unless
the magnet is in contact with the ferrofluid). I doubt that any conservation law is broken by the
magnetocaloric effect.

I'm sure you could do a very good experiment comparing the magnetocaloric effect of ferrofluid to
other iron based materials. That would be very interesting!

[andreas_varesi]

First results are available, but my thermometer is not sensitive enough to detect temperature differences that are less than 1 degree Celsius.
Very interesting is that a strong magnetic field forms spikes within the ferrofluid. But the magnetic field also superposes the Brownian movement so the nano particles within the ferrofluid begin to stick together. So after several hours the spikes disappear and the ferrofluid forms a drop. After removing the magnetic field, the Brownian movement needs about an hour to disperse the nanoparticles within the fluid again. Only after that the ferrofluid can form spikes again. As soon as I have a highly sensitive thermometer I will repeat the experiment and post the results.

Regards

Andreas

[betajim]

First results are available, but my thermometer is not sensitive enough to detect temperature differences that are less than 1 degree Celsius.

Hi Andreas,

To get the precision you need, you will likely have to use a thermocouple for the
temperature measurements. You might want to check what thermsisters digikey.com
has available, they may have something with the precision you need.

You will have to keep everything well insulated as well so that you get good
measurements.

Take care.

[andreas_varesi]

Hi betajim,

thanks for your advice. I think it will last two or three weeks to get the right thermometer and to set up an insulated measurement surrounding.

Regards

Andreas