Numerous tests have been done about this already. Nearly every tech related blog site has a version of this test somewhere in their archive if you look for it.

The conclusion is always the same, rice is no more effective than just leaving the device sitting on a counter in open air. Having a fan blowing on the device is more effective. The best option is putting it in a container with desiccant gel packets, ideally unused packets. This is what those water damage bags sold at some stores are, they are filled with desiccant beads.

Of course physically opening the device to dry and clean it internally is the most effective, but not something most users can do.