I have the same problem.
I need to convert chinese characters from a form, and then store it as NCR (like & #20126;& #27954;& #20195;& #34920) to store on a database using PHP. I used htmlentities and utf8_encode and utf8_decode but it doesn't seem to work..

You can see what I'm trying to do here:
http://www.redminera.com/modules/news/html/chino.php

I'd really appreciate your help.
Thank you!