Close DB connection on browser close

Close DB connection on browser close

I use Primefaces / JSF2. Due to a special case we use jdbc connection
instead of connection pool. Every logged in user will hold one and only DB
connection at a time. If a logged in user close the browser instead of a
proper logout, his DB connection get held till the idle timeout (15 mins)
and he cannot login again immediately within this 15 mins timeout.
Is there any way to close the user DB connection, if he closes the browser
instead of logout?