TempDB MDF File Is Increasing - Unable To Shrink It?

Output of below query is

SELECT session_id,
SUM(internal_objects_alloc_page_count) AS task_internal_objects_alloc_page_count,
SUM(internal_objects_dealloc_page_count) AS task_internal_objects_dealloc_page_count
FROM sys.dm_db_task_space_usage where internal_objects_alloc_page_count >10 and session_id> 50
GROUP BY session_id;

[Code] ....

Database MDF is 27806 MB and I tried to shrink but unable to shrink. It is production server.I do not want Restart sql server.There is no open transaction.