#Time Format, How to convert 12 hour time to 24 hour time? How

Appian defaults to showing you the time in the timezone set by your local calendar/timezone settings. So when you run gmt(local(now(), "EST")) it should be changing the time value correctly but still displaying "CST" on the end. To correct for this, you may have to manually display the timezone, to do so you can use the text() function to display just the date and time and then concatenate "EST" to the end of the string.

The "Date and Time Functions" page has more information about why this is the case: forum.appian.com/.../Date_and_Time_Functions.html

Try this...
append(text(gmt(local(now(),"EST")), "mm/dd/yyyy hh:mm aa"), " EST")

@harshav, from expression given by "aviroop" kindly replace "aa" with "ss" if you want the format in 24 Hrs format.

As 'ss' represents seconds, having it is optional and it won't influence 12 or 24 hours format. 'aa' shouldn't be used, as it appends AM to the time. So we can also just remove 'aa', rather than going for a replacement of it with 'ss'.

Oh yes, I missed the first question. To convert 12 hour time to 24 hour, just remove aa part from my expression.