Try typing the following into excel.
Change N15 to whatever the cell reference is that you want to convert eg A1, B4 etc. Make sure you get all the right brackets in the right place! This will display the result: 5h 12m 49s if your input cell reads 5.2136 etc.
=CONCATENATE(INT(N15),"h ",INT((N15-INT(N15))*60),"m ",ROUND(((N15-INT(N15))*60-INT((N15-INT(N15))*60))*60,0),"s ")