HTF mass flow rate

Dear Paul,
When simulating in egypt for 200 mwe plant, HTF Flow rate of storage HX is minus in some time step in morning for annually graph.
how mass flow rate comes in negative and what is physically meaning?

Also find attached excel sheet of HTF Mass flow rates total and per loop

highlighted yellow is chosed for example,

at 12.5 hrs average on year, total mass flow rate of 5.13 *1000000 kg/hr and 10.75 kg/sec for each loop

if the plant of 200 Mwe ,solar multiple factor of 1 , Euro trough,shott PTR 70 pipe and total no. of loops is 138

then mass flow rates of loop = total mass flow rate /no.loops = 10.326 kg/sec am i right?

Thanks