Hello colleagues,
Currently I'm designing "active heat recovery" in other words air to air reversing heat pump.
The main components the system composes are:
2 x tandem Scroll type compressors (1 variable speed, 1 fixed),
2 coils, electronic expansion valve,
reverse valve,
suction line accumulator and
liquid receiver.
The problem is that I couldn't find the proper type of liquid receiver. Furthermore, can anybody explain me how liquid receiver is working in reverse cycle, when the inlet and outlet port changed its direction. How does the liquid manage to move back to compressor?
I found one scheme according which I think I could design my systemScheme.png
but I could understand how the Tank which I circled in red, works. Is it conventional receiver with one pipe at the bottom and one at the top, or both pipes are at the same level (bottom) and it works like expansion vessel?

I forgot to mention:
Unit type - Reversing vary capacity air to air heat pump
Heating capacity - 98 kW (evap. temp. +7C; condensing temp. 40C)

Thank you in advance guys.