Numerical analysis of pressure drop oscillations in parallel channels

• PDO limit cycles in parallel channels differ notably from the single channel ones.
• Constant dry-out conditions during oscillations can be present.
• The system gets more stable than for one channel systems.
• Dry-out conditions can be met during maldistributed stable solutions.

In this study pressure drop oscillations in two parallel channels are analyzed taking into account the thermal capacity of the pipes. A different limit cycle than the one that takes place in a single channel system is found. During the instability one channel always follows the typical pressure drop oscillations limit cycle while the other channel oscillates always in the superheated vapor region. This behavior leads to very high wall temperatures at the outlet of the heated pipe. This undesirable situation with one channel operating in the superheated vapor region takes place also for the maldistributed stable solutions.