Physical Trough model "hangs" during a parametric with dispatch enabled

[qualand]

Describe the bug

The physical trough model will not progress in a reasonable time when conducting a parametric study on hours of storage and solar multiple with dispatch optimization enabled.

To Reproduce

Steps to reproduce the behavior:

1. Open the Parabolic Trough - Physical Single Owner Model
2. Click on System Control and "Enable dispatch optimization"
3. Click on Parametrics and Quick setup...
4. Add Hours of storage at design point {'tshours'} and Solar multiple {'specified_solar_multiple'}
5. Edit there values as follows: Hours of storage 4-18 using a 2 hour interval and solar multiple 1-4 using a 0.5 interval
6. Click Run simulations

Expected behavior

The model should solve for all combinations. However, some simulations do not solve (see screen) where simulation 19 failed (8 tshours and 2 solar multiple) and two cores are "hanging" making no progress after an extended period of time (about an hour). I will try to narrow down which simulations are causing the issue.
This csp solver hanging occurs with the following configurations about 33% through the simulation:

• 6 hours of storage, 4 solar multiple
• 4, 6 hours of storage, 3.5 solar multiple
• 4 hours of storage, 3 solar multiple

These are obviously "bad" designs but maybe it might be worth understanding why this causes the solver to hang and if the reason leads to a more stable solver.

Screenshots

Operating System and Version

• OS: [Windows]
• Version [SAM 2021.12.2]

Additional context

This is problematic for some analysis completed within HOPP using the physical trough model.

[qualand]

Current version on develop handles this parametric much better. It does not "hang" anymore; however simulations with Solar multiple of 1 do fail because solver results in MAX_ITER_SLOPE_POS_NO_NEG_ERR condition (line 2631 in csp_solver_trough_collector_receiver.cpp). This failed simulation in the parametric results in SAM crashing.

If you use relative mass flowrates rather than absolute, this is not a problem.

@tyneises how would you like to proceed?