This experiment illustrates how to indirectly fix the charge for the HeatPump system while running a steady-state simulation with the Physics-based Solving capability of Modelon Impact. For the dynamic simulation, this is done via
init.initType = 1 (Fixed charge), but this is not supported in PbS.
Note: This will not work with dynamic simulation unless PbS and PbS-only features are disabled.
This model extends from VaporCycle.Experiments.HeatPumpSteadyState.Base so the system is already setup to run with PbS. The following components are modified to control system charge.
compressor.fixedSubCool = trueThis will enable the functionality to control subCool with the compressor discharge pressure.
compressor.SubCoolSetPoint = init.T_scThis is the setpoint, propagated from the
init.T_sc = 3 KThis is the change
init.p_high = 2050000 PaFor this example, with subcool fixed, this parameter is used as a initial guess instead of the prescribed fixed pressure like in Base. This is updated to be a better guess value for the 3K subcool.
To observe the relationship between subcool and the system charge, run an experiment sweep.
- In Settings > Execution > Steady State > Compiler Options turn on
- Run the example using Modelon Impact's Steady State execution. Make sure 'Enable steady state simulation' is enabled in the Settings > Application
- From the Results mode, rename the result from
- Switch to the Experiment mode (or press  on the keyboard)
- Expand the right sidebar and in the Experiment section create a New Experiment and call it
- While still in Experiment mode, expand the parameter section for the
initrecord and set
T_sc = range(-4,4,9)
- This will tell the experiment to run a sweep of
init.T_scstarting from -4K to 4K taking 9 steps
- In the Experiment section, under Analysis, expand the Advanced section and for Initialize from select Nominal from the drop-down. This will initialize each case of the sweep using the results from the nominal experiment to assist with convergence.
- Run with Steady State again
summary record plot the
recLevel to see how the system charge changes based on the subCool that is fixed.
Check other summary variables and observe:
- High side pressure that was used as an IV to fix the subcooling,
- Heating power increases as charge increases,
- COP reaches an upper limit and starts decreasing at higher subcool,