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KULI Online library

Reynolds Prandtl Calculation

15.04.2021

KULI-System

Sometimes it is beneficial to know the current values of the Reynolds or Prandtl numbers during calculation, in particular if some theoretical investigations should be done. A typical example would be to calculate the current values of the axes in the dimensionless heat maps, where in most cases either the Reynolds number or Reynolds * Prandtl^(1/3) is used.

The cooling system model and the subsystem in this model show how these values can be calculated with the help of the KULI signal path in combination with a medium control object.

Usable from release: KULI 14.1
Necessary modules: KULI base

File, 8 KB
Documentation, 216 KB

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Rotary Valve

17.02.2021

KULI-System

This example demonstrates a way how to model a 4 way rotary valve. In such a valve there are two inlet ports and two outlet ports. In the middle there is a chamber with a rotary element. Depending on the angle of this element the ports are (partially) open or closed such that the flow can be controlled individually. The included documentation shows the modelling concept and also explains how this model can be adjusted to resemble a specific valve. The subsystem contains the valve itself (which only requires KULI base) whereas the KULI model includes a very simple transient simulation (thus requiring KULI drive) to show the effect of varying valve angles.

Keywords: throttle, mixing valve

Usable from release: KULI 14
Necessary modules: KULI base

File, 13 KB
Documentation, 219 KB

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Orientation depending solar radiation in simple passenger compartment

16.02.2021

KULI-System

In this example the simple passenger compartment model is enhanced by a more detailed modelling of the solar radiation. Within a subsystem the introduced heat into the passenger compartment is calculated based on the solar radiation intensity, the orientation of the sun rays relative to the vehicle and vehicle specific parameters like window size, their slope and transmittance.
For illustration purposes the vehicle starts driving to the north and changes the driving direction gradually to the east, south and west and ends the test cycle with heading north again. The sun rays remain coming from the east during the whole drive cycle so that the vehicle rotates 360 degrees around the sun and the impact of each window surface can be analyzed. The orientation dependency is considered by the usage of rotation matrices. The direction of the sun rays is defined with the help of two angles as it is done in the extended passenger compartment model

Keywords: sun rays, solar impact, enhancing cabin model, enhancing passenger compartment model

Usable from release: KULI 14.1
Necessary modules: KULI base, KULI drive transient, KULI hvac

Files, 32 KB
Documentation, 421 KB

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Subcooling controlled EXV

21.12.2020

KULI-System

Typically an expansion valve in an A/C circuit is controlled by taking a desired superheating temperature as the target. But for electronic expansion valves it would also be possible to control the valve by taking a desired subcooling at the condenser as the target. This example shows how such a configuration can be modeled by using the signal path to iteratively calculate the appropriate cross section of the expansion valve. The calculation method is based on the Newton method and works for both steady state and transient models. With the help of an appropriate map of desired subcooling temperatures the system can then be set up for optimal COP values.

The idea of using a Newton method in the signal path can be applied in many different applications, whenever some control of an input parameter is required and the built-in optimization cannot be used.

Usable from release: KULI 14
Necessary modules: KULI base, KULI hvac

File, 17 KB
Documentation, 333 KB

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PID controller optimization

17.12.2020

KULI-System

This example shows how a PID controller can be tuned automatically in KULI avoiding cumbersome manual tuning. For this task the cost function of the optimization problem is defined within a subsystem in KULI and allows easy adaption respectively reusage. The provided cost function penalizes control deviations and oscillations of the controlled variable. In this case the KULI model is externally controlled from Python addressing the COM interface offering a wide range of possibilities to adapt the optimization procedure to user specific needs.

To demonstrate this procedure the air temperature of a passenger compartment is controlled via the external heat supply of a point mass which represents for example a PTC heater. Several transient simulations will be conducted with different p-, i- and d-gains until the parameters for an optimal PID controller (in the sense that these minimize the cost function) are found by the python script automatically.

Keywords: step response, control theory, automatic tuning

Usable from release: KULI 14
Necessary modules: KULI base, KULI advanced, KULI drive transient, KULI hvac

Files, 14 KB
Documentation, 338 KB

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Refrigerant property files

06.11.2020

KULI-System

R290_V2.dat - Published 5.11.2020

The media data of R290 is limited to the critical pressure to stabilize the AC solver in high pressure levels nearby the critical point. Additionally the media data is using the full range of enthalpy defined in the media file.

To use the latest version of refrigerant files copy and paste the files to the KULI installation on your computer to the folder C:\Program Files\ECS\KULI_Version_Number\System\KULI\Refrigerant. Information about media handling can be found in the Online help https://kulihelp.magna.com/km/latest/kuli-base/media.

Usable from release:
Necessary modules:
Refrigerants, 3 MB

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Expansion Tank

08.10.2020

KULI-System

With the expansion tank model an example is given on how to model the influence of an expansion tank on the pressure level of a cooling circuit in a transient simulation. With rising average temperature of the incompressible coolant, the coolants volume increases. To compensate this thermal expansion an expansion tank is used in which air is being compressed as soon as the coolant in the cooling system expands. In this model the expansion tank is modelled in a subsystem so that it can be easily transferred to other KULI models as well (of course also to models where no KULI drive transient module is needed). Only the input values and eventually the media properties within the subsystem need to be adapted. Additional to the average coolant temperature the influence of quantities like the volume of the expansion tank and its filling status, the volume of the coolant as well as the influence of different reference conditions is considered.

Keywords: coolant recovery tank, coolant reservoir, surge tank

Usable from release: KULI 14
Necessary modules: KULI base, KULI drive transient

KULI File, 90 KB
Documentation, 288 KB

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Transient parameter variation

01.10.2020

KULI-System

This example describes a possibility to perform a parameter variation for a transient simulation with the help of an Excel script. Within the Excel sheet the different variants are defined, i.e., a table is given with the values of different input parameters for different variants. The script performs simulations for all these variants and also generates a separate hdmb output file for each variant such that the results can be compared in KULI lab later on. The script also shows how events can be used to display the value of selected variables during the simulation. In this way e.g. the maximum temperature that has occurred so far in the simulation can be put into a cell of the Excel sheet. The script is prepared in a way such that up to 10 input/output parameters can be considered; error and message handling via events is included as well.

Keywords: COM interface

Usable from release: KULI 13.2
Necessary modules: KULI base, KULI advanced com, KULI drive transient

File, 49 KB
Documentation, 308 KB

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Coolant Cooled Battery

30.06.2020

KULI-System

This example shows a coolant cooled battery with a setup of heat transfer based on cell level. The battery is used in an open coolant circuit to see the thermal behavior of the battery. The target current of the battery is set via actuator.

Keywords: battery simulation, coolant cooled battery, BMS, cell temperature, battery module, battery cell, 18650 cell, cooling plate

Usable from release: KULI 13
Necessary modules: KULI base, KULI transient, KULI eco

File, 20 KB
Documentation, 959 KB

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Delay Controller with adjustable start value

20.03.2020

KULI-System

The delay controller object in KULI provides the possibility to delay a signal for a certain period of time or number of timesteps. Within this object a start value needs to be specified that defines the return value until the delay period has passed. In some situations it could be beneficial to define this start value via a simulation parameter, a COM object or another source outside of the delay controller itself.

The attached subsystem shows an easy way to accomplish this task. The basic idea is to set the start value inside the delay controller object to zero and then subtract the intended start value from the signal right before the delay controller and add it again right after the delay controller. The value that will be subtracted and added can easily be defined in various was, including COM objects, constants, simulation parameters, etc.

Keywords: initial value

Usable from release: KULI 13
Necessary modules: KULI base + KULI drive

File, 5 KB

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