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Online Library

    KULI Online library
  • Simple way to model hysteresis
    16.09.2014
  • KULI-System

    This example shows a quite simple way how hysteresis can be modeled. The calculation controller differs between two cases, with respect on the previous operating state. To avoid that the temperature / fan RPM is oscillating around a certain value, a function is used. 

    To avoid a highly oscillating fan RPMs, a hysteresis in the controlling strategy is included. This is modeled by a calculation controller. If the temperature exceeds a certain value, the fan switches to the maximum RPM mode.  Additionally this high RPM mode is also used, if the temperature is between the two temperature limits and the high RPM cooling mode is already active. In case of underestimating the lower activation border or in case of an active min. RPM mode & actual temperature between the limits, minimal RPM mode is selected. To avoid a logical loop, a delay controller is used for sensing the input speed of the fan.

    Usable from release: KULI 9.1-0.01
    Necessary modules: KULI base + KULI drive


    KULI File, 49 KB
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  • Temperature control: Fan / blower RPM
    16.09.2014
  • KULI-System

    One possibility to set a target temperature in the cabin is to control the RPM of the blower (fan).
    This example demonstrates how a subsystem including several calculation controllers can easily be added to an existing HVAC simulation system.

    By adjusting the fan RPM, the cool down (heat up) performance of the cabin is influenced. This controlling strategy is included in a subsystem which mainly consists of calculation controllers.

    As a necessary input, the user has to define a required cabin temperature and the upper and lower limit for the fan RPM. The calibration coefficient is a kind of RPM offset for the controller, used in each simulation time step. 

    If the average cabin temperature exceeds the upper temperature limit plus the temperature tolerance, the max. fan RPM is used. 

    In all other cases the fan RPM is reduced or increased by the calibration coefficient. Due to the change of the fan RPM in each simulation time step, a smooth control characteristic is created.

    Usable from release: KULI 13.1
    Necessary modules: KULI drive + KULI hvac


    KULI File, 14 KB
    Documentation, 881 KB
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  • Temperature control: Recirculation ratio
    16.09.2014
  • KULI-System

    One possibility to set a target temperature in the cabin is to control the amount of recirculation.
    This example demonstrates how a subsystem including several calculation controllers can easily be added to an existing HVAC simulation system.

    By adjusting the recirculation rate, the cool down ( heat up) performance of the cabin is influenced. This controlling strategy is included in a subsystem which mainly consists of calculation controllers. 

    As a necessary input, the user has to define a required cabin temperature and the upper and lower limit for the recirculation rate. The calibration coefficient is a kind of recirculation offset for the controller, used in each simulation time step. 

    If the average cabin temperature exceeds the upper temperature limit plus the temperature tolerance, the max. recirculation rate. 

    In all other cases the recirculation rate is reduced or increased by the calibration coefficient. Due to the change of the recirculation in each simulation time step, a smooth control characteristic is created.

    Usable from release: KULI 13.1
    Necessary modules: KULI drive + KULI hvac


    KULI File, 16 KB
    Documentation, 1 MB
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  • Calculation of heat (latent / sensible / total)
    15.09.2014
  • KULI-System

    These two subsystems can be used to calculate the amount of heat exchanged by a heat exchanger. For HVAC components (evaporator), the subsystem “EVP heat calculation” computes the amount of latent and sensible heat. For all other heat exchangers, the subsystem “Heat calculation” can be used.
    Due to their modeling as a subsystem, both models could easily be used in the users KULI simulation.
     

    Both subsystems can be included in any existing KULI file. To insert it, use the subsystem import function. It might be possible that the signal receivers included in the subsystem must be adapted. Therefore double-click the signal receiver symbol and change the linked component. 

    Once successfully included, the system calculates the latent and sensible heat (subsystem “EVP heat calculation”). In case of not using it in an HVAC system, subsystem “Heat calculation” can be used to calculate the sensitive heat (which is also directly available by the component). 

     The calculation of the heat is done by several calculation controllers, the material properties (for the cp value) are computed by the Medium controller. To get the input values for the calculation controllers (mass flow, in- and outlet pressure / temperature), signal receivers are used.

    Usable from release: KULI 9.1-0.01
    Necessary modules: KULI base + KULI drive
    KULI File, 5 KB
    Image, 40 KB
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    Image
  • Cavitation alert
    15.09.2014
  • KULI-System

    This cavitation alert shows if the critical pressure is underestimated and cavitation can occur. This simple example does not consider local effects in the pump, but the inlet pressure.

    Cavitation is a very critical parameter for the pump, because it can lead to its mechanical destruction. Therefore it’s important to investigate the critical parameters. This simple submodel compares the inlet pressure at the pump with the critical pressure for the used medium. In case of underestimating this value, the result of the calculation controller will show that there is the risk of cavitation. Due to the 1D model, this alert does not consider local effects in the pump itself.

    Usable from release: KULI 9.1-0.01
    Necessary modules: KULI base + KULI drive
    KULI File, 23 KB
    Image, 45 KB
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    Image
  • Combined Heat pump - A/C System
    15.09.2014
  • KULI-System

    This simulation model demonstrates how a HVAC system featuring different operating modes (cool down, heat pump mode) can be realized in one simulation model.

    To combine both conditioning modes in one simulation model, it is necessary to split the system into two branches. Therefore the system consists of two condensers and two evaporators.

    Basically there are two ways to select the conditioning mode:

    • By setting one branch containing these HVAC components to an inactive state (locking the path), the conditioning mode can be chosen. This is basically done by reducing the pressure in the branch to zero.
    • Another possibility is to set a very small mass flow through a controlled orifice, which will cause a closed txv.

    The mode itself can be chosen in the Simulation parameter window.

    Usable from release: KULI 9.1-0.01
    Necessary modules: KULI hvac


    KULI File, 256 KB
    Documentation, 995 KB
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  • Phase Change Material (PCM)
    15.09.2014
  • KULI-System

    Phase change material can store a high amount of energy due to its very high thermal inertia. This energy can e.g. used for a fast engine warm-up, to provide cooling performance in the HVAC system (evaporator) while no compressor is available, … 

    The high amount of enthalpy for the phase change is modeled by changing the point masses cp value (thermal capacity) during the melting / solidification process. 

    The heat transfer to the PCM element depends on the amount of mass flow. By adding an additional medium component and a calculation controller, a speed / volume flow dependency can be modeled.

    Usable from release: KULI 9.1-0.01
    Necessary modules: KULI base + KULI drive
    KULI File, 14 KB
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  • Temperature control: A/C compressor RPM
    15.09.2014
  • KULI-System

    One possibility to set a target temperature in the cabin for a fixed displacement compressors is to control the compressors RPM.
    This example demonstrates how a subsystem including several calculation controllers can easily be added to an existing HVAC simulation system.

    By adjusting the compressor RPM, the performance of the compressor is controlled. This controlling strategy is included in a subsystem which mainly consists of calculation controllers.

    As a necessary input, the user has to define a required cabin temperature and the upper and lower limit for the compressor RPM. The calibration coefficient is a kind of RPM offset for the controller, used in each simulation time step.

    If the average cabin temperature exceeds the upper temperature limit plus the temperature tolerance, the max. RPM of the compressor is used.

    In all other cases the RPM is reduced or increased by the calibration coefficient. Due to the change of the RPM in each simulation time step, a smooth control characteristic is created.

    Usable from release: KULI 13.1
    Necessary modules: KULI drive + KULI hvac


    KULI File, 15 KB
    Documentation, 978 KB
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  • Compressor cycling
    12.09.2014
  • KULI-System

    This subsystem takes care that the cabin temperature is kept between specified borders and if the temperature in the cabin is reached, then the entire AC circuit is turned off. Additionally the inertia of evaporator is taken also into account.

    This simulation features a control system in which is the cabin temperature kept in specific borders by turning on and turning off the entire AC systems.

    When the AC system compressor is turned off and the air still flows through an evaporator the inertia of the evaporator causes the air to cool itself by rejecting heat and at the same time warming the evaporator until it reaches the ambient temperature. In order to take this phenomenon into account, this system was created.

    Also in this case is the transient behavior of an evaporator simulated by a point masses. In order to reach a smoother outlet temperature curve a heat conduction coefficient is positioned between the evaporator air side point mass and the evaporator refrigerant side point mass.

    Usable from release: KULI 9.1-0.01
    Necessary modules: KULI base + KULI hvac


    KULI File, 98 KB
    Documentation, 592 KB
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  • Modeling of an Air-Cooled Battery Pack in KULI
    09.07.2014
  • KULI-System

    KULI software for energy management optimization gives you the opportunity to efficiently investigate different concepts for EV/HEV batteries.

    A possible concept  is a nickel metal hydride battery which can be cooled by passenger cabin air.

    Focus on

    • Temperature distribution among cells

    Other results

    • Battery SOC
    • Battery discharge time
    • Finding optimum strategy for blower 

    Input Data

    • Dimension of cells and battery design
    • Battery internal resistance over SOC and temperature
    • Initial charge
    • Electric Current
    • Ambient air flow

    Input data loosely based on Honda Insight

    • KULI base and KULI drive required for Simulation
    Usable from release: KULI 9.1-0.01
    Necessary modules: KULI base + KULI drive


    KULI File, 1 MB
    Documentation, 2 MB
    Please login for Download.