The gearbox delivers a significant amount of heat to the gearbox oil, depending on the efficiency of the gearbox in the current operating conditions. This model demonstrates how the amount of heat can be calculated and put into the appropriate locations in the circuits.
The central element is an efficiency map, based on gear, torque, rpm, and temperature. The conversion from mean eff. pressure to torque is included with the help of calculation controllers. The heat of the gearbox is put into a point mass in an oil circuit. The point mass is also connected to another point mass via a heat conduction component with which it is possible to consider the heat transfer to the ambient.Usable from release: KULI 8.0-1.04
The COM interface, developed by Microsoft®, provides a standardized interface for programs to communicate with each other. KULI components has a set of built-in COM commands, which allows external programs to create KULI component files.
The part of KULI components that allows to save component files is implemented as a dynamic link library (DLL). This KuliCompInterface.dll can be called by any other application that supports COM. The current example is a simple demonstration of the KULI compinterface. An Excel datasheet for KULI input of a radiator component has an integrated button that allows to store the data directly as an *.kulirad-file.Usable from release: KULI 8.0-1.04
Only transient simulation allows using the full potential of computer aided engineering regarding component sizing & packaging.
For the simulation of realistic temperature profiles the thermal capacities of the engine should be considered.
In this example the existing engine component from KULI drive is remodeled using the primitive components point mass and heat conduction. The engine can be modeled as two direct masses and two indirect masses.The direct masses are heated by combustion processes, and exchange heat with each other, the oil and the water circuit respectively, the ambient air and with the indirect masses. The indirect masses exchange heat via conduction with their respective direct mass only.Usable from release: KULI 8.0-1.04
In this example we will investigate, how to model a hybrid passenger car with KULI. We will especially focus on the electric components and their integration into the overall cooling system.
The aim of a decent fan control strategy is to provide adequate air flow for the cooling system at minimum fan power and noise.
The KULI controller objects enable to implement an arbitrary control strategy for system optimization.
In the subsystem Fan control the controlling information is set up. For comfortable use you can change the values for the temperatures for changing the fan stage and the fan stages itself in the inner circuit window.
Based on the fan (electrical or mechanical fan) the fan stage or the fan speed can be used as the controlled parameter. In the provided model an electrical fan switches on as the air temperature rises above 60°C and switches off as the temperature falls below 55°C. The transient aspect of the example is the hysteresis which can be modeled using a delay controller. For better system overview the control strategy is packed into a KULI subsystem.Usable from release: KULI 9.1-0.01
In the coolant circuit the thermostatic valve is one of the most important control units to maintain the system’s desired set point temperature. Due to its mechanical technology usually the thermostat has some delay in its reaction, which should be considered in transient cycle simulation. This example is based on the tutorial example ExEngine. The major modification is that it includes a more detailed model for the thermostat, placed in the subsystem “Thermostat”.
The main idea is that a fluid point mass models the wax element including the metal housing of the thermostat. This point mass is responsible for the hysteresis of the thermostat. The mass of the point mass can be adjusted to fit the current application; moreover, also the heat transfer coefficient from the coolant to the mass can be adjusted, even depending on the flow rate. A corresponding characteristic line is prepared (but contains only a single value in this demo example).
The temperature of the mass (i.e., of the wax element) is then taken into a characteristic line in which the lift opening (between 0 and 100%) of the thermostat is calculated. Based on this lift opening two fluid resistances are calculated that have opposite behavior: If the temperature is still low, then the resistance of the bypass will be low, the resistance of the exit to the radiator branch will be high. If the temperature is high, then it is vice versa.
The example is given for a thermostat working as a branch; the method would work in the same way for a thermostat working as a confluence.Usable from release: KULI 8.0-1.04
This subsystem models a viscous clutch via a point mass.
The warming up hystereses are defined via the following inputs:
Furthermore the transmission ratio from engine speed to the input speed of the viscous clutch is modeled via a constant factor. And the transmission from the clutch-input speed to the fan speed is modeled via a 3D-map (“fan_rpm”) dependent on the engagement Ratio.Usable from release: KULI 9.1-0.01
Charge air cooler tanks may have a big impact on the efficiency of the heat exchangers behind. A simple approach to model those effects in KULI is the use of area resistances to block the air flow in the area where the tanks of the charge air cooler are located.
The area resistances correspond to the size of the real -life tanks.To consider the high air resistance typically caused by the tanks a high pressure loss coefficient has to be set. To model the local impact regarding the heat exchanger surfaces the area resistances simply can be integrated to the cooling package using the KULI block function.Usable from release: KULI 8.0-1.04
The heater matrix uses coolant to warm the air that enters the passenger cabin. Of course, this can influence the behavior of the complete coolant water circuit. This example illustrates how to add a heater matrix to a System.
To take care of an additional heater matrix in an existing KULI cooling system one has to add a radiator component to the KULI system. On the fluid side it is integrated to a normal coolant circuit using branch and confluence components. On the air side it is necessary to use two parallel branches to simulate separate air paths for the engine cooling part and for the HVAC part. The example is based on the basic example “Ex_Fluid.scs” from the KULI installation setup.Usable from release: KULI 8.0-1.04
In the passenger compartment typically a certain comfort temperature is demanded. In concept phase where only a few data are available, KULI supports the engineer in finding the required evaporator cool load to achieve the design temperature.
The current example represents a very basic configuration of an HVAC system. Air duct, blower and evaporator are simply modeled by heat flow sources, temperature- and mass flow targets with input based on rough assumptions. Using this model, the user can optimize the evaporator air outlet temperature such, that the evaporator cool load will lead to the desired cabin temperature.Usable from release: KULI 8.0-1.04