Due to its thermal inertia, the charge air cooler will show a special transient behavior. Especially if the volume flow or the temperature changes, this influence can lead to deviations in the temperatures, pressure losses, … The example demonstrates a possibility how the user can take care of this effect and easily include the model in an existing KULI model.
To take care of the charge air coolers (CAC) thermal inertia, point masses (PM) are included. Basically two different types of PM are used in the model:
- Point mass at the air side (mass ~ 40% of the CAC overall mass)
- Point mass in the circuit (mass ~ 60% of the CAC overall mass)
A separation of the CAC into two parts in combination with 3 point masses (inner side) and 2 point masses at the air side shows a very realistic behavior.
A separation of the inner circuits’ point mass of 10%, 70% and 20% (based on 60% of the overall mass) is recommended. The heat transfer area is calculated from the dimensions of the fins (inner side) and from the CACs’ net dimensions (air side). For the heat transfer coefficient a separation into inner and outer side is recommended.