Session: 11-09-01: Thermal Transport Across Interfaces I

Paper Number: 69159

Start Time: Wednesday, 10:05 AM

69159 - Investigations to Consider Thermal Interactions Between Spatially Separated Subsystems: Concept of a Thermal Coupling System for X-in-the-Loop Test Benches 

Early validation of product properties enables the product development process to be accelerated while reducing development risks and costs. In terms of product generation engineering, this can be realized with X-in-the-Loop test benches. In such test benches, the entire product is divided into subsystems, which can result in a spatial separation compared to the original assembly situation. The subsystems are connected via coupling systems, which can transfer the mechanical or electrical interactions using a combination of sensors and actors to maintain the main functionality of the overall system. Due to increasing power densities, the consideration of thermal interactions between the individual subsystems is becoming more and more relevant. There is no suitable coupling system that can transfer thermal interactions by heat conduction between spatially separated subsystems for the application in X-in-the-Loop test benches. The spatial separation of the subsystems changes the transfer of heat flows. As a result, the temperature distribution changes in the overall system. This leads to two significant problems in product validation. First of all, a statement about compliance with the thermal load limit is not possible. Second, many functionally relevant parameters are temperature-dependent. Without considering the thermal interactions, the system behavior can change and reduces the reliability of the results in product validation.

The research aim is to develop a concept of a thermal coupling system that can transfer thermal interactions by heat conduction between spatially separated subsystems as they would be connected in the original assembly. Additionally, the concept is evaluated by simulation using MATLAB Simscape.

The concept of the thermal coupling system is described in detail. Two temperature sensors, one located on each side of the original contact area, are used. As the contact resistance is neglected, there must be no temperature difference between these two temperature sensors. To comply with this so-called thermal coupling condition, actuators are needed which can generate a heat flux. Peltier elements are particularly well suited due to the thermoelectric effect, which allows controlling a heat flow in both directions. Therefore, a Peltier element is applied to each original contact surface.

To evaluate the concept of the thermal coupling system, a basic thermal model is simulated, which is reduced to two thermal masses and two resulting heat flows and can be verified by considering basic thermal load cases. Three different scenarios are considered. Scenario A is the basic thermal model with a heat transfer between the two masses. The use-case when the two subsystems are spatially separated compared to the original assembly situation is described with scenario B. Scenario C additionally has the thermal coupling system between the spatially separated subsystems. The temperature distribution between the three scenarios is compared. The evaluation variable is thus the deviation from the temperature distribution of scenario A. The applied heat flows, geometric dimensions and others are varied as independent variables.

If scenario B is compared to scenario A, it shows that the spatial separation of the subsystems has a distinct influence on the temperature distribution. Depending on the variables, the deviation is more than 100 Kelvin after a few minutes. When using the thermal coupling system (scenario C), the deviation from the original assembly situation (scenario A) is less than 2 Kelvin. This is a relative deviation of less than 1% and can be often accepted for the validation of technical systems in the context of X-in-the-Loop test benches.

The results demonstrate the feasibility of the described concept of a thermal coupling system. For future steps, the system should be physically built and tested again under real conditions. With such a thermal coupling system, thermal interactions by heat conduction between spatially separated subsystems can be transferred. It therefore improves the product validation by using it on X-in-the-Loop test benches.

 

Presenting Author: Felix Leitenberger IPEK - Institute of Product Engineering at Karlsruhe Institute of Technology

Authors:

Felix Leitenberger Karlsruhe Institute of Technology (KIT)
Michael Steck Karlsruhe Institute of Technology (KIT)
Thomas Gwosch Karlsruhe Institute of Technology (KIT)
Sven Matthiesen Karlsruhe Institute of Technology (KIT)