Energy Performance Simulations of a Scania Truck Cabin

Sammanfattning: The vast majority of trucks in the European Union are reliant on fossil fuels as their primary mode of propulsion. In efforts to decarbonise the truck transport sector manufacturers are developing electrified trucks. An electrification may serve to reduce the tailpipe emissions of trucks, but it introduces a new challenge to supply the cabin with energy. This energy is primarily used to maintain a comfortable cabin climate for the driver and passenger. In order to maximise the range of an electric truck the cabin energy requirement needs to be minimised. This thesis evaluates the current energy performance of a Scania S20H cabin through experimental testing as well as simulations using the simulation software GT-SUITE. Based on the results from the tests and the models, energy saving concepts were generated and their performance was evaluated. The experimental tests were performed on a truck in a climate chamber where the ambient temperatures, HVAC system fan speeds, air recirculation rate and inlet air temperatures were varied. The test data was used to build a one-dimensional simulation model in GT-ISE as well as a three-dimensional model in GT-TAITherm. The one-dimensional model was calibrated against 10 experimental tests and yielded an average relative error for the chosen temperature calibration parameters between 0.05% and 0.43%. The one-dimensional model showed that the largest energy loss was through air evacuation and air leakage, accounting for 70-90% of the input energy. The structural energy losses were primarily through the windshield and the side windows, accounting for 32% and 23% of the total structural losses respectively. Energy saving concepts in the form of low emissivity window glazing, double pane windows, xenon filled gas panel insulation and low levels of air recirculation were simulated. The best and most plausible combination of the aforementioned concepts yielded an average input energy decrease of 31.6%, air loss decrease of 32.9% and a structural loss decrease of 27.6% compared to the simulated base cases. The three-dimensional model was calibrated against one test case and yielded an average relative error of 0.15% for the chosen temperature calibration parameter. One energy saving concept in the form of double pane side windows in conjunction with low emissivity glazing on all windows was simulated. This concept had a slight impact in raising the average cabin air temperature and the interior surface temperatures of the windows. The surface temperature change resulted in a decrease of cold downdraught from the top roof window and the driver side window. In conclusion, the models work as intended providing a time efficient way of evaluating the energy performance of structural changes. In order to improve the performance, usefulness and accuracy of the models the initial values should be more exact. This can be achieved by standardised testing procedures as well as data collection with wind speed.