Development of heat recovery solution for heavy duty truck cabs to improve energy efficiency

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Insinööritieteiden korkeakoulu | Master's thesis
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Nordic Master Programme in Innovative and Sustainable Energy Engineering (ISEE)
189 + 52
The recent climate actions to reduce greenhouse gas (GHG) emissions have set the stage for decarbonizing the transportation sector through electrification, which has led to a surge in the deployment of battery electric Trucks (BET). While tail-pipe emissions are reduced drastically, certain aspects of BET prevent its widespread deployment, prominent of which is the range anxiety. BET range is heavily impacted in cold weather as energy from traction batteries is also used to warm the battery pack and cabin. The thesis mainly focuses on the cabin exhaust air ventilation, which accounts 7-42% of the heat losses. In this study, three heat recovery techniques were investigated to harness the waste heat from evacuating cabin air to reduce the heating energy consumption in a BET. One proposed technique employed an air-to-air heat recovery system (AAHRS). Baseline experiments were conducted on a Scania R20H test truck to analyse the performance of the installed Heat Ventilation and Air Conditioning (HVAC) system, which aided the design and prototyping of the AAHRS system. Validation experiments evaluated the energy savings from the prototype in a climate chamber under different ambient temperatures and HVAC fan speed settings. The study found a 20-53% reduction in heating load with the implementation of AAHRS. In contrast, the electrical power consumption increased 1.7-3.3 times higher than the baseline cases because of the additional power-consuming components and the changed system resistances. Overall, 19-47% energy saving was observed from integrating the AAHRS prototype with the existing HVAC system. Two other presented techniques operate on air-to-liquid heat recovery systems (ALHRS), which were coupled separately to a heat pump-assisted integrated thermal management system (ITMS). The two schemes were evaluated via vapour compression system performance analysis to see the potential to increase the coefficient of performance (COP), which is beneficial in terms of available heat that can be dissipated into the battery cold plates and cab heater core. To assess the energy-saving potential of proposed ALHRS solutions, a simulation model of an adopted baseline ITMS concept was developed using Engineering Equation Solver (EES) software. It was then validated against internal bench test results for a mock-up ITMS model. The results of the initial validation test indicated an absolute error between the simulation outputs and bench test results of 8-14% for condensation heat, while it was below 7% for all the other relevant performance parameters.
Vuorinen, Ville
Thesis advisor
Axenholm Strömberg, Niklas
Gavelin, Josefine
air-to-air heat recovery, air-to-liquid heat recovery, integrated thermal management system, heat wheel, heat pump, battery electric vehicle
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