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<div class="section abstract"><div class="htmlview paragraph">Designing an efficient vehicle coolant system depends on meeting target coolant flow rate to different components with minimum energy consumption by coolant pump. The flow resistance across different components and hoses dictates the flow supplied to that branch which can affect the effectiveness of the coolant system. Hydraulic tests are conducted to understand the system design for component flow delivery and pressure drops and assess necessary changes to better distribute the coolant flow from the pump. The current study highlights the ability of a complete 3D Computational Fluid Dynamics (CFD) simulation to effectively mimic a hydraulic test. The coolant circuit modeled in this simulation consists of an engine water-jacket, a thermostat valve, bypass valve, a coolant pump, a radiator, and flow path to certain auxiliary components like turbo charger, rear transmission oil cooler etc. A commercial CFD software, Simerics-MP+®, is used to simulate the hydraulic test for two different positions of the poppet valve of the thermostat, viz. a closed position and an 50% opening, at different speeds of the engine. In the CFD model, the complete geometrical details of water-jacket, thermostat, and pump are considered. The remaining components are approximated as pipes with flow resistance models to account for flow and pressure drop at different engine speeds. Firstly, the standalone pump performance is validated in the operating regime of interest, followed by the calibration of the resistance models for the simplified components. At the end, complete system level 3D simulations are conducted and validated for the above mentioned two positions of the poppet valve. The flow distribution and pressure drop across different components show good comparison with the hydraulic test data within 7% error band.</div></div>
<div class="section abstract"><div class="htmlview paragraph">Designing an efficient vehicle coolant system depends on meeting target coolant flow rate to different components with minimum energy consumption by coolant pump. The flow resistance across different components and hoses dictates the flow supplied to that branch which can affect the effectiveness of the coolant system. Hydraulic tests are conducted to understand the system design for component flow delivery and pressure drops and assess necessary changes to better distribute the coolant flow from the pump. The current study highlights the ability of a complete 3D Computational Fluid Dynamics (CFD) simulation to effectively mimic a hydraulic test. The coolant circuit modeled in this simulation consists of an engine water-jacket, a thermostat valve, bypass valve, a coolant pump, a radiator, and flow path to certain auxiliary components like turbo charger, rear transmission oil cooler etc. A commercial CFD software, Simerics-MP+®, is used to simulate the hydraulic test for two different positions of the poppet valve of the thermostat, viz. a closed position and an 50% opening, at different speeds of the engine. In the CFD model, the complete geometrical details of water-jacket, thermostat, and pump are considered. The remaining components are approximated as pipes with flow resistance models to account for flow and pressure drop at different engine speeds. Firstly, the standalone pump performance is validated in the operating regime of interest, followed by the calibration of the resistance models for the simplified components. At the end, complete system level 3D simulations are conducted and validated for the above mentioned two positions of the poppet valve. The flow distribution and pressure drop across different components show good comparison with the hydraulic test data within 7% error band.</div></div>
<div class="section abstract"><div class="htmlview paragraph">Trapped air bubbles inside coolant systems have adverse effect on the cooling performance. Hence, it is imperative to ensure an effective filling and de-aeration of the coolant system in order to have less air left before the operation of the coolant system. In the present work, a coolant/air multiphase VOF method was utilized using the commercial CFD software SimericsMP+® to study the coolant filling and subsequent de-aeration process in a Battery Electric Vehicle (BEV) cooling system. First, validations of the numerical simulations against experiments were performed for a simplified coolant recirculation system. This system uses a tequila bottle for de-aeration and the validations were performed for different coolant flow rates to examine the de-aeration efficiency. A similar trend of de-aeration was captured between simulation and experimental measurement. Next, the same numerical techniques were further applied to a BEV cooling system to evaluate the efficiency of de-aeration processes. The first step of the process involved a vacuum filling simulation. After the filling process, the air remained in the system is about 10% of total system volume. Different combinations of a multi-position valve and pump on/off cycles strategies were explored to decrease trapped air in the system. It is found that the opening/closing strategy of the multi-position valve plays a crucial role for an effective de-aeration. The devised methodology is observed to be numerically robust and accurate, while having good computational efficiency for modelling the coolant filling and de-aeration process that takes large physical time.</div></div>
<div class="section abstract"><div class="htmlview paragraph">The thermal performance of an engine coolant system is efficient when the engine head temperature is maintained within its optimum working range. For this, it is desired that air should not be entrapped in the coolant system which can lead to localized hot spots at critical locations. However, it is difficult to eliminate the trapped air pockets completely. So, the target is to minimize the entrapped air as much as possible during the coolant filling and deaeration processes, especially in major components such as the radiator, engine head, pump etc. The filling processes and duration are typically optimized in an engine test stand along with design changes for augmenting the coolant filling efficiency. However, it is expensive and time consuming to identify air entrapped locations in tests, decide on the filling strategy and make the design changes in the piping accordingly.</div><div class="htmlview paragraph">In the current effort, a simulation-based testing method for coolant filling and deaeration processes is developed for an engine coolant system using an advanced 3D Computational Fluid Dynamics (CFD) tool, Simerics-MP+. The multiphase flow of coolant and air in a 38-litre coolant system for Cummins OFF-highways Tier 4 engine are modeled and analyzed in detail to identify the air entrapped locations and predict the coolant filling efficiency. Explicit Volume of Fluid (VOF) approach with high resolution interface tracking scheme is used to capture the sharp coolant-air interface for better conservation of mass for both the phases. The simulation is performed for gravity filling followed by stabilization, deaeration at different pump speeds, and a drawdown process to understand the effect of leakages. The computed coolant filling efficiency matches within 5% with the test data at the end of gravity filling and deaeration processes. The complete simulation process is automated through a Python script which helps to reduce the run time up to 30% without any manual intervention.</div></div>
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