UHC System Sizing to Eliminate Engine Overheating when Grill and Radiator Fronts are Partially Blocked by Mud & Dirt Integrated Simulation Technologies Pvt Ltd Subir Mandal IST India GT-SUITE Conference 2018 1
Engine Cooling System Maintain the working temperature of every engine components below the safety limit Thermal balance between the heat extracted from the engine hardware and the heat released to external ambient through radiator 1 2 Engine performance/efficiency Emissions Reliability of the components Clearance of the engine s static and moving parts Carburetion Lubricant properties 3 Rated power Peak torque Idle Hot air Blockage Climbing 4 Heat transfer area Coolant flow Airflow 2
Problem Statement Tractor engine 50 O C ambient air temperature 25% of both front grill and radiator core are blocked by mud and dirt Less temperature gradient between coolant & ambient air Less heat rejection in radiator Less airflow through radiator Less heat rejection in radiator Engine overheating (T_Coolant_EngOut > 110 O C) Suggest design improvement to eliminate engine overheating when it operates under worst conditions 3
Virtual Cooling System Model Pump Flow domain Engine Grill Opening Heat addition Radiator UHC Discretized UHS Engine cooling system circuit Front grill blocked Radiator front blocked Underhood system in Quasi-3D environment Underhood system in Quasi-3D environment Fan shroud Fan Outlet Quasi-3D UHS Radiator Fan 4
Challenges Fan map data: Insufficient number of data points Extremely raw data set Map was rationally scaled to match performance Radiator performance map data: Insufficient number of data points Data was rationally pre-processed to get a good fit of performance parameters Coolant properties vs engine heat addition: Heat addition from engine to coolant was calculated analytically Adjustment to make heat addition, temperature rise, and coolant properties (ρ, Cp) compatible Modeling blockage due to mud and dirt: Front grill Front of radiator 5
Model Calibration 8 operating points including rated power, peak torque Ambient temperature = 42 O C No blockage of front grill and radiator front Predicted radiator inlet and outlet temperature w.r.t. their measured values within ±1.2 O C 6
Performance under Worst Conditions (1/2) Engine overheating limit is crossed by 1 O C 6 O C under 50 O C hot ambient & no blockage conditions Engine overheating limit is crossed by 17 O C 24 O C under 50 O C hot ambient & blockage conditions 7
Performance under Worst Conditions (2/2) 8 O C increase in ambient temperature leads to 8.5 O C temperature rise for both engine out coolant and radiator out air 25% blockage resulted in temperature rise of 17 O C for engine out coolant; and 6 O C for radiator out air There is a reduction in airflow through radiator by 16.5% due to 25% blockage 8
Model Validation 25% of front grill blocked 25% of radiator front blocked Parameters Unit Rated power Peak torque Simulation Measured Simulation Measured dt_coolant_engout for T_Amb change 42 O C to 50 O C K 8.6 8 8.7 8.1 dt_coolant_engout due to 25% blockage K 18.5 19.7 17.7 18.4 dairflowrate_rad due to 25% blockage % -16.6-15.8-16.5-16.2 Virtual cooling system model is robust enough to be used for further investigation 9
Approach to Eliminate Engine Overheating 25 mm taller & 20 mm wider radiator core - Tube length = +25 mm - Number of tubes = +(2x5=10) 100% increase in coolant flow rate - Higher pump power consumption Temperature reduction of 6 O C 8 O C A-1 A-2 100 mm taller & 100 mm wider radiator core - Tube length = +100 mm - Number of tubes = +(10x5=50) 100% increase in coolant flow rate - Higher pump power consumption 25% increase in airflow rate - Fan drive ratio from 1.7 to 2.6 OR through larger diameter fan - Higher fan power consumption - More space required 25 mm taller & 20 mm wider radiator core - Tube length = +25 mm - Number of tubes = +(2x5=10) 100% increase in coolant flow rate - Higher pump power consumption A-3 65-80% increase in airflow rate - Fan drive ratio from 1.7 to 3.2 OR through larger diameter fan - Higher fan power consumption - More space required Temperature reduction of 19 O C 26 O C Temperature reduction of 19 O C 27 O C 10
Contours Plots of Radiator Air velocity at radiator inlet No blockage @ 50 O C 25% blockage @ 50 O C 25% blockage @ 50 O C @ Optimized Coolant side temperature No blockage @ 50 O C 25% blockage @ 50 O C 25% blockage @ 50 O C @ Optimized 11
Conclusion Recommended UHC system arrangement to eliminate engine overheating 25 mm taller & 20 mm wider radiator core - Tube length = +25 mm - Number of tubes = +(2x5=10) 100% increase in coolant flow rate - Higher pump power consumption 65-80% increase in airflow rate - Fan drive ratio to be increased from 1.7 to 3.2 OR through larger diameter fan - Higher fan power consumption - More space required The new radiator has heat rejection capacity 12 kw higher than the existing one 12