Date of Award

12-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Wagner, John

Committee Member

Dawson , Darren

Committee Member

Schweisinger , Todd

Abstract

The depletion of fossil fuel reserves and the limited renewable energy resources have raised public awareness about the need to improve fuel efficiency in ground transportation vehicles. The internal combustion engine remains one of the primary industrial machines using gasoline or diesel fuel to produce mechanical work. In these engines, the cooling system performs the vital role of removing waste heat to ensure normal combustion processes in the cylinders. To accomplish this task, the radiator, the radiator fan(s), the thermostat valve, and the water pump operated by circulating cooling fluid through the engine block and rejecting heat to the atmosphere. Studies have shown that the cooling system removes approximately 30% of the engine`s indicated power as waste heat. Since the cooling system consumes a portion of the engine power, it is important that its operation use minimum input energy. In this study, multiple radiator fans were controlled to minimize energy usage for subsequent efficiency gains. Simply put, this research found that improvements in the thermal management system can improve overall engine efficiency.
A reconfigurable smart cooling system test experimental bench was fabricated at Clemson University to test and analyze the cooling effect multiple electric radiator fans. This cooling system emulated a 6.8L International Truck and Engine Corporation V8 diesel engine application with an array of 3 rows by 2 columns (6 total) radiator fans. The speed of each fan was controlled from 0% to 100% maximum capacity. A dedicated controller area network (CAN) bus controller was interfaced to the fan driver hardware and electric power source to control the system operation. The air speed, coolant flow rate, fluid (air, coolant) temperature, and power consumption sensors were connected to a dSPACE data acquisition board, on which data were recorded. The dSPACE and Plus+1 hardware were controlled in real-time using a MATLAB/Simulink algorithm operating at a 10 Hz frequency.
A series of laboratory tests were conducted with different fan combinations and rotational speeds, the objective being to cool a constant thermal loaded engine. A simplified mathematical model for the combustion process and the forced convection radiator system was developed to establish a basis to formulate a smart cooling control problem. The collected data was analyzed to determine the fan power consumption and radiator system cooling effectiveness. The experimental results demonstrated that the selection of specific fan combinations and fan motor speeds can achieve up to a 20% reduction in fan matrix power consumption for the specified cooling load. Further, air velocity surface plots offered a visual representation of the air flow profile across the radiator for different fan matrix configurations.

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