Abstract
About 2/3 of the combustion energy of internal combustion engine (ICE) is lost through the exhaust and cooling systems during its operation. Besides, automobile accessories like the air conditioning system and the radiator fan will bring additional power consumption. To improve the ICE efficiency, this paper designs some coupled thermal management systems with different structures which include the air conditioning subsystem, the waste heat recovery subsystem, engine and coolant subsystem. CO2 is chosen as the working fluid for both the air conditioning subsystem and the waste heat recovery subsystem. After conducting experimental studies and a performance analysis for the subsystems, the coupled thermal management system is evaluated at different environmental temperatures and engine working conditions to choose the best structure. The optimal pump speed increases with the increase of environmental temperature and the decrease of engine load. The optimal coolant utilization rate decreases with the increase of engine load and environmental temperature, and the value is between 38% and 52%. While considering the effect of environmental temperature and road conditions of real driving and the energy consumption of all accessories of the thermal management system, the optimal thermal management system provides a net power of 4.2 kW, improving the ICE fuel economy by 1.2%.
Highlights
The internal combustion engine accounts for about 66% of the oil consumption [1,2,3]
The coolant radiator fan consumes about 10% of the output power of the internal combustion engine [5]
There are many subsystems and components in the coupled heat management system, and the structure is complex, so the analysis of subsystem performance can provide the foundation for coupling subsystems and designing a comprehensive thermal management system
Summary
The internal combustion engine accounts for about 66% of the oil consumption [1,2,3] It can only convert 1/3 of the total energy of fuel combustion into power output when it works, and most of the energy is removed by the exhaust and coolant systems [4]. Internal combustion engine waste heat utilization and vehicle accessory system offer a great energy saving potential. Chen [9] in Sweden used a CO2 power cycle for waste heat utilization of internal combustion engines, and 20% of the exhaust energy was converted into output power. Few scholars have integrated integrated and and optimized optimized the the thermal thermal management management system system as as a whole system, failing to integrate waste heat recovery technology, technology, air air conditioning conditioning systems, systems, engines engines and and coolant coolantsystems.
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