Design and Analysis of an Exhaust Gas Hybrid System for Automotive Air Conditioning

Automotive air conditioning systems consume a significant amount of fuel energy. In this study, the enthalpy energy available in exhaust gases is evaluated and different factors, affecting it, are discussed. Then an exhaust gas hybrid system for automotive A/C is designed. Based on conducted dynamometer tests, it is found that the exhaust gases can drive the system power turbine; hence enabling it for rotating the A/C compressor. The produced power depends on many factors. Indeed it increases from (1.316 kW) to (2.633 kW) as the engine is loaded up to 100%. Similar effects on this power are observed as engine (rpm), size, number of cylinders and compression ratio augment. Concerning the engine backing power for the produced power; it is found that it decreases as the engine loading increases and Tambient decreases, thus reducing fuel consumption. Furthermore, the new system is more suitable for vehicles with large size engines and smaller cabins where lesser engine partial loads can mostly provide sufficient power for driving the A/C compressor. For the system design, the incorporation of a motorized adjustable tensioner with a torque sensor and an (ECU) enables the system to minimize the engine energy consumption and decrease the exhaust gas pollution. Indeed the findings show that if the engine runs at a partial load (50%) the new A/C system will save about (60%) of the power consumption for air conditioning.