Design And Optimization Of Air Supercharging System For Fuel Cell Vehicles

With the depletion of petroleum resources and the increased pollution of environment,people begin to search for new clean energy.PEMFC(proton exchange membrane fuel cell)has aroused extensive research by scholars due to its high energy conversion rate,zero emission and low operating noise.However,the fuel cell system is difficult to be widely adopted due to its high manufacturing cost.As the air supply component of fuel cell cathode,air supercharging system has a large parasitic power consumption,accounting for 80% of the fuel cell's auxiliary power consumption.Its performance directly affects the efficiency of the fuel cell system.Thus,a fuel cell vehicle air supercharging system with low power consumption is designed in this paper in order to promote the use of fuel cell systems.The research contents are as follows:Firstly,an air supercharging system was designed for PEMFC,equipped with a compressor to pressurize the air and an expander to recover the exhaust energy of the electric reactor.Numerical simulations of fluid field of compressor and expander indicated that the designed compressor and expander can meet the requirements of rated working condition.According to the design of compressor and expander structure,this paper disposed a high speed motor and completed the structure of air supercharging system.Secondly,the effects of the compressor's blade inlet installation angle,blade outlet installation angle,blade package angle,blade profile and diffuser outlet diameter on its performance were studied.In order to decrease the power consumption of centrifugal compressor,the Kriging approximation model combined with grey wolf optimization algorithm were used to optimize the compressor with multiple parameters at the same time.The optimization results demonstrated that,while meeting the requirements of rated operating conditions,the optimized centrifugal compressor's isentropic efficiency increased by 4.23%,the power consumption decreased by 5.31%,and the surge margin increased by 2.4% under the rated flow.Meanwhile,when the flow rate of the compressor is less than the rated flow rate,the pressure ratio is increased and the power consumption is reduced,which contributes to the improvement of the net output power of the fuel cell system.Thirdly,the strength of compressor impeller and expander impeller in overspeed state and working state and the influence of aerodynamic force and temperature field on the maximum stress of impeller were analyzed.By calculating the maximum axial force of the rotor system,it was verified that the thrust force of the air bearing can balance the axial force.Through modal analysis,it was proved that the rated working speed of the rotor system can avoid the vibration point.Finally,the experimental flow and measurement system of the fuel cell vehicle air supercharging system are designed,which provides technical support for future experiments.In this paper,the air supercharging system prototype is obtained through design and numerical simulation.Then the performance of the compressor is optimized by using the multi-parameter optimization method,and the strength of the impeller and the dynamic characteristics of the rotor system are explored.The research results can provide a technical reference for the design of high-performance air supercharging system for fuel cell vehicles.