The Key Technology Research On Vehicle Occupied-zone Air Conditioning System Based On Semiconductor Refrigeration

With the rapid growth of car ownership,the emergency of environmental and energy issues are becoming more and more prominent.It’s worth noting that when a car running with only a driver,the power consumption of the traditional air conditioning system used to cool the whole cabin will reach 3 kW,which will cause a great waste of energy and have negative impact on vehicle dynamic characteristics.What’s worse,the leakage of refrigerant HFC-134 a will intensify the greenhouse effect.On this occasion,it is worth to study the novel vehicle occupied-zone air conditioning system(OZAC)which is used to only adjust the local thermal environment around the driver.OZAC system is able to ensure the driver’s local thermal comfort and save energy.Compared with the conventional refrigeration technology,semiconductor refrigeration technology posses the advantages such as no refrigerants,compact conformation,no moving parts,precise temperature control,so semiconductor refrigeration is very suitable for the local thermal environment adjustment in the cabin.OZAC system comprised by several thermoelectric cooling devices(TEDs)can not only satisfy driver’s local thermal comfort but also save energy,but the study of OZAC system is just confined to buildings and the application in vehicle is almost blank.This paper will study the key techniques of OZAC system through theoretical research,numerical simulations and experimental study.First of all,the paper studies the fundamental theories of semiconductor refrigeration,establishes the thermodynamic model which is based on heat transfer and analyzes the influences of different factors on the refrigerating performances of TEDs,which provides the theoretical foundation for the design of OZAC system.The paper presents 2 design schemes of the OZAC system,simulates two schemes which are adapt to the cabin environment and studies the change rules of the refrigerating performances.The paper studies the relationship between working current,outlet air temperature and input power through bench tests of TEDs.Then put the TEDs into the truck cab and study the refrigeration effects and comfort effects of OZAC system through real vehicle tests.The paper establishes the 3D model of a truck containing a precise human model and studies the internal flow field distribution in the truck cab and the temperature distribution of the human model surface based on CFD technology.Two thermal comfort evaluation indexes are chosen to analyze driver’s thermal comfort under different operating conditions of OZAC system and potential defects of OZAC system are found.Then six outlet air temperatures of TEDs are chosen to be design variables,human thermal sensation aberration and input power of OZAC system are chosen to be optimization goals.The integrated performances of OZAC system are optimized by the approximation model and the genetic algorithm.The study of this paper shows that under the optimal solution,the human overall thermal sensation aberration is about 0.363 and almost all parts of the driver’s body are kept in the thermal comfort states.What’s more,the total energy consumption of OZAC system is about 803.8W and OZAC system uses less 66% energy than the traditional automotive air conditioning system.The above results indicate that OZAC system based on semiconductor refrigeration has obvious energy saving effects.