The Design And Development Of Emissivity Online Measuring System

With the booming development of China’s aviation, aerospace, national defense andenergy, the research on the object’s thermal condition has increasingly been paid attentionto. Emissivity is a parameter to assess the heat emission and thus is much of value. Theemissivity is susceptible because of various factors, so it is a hot issue to measure theemissivity online in situ, portably and reliably.This thesis analyzes the radiation response mechanism of the photoconductive (PC)sensor and suggests the variation of the sensor’s photosensitive resistance has a linearrelationship with the radiation energy, furthermore, the emissivity can be calculated by theradiation energy method. According to the requirement, this thesis proposes the overallscheme which consists of PC sensor with thermoelectric cooler (TEC) inside, thesingle-cover probe, circuit design, software design of signal detecting and informationprocessing. It introduces the design of temperature measuring and controlling module indetail and accordingly, the PID control algorithm is realized. A lot of experiments arecarried out, such as temperature control test, background radiation test, sample plateradiation test and sensitivity test. Then it gives out the measuring values of sample plates’emissivity preliminarily and analyses the test results. The result proves it is reasonable thatthe resistance variation of PC sensor is linear with radiation.The emissivity online measurement system has a portable and small probe structureand the ability of overcoming the temperature influence on the system. It can measure theemissivity steadily and basically reach the requirements of online measurement. It lays thefoundation of the future design of the portable online emissivity measuring equipment andalso accumulates much experience.