Study On CO₂ Detection Technology Based On TDLAS In Agricultural Transportation Refrigerated Vehicle

China is a big agricultural country, in recent years, China’s main agricultural products are all growth. However, with the increasing of agricultural products, coupled with agricultural postharvest will continue respiration and produce gases such as carbon dioxide, lots of agricultural products appeared contamination, deterioration, decay and so on. One of the main reasons for this phenomenon is the poor circulation of agricultural products cold chain, and the lagging of the agricultural products cold chain is the key factors influencing the circulation of agricultural products. Refrigerated vehicle as the important link in storage, transportation, and distribution of the cold train logistics, its characteristics, such as insulating, refrigeration, convenience, play an advantage role in perishable agricultural products logistics such as fruits and vegetables, eggs, meat, aquatic products.TDLAS (Tunable diode laser absorption spectroscopy) is a new developed spectrum detection technology in recent years, because of its high sensitivity, high precision, rapid response, and is suitable for bad environment and so on, it is widely used in the field of gas detection. In this paper, put forward CO2 gas detection technology in refrigerated vehicle based on TDLAS. On the basis of basic theory, expound the principle of TDLAS, discussed the relationship between the second harmonic and the gas concentration, and chose the absorption spectroscopy line of carbon dioxide.Designed the TDLAS system, each parts of the TDLAS system was introduced, and every device was selected, at last CO2 gas detection system in refrigerated vehicle based on tunable diode laser absorption spectrum technology was set up.On the basis of the set up system, adjust the parameters of every device to make the TDLAS system reach the optimal conditions, took the 100%concentration of CO2 gas for example, the system noise and pretreatment process were discussed. Then 1%-10% concentration of gas were collected, data preprocessed and inversion of the concentration respectively, finally get the conclusion of TDLAS system can be applied in refrigerated vehicle to detect the CO2 gas.As the CO2 gas concentration is not stable in the refrigerated vehicle, the CO2 concentration is too high or too low will harm to the agricultural production in refrigerated vehicle. Therefore, grey-RBF predict model was used in this paper to predict the CO2 concentration in the refrigerated vehicle, and Statistics Process Control theory was used to give an alarm,to control the concentration in a stable state, prolong the preservation time of agricultural products.