DETECTION METHOD OF AMMONIA LEAKAGE FROM LIQUID LINE OF COLD STORAGE REFRIGERATION SYSTEM BASED ON PRESSURE AND FLOW RATE TIAN S.(*,**), DU J.(***), GAO Y.(*,**), SHAO S.(*), TANG M.(*), ZOU H.(*) (*) Beijing Key Laboratory of Thermal Science and Technology, Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, China, (**) University of Chinese Academy of Sciences, China, (***) Henan University of Animal Husbandry and Economy, China