Study On Ammonia Leakage Diffusion And Hot Gas Defrosting Liquid Hammer Of Refrigeration System

Some special properties of ammonia make it an ideal material for cold storage. About 80% of the Chinese cold storage use ammonia as refrigerant. However, ammonia is dangerous. The leakage of ammonia in the cold storage refrigeration system will cause the production safety and food safety accidents, even affect public safety. There is a big risk hidden in the process of hot ammonia defrosting in cold storage and it is often ignored by people. Therefore, it is very necessary to study the ammonia leakage diffusion and hot ammonia defrosting process of the cold storage refrigeration system, to find the regularity and take corresponding measures quickly and timely and reasonably for accident prevention. The research of this paper will play an important role in ensuring food safety and public safety in the process of urbanization in China, broaden and deepen the research meaning of the safety of cold storage and cold chain. This will promote the development of related disciplines and related technologies, to provide a theoretical basis for the relevant decision-making at all levels of governmentFirst of all, the ammonia leakage accidents occurred in recent years were counted. The research process of dangerous gas leakage at home and abroad were analyzed. And a brief introduction to the ammonia detection method was introduced. Secondly, the paper introduced and analyzed the principle of the ammonia leakage, diffusion, hot ammonia defrosting, different leakage source model, diffusion model and the factors affecting the diffusion. Thirdly, the ammonia leakage model was established under the condition of accident, and the leakage of ammonia in several typical thermal state were simulated by using ANSYS software. Through the detection and analysis, the equipment and parts prone to leak and the ammonia concentration distribution in the refrigeration room caused by micro leakage under normal condition were found in the refrigeration room. In the end, the destructive effect of the liquid hammer was analyzed. A program was wrote by Visual Basic to calculate the length of pipeline which liquid hammer could make it broke up. ANSYS software was used to establish the force model of the pipeline, and the force of the pipeline was simulated and analyzed.The simulation results of ammonia gas, ammonia liquid and gas liquid mixtures in the refrigeration system were in agreement with the theory. The diffusion process of ammonia leakage was effected by the different thermodynamic parameters. The suggestion length of the gas return pipe was put forward, and the length of the pipeline which calculated by programming was in accordance with the results of the simulation.