Experimental And Numerical Study On The Fire Extinguishing System Of High-rack Storage

With the rapid development of the logistics industry in our country, the demand for warehouse is increasing. High-rack storage, featured high space utilization, low cost investment and rapid building speed, is widely used in bulk goods logistics and storage. Due to special structure traits and storage characteristics, the fire risk of high-rack storage is greater than the one of ordinary warehouse. Consequently, the fire system design of high-rack storage is increasingly valued.The main method of this research is the combination of practical fire experiment and numerical simulation.Currently, in the research field of high-rack storage practical fire experiment, previous researches focused on ESFR and rarely compared the differences of the extinguishment characteristics between various fire extinguishing systems. On the experiment platform builded in the water mist laboratory of Kdlian safety technology Co.Ltd, the experiments are done on the experimental conditions ruled by GB5135.9-2006Automatic sprinkler system-Part9:Early Suppression Fast Response(ESFR) Automatic Sprinklers which is similar to the one on which FM Global laboratory and Tianjin fire research institute’s ESFR experiments are done. On the experiment platform, four kinds of fire extinguishing system are used in high-rack storage practical fire experiment:they are ESFR sprinkler system, closed high-pressure water mist fire extinguishing system, open low-pressure water mist fire extinguishing system and spray-type automatic jet fire extinguishing system. In experiments, the working pressure of sprinkler, ignition time, spray start time, flame extinction time and the quantity of goods burned were recorded, the temperature, heat radiation strength and sprinkler discharge rate were analyzed, and the system suitability, heat radiation strength, amount of lost carton, time needed for fire suppression and water consumption of different systems were compared. The results illustrate that:(1) ESFR and low-pressure water mist protect high-rack storage very well under the situation of the limiting height of storage and shelf on the experimental conditions ruled by GB5135.9-2006, while high-pressure water mist and spray-type automatic jet fire extinguishing system do not;(2) to all ordinary high-rack storages, ESFR would ensure that flames won’t spread between adjacent shelves when fire occurs in the high-rack storage, while low water mist also would ensure that but to the high-rack storage stored combustibles;(3) cartons are all damaged in ESFR experiment, while30%cartons are damaged in low-pressure water mist experiment;(4) to ESFR system and low-pressure water mist sysytem, the time needed for fire suppression is same;(5) the water consumption for fire suppression of low-pressure water mist system is15%of the one of ESFR system.On the basis of practical fire experiments, the model was built through FDS. The model was used to numerically simulate the fire of high-rack storage with ESFR sprinkler system and open low-pressure water mist fire extinguishing system respectively. First, the model was verified its suitability compared to the results of practical fire experiments; Next, change the ignition source to see if the two fire extinguishing systems still apply to high-rack storage fire. The results illustrate that:(1) the FDS model could predict the development process of fire of high-rack storage with ESFR sprinkler system and open low-pressure water mist fire extinguishing system;(2) ESFR could extinguish the fire of high-rack storage with the ignition source on the bottom of the third and fourth level of the storage rack, while open low-pressure water mist fire extinguishing system could also do that but to the condition that the ignition source is on the bottom of the fourth level.