Research On Testing System Of Heat Release Rate In Multichannel Parallel Method

In recent years, with the rapid development of economy and the improvement of people’s living standard, the frequency of fire is gradually increased, which causes great harm not only to the personal safety and property but also to the economy. Science research on fire plays a key role in the prevention of fire and reducing casualties and property losses, among which the heat release rate is the most important parameter in fire research and engineering design.Based on oxygen consumption method for heat release rate, this paper sets up the multichannel parallel testing system for heat release rate, combining with the establishment of railway tunnel rescue station. On the basis of this test system, a series of fire experiments of both standard combusted material and train fire simulation were implemented. Using the numerical simulation method, the author study the spill of smoke and the effect of different wind speed within the smoke exhaust passage on test results of heat release rate.This paper, first of all, analyzes the oxygen consumption testing theory for heat release rate and still the feasibility of multiple parallel test modes from the theoretical perspective, which laid the theoretical foundation for this article. Based on this theory, employing fullsize physical model of railway tunnel rescue station, this paper built two parallel test systems for heat release rate: smoke exhaust system and smoke testing system. Smoke exhaust system included combustion chamber, smoke collecting cover, two paralleled smoke exhaust pipes, rectification of parallel grating, smoke extraction fan and its control system of frequency conversion, etc. In the smoke test system, this paper analyzed test results of the zirconia sensor and of the magnetic needle of the oxygen analyzer. Results showed that paramagnetic oxygen analyzer and zirconia sensor both can be used for the measurement of O2 level, and the precision and response speed of paramagnetic oxygen analyzer are better than the zirconia sensor, when the measurement accuracy is not high, we can use the zirconia sensor instead of paramagnetic oxygen analyzer. At the same time, the control configuration software to monitor the operational status of entire system is used.This paper also implemented fire experiments using standard combustion material and monitored the multichannel parallel testing system for heat release rate, which investigated the system’s relative error and repeatability. Besides, this paper studied the effect of opening system and semi-opening system on fire development using simulated fire experiments of train carriages. Results showed that when the fuel is burned in a semi-open system, affected by the space of half open system, it can not make the combustion heat discharge from the system in time so as to strengthen the heat feedback effects of fuel, accelerate fuel paralysis process with the result that the combustion process is more violent, leading to that the peak of heat release rate, fire growth rate, the radiation heat flux and the concentration of CO2 in flue gas are greater than these of the open system. At the same time, since the heat can’t deliver ou of train, leading to the temperature above fire source of test bench in rescue station and of measuring section in smoke exhaust passage are lower than that of fire in open system.Finally, this paper used FDS to simulate and calculate the effect of smoke spilling and uncoordinated wind speed within the smoke evacuation on test result of hest release rate, and then verify the feasibility of multichannel parallel test system from the aspect of numerical calculation. The results showed that the smoke overflow system will affect the measurement result of heat release rate. First of all, smoke overflow will make test results of oxygen consumption for heat release rate less than actual heat release rate, the greater the amount of smoke leakage, the smaller the system test peak of heat release rate. Second, compared with the actual combustion process of fuel, oxygen consumption test method can make the measurement results lag behind to some extent, the smaller the wind speed in smoke evacuation passage, the greater the amount of smoke leakage, the more the measurement results will be delayed.Innovations of the paper lie in the proposal of multichannel parallel test method of heat release rate based on oxygen consumption, and the establishment of multichannel parallel test system combined with railway tunnel rescue station. In the form of two parallel patterns, the system can be used in experiment research on heat release rate in both large scale fire and train fire; the numerical simulation method can be used for studying the influence of smoke spillover, uncoordinated wind speed in smoke evacuation passage on the test result heat of release rate.Due to the limited time, this paper only made some experiments for multichannel parallel test system for heat release rate. In the later study, the material source types can be expanded, the experiment data can be rich and multichannel parallel can be developed and its application on various circumstances can be studied with the aim to optimize this system. In addition, developing the low cost and high precise test methods for O2 level is another important research orientation.