Title: Cone calorimeter- Energy transfer and ThermodynamicsIntroductionA cone calorimeter is a modern device that is used for the burning of samples of different materials and together relevant information relating to the combustion products, release of heat and other disciplines as are associated with the combustion process. The device is widely used in the field of fire safety engineering regarding the mass loss, ignition time, heat release rate, combustion product along with other parameters as are associated with the burning properties of the materials. The device usually permits the fuel samples to expose to the different heat fluxes through the Hogget's principle that describes that the grass heat of combustion of any organic material is directly proportional to the amount of oxygen required for the combustion process (Hugget, 1980).
The principle of oxygen calorimetry is applied for the measurement of heat through the cone calorimeter (Babrauskas and Peacock, 1992). The device is basically used to determine different properties of fire like, the rate of heat release per unit area, effective heat combustion, cumulative heat released, and time to ignition, mass loss rate, smoke obstruction and total mass loss during the process of combustion.
(Blomqvist and Rosell, 2004). The name of the device comes from the conical shape of the radiant heater that usually produces a uniform heat flux over the surface of the sample under study through the cone hoods as with the utilization of the cone calorimeters. Heat flux is also called as thermal flux is the heat flux density or heat flow rate intensity which is a flow of energy per unit area of time and in SI units its units are W·m-2·s-2 and is only measured with the help of cone calorimeter.
The results of the experiments have been drawn with the use of blue carpets, green carpet sample and underlay samples. A diagram of the cone calorimeter is attached at annex –A. Results of the Experiment with the Blue Carpet SamplesA blue carpet sample of with a mass of 21.966g, surface area as 100 centimeter square with a thickness of 8mm has shown a heat flux of 25kW/m2. The test was lasted for 490 seconds for first blue carpet, 370 seconds for second blue carpet, 710 seconds for third blue carpet and 450 seconds for fourth blue carpet.
The results as were recorded are summarized below: Parameters testedFirst blue carpet Second blue carpetThird blue carpetFourth blue carpet. Sample of mass 21.966g17.60g25.1g27.8gSurface area100cm2100cm2100cm2100cm2Thickness 8mm8mm8mm8mmHeat flux of the experiment25kW/m235kW/m245kW/m255kW/m2Time of test490 seconds370 seconds710 seconds450 secondsTotal heat evolved45.5MJ/m234.3MJ/m239.4MJ/m238.8MJ/m2Total amount of oxygen consumed31.6g24.5g27.3g 27.2gSmoke released650m2/m2472m2/m2449.7m2/m2736.5m2/m2Mass lost during the experiment12g13.1g12.6g13.4gSpecific mass loss rate2.80g/m2s5.10g/m2s1.84g/m2s3.1g/m2sAverage heat release109kW/m2103.50kW/m257.35kW/m287.98kW/m2Effective heat of combustion38.88MJ/Kg20.90MJ/Kg31.45MJ/Kg28.87MJ/KgMass loss rate0.030g/sec0.053g/sec0.020g/sec0.031g/secSpecific extinction area494.86m2/kg204.50m2/kg180.14m2/kg506.13m2/kgCarbon monoxide yield0.0195Kg/kg0.0150Kg/kg0.0128Kg/kg0.0172Kg/kgCarbon dioxide yield2.06Kg/kg1.23Kg/kg1.70Kg/kg1.67Kg/kgThese results have shown that the average heat release rate has been recorded as 57.35kW/m2 as the minimum heat release rate and 109kW/m2 as the maximum heat release rate for the first blue carpet.
The total amount of oxygen as consumed during the combustion process has demonstrated 31.6 g for the first blue carpet as the highest amount of oxygen as was used during the experiment and 24.5 g as the lowest amount of oxygen consumed during the process. However, the amount of mass lost during the experiment does not correspond with the amount of oxygen consumed for the blue carpets as the results have demonstrated 13.4g for the fourth blue carpet whereas the results would have to be on the higher side for the 1st blue carpet where the oxygen combustion was the highest that is 31.6g.
The high average mass loss during the experiment as remained 13.4g was probably due to small sample weights that was used in the experiment as 17.60g as the minimum and 27.8g as the maximum sample mass (Blomqvist and Rosell, 2004). Total heat evolved as 34.3MJ/m2 as the minimum heat evolved for the second blue carpet and 45.5MJ/m2 as the maximum heat evolved first blue carpet has demonstrated partial results as in their correct format as was expected in relation to the oxygen used and partial as a deviation from the expected result as for the second blue carpet.
All of the remaining values have followed a similar pattern that of oxygen consumption and heat release for the first, second, third and fourth blue carpets.