The Operations of the Cone Calorimeter by Using it to Quantitatively Analyze Various Samples - Lab Report Example

Abstract Calorimetry is the measure of the heat evolved during a chemical process or heat required to sustain a chemical process. Calorimeter is a device used to measure the heat in a quantitative manner within control conditions. The same principle is applied in cone calorimeter. Cone calorimeter is an important laboratory device used to measure the characteristics of fire of small samples of various materials. Cone calorimeter measures the various aspects of combustion of substances utilising the principle of oxygen combustion calorimetry. Cone calorimeter has been specifically made to use the oxygen consumption calorimetry principle. (Mouritz, A. Gibson, 2007). The most important element in any combustion is the availability of oxygen. The overall heat produced during the combustion of an organic material has a direct correlation to the quantitative aspect of oxygen. There are various basic aspects of heat that provide much information when doing experiments concerning heat. Heat capacity can be quantified in terms of molar heat capacity which is the heat capacity of a particular compound divided by the number of moles of that compound. Another quantitative aspect of heat capacity is specific heat which is the heat of an element divided by its mass. It is also important to note that heat capacity of any substance always has a positive value. Other aspects of fire and combustion in general that need consideration when working with a cone calorimeter include: the cumulative quantity of heat released, the rate of heat released per unit area, the time of ignition, the effective heat of the combustion, the total loss of mass, the rate of the loss of the mass and the smoke obstruction. These are important aspects during an experiment because they may lead to variable results for the same material if at all they are not considered during the experiment. (Taylor and Francis, 2006). Introduction The cone calorimeter works by measuring the heat produced by a sample burned in a closed oxygen atmosphere, enclosed by water and in control experimental conditions. The basic principle behind the functioning of cone calorimeter still remains the same. The instrument is made from the understanding of the engineering aspects of fire. Aim of the Experiment The aim of the experiment is familiarization of the operations of the cone calorimeter by using it to quantitatively analyse various samples. The samples include blue carpets, green carpets and experiments on various underlay. Objective of the experiment The objective of the experiment is to analyse the various properties of fire which include: the cumulative quantity of heat released, the rate of heat released per unit area, the time of ignition, the effective heat of the combustion, the total loss of mass, the rate of the loss of the mass and the smoke obstruction. The blue carpets, the green carpets and the underlay will both be analysed by doing each of the experiments three times in order to find a more reliable average of the results. Background The cone calorimeter has been used for many years for the analysis of combustion properties of various substances; therefore the results from the experiment should be able to provide a credible source of information about the different substances. (Haines, B. 2006). Results and Discussion 21.69g of the blue sample having a surface area of 100cm2 and 8mm thick produced a heat flux of 25KW/m2. The following observations were made in a time of 481 seconds. The heat evolved by the first blue carpet was 45.5MJ/m2. The subsequent results were then tabulated as follows: Tested properties First blue carpet Second blue carpet Third blue carpet Fourth blue carpet Sample of mass Surface area Thickness Heat Flux of the experiment Time of test 21.96g 100cm2 8mm 25KW/m2 418seconds 17.3g 100cm2 8mm 35KW/m2 378seconds 24.9g 100cm2 8mm 45KW/m2 715seconds 27.6g 100cm2 8mm 55KW/m2 458seconds Total heat evolved Total amount of oxygen consumed 45.5MJ/m2 31.8g 34.9MJ/m2 24.7g 34.9MJ/m2 27.5g 38.8MJ/m2 24.7g Smoke released 651m2/m2 474m2/m2 449.4m2/m2 736.3m2/m2 Mass lost during the experiment Specific mass loss rate Average heat released rate 12.1g 2.79g/m2 108.79KW/m2 13.2g 5.09g/m2 103.45KW/m2 12.4g 1.82g/m2 57.32KW/m2 13.2g 3g/m2 87.95KW/m2 Effective heat of combustion Mass loss rate Specific extinction area Carbon monoxide yield 38.66MJ/Kg 0.028g/sec 494.81m2/kg 0.0194kg/kg 20.88MJ/Kg 0.051g/sec 204.47m2/kg 0,0149kg/kg 31.41MJ/Kg 0.018g/sec 180.12m2/kg 0.0126kg/kg 28.83MJ/Kg 0.030g/sec 506.11m2/kg 0.017kg/kg Results of the Experiment with blue carpet sample In the experiment it was observed that as the heat flux increased there was a decrease in the rate at which the heat was evolved with the minimum value being 45kw/m2. The total amount of oxygen consumed was uniform regardless of the recorded heat of flux. The mass of the specimen that was lost was constant and was not dependent on the rate of heat of flux. The lowest recorded heat of release was 45kw/m2. Properties tested First blue carpet Second blue carpet Third blue carpet Fourth blue carpet Sample of mass Surface area Thickness Heat Flux of the experiment Time of test 13.68g 100cm2 5.5mm 25KW/m2 495seconds 12.95g 100cm2 5.5mm 35KW/m2 281seconds 12.65g 100cm2 5.5mm 45KW/m2 265seconds 12.17g 100cm2 5.5mm 50KW/m2 460seconds Total heat evolved Total amount of oxygen consumed 25.9MJ/m2 18.6g - - 309.7MJ/m2 -1174.7g 28.2MJ/m2 20g Smoke released 393.9m2/m2 - 486.2m2/m2 517.9m2/m2 Mass lost during the experiment Specific mass loss rate Average heat released rate 9g 2.45g/m2 57.53KW/m2 - - - 8.1g 3.25g/m2 1237.36KW/m2 9.6g 2.11g/m2 62.3KW/m2 Effective heat of combustion Mass loss rate Specific extinction area Carbon monoxide yield 23.10MJ/Kg 0.025g/sec 131.71m2/kg 0.0140kg/kg - - - - 380.66MJ/Kg 0.033g/sec 549.7m02/kg 0.0126kg/kg 29.21MJ/Kg 0.021g/sec 423.16m2/kg 0.017kg/kg Results of the Experiment with Green Carpets Sample The results with the green carpets established that there were no observable results at 35KW/m2 flux and that most values observed at 45KW/m2 were erroneous. It was only at 25KW/m2 and 50KW/m2 flux that comparison of the results could be made. However it was also observed that all the values were high as compared to the values at 25KW/m2 except for the average specific loss. The highest recorded amount of smoke was at 50KW/m2 The average amount of effective heat of combustion, heat released rate, specific extinction area, carbon dioxide and carbon monoxide yield were so high although the mass loss rate was slightly less at 50 KW/m2 Properties tested First blue carpet Second blue carpet Third blue carpet Fourth blue carpet Sample of mass Surface area Thickness Heat Flux of the experiment Time of test 10.46g 100cm2 10mm 45KW/m2 139seconds 11.6g 100cm2 10mm 25KW/m2 225seconds 12.12g 100cm2 10mm 35KW/m2 303seconds 27.6g 100cm2 10mm 55KW/m2 240seconds Total heat evolved Total amount of oxygen consumed 16.2MJ/m2 12g 16.3MJ/m2 11.9g 18.3MJ/m2 13.4g 23.6MJ/m2 17.4g Smoke released 416.6m2/m2 291m2/m2 305.7m2/m2 553.6m2/m2 Mass lost during the experiment Specific mass loss rate Average heat released rate 12g 8.63g/m2 118.71KW/m2 12.4g 6.85g/m2 74.94KW/m2 9.3g 3.15g/m2 61.44KW/m2 58.4g 21.93g/m2 99.55KW/m2 Effective heat of combustion Mass loss rate Specific extinction area Carbon monoxide yield 13.66MJ/Kg 0.086g/sec 338.71m2/kg 0.0291kg/kg 10.69MJ/Kg 0.069g/sec 154.9m2/kg 0.79kg/kg 19.49MJ/Kg 0.031g/sec 221.93m2/kg 0.0269kg/kg 4.48MJ/Kg 0.219g/sec 102.46m2/kg 0.0093kg/kg Results of the Experiment with Underlay samples The experiment with underlay samples only obtained reliable values at 35KW/m2 flux because at this flux all the recorded values were reduced to zero in four minutes. All the values were equally reduced to zero in 5 minutes at 25KW/m2 after 6 minutes at 55KW/m2 flux. The total mass lost, smoke released and the specific mass lose rate were all proportional to the heat fluxes that were used. At 55KW/m2 the mass lost and the average specific mass loss rate was very high as compared to other heat fluxes. The carbon monoxide and dioxide yields from ignition to ignition plus were almost steady at 35KW/m2 flux at all time intervals. Conclusion and Analysis The overall heat produced during the combustion of an organic material has a direct correlation to the quantitative aspect of oxygen. There are various basic aspects of heat that provide much information when doing experiments concerning heat. Heat capacity can be quantified in terms of molar heat capacity which is the heat capacity of a particular compound divided by the number of moles of that compound. Another quantitative aspect of heat capacity is specific heat which is the heat of an element divided by its mass. It is also important to note that heat capacity of any substance always has a positive value. (Babrauskas, V. 1990). In the experiment it was difficult to provide a comparison of the three materials that were used because the experimental conditions were different however rough comparison about heat fluxes could be made. For instance the blue carpet produced the largest total heat evolved and the highest quantity of smoke. Green carpet on the other hand recorded the lowest mass while the underlay had the highest average loss of mass. As for the specific extinction area the highest values were recorded with the blue carpet. The blue carpet also gave the highest records of the carbon dioxide and carbon monoxide. Usually the observed rapid reduction in ignition time is due to increasing heat flux caused by pyrolysis rate References Babrauskas, V. Heat Release in Fires, 1990 Crompton, T. Polymer Reference Book, Smithers Rapra Press, 2006. Haines, B. Principles of Thermal Analysis and Calorimetry, Springer publishers, 2008. Mouritz, A. Gibson, G. Fire Properties of Polymer Composite Materials, 1st edition, Springer Publishers, Pg 106-120, 2007. Taylor and Francis, Flammability testing of materials used in construction, transport and mining Woodhead Publishing in materials, 2006. Vytenis, B. Development of the Cone Calorimetry: A Bench Scale Heat Release Rate Appartus Based on Oxygen Consumption, National Technical Information Service. 1982 Read More