Semi-Volatile Unadulterated Artificial Laser Doppler Imaging of Blisters - Assignment Example

A1. Dimethylnitrosamine (DMN), is a semi-volatile organic chemical that is highly toxic and is a suspected human carcinogen and appears to poison the human liver. Other symptoms included headache, fever, vomiting, abdominal pain, scattered intradermal hemorrhage, lethargy, nausea, and diarrhea. This substance C2H6N2O is water-soluble, colorless, and has at best a weak taste and odor. If DMN is perfectly combusted in air, what are the maximum possible yields of CO2, and H2O? (You may assume the composition of air is 21% O2 and 79 % N2) Considering a small sample of C2H6N2O First scenario Assuming that there is complete burning of Dimethylnitrosamine the stoichiometric fuel ratio-to-air ratio (noting the composition of air is 21% O2 and 79 % N2.) C2H6N2O + 3O2  2CO2 + 3H2O +N2 Putting into consideration the composition of air the equation changes to C2H6N2O + 3O2 + N2  2CO2 + 3H2O +11.28N2 From the calculations it is clear that for complete burning of one volume of Dimethylnitrosamine 3 +11.28= 14.28 volumes of air is required. This puts the fuel-to-air ratio requirement at 1:14.28 to achieve complete combustion and for one volume of C2H6N2O there is a maximum of two volumes of 2CO2. Second scenario If DMN is not perfectly combusted in air, then the maximum possible yield of CO and CO2 will be as follow For maximum generation of CO the following equation will be applicable C2H6N2O + 2O2  2CO + 3H2O +N2 C2H6N2O + 2O2 +N2 = 2CO + 3H2O +N2+7.52N2 From the equation it can be seen that for 1 volume of DMN 2 volumes is maximum CO that can be generated A2. The underside of a smoky layer 8m x 11m is radiating like a flat, isotropic plate at 240C to the floor of a compartment 2.25m below. The mean emissivity is 0.25 and the floor is homogenous/flat plate at 50C. What is the rate of heat transfer from the smoke to the floor? The formulae to be used (1) Where  is the view factor between the two surfaces where heat is being transferred  Stefan Boltzmann Constant, 5.67x10-8 W/m2/K4  is the temperature of the hot surface in this case 240C  is the temperature of the cold surface in the current case 50C A is the area of the radiating surface in the case 8x11 Now to calculate the view factor the formula to be used is (2) Where and Now applying the formula by first calculating the components in the brackets independently the results will be 1- = 1.1 2- 3.5 3- 4.8 4- 3.5*tan-1 (3.5) = 259.19 5- 4.8*tan-1 (4.8)= 78.23 Now substituting for the components in the bracket F12=  Then applying Q= (45.32)(0.25)(0.56*10-8)(8*11)((240)4-(50)4) Q= 18.49 KW B1. Critical review and distinguishing superficial, partial-thickness and full thickness burns and explaining the significance of ‘eschar’. How would eschar appear on a Lund-Browder chart? Assessing the depth of a burn is a great importance partly because it will determine the dressing required, but most important is depth of the burn is the major determining factor as to whether there will be natural healing with no necessity of surgical intervention (Andronicus M. et al ,1998). The depth of burns also is the determining factor of how severe the residual scar will be. Burns are broadly classified as superficial (epidermal), partial-thickness (dermal) and full thickness this being in correspondence to the level of involvement of the skin in addition to the underlying tissues (British Burn Association, 2008). Partial-thickness burns are subdivided into superficial partial thickness and deep partial thickness. The Lund Browder Chart has been found to be a useful tool due to its high accuracy as it takes age and body proportions of the patient into consideration. This makes it to be useful across different age groups (Manchester et al, 2009). more so where children are concerned. However it is required that a specific chart to be put into use when calculations are being made. In classifying the burns Escher is significant as it changes the conditions of the burns. From the relationship And given exposure time texposure 18min From the toxicological data tables Hyperventilation factor (HVF) = 1.25 and Acidosis factor (A) = 0.10 And from the relation ship Where C is concentration in ppm and being time FLDi = CHCNT/(CtHCN)50% = 62*18/4982 = 0.227 Now applying the relation FLD = 1.25(0.277) +0.10= 0.38 To calculate the fractional incapacitating dose the relationship used is In this case tincapacitating is the HCN incapacitating time abbreviated tHCN Calculated as tHCN=e5.396-0.023(62) = 52.985 Min Thus FID = 1.25( = 0.525 Critically review zone and field models used for compartment fire modelling. Provide examples and critically analyse the main assumptions, limitations, advantages and disadvantages of these models. A good understanding of compartmental fire behaviour is of significant importance as it makes it possible to derive straight predictions over the impact the fire has on the structural elements. Takede and Akita are some of the authors who have researched on the topic of regions with limited ventilations at great length. The research revealed that increasing in the opening area of compartment resulted in a change in the regimes including: stable laminar burning, extinction, unstable oscillation and stable burning that including a possibility of oscillation (Yang, D & Hu, L, 2010). A close look of field models has led to a discovery that it is difficult to achieve accurate prediction of thermal conditions and chemical species when considering ventilated compartment fires. It has been further found that, for formal ventilation progress where there is access to a well ventilated compartment, field models have been proved to have better performance well in predicting temperatures and species on condition that there is accounting of the experiment uncertainties (Merci , B & Vandevelde, 2007; Epstein, 1988; Bishop. et al. 1992 . Combustion modeling types Laminar flamelet model. This is a model through which it is possible to incorporate finite rate chemistry effects involving turbulent combustion. There is an assumption that combustion reaction may occur locally in microscopic elements in turbulent flames. Under the process concentration of major species and temperature mixture fractions are given. In predicting of flowfield of Favre-averaged mixture fraction mean a, variance ξ and g it makes it possible to compute the probability density function in its standard form. For the situation where PDF has two components, one of the parts will be applicable inside the turbulent jet this being a Beta function with the other being a Delta function. Detailed chemical-kinetic computations that are coupled with turbulence modeling are achievable when considering the flamelet model (Norwegian Fire Research Laboratory, 1996). Constrained equilibrium method. This entails calculating temperature, species concentration through correlation of the variables and the mixture fractions where it is possible to make evaluation by rigorous computation of laminar diffusion flame. However this has been found to make it difficult to incorporate the radiation model into the model as a result of there being strong energy losses that are as a consequence of sooting diffusion flames. The problem solution is the constrained equilibrium approach that involves taking of equilibrium calculations and a value of enthalpy being imposed on the problem. This approach has similarity with putting the system through some form of cooling. When the equilibrium calculations are being performed knowledge of thermodynamics properties that is involved in the system always is of great concern with information about reactions being irrelevant thus making it possible to relax to equilibrium if the reaction exist. (Kerrison, 1998). This has an implication that a reaction mixture at equilibrium composition will not be dependant, in any way, to reaction mechanism. The energy is given by the equation () = - With h representing the static enthalpy,  being the velocity component,  the density of the mixture,  representing the transport coefficient,  standing for jth coordinate,  being the description of the mass fraction of species I, the Lewis number of a species i is represented by  while  stands for the heat flux. After enthalpy distribution is obtained, calculation of heat loss factor is through the equation  = , Where h represent enthalpy calculated from equation,  being the enthalpy value that corresponds to isothermal mixing and  being the enthalpy value in the fully burning conditions. Through the equation it is possible to have a two dimensional look-up table that can be used in giving the flow properties as functions of mixture fraction thus making it possible to produce heat loss factor. Eddy break-up model . In this model the solution of an explicit equation is given for fuel mass fraction The equation involved being: +) -  = -. In the eddy break-up combustion model the assumption is that there is a fast chemistry meaning turbulent mixing is rate controlling. In the turbulence timescale , it is possible to express  as  = min, With ,  and  representing time-averaged mass fractions of the fuel, the oxidant and the product respectively. The stoichiometric oxygen-to-fuel mass ratio has a denotation “s”,  stands for the density of the fluid.  stands for laminar viscosity while  representing turbulent viscosity.  is laminar Prandtl number,  is turbulent Prundtl number t being the time transient cases. CR and CA being constants that can be determined empirically this being dependant on the mixing model and the reaction rate chemistry. C2. Critical examination of the standard fire temperature-time curves* utilized in fire resistive design of buildings. *You may use the ISO (International Standard Organisation) curve (4) where t = time (min), T = fire temperature (0C), T0 = initial temperature (0C), to comment on the standard fire temperature-time curves. Through the use of standard-temperature-time-curve it is possible to illustrate the phase of the fire takes hold. Usually there will be no taking into account the initial start phase of the real fire and thus limiting any similarity with real times in fire. According to normal practice a standard-temperature-time-curve will be put into use in special test institutions thus enabling building components being classified according to the level of fire resistance by use of fire resistance testing. When building materials are being tested the kiln temperature will always be a reflection of the standard-temperature-time-curve unit which is in accordance DIN[German Standard] 4102-2, illustration 3. When a fire resistance test is performed it will lead to the certification of particular properties that have been demonstrated in the idealized fire at the classification period through the means of testing in a well accredited centre or by use of verifiable measurements. References Andronicus M. et al (1998) Non-accidental burns in children. Burns 24: 552–8 Bishop , S & Drysdale, D (1995) Experimental Comparison With A Compartment Fire Model. International Communications in Heat and Mass Transfer. British Burn Association (2008) Emergency management of severe burns course manual, UK version. Wythenshawe Hospital. Epstein M. (1988). Buoyancy-driven exchange flow through small openings in horizontal partitions. J Heat Transfer. Hudspith J and Rayatt S (2004) First aid and treatment of minor burns. Br Med J 328:1487–9 La Hei et al(2006).Laser Doppler imaging of paediatric burns: burn wound outcome can be predicted independent of clinical examination. Burns 32: 550–3 Manchester Enoch S, Roshan A, Shah M (2009). Emergency and early management of burns and scalds. Br Med J 338: 937–41 Merci , B & Vandevelde, P (2007) Experimental study of natural roof ventilation in full-scale enclosure fire tests in a small compartment . Fire Safety Journal. 42 () p523-535 Novozhilov, V (2001) Computational fluid dynamics modeling of compartment fires. Progress in energy and combustion science. 27 p611-666 Yang, D & Hu, L (2010) Comparison on FDS predictions by different combustion models with measured data for enclosure fires. Fire Safety journal. 45 Read More