Sought quantities

The objectives of this project are consistent with the objectives (1) and (4) above. The general objective of this project has been to verify a new measurement method to analyse the thermochemical conversion of biofuels in the context of PBC, which is based on the three-step model mentioned above. The sought quantities of the method are the mass flow and stoichiometry of conversion gas, as well as air factors of conversion and combustion system. One of the specific aims of this project is to find a physical explanation why it is more difficult to obtain acceptable emissions from combustion of fuel wood than from for example wood pellets for the same conditions in a given PBC system. This project includes the following stages ... 

Secondly, the method and its results, that is, the sought quantities, can be applied in... 

The sought quantities of the method are (1) mass flow of conversion gas, (2) stoichiometry of the conversion gas, (3) air factor of the conversion system, and (3) air factor of the combustion system. Mass flow and stoichiometry of the conversion gas are illustrated in Figure 13 above. 

Due to the fact that the measurands are stochastic variables an uncertainty propagation analysis was carried out. An uncertainty analysis can answer two questions (1) the expected accuracy (uncertainty) of the method, that is, the expected uncertainty with respect to the sought quantity (2) the most uncertain (sensitive) measurands. 

The result of the uncertainty analysis was promising. The expected relative uncertainty with respect to the sought quantities is in the range of 7%, with a 95% confidence interval. The most uncertain measurand is the water vapor, that is, the water vapor measurements are believed to contribute the biggest error. 

Paper IV presents the first experimental series with the new measurement method. Results are given for all the four sought quantities defined in Paper II. The conversion concept of the conversion system is the same as in Paper El, see Figure 16. 

The above mentioned sought quantities were measured as a function of six levels of standard volume flux of primary air in the range of 0.06-0.46 m n/m, s for all the wood fuels. Altogether, eighteen (3x6) single tests were carried out. 

A new method to analyse the thermochemical conversion of biomass, in the context of packed-bed combustion, is modelled and verified. The sought quantities of the method are the mass flow and stoichiometry of conversion gas, as well as the air factors of the conversion system and the combustion system. 

Below is the definition of the mathematical relationship between the concepts of the sought quantity (output quantity) and the measurands (input quantifies). 

The theory behind every measurement method can be generalised by Eq (1) [1]. Some quantity (or quantities, measurands) is measured, which has a specific relationship to the sought quantity. The measurand can be regarded to be a stochastic variable associated with an uncertainty, which implies that the sought quantity is also a random variable. The mathematical relationship depends on the physical model, that is, the model of the physical phenomenon of interest, for example temperature, pressure, and volume flow. The physical model always includes limitations, which implies that the measurement method has restrictions that is, it will only function in a certain measuring range and according to the assumption of the model. 

The subsection, results and conclusions, focuses on the results and conclusions with respect to sought quantities, that is, the ignition front rate, conversion rate, and conversion stoichiometry. Each work is rounded off with comments by this author, with respect to the content of the physical model and the mathematical model making up the theory of the measurement method, as well as the application of verification methods. 

The sought quantities are not explicitly formulated in these molar balances. However, these equations are the starting points for developing the functional relationship between sought quantities and measurands, according to Eq (1) above. 

No sought quantities of relevance for this thesis were studied in this work. 

No explicit mathematical models between the interested sought quantities and measurands are formulated in Gort s work. However, short descriptive models... 

This author has classified the theory of the method with respect to physical model and mathematical model. The physical model can be broken down into system definition, descriptive definition of the sought quantity, measurands, and main assumptions. The mathematical model can be divided into mathematical definition of the sought quantities, and mathematical relationship between sought quantity and measurands. 

Author Conversion concept Sought quantity Measurands Theory of method Verification method Uncertainty analysis... 

The more the experimental knowledge on the system in question is available, the more reliable is the estimation of the sought quantity. On the other hand, it is sometimes better to omit a dubious value of the experimentally determined input quantity. 

Since G(H202)02 depends on the radiation dose and ranges within 1.4-1.2 molecule/100 e.v., this yield will be considered a sought quantity, satisfying Equations 4, 5, and 6. 

Often, it is not directly the amount of substance n that is interesting or known to us but rather a volume Ay of a reagent solution that is either given or consumed, the concentration c of a sample or standard solution, or the increase of mass Aw of a filtering crucible where a precipitate was collected, etc. The A values are then expressed by the given, measured, or the sought quantities. For example, A a = Ca Ay for the consumed acid or A p = mlMp for the weighted precipitate, where Mp stands for the molar mass of P. 

The deformation calorimeter serves to measure the heat released in the sample during a deformation. Calorimeters involving a liquid-gaseous transformation as well as other calorimetric procedures can be used for this purpose. The difference between the performed deformation work and the measured heat represents the energy stored in the deformed material. An obvious and common drawback of all measurements with deformation calorimeters stems from the fact that the sought quantity constitutes a minute difference between two measured values that are subject to uncertainties (i.e., deformation work and released heat) and are measured independent of one another and in different ways. If the stored energy accounts for about 10% of the deformation work, the heat and the deformation work must be measured with an uncertainty of 0.5% to determine the stored energy with an uncertainty of 10%. 

Fig. 1.6(a) is if the connector clip/solution interface, on the left, passes the tiny current of electrons. If no electron passage occurs then we fail to measure the sought quantity. We might introduce the connector clip into the solution but this generally does not make electrical contact since free electrons will not transfer between the clip and the solution and so the experiment depicted is doomed to failure. 

Solution. The sought quantities ASa, AS), and ASab are determined from the relation (4.18). In the calculation the thermodynamic temperatures Ta, Tb, Tab are inserted corresponding to the specified Celsius values... 

---