Measuring Global Temperatures

Temperature measurements, global warming and the usefulness of indirect measurements... 

Lack of reliable measurement is the first reason, as reliable ground-based measurements by scientific instruments have been made just in this century. These measure conditions only at the location of each instrument, and they are usually land-based, although 75% of the Earth is covered with water. We have been able to take precise, direct measurements only in the last four decades, and not until the advent of precision space borne instruments in the 1970s were we able to measure global temperatures at a range of altitudes across the entire atmosphere. 

Fig. 6. COj components, nutrients and temperature in a north-south section along 150 west in 1979. Note the high PCO2, phosphate and nitrate concentrations along the Equator, and the relatively low temperature. Measurements by C. D. Keeling and others during the First Garp Global Experiment (FGGE).

Example 13-5 Using the one-dimensional method, compute curves for temperature and conversion vs catalyst-bed depth for comparison with the experimental data shown in Figs. 13-10 and 13-14 for the oxidation of sulfur dioxide. The reactor consisted of a cylindrical tube, 2.06 in. ID. The superficial gas mass velocity was 350 lb/(hr)(ft ), and its inlet composition was 6.5 mole % SO2 and 93.5 mole % dry air. The catalyst was prepared from -in. cylindrical pellets of alumina and contained a surface coating of platinum (0.2 wt % of the pellet). The measured global rates in this case were not fitted to a kinetic equation, but are shown as a function of temperature and conversion in Table 13-4 and Fig. 13-13. Since a fixed inlet gas composition was used, independent variations of the partial pressures of oxygen, sulfur dioxide, and sulfur trioxide were not possible. Instead these pressures are all related to one variable, the extent of conversion. Hence the rate data shown in Table 13-4 as a function of conversion are sufficient for the calculations. The total pressure was essentially constant at 790 mm Hg. The heat of reaction was nearly constant over a considerable temperature range and was equal to — 22,700 cal/g mole of sulfur dioxide reacted. The gas mixture was predominantly air, so that its specific heat may be taken equal to that of air. The bulk density of the catalyst as packed in the reactor was 64 Ib/ft. ... 

Dielectric spectroscopy was also employed in order to study the local and global dynamics of the PI arm in these miktoarm samples [347]. Measurements were made in the ordered state and the dynamics of PI chains tethered on PS cylinders were observed in different environments (one of pure PI in the (PI PS case and one of a mixture of PI and PB for the (PS)(PI)(PB) case). At low temperatures the PI segmental dynamics are different due to the introduction of the faster PB chains in the terpolymer with the effect diminishing by increasing temperature. The global PI dynamics resemble the dynamics of PI stars with additional entanglement effects when PB is present in the system. 

We notice however, that the anisotropies are more important in the Weber method. This can be explained by the fact that in the Weber method, anisotropies were calculated at low temperatures (-33 and -16°C for the buried and surface Trp residues, respectively), while in the QREA method, the anisotropies were measured at 20°C. At low temperatures, the global rotation of the protein and the local motions ai ound the Trp residues are decreased. 

Adiabatic measurements and kinetic parameters. The experimental temperature measured in a semi adiabatic box and the adiabatic temperature rise, obtained from a paste with w/c=0,45, is shown in the Fig. 1. Once the adiabatic temperature is known the global heat transfer coefficient (U) can be determinate with a good correlation coefficient (Fig. 2). 

The kinetics were successfully solved, using an extension of the Birks method, by measuring the decays as a function of temperature, and globally fitting the data, under a number of reasonable assumptions on the temperature dependence of the rate constants [58]. 

Core temperature monitoring All the fuel subassemblies are provided with temperature measurement at the outlet by 2 Cr-Al thomocouples. The signals are scanned every second by 3 dedicated computers. The gnals are processed to detect overheating due to global or individual subassembly loss of flow. Inlet flow to the core from the discharge of the 2 primary pumps is measured using eddy-current flowmeters. 

The differences in the bias values were expected and are attributed to the sources of uncertainty in the calculations and temperature measurements, and also to local and global variations in coolant flow in the core. The latter, discussed further in Reference 8, are accounted for in the analysis by including a statistical uncertainty in the mean bias value. The mean bias has a value of 11.4 K where the convention is chosen such that a positive bias corresponds to a calculated temperature greater than the measured temperature. The uncertainty in the bias is determined from the following four sources ... 

The adsorption equilibria measurements of N2 and CO2 on activated carbon were performed using a standard static gravimetric method. Further details of these measurements are reported elsewhere." " The Sips isotherm extended to multi-component adsorption was adopted to fit the experimental equilibrium data (Table 9.2). This model has the Langmuirian form applied to non-uniform surfaces and it has been extensively used to model gas adsorption on micro-porous adsorbents and PSA systems. Optimal parameters were found for the adsorption isotherm model, by fitting simultaneously all the data at multiple temperatures. A global isotherm was obtained for each species as illustrated in Figure 9.15." ... 

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