Calorimetry loss calculation

To improve the measured AT, in isoperibol calorimetry, the heat losses must naturally be corrected for. Loss calculations are carried out using Newton s law of cooling, written as Eq. (1) in Fig. 4.31 (see also Fig. 4.9). The change in temperature with... 

Figure 4.49. Apparent heat capacity of poly-p-dioxanone (PPDX) using adiabatic calorimetry by calculation of Cp = (AT/corrected for heat loss/A corrected for temperature drift)p,n Standard DSC using Eq. (10), and quasi-isothermal MTDSC evaluated with Eq. (11). The data were...

The heat transfer in calorimeters is described in terms of the effective heat transfer coefficient, involving the heat transfer of convection, conduction and radiation. In calorimetry, it is more common to use coefficient G, called the heat loss coefficient, which is equivalent to the effective heat transfer coefficient calculated for the whole surface S. 

In practice, the enthalpy of gasification is rarely calculated because detailed and reliable thermodynamic data for the polymer and its decomposition products are generally unavailable. Direct laboratory measurement of Lg using differential thermal analysis and differential scanning calorimetry has been reported, but Lg is usually measured in a constant heat flux gasification device or fire calorimeter (see under Steady Burning). In these experiments a plot of mass loss rate per unit surface area (mass flux) versus external heat flux has slope 1/Lg where... 

Thermal analysis techniques, in particular differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), are valuable tools to study the thermal behavior of PEs. DSC allows us to calculate the proportion of crystallinity, to detect the formation of new crystalhne phases, free guest salt or uncomplexed polymer chains, to monitor the loss of solvent(s) (e.g. occluded water, alcohol), to determine the Tg value and to distinguish between endo- and exothermic events. TGA provides rich information... 

Battley [39] presented a critical survey about advantages and drawbacks of direct and indirect techniques for different types of calorimetry. Kleiber [33] stated that Indirect calorimetry measures the heat production of an animal direct calorimetry measures the heat loss. Heat gain and heat loss are equal only when heat capacity and body temperature remain constant. One may define indirect calorimetry as the determination of heat production rates by means of some methods other than direct calorimetry. But one has to bear in mind that with the exception of the determination of heat production by ergometry, all indirect methods of calorimetry depend ultimately on previously made direct calorimetric measurements of one kind or another that are used in the calculation of the heat produced. [39]... 

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