Heat transfer coefficient global

It is important to note that the compacityfactor is defined by the ratio of the surface area offered to heat transfer over the volume of the reactive medium. The thermal performances are estimated from the product between this compacity factor and the global heat-transfer coefficient. Consequently, owing to the large value of this factor combined with the conductivity performances of the SiC material, the heat-exchange performances are expected to be very high, which can be noticed from the last column of this table. 

Then, the quantity of heat that could be removed in batch reactors whose volume varies from 11 to 1 m is calculated. In order to compare with experimental results, the temperature gradient is fixed at 45 °C (beyond which water in the utility stream would freeze and another cooling fluid should be used). The maximum global heat-transfer coefficient is estimated at an optimistic value of 500 W m K h The calculated value of the global heat transfer area of each batch reactor. A, is in the same range as the one given by the Schweich relation [35] ... 

Finally, the global heat-transfer coefficient includes the resistance of the jacket wall ... 

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 global heat transfer coefficient comprises all transfer resistances as shown in Equation 5.8. In general, a minimum volumetric heat transfer coefficient of U, >1 MW m is required for fast and exothermic reactions [16]. 

In this equation, m represents the mass flow rate, is the mean specific heat capacity of the mixture in the considered temperature range, and U is the global heat transfer coefficient. 

With a volumetric global heat transfer coefficient of = 1.06 10 kWm K and a temperature difference of AT = 10 K, the maximum total heat generated can be evacuated. 

Distribute the total DT (increment of temperature) into the number of effects inversely proportional to the global heat transfer coefficient... 

He. 3t trans l rer temperature difference at process start / end required heating / cooling time local / global heat transfer coefficient specific heat capacity and heat conductivity of the product... 

In addition, for a relatively longer frontal part of the response peak we can directly determine the overall data of the mean heat capacity involved, Cp and the global heat transfer coefficient, A. It is in fact a traditional technique known as a ballistic method often applied in calorimetry when measuring amplitude... 

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