Thermal conductivity Sample Clauses

Thermal conductivity. The thermal conductivity is a bulk property that describes the ability of a material to transfer heat. In the following equation, thermal conductivity is the proportionality factor k. The distance of heat transfer is defined as ∆x, which is perpendicular to area A. The rate of heat transferred through the material is Q, from temperature T1 to temperature T2, when T1>T2. The thermal conductivity was measured using few types of equipment. On the one hand, Acciona measured the thermal conductivity using an HFM (Heat Flow meter) while UCLM used DSMC and an innovative equipment designed by themselves.

Thermal conductivity. The thermal conductivity coefficient is defined the same way as in bubbling regime and the axial dispersion coefficient for solids required in Xxxxxx'x approach is also described by the same correlation (Equation 44) since it is valid for both regimes. 𝑔𝑑𝑡 0.653 𝐷𝑠 = 𝐷𝑠 = 1.058(𝑈0 − 𝑈𝑚𝑓)𝑑𝑡 ( ) 𝐴𝑟−0.368 𝑡𝑢𝑡𝑡𝘣 xxxx 𝑈0 − 𝑈𝑚𝑓 (53) 4 Fast Fluidization The fast fluidization regime is characterized by high velocities and a continuous decrease of solids content over the height of the reactor (the dense bed and freeboard are indistinguishable). Several models have been proposed for fast fluidization fluidized bed reactor. The two zone core-annulus model is the most realistic model because it considers a more dilute phase in the core and a denser phase in the annulus where the particles tend to accumulate and move downwards. The core- annulus model is used in Phenom under fast fluidization conditions therefore the correlations presented below are consistent with this formulation. The parameters described through these correlations are presented in Table 11. Table 11 - Variables defined though material relations under fast fluidization regime Variable Description Units Section 𝜀𝜀𝑓𝑎𝑠𝑡 Bed voidage under turbulent regime [-] 4.1 𝜀𝜀𝐿𝑓𝑎𝑠𝑡 Bed voidage in L-phase under turbulent regime [-] 4.3 𝐾𝐿𝐻𝑓𝑎𝑠𝑡 Mass transfer coefficient [s-1] 4.4 𝜓𝜓𝐿𝑓𝑎𝑠𝑡 = 𝜓𝜓𝑐 Volume fraction of core zone [-] 4.5 𝐷𝐿𝑓𝑎𝑠𝑡 Gas dispersion coefficient for L-phase [m2 s-1] 4.6 𝐷𝐻𝑓𝑎𝑠𝑡 Gas dispersion coefficient for H-phase [m2 s-1] 4.6 𝜆𝑓𝑎𝑠𝑡 Thermal conductivity under turbulent fluidization [W m-1 K-1] 4.7 𝑢𝐿𝑓𝑎𝑠𝑡 , 𝑈𝑏 Intrinsic gas velocity in L-phase under turbulent fluidization [m s-1] 4.2

Thermal conductivity. The thermal conductivity for fast fluidization is also defined by the Xxxxxx'x approach (see section 2.8) therefore correlations for the gas dispersion are required. Table 14 presents the correlations that are more commonly referred in literature also represented in Figure 6 . Table 14 – Correlations for the axial dispersion coefficient for the solid particles[24]–[26]