Measuring effective thermal conductivity of micro-particle porous materials in fixed bed by thermal probe method
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ORIGINAL
Measuring effective thermal conductivity of micro-particle porous materials in fixed bed by thermal probe method Ruitong Ge 1 & Yihua Zheng 1 Received: 11 December 2019 / Accepted: 29 May 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract For exploring the complex heat and mass transfer in the micro-particle fixed bed, the device to measure thermal conductivity was designed and built. The experiments showed that the error was less than 2.97% after calibrated, and reproducibility was good. Effects of particles diameters, porosity, flow rate and ion exchange on the thermal conductivity of micro-particle porous materials were investigated experimentally by thermal probe. The results indicated that the effective thermal conductivity in dry condition declined with the size of particles and porosity increase. The effective thermal conductivity in low flow rate (0.8 mL/min, 1.6 mL/ min, 3.2 mL/min) is converse. The thermal conductivity of the resin particles after the ion exchange with the conditions of dry and low flow rate has not changed much. The chemical reaction and interrelated processing have no significant influence on the thermal conductivity by comparing with exchange of the ions of particles. The thermal conductivity of the soil from different areas in different ions further verified the above conclusions. The numerical simulation showed that the probe had little effect on the temperature field of fixed bed. It is a reliable and effective on-line method to measure the effective thermal conductivity of the micro-particle porous materials in fixed bed by thermal probe method. Nomenclature Temperature T [K] Voltage U [V] Current of heating wire I [A] Probe coefficient k Fluid density ρf [kg/m3] Solid skeleton density ρs [kg/m3] Porosity ε
Fixed bed penetration K [m2] Resin particle size dp [m] Gradient operator ▽ Divergence operator ▽· Fluid specific heat capacity Cf [J/kg]
Solid skeleton specific heat Cs [J/kg] Average of the product of density and specific heat capacity Time τ [s] ρeCe [J/(m3·K)] Horizontal vector of Fluid thermal conductivity fluid velocity u [m/s] λf [W·m−1·K−1] Vertical vector of fluid Solid skeleton thermal velocity v [m/s] conductivity λs [W·m−1·K−1] Pressure P [Pa] Effective thermal conductivity λ [W·m−1·K−1]
* Yihua Zheng [email protected] 1
College of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071, Shandong, China
Hydrodynamic viscosityAverage outlet temperature μ [kg/(m·s)] (probe model) Tprobe [K] Dimensionless Average outlet temperature resistance coefficient (no-probe model) Tno-probe [K] Cf
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