Bed-to-surface heat transfer of pure biomass particles in a pulsed fluidized bed with a tapered bottom section was investigated. Three biomass species — Douglas fir, pine, and switchgrass — were studied under various operating conditions. Their heat transfer coefficients were found to be closely associated with hydrodynamics dominated by gas pulsations. A higher superficial gas velocity generally yielded better gas–solid contact and higher heat transfer rates. A moderately increasing pulsation frequency promoted convective heat transfer of particles but also reduced pulsation intensity, leading to undesired flow behaviours such as channelling and partial defluidization. The study of the pulsation duty cycle revealed that, for cohesive particles, a smaller duty cycle was preferred to generate powerful pulsations to break up inter-particle forces. Moreover, a duty cycle increase allowed higher gas throughput as long as a suitable fluidization was maintained. The addition of finer particles to a coarse fraction increased particle mobility, and subsequently heat transfer, which also explained the higher heat transfer coefficients of switchgrass as it contained more fines compared with fir and pine. Experimental results in the tapered bed were also compared with those of non-tapered geometry where a 10%–20% increase in heat transfer was observed.

研究了底部底部呈锥形的脉冲流化床中纯生物质颗粒的床到表面传热。在不同的操作条件下研究了三种生物量物种：花旗松，松树和柳枝—。发现它们的传热系数与以气体脉动为主的流体动力学密切相关。较高的表观气体速度通常会产生更好的气固接触和较高的传热速率。适度增加的脉动频率促进了颗粒的对流传热，但同时也降低了脉动强度，从​​而导致了不希望的流动行为，例如窜流和部分流失。对脉动占空比的研究表明，对于粘性粒子，较小的占空比更可产生强大的脉动，以打破粒子间的力。而且，占空比的增加允许较高的气体通过量，只要保持适当的流化即可。将较细的颗粒添加到较粗的颗粒中会增加颗粒的迁移率，并随后进行热传递，这也解释了柳枝fir的传热系数较高，因为与冷杉和松木相比，柳枝contained包含更多的细粉。锥形床的实验结果也与非锥形几何体的实验结果进行了比较，非锥形几何体的传热增加了10％–20％。