Experimental study on drying characteristic of corncob in plate rotary heat exchanger

Agricultural processing residues, such as corncobs, can be used as good biomass pellet fuels. To thoroughly study the drying characteristics of corncobs in a rotary dryer, a plate rotary heat exchanger (PRHE) was applied to the drying of corncob particles in the present article. The PRHE had an inner diameter of 273 mm and a length of 1,000 mm. Twelve rectangular plates were designed as the heating plate. The influence of several parameters on the corncob drying characteristics was experimentally investigated. The results indicated that the drying rate increased with increasing corncob initial moisture content, increasing dryer heating power, and decreasing corncob particle diameter. Then, based on the experimental results, two exponential correlations were regressed by the least squares method. Both the correlations were valid and the three-parameter model had a better fitting degree than the two-parameter model. The trend in the drying rate of corncobs in PRHE clearly included a rising-rate stage and a falling-rate stage. The Taguchi approach was employed to study the impact degree of different factors on the maximum drying rate, which showed that initial moisture content had the largest impact degree, followed by heating power; furthermore, the effect of particle diameter was not significant. Practical applications: Promoting the use of biomass energy is an effective means to respond to the climate change challenge. As one of the major agricultural processing residues in mainland China, corncob can be processed into biomass pellet fuels with easy storage, high energy density, and low pollutant emissions after crushing, drying and compression molding. For the sake of settling the uncontrollable limitations of traditional open air-drying method for corncob, author developed a new type of plate rotary heat exchanger (PRHE). By investigating the drying characteristics of corncob in PRHE with various experimental conditions, research findings provide references for the development and large-scale industrial application of plate rotary drying technology in the drying of agricultural processing residues in the future.