Phani Adapa - Academia.edu (original) (raw)

Papers by Phani Adapa

$Research paper thumbnail of Prediction of hardness and durability of alfalfa cubes processed from fractionated sun-cured and dehydrated alfalfa chops$

Biosystems Engineering, 2007

Analysis of hardness and durability values of cubes manufactured from fractionated sun-cured and ... more Analysis of hardness and durability values of cubes manufactured from fractionated sun-cured and dehydrated alfalfa chops was performed to determine predictive equations. The initial moisture contents of dehydrated and sun-cured chops were 6% and 7% (wet basis), respectively. A forage particle separator was used to fractionate (separate) leaf and stem fractions. The leaf and stem fractions were combined to obtain five different samples each for sun-cured and dehydrated alfalfa with leaf content ranging from 0% to 100% in increments of 25% by mass. A single cubing unit having die dimensions of 30 mm by 30 mm in cross section and an effective depth of compression of 0.38 m was designed and constructed. A hydraulic cubing machine was used to apply compressive pressures of 9.0, 12.0 and 14.0 MPa on the sample chops. After compression, the plunger was held in place for 10 and 30 s, before the compacted forage was extracted. The lowest hardness and durability values for dehydrated and sun-cured cubes were obtained at leaf contents of 50% and 100%, respectively. Statistical analysis was conducted considering hardness and durability as dependent variables and pressures, holding time and leaf content as independent variables to determine best-fit regression equations.

Biosystems Engineering, 2005

Fractionation/separation of chopped alfalfa into leaf and stem components was investigated using ... more Fractionation/separation of chopped alfalfa into leaf and stem components was investigated using a small industrial three-pass rotary drum dryer. Both drying and fractionation of chopped alfalfa were successfully achieved in a single operational process. Generally, fractionation is carried out only as a separate process and, therefore, more costly overall. The success of fractionation was determined by the total amount of the desired component (leaf or stem) recovered, relative to the amount entering the process (i.e. separation efficiency) and by the purity (leaf or stem proportion) of the component in a product stream collected at the cyclone or drum exit. A series of experiments under different operating conditions were performed to establish the optimum process conditions leading to maximum separation efficiency and leaf purity. The operating variables used during experimentation were the outer drum end gate opening area, material feed rate, gas flow rate and gas temperatures at the drum inlet. The experimental results indicated that leaf purity decreased and separation efficiency increased with a decrease in dryer drum end gate opening area. A decrease in separation efficiency was observed with an increase in material feed rate. On the other hand, leaf purity increased and separation efficiency decreased with a decrease in gas flow rate. The decrease in separation efficiency was most significant at low gas flow rates. Separation efficiency decreased with a decrease in gas inlet temperature. Stem moisture content was observed to be consistently higher than the leaves. Lowering stem moisture levels to an acceptable level of 8% moisture content results in over drying of the leaves, leading to a loss in product quality. It was determined that the relative difference in moisture levels of stems and leaves at the drum and cyclone exit, respectively, can be averted by re-circulating in the order of 20% of the wet material (stems) from the drum exit back through the dryer inlet.

Drying Technology, 2003

... Edwin A. Arinze,1,* Greg J. Schoenau,1 Shahab Sokhansanj,2 and Phani Adapa1 ... A new efficie... more ... Edwin A. Arinze,1,* Greg J. Schoenau,1 Shahab Sokhansanj,2 and Phani Adapa1 ... A new efficient approach to combined drying and separation in a rotary drum dryer is described in which fresh or pre-wilted alfalfa mixture is dried at a moderate temperature, and in the same ...

Biosystems Engineering, 2006

Biosystems Engineering, 2009

Agricultural biomass has the potential to be used as feedstock for biofuel production. However, c... more Agricultural biomass has the potential to be used as feedstock for biofuel production. However, crop residue after harvest must be gathered, processed and densified in order to facilitate efficient handling, transportation and usage. In this study compacts were prepared by densifying material against a base plate (representing the specific energy required to overcome friction within the straw grinds) as opposed to the process that occurs in a commercial operation where compacts are formed due to back-pressure effect in the die. Densification was measured using four selected biomass samples (barley, canola (oilseed rape), oat and wheat straw) at 10% moisture content (wb) and 1.98 mm grinder screen size using a compaction apparatus which applied four pressure levels of 31.6, 63.2, 94.7 and 138.9 MPa. The specific energy required to extrude the compact was measured; this will closely emulate the specific energy required to overcome the friction between the ground straw and die. The mean densities of barley, canola, oat and wheat straw compacts ranged from 907 ± 31 to 988 ± 26 kg m−3, 823 ± 73 to 1003 ± 21 kg m−3, 849 ± 22 to 1011 ± 54 kg m−3 and 813 ± 55 to 924 ± 23 kg m−3, respectively; while the mean total specific energy for compaction of grinds ranged from 3.69 ± 0.28 to 9.29 ± 0.39 MJ t−1, 3.31 ± 0.82 to 9.44 ± 0.33 MJ t−1, 5.25 ± 0.42 to 9.57 ± 0.83 MJ t−1 and 3.59 ± 0.44 to 7.16 ± 0.40 MJ t−1, respectively. Best predictor equations having highest coefficient of determination values (R2) and standard error of estimate or root mean square error were determined for both compact density and total specific energy required to compress the ground straw samples. The resulting R2 for pellet density from barley, canola, oat and wheat straw were 0.56, 0.79, 0.67 and 0.62, respectively, and for total specific energy the values of R2 were 0.94, 0.96, 0.90 and 0.92, respectively.

$Research paper thumbnail of Compression of fractionated sun-cured and dehydrated alfalfa chops into cubes--specific energy models$

Bioresource technology, 2007

The objective of this study was to determine the specific energy requirements for the compression... more The objective of this study was to determine the specific energy requirements for the compression of fractionated sun-cured and dehydrated alfalfa chops, when subjected to different pressures and holding times. The compression behavior of fractionated sun-cured and dehydrated alfalfa chops was studied using a single cubing unit capable of making one cube in a single stroke of the plunger. The cube die dimensions were 30 mm × 30 mm in cross-section and an effective depth of compression of 0.38 m. The initial moisture content of dehydrated and sun-cured chops were 6% and 7% (wb), respectively. A stack of two sieves (instead of five) was used along with a pan to achieve leaf and stem separation. The nominal opening sizes of two sieves with square holes were 3.96 and 1.17 mm, respectively. Leaf and stem fractions were combined later to obtain five different samples each for sun-cured and dehydrated alfalfa with leaf content ranging from 0% to 100% by mass in increments of 25%. The chop moisture content and preheat temperature before compaction was 10% (wb) and 75 °C, respectively. The cube die temperature was maintained at 90 ± 5 °C. The mass of chops used for making each cube was 23 ± 02 g. A hydraulic press was used to apply 9.0, 12.0 and 14.0 MPa of pressures through a plunger. After compression, the plunger was held in place for 10 and 30 s, before the compacted forage was extracted. Empirical equations were fitted to the data relating specific energy for cube making to pressure, residence time, and leaf content.

Biomass and Bioenergy, 2011