Numerical Study on Thermo-Hydraulic Performance in the Shell Side of Spiral-Wound Heat Exchanger

The spiral-wound heat exchangers are widely used in industrial applications, but the mechanism of flow and heat transfer in shell side has not been clarified yet. A three-dimensional model is developed based on the FLUENT software in this study, with emphasis on quantifying the effects of the main geometry parameters, such as the tube number per circle in the first layer, the tube external diameter, the central cylinder diameter and the tube pitch, on the flow and heat transfer are discussed respectively. It is found that as the tube number per circle in the first layer increases, the Nusselt number increases and the pressure loss per unit length increases first and then decreases and the similar trend is obtained as the central cylinder diameter increases. The Nusselt number and pressure loss both increase with the increase of tube external diameter. As the tube pitch increases, the Nusselt number and the pressure loss both decreases.

Effects of pollen tube number and archegonium number on reproduction in Douglas-fir: significance for seed orchard management

Analyses of the relationships between pollen tube number and fertilization number and between archegonium number and fertilization number in Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) indicate strong trends toward higher levels of simple polyembryony as both pollen tube number and archegonial number increase on a per-seed basis. These relationships have a significant bearing on the management of conifer seed orchards. Simple polyembryony has been proposed to be an effective means of increasing competition on a per-seed basis in conifers and, potentially, the overall fitness of progeny. In conifers, supplemental mass pollination has the direct effect of increasing the number of pollen tubes per ovule. Clonal variation in average number of archegonia per ovule is also likely to exist among conifers. We propose that when used together, supplemental mass pollination and selection of clones with high archegonial averages may enhance the fitness of seed orchard progeny.

Ruggedness Testing of the Official Method for Rot Fragments in Comminuted Tomato Products

The official AOAC method for rot fragments in comminuted tomato products (44.224) has been revised on the basis of Youden's ruggedness testing procedures to provide better control over the sources of variability. Two sets of ruggedness tests were carried out to evaluate the type of balance used to weigh the sample, amount of stain, staining time, sieve design, technique used to transfer stained material from beaker to sieve, washing technique used to accumulate stained material at edge of sieve, diameter of eye dropper used to transfer sample from sieve to graduated tube, number of 0.5 mL portions examined, and magnification used to examine prepared slides. A 3-way analysis of variance conducted on amount of stain, transfer technique, and washing technique showed that the transfer and washing techniques were significant areas of variability.