International Journal of Environmentally Conscious Design & Manufacturing 

Volume 10, Number 4, 2001-2002

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Contents
Contents 

Enhanced Steam Condensation as a Result of Heat Transfer Additives, by A. STONE, A. RAZANI, K. KIM, AND J. PAQUETTE

    In this paper, the importance of heat transfer additives as they pertain to steam
condensation in a single, internally cooled, vertical tube is discussed. The authors report
that the condensation heat transfer rate can be significantly enhanced by using effective
additives as compared to the heat transfer rate without additives. When heat transfer
additives function effectively the condensate becomes more active and exhibit dropwise-like
behavior. Beginning at the top of the tube small droplets, as opposed to the typical falling
film condensation, form along the entire length of the tube. This behavior can be explained
by the Maraongoni effect, which relates the importance of dynamic surface tension.
Normal octanol, a non-ionic surfactant, is noted as an effective one in this study.

A Simulation Study on Telephone Remanufacturing Processes, by J.G. KANG, G. KRAFTSIK, D.H. LEE AND P. XIROUCHAKIS

    This paper focuses on modeling and simulation of two real telephone remanufacturing
processes with the objective of improving the system throughput. We start with the system
description and then build the corresponding simulation models. A series of simulation
experiments are done with different values for the model parameters and the results show
that they are close to reality. In particular, the bottleneck processes are the same as those of
the real systems. Using the simulation results, a method to improve the system throughput is
proposed by adding more workstations to the bottlenecks. Also, we extend the basic
simulation models to include multiple telephone types. Comparisons of dispatching rules are
performed using the extended models and the result shows that the suggested rules are much
better than the existing one.

Influence of Hot Melt Adhesive Contaminants on the Mechanical Properties of Recompounded Thermoplastics, by T. FORSS, M. PUIDE AND B. TERSELIUS

    The influence of hot melt adhesive (HMA) contaminants on the mechanical properties of thermoplastics has been studied with the aim of exploring the possibility of materials recycling of thermoplastic components containing HMA-residue. Samples of polypropylene (PP), ABS or high impact polystyrene (HIPS) containing 0-8 w% of PUR- or EVA-HMA were prepared and tested. The tensile and impact properties of the thermoplastics could be significantly affected at high contents (8 w%) of PUR- or EVA-HMA. However, at relevant contents of HMA-contamination (1-2 w%) the influence was negligible. It was shown by differential scanning calorimetry that the melt enthalpy of PP was not significantly affected by contents of up to 8 w% of PUR- or EVA-HMA. Nor was the glass transition temperature, Tg, of the PS and ANS-phase in HIPS and ABS respectively affected by contents of up to 8 w% of PUR- or EVA-HMA, thus indicating that the PUR- or EVA-residue was present as a separate phase in the thermoplastics. This could also be confirmed for the PUR-residue in PP from scanning electron microscopy (SEM) studies on samples etched in sulphuric acid. By SEM analysis it was also shown that the tensile and impact fractures were initiated at a particle of 50-100 µm size and varying shape, with no correlation to the type and concentration of HMA contaminant present in the thermoplastic. It is concluded that recycling of thermoplastic components contaminated with HMA-residue can be performed without removal of the residue.