Entropic analysis of adsorption open cycles for air conditioning. Part 2: interpretation of experimental data

The full second‐law analysis, developed in Part 1 (M. Pons and A. Kodama, Int. J. Energy Res. 2000; 24 : 251–262) is applied to experimental results. That approach takes into account the irreversibilities due to the open character of the cycle. Measurements are performed on a solid desiccant cooling unit operated in the ventilation mode. Experimental data permit us to establish the entropy balance of the unit. The results show that the sum of all the considered entropy productions completely explain the difference between the Carnot COP and the actual COP of the unit. The effects of three experimental parameters are investigated: the rotation speed of the dehumidifier (desiccant wheel), the air velocity and the regeneration temperature. Experimental results show that there exists an optimal rotation speed which results from a combination between the different entropy productions in the cycle. When the air velocity is increased, together with an accordingly optimized rotation speed, the cooling capacity increases while the COP decreases due to increases in the entropy productions in the dehumidifier and sensible heat exchanger. Moreover, it appears that the most significant entropy productions take place in the dehumidifier and heating system. In the investigated experimental unit, these two entropy productions have similar magnitudes. However, when the regeneration temperature is increased, the irreversibilities due to mass exchanges with outside air become comparable to these and surely should not be forgotten in a global optimization of the process. The present analysis is a solid basis for reducing the largest entropy productions thus optimizing the process. Copyright © 2000 John Wiley & Sons, Ltd.     

Preparation of superabsorbent polymer hydrogels from trialkyl‐4‐vinylbenzyl phosphonium chloride–acrylamide–methylenebisacrylamide terpolymers and their properties

Superabsorbent polymer gels were synthesized by terpolymerization of three kinds of tri‐n‐alkyl‐4‐vinylbenzyl phosphonium chloride (TRVB) with alkyl chains of different lengths, with acrylamide (AAm), and with N,N′‐methylenebisacrylamide (MBAAm). The water‐absorption ability and antibacterial activity of the gels against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were investigated. The water content of TRVB–AAm–MBAAm terpolymers increased with increasing phosphonium groups in the terpolymers, while the water content decreased with increasing chain length of alkyl groups in the phosphonium groups as well as an increasing degree of crosslinking in the terpolymers. The water content of the terpolymers was depressed by the addition of NaCl. The degree of effect of NaCl addition became higher as the chain length of alkyl groups in the phosphonium groups of the terpolymers became longer. The tri‐n‐octyl‐4‐vinylbenzyl phosphonium chlorides (TOVB)–AAm–MBAAm terpolymers exhibited high antibacterial activity against S. aureus and E. coli in deionized water. The antibacterial activity decreased in 0.9 wt % NaCl solution. The antibacterial activity of TOVB–AAm–MBAAm terpolymers with almost the same phosphonium content increased with the increasing swelling ratio of the terpolymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1833–1844, 2000     

Novel functional polymers: Poly(dimethylsiloxane)‐polyamide multiblock copolymer. IX. Surface properties of blend film of aramid–silicone resins with aramid

A blending technique was studied in order to widen the applications of aramid–silicone multiblock copolymer (PAS). A PAS/aramid blend film was prepared and the characterization of the surfaces was investigated. The two‐phase nature of poly(dimethylsiloxane) (PDMS) and the aromatic polyamide (aramid) multiblock copolymer (PAS) were clarified in part by evaluating the surface enrichment in PAS/aramid blend films. There were no significant differences among the PASs as additives; however, the PASs were able to alter the aramid surface to that of silicone, even though they were used at low concentration. The atomic force microscopy observation suggested that the mobility of the silicone segment that existed on the surface was restricted by the associated aramid segments. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2198–2205, 2000     

Separation of aqueous phenol through polyurethane membranes by pervaporation. II. Influence of diisocyanate and diol compounds and crosslinker

The influence of diisocyanate and diol compounds of polyurethane and crosslinking agent on the separation of phenol aqueous solution by pervaporation was investigated. Polyurethanes were prepared by polyaddition of diisocyanate and diol compounds and trimethylolpropane (TMP) using dibutyltindilaulate as a catalyst. The polyurethane membrane was prepared by a casting method and was sandwiched with a porous polypropylene membrane (Celgard® 2500). Pervaporation measurement was carried out under vacuum on the permeate side, and the permeant was collected with a liquid nitrogen trap. Little influence of diisocyanate compounds on the phenol permselectivity through diisocyanate–polytetramethyleneglycol [PTMG(1000)] membranes was observed since the influence on the solubility and the diffusivity was small. The phenol permselectivity was increased with an increase in the molecular weight of PTMG and polycaprolactone diol (PCL) for the 1,6‐diisocyanato hexane (HMDI)–PTMG and HMDI–PCL membranes. It was considered that the increase in phenol diffusivity can be attributed to an increase in phenol selectivity. The permeability and selectivity of HMDI–[PTMG(2900)–TMP] membrane was relatively constant below the 2% TMP content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 439–448, 1999     

Modification of bismaleimide resin by poly(phthaloyl diphenyl ether) and the related copolymers

Poly(ether ketone ketone)s were prepared and used to improve the brittleness of the bismaleimide resin. The bismaleimide resin was composed of 4,4′-bismaleimidediphenyl methane (BMI) and o,o′-diallyl bisphenol A (DBA). Poly(ether ketone ketone)s include poly(phthaloyl diphenyl ether) (PPDE), poly(phthaloyl diphenyl ether-co-isophthaloyl diphenyl ether) (PPIDE), and poly(phthaloyl diphenyl ether-co-terephthaloyl diphenyl ether) (PPTDE). PPIDE (50 mol % isophthaloyl unit) was more effective as a modifier for the bismaleimide resin than were PPDE and PPTDE (50 mol % terephthaloyl unit). Morphologies of the modified resins changed from particulate to cocontinuous and to phase-inverted structures, depending on the modifier structure and content. The most effective modification for the cured resins could be attained because of the cocontinuous phase or phase-inverted structure of the modified resins. For example, when using 10 wt % of PPIDE (50 mol % IP unit, MW 349,000), the modified resin had a phase-inverted morphology and the fracture toughness (K_IC) for the modified resins increased 75% with retention in flexural properties and the glass transition temperature, compared to those of the unmodified cured bismaleimide resin. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:769–780, 1998     

Carbonization and graphitization of polyimide films: Effect of size of leaving group at imidization

Polyamide acid was prepared from pyromellitic dianhydride and p-phenylenediamine and was then reacted with NaH and various kinds of alkyl halides to transform into alkyl esters. The cast films were imidized as fixed on glass substrate to give polyimide films and were then carbonized by heating to 900°C. The electrical conductivity of the carbonized films decreased with the increase of the size of the leaving group at the imidization step. The carbonized films were further heated to 2800°C for graphitization. Their degrees of graphitization and orientation of the graphite crystallite as a function of weight loss at imidization were studied by X-ray diffraction measurement at room temperature and magnetoresistance measurement at liquid nitrogen temperature. Both measurements clearly indicate that the graphitized films prepared from polyamide acid alkyl ester have high degrees of graphitization. It was also made clear that the orientation of the graphitized films increased with the increase of the size of the leaving group at the imidization step. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci John Wiley & Sons, Inc.J Appl Polym Sci 68: 1613–1620, 1998     

Basic experiments on robot-base vibration control of the hot-line work robot system using genetic algorithm

Past studies on hot-line robot systems have focused on the execution of various hot-line works such as the cutout/connection of electric wires and replacement of insulators. Robot-base vibration control methods, however, have seldom been discussed [1–5]. The high-speed operation of the hot-line work robot system, Phase II, in tasks is being worked on with the goal of practical utilization in the near future. Speed increases in boom and manipulator movements are a key part of this. The Phase II system's boom has a natural frequency of 1.0 Hz in commonly used angles. If the boom or the manipulator is rapidly accelerated, the robot base vibrates violently, hampering task execution. This paper proposes a vibration control method, in which control gain and position command acceleration/deceleration time are optimized for the movement of the robot base. In conjunction with the vibration control, we also focus on the optimization for positioning accuracy and preventing overshoot of the manipulator. These three issues are simultaneously solved using the genetic algorithm. The proposed method has been determined for use in a preliminary experiment for the Phase II system development. A simplified test-bed manipulator of the two-axis horizontal scalar type was employed for simulation and experimentation in order to reduce modeling error. The initial effects brought about by the proposed method are verified. © 1998 Scripta Technica, Electr Eng Jpn, 123(2): 40–52, 1998     

A new recycling system for expanded polystyrene using a natural solvent. Part 1. A new recycling technique

A new recycling technique has been developed which uses a natural solvent, d limonene, to shrink expanded polystyrene (EPS). d-Limonene is a natural vegetable oil which is extracted from the rinds of citrus fruits and is a good solvent of EPS. Limonene has almost the same solubility as toluene at room temperature. This technique reduces the volume of EPS to about 1/20th of the original. Contracted EPS is recyclable with almost no molecular weight degradation because d-limonene acts as an antioxidant of polystyrene during the heating process. © 1998 John Wiley & Sons, Ltd.     

Electrical characteristics of a fully superconducting brushless generator equipped with a magnetic flux pump

The study of efficient excitation systems is important in order to enhance the potential of superconducting ac generators. We have fabricated a model machine for generating electricity with a brushless exciter system, which consists of a superconducting dynamo or “magnetic flux pump.” A fully superconducting generator in which both armature and field windings are made of superconductors has also been studied. The paper presents power output tests and calculated results on transients as well as the static electrical characteristics of a model machine equipped with a magnetic flux pump when operated as a fully superconducting brushless generator in persistent current mode. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120 (3): 64–72, 1997     

Fabrication and excitation testing of a fully superconducting brushless generator with magnetic flux pump

Development of a highly efficient excitation system is important in enhancing the potential of superconducting ac generators. A new conceptual design in which electricity is generated with a brushless exciter system using a superconducting dynamo (the magnetic flux pump) has been proposed. Research on a fully superconducting generator using both a superconducting armature and a superconducting field winding has been under way for the past 7 years. In this paper an experimental model of the machine is described and test results on brushless excitation with the magnetic flux pump, with the machine operating as a fully superconducting brushless generator with an estimated capacity of 20 kVA, are presented. © 1997 Scripta Technica, Inc. Electr Eng Jpn. 118 (4): 35–45, 1997