S.J. Pickering

A fluidised-bed process for the recovery of glass fibres from scrap thermoset composites

A fluidised bed combustion process was developed for the treatment of thermoset composites in the form of process scrap or end-of-life components. The process was shown to be robust, coping with contaminated scrap of variable composition and providing useful outputs in the form of recovered fibres, particulate materials and heat. Comminuted feeds were decomposed at a bed temperature of 450°C and a fluidising velocity of 1.3 m/s. Fibres with mean lengths of up to 5 mm were collected at purities of up to 80% by using a novel rotating sieve separator. Shorter fibres were collected with the particulate mineral fillers. The tensile strength of recovered E-glass fibres was reduced by up to 50% although this depended on the thermal history within the process. Fibre modulus was relatively unaffected by the exposure to high temperatures. Recovered fibres were successfully reused in DMC formulations and veil products. A simple economic model suggests that the process would break even at a throughput of approximately 9000 tonnes scrap composite per year.

The characterisation and reuse of glass fibres recycled from scrap composites by the action of a fluidised bed process

This paper describes a new fluidised bed process for recovering reinforcing fibres from scrap thermoset composites. Glass fibres recovered from scrap sheet moulding compound at 450°C using this process have a strength reduced to about half that of virgin fibre. These fibres have been used as partial and full replacement for virgin fibres in a dough moulding compound (DMC). The main physical properties of plaques moulded with the experimental DMCs have been measured. Flexural and Youngs moduli are unaffected by the level of reclaimed fibre used. Flexural and tensile strength are reduced when over 50% of the virgin reinforcement is replaced by fibres recovered at 450°C.

Characterisation of carbon fibres recycled from scrap composites using fluidised bed process

Abstract A carbon fibre recycling process for scrap composites based on fluidised bed technology has been developed. This paper describes the recycling process and the characterisation methods used to analyse the quality of recycled fibre. They include: the measurement of fibre length distribution by image analysis; tensile properties by single fibre testing; and the examination of surface contamination and surface chemistry of fibre by SEM and XPS. Recycled fibres of up to 10 mm mean length were recovered and they retained ~75% of their tensile strength, while the Youngs modulus remained unchanged and the surface condition was similar to the virgin fibre.

Thermal stability of transition phases in zirconia-doped alumina

Alumina was prepared from an aqueous salt solution by homogeneous precipitation followed by calcination in air. Dependence of the thermal stability of transition phases on the presence of a zirconia dopant and on autoclave treatment prior to calcination was investigated using X-ray diffraction (XRD), differential thermal analysis coupled with thermogravimetric analysis (DTA–TGA) and transmission electron microscope (TEM) analysis. Homogeneous precipitation produced an amorphous trihydrate precipitate; the autoclave treatment converted this to crystalline boehmite (monohydrate). The zirconia was soluble in the transition alumina but was insoluble in α-Al2O3 so that phase transformation to α-Al2O3 was accompanied by a phase separation to form an alumina-zirconia nanocomposite. The thermal stability of the transition phases was increased both by the dopant and by the autoclave treatment. A combination of both parameters yielded the most stable transition alumina, which withstood 1 h at 1200°C without transformation to α-Al2O3.

Improved Cooling in the End Region of a Strip-Wound Totally Enclosed Fan-Cooled Induction Electric Machine

Computational fluid-dynamics modeling has been used to investigate the cooling of the end region of a two-pole strip-wound totally enclosed fan-cooled induction motor. The modeling is validated by experimental measurements. The changes in airflow and heat transfer that each configuration gives are discussed, and recommendations are made of features that can be used to achieve lower convective thermal resistance in the end region.

The results do mesh

This article considers the effects of open-circuited phase windings and of shorted coil turns of the stator winding on the operation of the induction machine. The analysis and comparison of faulted modes of operation is achieved by simulation, using the dynamic mesh reluctance model (DMRM) approach. The DMRM approach gives valuable insight of induction motor detection of the faulted windings. Clearly, five-phase motors with third harmonic control give the best performance for machines with one-phase open circuit, and careful machine design can minimize adverse effects of torque ripple

A fully integrated 30 kW motor drive using matrix converter technology

This paper explores the viability of using direct power converter technology to realize integrated motor drives, at power levels significantly higher than is possible with traditional approaches, fitting within the same space envelope as an equivalent motor. The integrated motor design was targeted at pump and fan applications where the need to install motor drives in a separate location is often an impediment to the replacement of fixed speed motors. In order to achieve this objective the thermal and electrical design of the integrated drive have to be considered together. This paper presents the final design that achieves all these objectives, including fully tested and evaluated demonstrations of the power converter and the cooling arrangements. The final integrated motor drive design only differs from a standard motor in terms of one end plate, the terminal box and the shaft driven fan. Full practical results of the 30 kW demonstrator are presented in the paper

Conjugate heat transfer analysis of a salient pole rotor in an air cooled synchronous generator

A study of combined heat transfer by conduction and convection for the rotor of an air-cooled, 4-pole generator was carried out using a general purpose CFD code. A simplified generator design was used to demonstrate a technique to analyse temperature distribution through the salient pole rotor at the design stage. Whilst CFD has the capability to predict airflow and convective heat transfer, it is shown that it is also necessary to model heat conduction, including the heat input from the losses, to produce a realistic thermal model of the rotor. A strip-on-edge coil structure is considered and it is shown that modelling the coils as homogeneous materials with anisotropic thermal conductivity provides sufficient accuracy for the prediction of local coil temperatures. Consideration is given to the effect of the coil size and structure on the cooling. To demonstrate the capability of the method, a modification to the test model considered is presented in which the airflow is modified, leading to enhanced heat convection and field coil temperature reduction.

An Integrated 30kW Matrix Converter based Induction Motor Drive

This paper explores the viability of using direct power converter technology to realize integrated motor drives, at power levels significantly higher than is possible with traditional approaches, fitting within the same space envelope as an equivalent motor. The integrated motor design was targeted at pump and fan applications where the need to install motor drives in a separate location is often an impediment to the replacement of fixed speed motors. In order to achieve this objective the thermal and electrical design of the integrated drive have to be considered together. This paper presents the final design that achieves all these objectives, including fully tested and evaluated demonstrations of the power converter and the cooling arrangements. The final integrated motor drive design only differs from a standard motor in terms of one end plate, the terminal box and the shaft driven fan. Full practical results of the 30 kW demonstrator are presented in the paper

Modelling ventilation and cooling of the rotors of salient pole machines

Computational fluid dynamics (CFD) offers the potential to model ventilation and cooling in electrical machines. This can provide the opportunity to optimize the thermal design of machines at an early stage without the need for extensive and costly experimentation. However, designers need to have confidence in the use of CFD and this paper summarizes the results of research work to validate the CFD modelling of large salient pole machines. It is shown that the commercial CFD code Fluent demonstrates a good ability to predict air flow and heat transfer on the rotor of a salient pole machine.