An-Najah Staff

A specially developed two-dimensional cohesive zone finite element (CZFE) scheme is applied to simulate the fracture and delamination phenomena that occur in spray-applied fire-resisting material (SFRM) on steel structures. A cohesive zone material model for the SFRM is introduced and utilized to model both the internal cohesion in SFRM and the interfacial adhesion at the steel-SFRM interface. The CZFE model is validated by comparing predictions from the model with results from an adhesion test conducted at ambient temperature. The validated model is successfully applied to simulate the spontaneous initiation and propagation of cracks in the SFRM under static and impact loads. Results from the numerical studies indicate that the proposed model is capable of predicting the initiation and propagation of cracks within the insulation material and at the interface. The results show that the development of transverse cracks in the insulation layer help prevent further delamination of the SFRM. Also, it was found that for larger thicknesses of insulation, delamination occurs at less direct tension or flexural stresses. Results from impact simulations show that there is an optimum insulation thickness for resisting the delamination induced by impact loads.

A combined finite element based method (FEM) and a modified method of characteristics (MMC) is developed for the analysis and computation of the current density profiles, corona current and hence corona power loss associated with WDEP under particle loading conditions. To test the developed algorithm, comparison with experimental and numerical findings reported in the literature has been made. Comparisons showed high accuracy of the developed algorithm accompanied with a reduction in the number of iterations needed to converge. One major problem reported in the literature, namely, that the characteristic lines never follow the FE grid pattern, is eliminated in the present work. A proto-type design that represents a WDEP, which has been fabricated at the research institute of KFUPM (RI-KFUPM), is used to test the developed algorithm. Smoke of fired coal is used as a source of seed particles of PM10 category (with 75–80% of particles lying below 10 μm). A group of experiments were carried out under laboratory conditions. The results show how different design parameters influenced the corona current and current density profiles.

This paper investigates numerically and experimentally the performance of a single stage wire-duct electrostatic precipitators (WDEP) as influenced by different geometrical and operating parameters. To numerically solve the governing equations, namely Poisson’s and the current continuity equations, the finite element method (FEM) and a modified method of characteristics (MMC) were used. One major advantage of the present work over those reported in the literature is that the characteristic lines follow the FE grid pattern which results in fast convergence and reduction of the computational time. To verify the results experimentally, a proto-type WDEP was successfully designed and fabricated at the research institute of KFUPM (RI-KFUPM). The experiments were carried out under laboratory conditions and a smoke of fired coal was used as a source of seed particles of PM10 category (around 78% of particles lying below 10 μm). The results show how different parameters (such as discharging wire radii’s, wire-to-wire spacing and wire-to-plate spacing as well as the fly ash flow speed and applied voltage polarity) influenced the corona power loss and current density profiles. An indication of the effectiveness of this approach was carried out through a comparison of previously computed results and previously as well presently obtained experimental data.