Design and testing of a solar kiln simulator

The solar simulation system as previously described (Steinmann 1990) was used to simulate an actual drying run in a solar kiln. Adjustments necessary to compensate for difference in scale are described. The simulated weather conditions were in close agreement with the actual weather. The conditions in the solar kiln simulator and the solar kiln were so similar that the drying rates were virtually identical. Repeatability of runs in the simulator was good and it was concluded that valid results on solar drying could be produced in the solar simulation system.     

Investigations on the curing of epoxides with phthalic anhydride

The anhydride curing of epoxides was studied by performing copolymerizations of epichlorohydrin, phenyl glycidyl ether (PGE), or bisphenol-A-diglycidyl ether (BADGE) with phthalic anhydride (PSA). As initiators, tertiary amines or ammonium salts were used. In the case of epichlorohydrin, linear polyesters were obtained at 100°C. At higher temperatures (140–160°C), a side reaction of the CH₂Cl group took place which caused branching and partial crosslinking of the polymer. The reaction of phenyl glycidyl ether with phthalic anhydride gave linear, strongly alternating copolymers at temperatures of 120–160°C. Molecular weights (M¯_n) were in the range of 4000–87,000, depending on the purity of the starting materials and the initiator used. The reaction of the diepoxide BADGE with phthalic anhydride yielded highly crosslinked products. Their crosslink densities (which correlate with the glass transition temperature T_g). however, did not show the same dependence on initiator and purity of the starting materials as the molecular weights of the linear polyesters obtained by the “model reaction” of PGE with PSA. Possible reasons for this effect are discussed.     

A non-invasive form finding method with application to metal forming

Inverse form finding aims in determining the optimal material configuration of a workpiece for a specific forming process. A gradient- and parameter-free (nodal-based) form finding approach has recently been developed, which can be coupled non-invasively as a black box to arbitrary finite element software. Additionally the algorithm is independent from the constitutive behavior. Consequently, the user has not to struggle with the underlying optimization theory behind. Benchmark tests showed already that the approach works robustly and efficiently. This contribution demonstrates that the optimization algorithm is also applicable to more sophisticated forming processes including orthotropic large strain plasticity, combined hardening and frictional contact. A cup deep drawing process with solid-shell elements and a combined deep drawing and upsetting process to form a functional component with external teeth are investigated.     

Co‐optimization of SnS absorber and Zn(O,S) buffer materials for improved solar cells

Thin‐film solar cells consisting of earth‐abundant and non‐toxic materials were made from pulsed chemical vapor deposition (pulsed‐CVD) of SnS as the p‐type absorber layer and atomic layer deposition (ALD) of Zn(O,S) as the n‐type buffer layer. The effects of deposition temperature and annealing conditions of the SnS absorber layer were studied for solar cells with a structure of Mo/SnS/Zn(O,S)/ZnO/ITO. Solar cells were further optimized by varying the stoichiometry of Zn(O,S) and the annealing conditions of SnS. Post‐deposition annealing in pure hydrogen sulfide improved crystallinity and increased the carrier mobility by one order of magnitude, and a power conversion efficiency up to 2.9% was achieved. Copyright © 2014 John Wiley & Sons, Ltd.     

Classification of Concepts in Thermodynamically Consistent Generalized Plasticity

A classification of various formulations coined as generalized plasticity is introduced. Thereby the authors present variants of both gradient and micromorphic plasticity, which prove thermodynamically consistent by fulfilling the second law of thermodynamics. In a structured manner, they vary key characteristic features of the formulation and compare their influence on the complexity and, in particular, on the benefit of the individual formulations.     

Design and testing of a solar kiln simulator

To overcome the need for repeatable weather conditions when investigating solar wood drying, a solar simulation system was designed consisting of a climatic chamber for producing ambient wet and dry bulb conditions, a solar energy simulator to simulate the solar energy falling on the collector, and a small solar kiln to fit inside the climatic chamber. A fully automated control system, as used in an experimental solar kiln, controlled the simulation system. The design parameters, construction, and control logic of the system are discussed in Part 1 while the testing and performance of the system will be discussed in Part 2.