3D Analysis of Heat Transfer Intensification by Re-Entrance Flow Pin-Fins Microstructures with a Highly Thermal-Conductive Plate

Joule heat-induced hot-spot formation sets severe limits in the operation of continuous annular electrochromatography (CAEC), a new concept for preparative separation as an analog to analytical capillary electrochromatography (CEC). This may lead to eluent flow perturbance, even to boiling, which would massively weaken separation efficiency and may even hamper the stationary phase used for separation. For reasons of system integration and high-efficiency heat transfer, micro flow heat exchangers are considered with a separate coolant flow. A 3D numerical analysis of the heat transfer of water single-phase laminar flow in a square microchannel and different arrays of micro pin-fins was carried out using COMSOL Multiphysics. Several advanced materials with low electric conductivity and at the same time with high heat conductivity were put forward to be used in the CAEC system. As essential design point, it is proposed to constitute the micro heat exchanger from two different parts of the CAEC system, namely a microstructured pin-fins plate and a so-called conductive plate.

Eating from the same plate? Revisiting the role of labile carbon inputs in the soil food web

An increasing number of empirical studies are challenging the central fundamentals on which the classical soil food web model is built. This model assumes that bacteria consume labile substrates twice as fast as fungi, and that mycorrhizal fungi do not decompose organic matter. Here, we build on emerging evidence that points to significant consumption of labile C by fungi, and to the ability of ectomycorrhizal fungi to decompose organic matter, to show that labile C constitutes a major and presently underrated source of C for the soil food web. We use a simple model describing the dynamics of a recalcitrant and a labile C pool and their consumption by fungi and bacteria to show that fungal and bacterial populations can coexist in a stable state with large inputs into the labile C pool and a high fungal use of labile C. We propose a new conceptual model for the bottom trophic level of the soil food web, with organic C consisting of a continuous pool rather than two or three distinct pools, and saprotrophic fungi using substantial amounts of labile C. Incorporation of these concepts will increase our understanding of soil food web dynamics and functioning under changing conditions.

Improved Equivalent Frame Analysis Method for Flat Plate Structures in Vicinity of Edge Columns

This paper proposes a modification to the ACI 318-02 equivalent frame method of analysis of reinforced concrete flat plate exterior panels. Two existing code methods were examined: ACI 318 and BS 8110. The derivation of the torsional stiffness of the edge strip as proposed by ACI 318 is examined and a more accurate estimate of this value is proposed, based on both theoretical analysis and experimental results. A series of 1/3-scale models of flat plate exterior panels have been tested. Unique experimental results were obtained by measuring strains in reinforcing bars at approximately 200 selected locations in the plate panel throughout the entire loading history. The measured strains were used to calculate curvature and, hence, bending moments; these were used along with moments in the columns to assess the accuracy of the equivalent frame methods. The proposed method leads to a more accurate prediction of the moments in the plate at the column front face, at the panel midspan, and in the edge column. Registered Subscribers: View the full article. This document is available as a free download to qualified members. An electronic (PDF) version is available for purchase and download. Click on the Order Now button to continue with the download.