06/02224 Effect of the thermal conductivity of building materials on the steady-state thermal behaviour of underground building envelopes: Yuan, Y. et al. Building and Environment, 2006, 41, (3), 330–335.
- Publisher
- Elsevier Science
- Year
- 2006
- Weight
- 335 KB
- Volume
- 47
- Category
- Article
- ISSN
- 0140-6701
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✦ Synopsis
The pinch analysis (PA) concept's main drawback is that it is suboptimal since it disregards the chemical reactors network (CRN) contribution to the total flowsheet entropy generation, as it does with the separation trains, if any. The chemical reactors energy integration (CREI) through virtual heat exchangers (VHE) emerged and became, during its crystallization period, an expansion of the classical PA, allowing the CRN to be seen as part of the heat exchangers network (HEN), perhaps leading to a better decrease in the total entropy production both through the inclusion of CRN sources and sinks into the HEN topology, and the improvement of the reactors operating conditions, while preserving their performance, in terms of chemical transformation. Throughout the considered case study, two-bed methanol synthesis heat integrated reactor, the benefits and the drawbacks of the CREI will be emphasized.
06•02217 Constructal multi-scale structures for maximal heat transfer density
da Silva, A. K. et al. Energy, 2006, 31, (5), 620 635. This paper reviews recent constructal-theory advances: the optimal distribution of discrete heat sources cooled by laminar natural convection. Three scenarios are investigated: (i) many small heat sources mounted on a vertical wall, (i) a few small finite-size heat sources mounted on the side wall of a two-dimensional enclosure, and (iii) one heated area on the wall of a vertical diverging or converging channel with chimney flow. In (i) and (ii), the optimally distributed heat sources are not equidistant. In (iii), the geometry changes by varying the space between the walls, the distribution of heating along the walls, and the angle between the two walls. Numerical simulations in the Rayleigb number range 105 <_ Rail _< 107 show that for maximal heat transfer rate density it is better to install heated sections at the channel entrance. The optimal angle between the two walls is approximately zero when Ran is large. The robustness of flow architectures with optimized distribution of heat sources is discussed.
Desalination using spray tower and vapour compression refrigeration system