Here we document the performance of a radiant cooling panel made of flow channels sandwiched between a suspended metal plate and an insulation layer. The flow passages represent the crucial element of the panel. In the present work, the heat transfer and flow characteristics of the panel are investigated. A numerical study is conducted to explore the role played by the flow architectures on the overall performance of the panel in steady state, subjected to radiation and convection heat fluxes from the bottom. A comparison between serpentine and canopy-to-canopy (dendritic) flow channels is presented. In all the cases, the following geometrical constrains apply: fixed plate area and flow volume. From one configuration to the other, the flow is given more freedom to morph in accord with the Constructal approach. We demonstrated that the dendritic architecture allows a significant improvement in the cooling panel performance, with more cooling capacity and less pumping power. In addition, we showed that the morphing of the panel itself toward more compactness is also a way to increase the ratio of cooling capacity/pumping power.
The influence of flow structures on the design of radiant cooling panel is explored Serpentine and Constructal flow layouts are investigated A numerical model is employed to evaluate the thermo-fluid performance of the panel Branching flow arrangements have the potential of improving the global performances
The use of radiant systems for cooling purposes in buildings is attracting considerable attention, particularly for Suspended Radiant Ceiling Panels (SRCPs). However, the arrangement of the panels on the ceiling and the influence on radiative heat transfer is rarely discussed in the literature. The objective of this paper is to provide a numerical study of the radiative heat transfer at room scale when the size and the number of SRCPs varies. It has been observed that the use of a single large panel would result in a low average temperature, which is desirable, but also in poor uniformity of the temperature field. Here, a genetic algorithm is proposed and tuned to determine the positions of multiple SRCPs that would improve uniformity. It is shown that much better uniformity can be obtained, with only a moderate increase in the average temperature, for 10 panels or more. The differences between the use of a single large panel and multiple panels is noteworthy when SRCPs cover from 10 to 70% of the ceiling area.
The present work highlights how the constructal law is implemented in the search for buildings' performance from a thermal lookout. The authors reviewed some of their research efforts through two applications: radiant cooling panels and thermochemical energy storage in buildings. In a deterministic approach, it was demonstrated that the overall performance of such systems could be anticipated. Under the same operating conditions, cooling panel with dendritic flow configurations exhibited better global performance compared to the design with a serpentine flow layout. Two configurations of elemental reactors for thermochemical energy storage were studied: reactive material in beds layers and impregnated within a tube. A theoretical approach allowed to predict the impact of the Bejan number on the sensible heat output for the first configuration, when numerical experiments allowed to determine how to morph the tube shape to increase thermal performances.
Absorber is the most important component in LiBr-H2O absorption systems as its operating performance directly influences the performance of the whole system. In simulating absorption heat and mass transfer in horizontal tube absorber, many authors, for simplicity, make some assumptions. One of these assumptions is that the thermo-physical properties of the solution are constant across the absorber. In this paper, LiBr-H2O horizontal tube absorber was simulated with constant and variable thermo-physical properties and a comparison between the performance parameters (solution concentration, solution temperature, absorber heat duty and rate of vapor absorption) was made. Two solution flow rates are used in this simulation ([Formula: see text][Formula: see text][Formula: see text][Formula: see text] and [Formula: see text][Formula: see text][Formula: see text][Formula: see text]) and a computer program was developed to simulate the two cases (constant and variable thermo-physical properties). The comparison results show that, in case of variable thermo-physical properties, the heat duty and vapor absorption rate are less than those in case of constant thermo-physical properties whereas solution concentration and temperature are slightly greater. Also, it is found that increasing solution volume flow rate [Formula: see text] increases the difference in heat duty and absorption rate and slightly decreases the difference in solution concentration and temperature.
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