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  • Publication
    Experimental determination of the forced convection heat transfer coefficient of an aluminum cooling plate with a channel shape inspired by nature
    (HEFAT, 2022-08-08) Guil Pedrosa, José Félix; Coll Franck, Anne Maren; García Gutiérrez, Luis Miguel; Soria Verdugo, Antonio; Comunidad de Madrid; Universidad Carlos III de Madrid
    Cooling is a crucial aspect in numerous applications where the optimal operation of electric, electronic, or electrochemical devices requires a controlled operating temperature. In this sense, metallic cooling plates are a suitable solution to dissipate heat from the surface of these equipment. The refrigeration capacity of cooling plates can be improved by circulating cold fluid along channels drilled in the metallic plate. The shape of these channels plays a critical role on the performance of the cooling plate since they affect both the distribution of temperature across the plate and the pressure drop required to pump the cooling fluid along the channel. The channel shape of a cooling plate can be optimized considering the Constructal law, which proposes the use of configurations found in nature to improve the performance in industrial applications. Following the Constructal law, a cooling plate made of aluminum, inside of which there is a channel with a shape resembling the outline of a flower, was built by a 3D printer. The performance of the plate was experimentally evaluated refrigerating the plate with various flow rates of cold water. To that end, an experimental facility was specifically designed and built to test the cooling capacity of the plate. The experimental setup consists of an enclosure inside of which the temperature of the atmosphere is controlled by a PID system connected to a thermoresistance and a heater, and a thermostatic bath to control the temperature of the cooling water at the inlet of the plate. The temperature of the plate was measured by an IR camera and the heat transfer coefficient by forced convection to the fluid were derived from the tests for both laminar and turbulent flow regimes of the fluid, obtaining values of 1703 and 3639 W/m2K, respectively, with maximum variations of 1 % for three replicates of each test, proving the high repetitiveness of the experimental procedure proposed. The average characteristic cooling time of the plate was measured to be 34.9 and 16.5 s for Reynolds numbers of the cooling flow of 1249 and 4918, respectively. Thus, an increase on the flow rate by 4 times results in a reduction of the characteristic cooling time by approximately 50 %.
  • Publication
    Performance evaluation of H2O-LiBr absorber operating with microporous membrane technology
    (American Society of Thermal and Fluids Engineers (ASTFE), 2015) Vega Blázquez, Mercedes de; Venegas Bernal, María Carmen; García Hernando, Néstor; Ruiz-Rivas Hernando, Ulpiano
    With the aim of reducing the size and increasing the energy efficiency of absorption chillers, the use of microporous membrane technology in these systems is at present under study. In particular, the simulation of a H2O-BrLi absorber using porous fibers for the heat and mass transfer between the solution and the vapor phase is considered in the present work. Heat and mass transfer process are modeled by means of selected correlations and data gathered from the open literature. Using the model developed, a simulation of the absorber is performed using typical operating conditions of absorption cooling chillers.