Yazar "Akhtar, Mohammad Nishat" seçeneğine göre listele

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    Analysis of bubble departure and lift-off boiling model using computational intelligence techniques and hybrid algorithms
    (Elsevier France-Editions Scientifiques Medicales Elsevier, 2024) Quadros, Jaimon Dennis; Mogul, Yakub Iqbal; Agbulut, Umit; Gurel, Ali Etem; Khan, Sher Afghan; Akhtar, Mohammad Nishat; Jilte, R. D.
    The bubble departure and lift-off boiling (BDL) model was studied using computational intelligence techniques and hybrid algorithms. Quite a few studies have predicted the relationship between wall heat fluxes and wall temperature in the form of flow boiling curves. The output wall temperature is a performance indicator that depends on many operating parameters. The current study, therefore, analyses the predictability of the wall temperature in terms of operating pressure, bulk flow velocity, and wall heat flux, based on the BDL model developed by Zenginer, which included two suppression factors namely, flow-induced and subcooling factors, respectively. The soft computing techniques used for prediction were - the artificial neural network (ANN), and the Fuzzy Mamdani model, and the hybrid algorithms were adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network trained particle swarm optimization (ANN-PSO). In addition, the ANN-PSO conducted a parametric analysis to evaluate the best model configuration by considering various factors. The comparison of all four techniques showed that the ANFIS model exhibited the prediction performance for wall temperature. Moreover, the results obtained from the ANFIS model have been compared with the different flow boiling curves from the literature and observed that the curve fitted well for higher bulk flow velocities with an MSE and R2 was found to be 0.85 % and 0.9933, respectively.
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    Experimental investigation of the thermal efficiency of a new cavity receiver design for concentrator solar technology
    (Elsevier, 2024) Alkhalaf, Qusai; Lee, Daeho; Kumar, Raj; Thapa, Sashank; Singh, Amar Raj; Akhtar, Mohammad Nishat; Asif, Mohammad
    The most popular design for solar energy receivers that achieves great thermal performance is a cavity receiver. This study experimentally compared two novel shapes of cavity receivers: conical-cylindrical-conical (CCC) and double cylindrical, with conventional conical and cylindrical designs, to examine the effectiveness of solar energy receivers. The findings indicate that the CCC shape demonstrated a higher level of efficiency, as it performed better than all other shapes that were examined. Results emphasized the influence of radiation intensity on receiver efficiency, with all shapes exhibiting improved performance at higher intensities, maximizing at 1000 W/m2. Lower friction factors were desirable for minimizing heat losses and maximizing efficiency, resulting in values of 0.078, 0.09, 0.1, and 0.12 for CCC, conical, double cylindrical, and cylindrical shapes at a flow rate of 2 L/min, respectively. The temperature differences for CCC, conical, double cylindrical, and cylindrical shapes are computed as 6.4 degrees C, 5.7 degrees C, 5 degrees C, and 4.3 degrees C, respectively. The thermal efficiencies of the CCC, conical, double cylindrical, and cylindrical shapes are computed as 86.5 %, 81.5 %, 79.9 %, and 68.9 %, respectively, at a flow rate of 2 L/min.