Multi-objective design optimization of a micro heat sink for Concentrating Photovoltaic/Thermal (CPVT) systems using a genetic algorithm

• Published in: Applied thermal engineering 2013-09, Vol.59 (1-2), p.733-744
• Main Authors: Karathanassis, Ioannis K., Papanicolaou, Elias, Belessiotis, Vassilios, Bergeles, Georgios C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Conjugate heat transfer; CPVT; Energy; Energy. Thermal use of fuels; Equipments, installations and applications; Exact sciences and technology; Fluid flow; Genetic algorithm; Heat sinks; Heat transfer; Mathematical analysis; Mathematical models; Microchannel heat sink; Microchannels; Multi-objective optimization; Natural energy; Photovoltaic conversion; Pressure drop; Response surfaces; Solar energy; Theoretical studies. Data and constants. Metering; Thermal resistance
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2012.06.034

An optimization methodology for a microchannel, plate-fin heat sink suitable for the cooling of a linear parabolic trough Concentrating Photovoltaic/Thermal (CPVT) system is applied in this study. Two different microchannel configurations are considered, Fixed (FWμ) and stepwise Variable-Width (VWμ) microchannels respectively. The performance evaluation criteria comprise the thermal resistance of the heat sink and the cooling medium pressure drop through the heat sink. Initially, the effect of the geometric parameters on the heat sink thermal and hydrodynamic performance is investigated using a thermal resistance model and analytical correlations, in order to save computational time. The results of the 1-D model enable the construction of surrogate functions for the thermal resistance and the pressure drop of the heat sink, which are considered as the objective functions for the multi-objective optimization through a genetic algorithm that leads to the optimal geometric parameters. In a second step, a 3-D numerical model of fluid flow and conjugate heat transfer for the optimized FWμ heat sink is developed in order to investigate in detail the flow and thermal processes. The overall analysis demonstrates that microchannel heat sinks achieve very low values of thermal resistance and that the use of variable-width channels can significantly reduce the pressure drop of the cooling fluid. Furthermore, it is proven that the 1-D model is capable of providing a good estimate of the behavior of the heat sink. ► Overall performance of fixed- and variable-channel-width heat sink is evaluated. ► Multi-objective optimization for geometric parameters and CFD model are applied. ► Introduction of stepwise channel-width variation enhances overall performance. ► Thermal entry length is negligibly small for the fixed-width configuration. ► The combined methodology proven valid in predicting the overall performance.