Modeling the external flow of a novel HorseShoe receiver and the evaluation of thermal performance

The linear receiver of a Parabolic Trough Collector is the most critical element in the entire system. The Universal Vacuum Air Collector concept is the most extended type of receiver in both experimental and industrial facilities. Besides their considerable cost, their efficiency usually drops as operation time passes. This is mainly due to a partial loss of vacuum in the evacuated annulus between the absorber and the glass cover. An alternative design called HorseShoe receiver is proposed in this work, whose main goal is to maintain the thermal performance throughout its entire lifespan. This innovative receiver is indicated for low-to-medium temperature ranges, which is particularly suitable for solar heat for industrial processes. It consists of a horseshoe-like cavity absorber having its upper border insulated. In addition, two main advantages can be taken by using two symmetric lenses as glass cover: reconcentrate solar radiation into the cavity (improvement of the intercept factor) and protect stratification conditions (reduction of thermal losses). A transient numerical model with customized boundary conditions has been implemented to evaluate both thermal performance and temperature difference in the absorber domain, which is critical for the thermal stress conditions. For that purpose and as a key contribution, not only the Heat Transfer Fluid (HTF) temperature but also the heat transfer coefficient in the duct are set. In particular, HTF temperature ranges from 80 °C to 220 °C and the inner heat transfer coefficient from 600 W/(mK) to 1800 W/(mK). Results show that numerical thermal performance is above 96%, which is mainly due to the reduction of thermal radiation losses, where the absorber active surface emittance is . (...)Second (corresponding) author J.J. Serrano-Aguilera acknowledges the support provided by Junta de Andalucía (Government of Andalusia) and Universidad de Málaga for the source of funding for the HERTERSOL project (UMA18-FEDERJA-195), as well as to Ministerio de Ciencia, Innovación Universidades (Spain) by means of the postdoc position: Ref No. FJCI-2017-32403 (Juan de la Cierva-Formación Postdoc Grant). Third author acknowledges the support of Universidad de Málaga, Spain through the Project WALICON, 2021. Authors also acknowledge funding for open access charge: Universidad de Málaga / CBUA

Optimization of Heat Sinks in a Range of Configurations.

In this study, different heatsink geometries used for electronic cooling are studied and compared to each other to determine the most efficient. The goal is to optimize heat transfer of the heat sinks studied in a range of configuration based on fin geometry. Heat sinks are thermal conductive material devices designed to absorb and disperse heat from high-temperature objects (e.g. Computer CPU). Common materials used in the manufacturing of heat sinks are aluminum and copper due to their relatively high thermal conductivity and lightweight [1]. Aluminum is used as the material for the heatsinks studied in this research project. To start, experimental results from a wind tunnel test conducted were compared to numerical results generated to establish a validation case. Best practices in running numerical simulations on heat sinks along with suitable models for simulating real-world conditions were determined and analyzed. The two main thermal performance-evaluating parameters used in this project are pressure drop (ΔP) and thermal resistance (R). Thirteen numerical CFD simulations were run on different heatsink fin extrusion geometries including the traditional rectangular plate, arc plate, radial plate, cross pin, draft pin, hexagonal pin, mixed shape pin fin, pin and plate, separated plate, airfoil plate, airfoil pin, rectangular pin, and square zig-zag plate heat sinks. It was observed that different fin geometries and dimensions affect the performance of heat sinks to varying extents. The square zig-zag plate heat sink from results obtained had the lowest thermal resistance of 0.25 K/W with the separated plate having the lowest pressure drop of 11.94 Pa. This information is relevant in the selection of fan type, size, and model of heat sink for electronics cooling. Also, another important conclusion drawn from this project is the existence of no definite correlation between the thermal resistance (R) and pressure drop (ΔP) parameters when evaluating heatsink performance

Multi-material heatsink design using level-set topology optimization

In this article we apply a Level-set topological optimization algorithm to the design of multi-material heat sinks suitable for electronics thermal management. This approach is intended to exploit the potential of metal powder additive manufacturing technologies which enable fabrication of complex designs. The article details the state-of-the-art in topological optimization before defining a numerical framework for optimization of two-material and three-material based heatsink designs. The modelling framework is then applied to design a pure copper and a copper-aluminum heatsink for a simplified electronics cooling scenario and the performance of these designs are compared. The benefits and drawbacks of the implemented approach are discussed along with enhancements that could be integrated within the framework. A benchmarking study is also detailed which compares the performance of topologically optimized heat sink against a conventional pin-fin heat sink. This is the first time that topological optimization methods have been assessed for multi-material heat sink design where both conduction and convection are included in the analysis. Hence, the reported work is novel in its application of a state-of-the-art Level-set topology optimization algorithm to design multi-material structures subject to forced convective cooling. This paper is intended to demonstrate the applicability of topological optimization to the design of multi-material heatsinks fabricated using additive manufacturing processes and succeeds in this objective. The paper also discusses challenges, which need to be addressed in order to progress this modelling as a design approach for practical engineering situations. The presented methodology is able to design thermal management structures from a combination of aluminum and copper that perform similarly to pure copper but utilizing less expensive materials resulting in a cost benefit for electronics manufacturers