A new high entropy alloy brazing filler metal design for joining skutterudite thermoelectrics to copper

A new High Entropy Alloy (HEA) in the ZnGaCu-(AuSn) system was designed to join skutterudite thermoelectrics (CoSb2.75Sn0.05Te0.20), with a diffusion barrier of Ni applied, to Cu. Such a joint could be part of a device for thermal energy recovery within automotive exhaust systems. A rapid large-scale screening calculation technique based on Python programming has been introduced to conduct the HEA selection process, resulting in a series of alloys, which have been experimentally verified. It is demonstrated that a particular ZnGaCu-(AuSn) HEA alloy can join Ni and Cu successfully; a good joint is formed, and the average electrical contact resistance of the interfaces after joining is promising at room temperature, which shows that it has the potential to improve on the existing fillers used in such applications. The alloy design methodology used here suggests a potential efficient route to design new filler metals for a wide array of applications in which existing filler metals are not suitable

Tip cap for a rotor blade

A replaceable tip cap for attachment to the end of a rotor blade is described. The tip cap includes a plurality of walls defining a compartment which, if desired, can be divided into a plurality of subcompartments. The tip cap can include inlet and outlet holes in walls thereof to permit fluid communication of a cooling fluid there through. Abrasive material can be attached with the radially outer wall of the tip cap

Kirigami-Inspired Organic and Inorganic Film-Based Flexible Thermoelectric Devices with Built-In Heat Sink

Thermoelectric (TE) devices can convert heat to electricity directly, which offers a unique opportunity to realize waste heat recovery. However, conventional TE devices inevitably use heat sinks, which are bulky, rigid and heavy, limiting practical applications. Herein, we propose a fully integrated film-based TE device with intrinsically built-in fins as heat sink in a hexagonal honeycomb device structure, that simultaneously achieves high TE performance and conformability, as confirmed by experiments and modelling. A flexible Kapton substrate with copper electrodes, integrating either carbon nanotube (CNT) veils or bismuth telluride (Bi2Te3) TE ‘legs’, both of n- and p-type, achieved a remarkable specific power of 185.4 nW K−2 for a Bi2Te3-based device and 53.1 nW K−2 for a CNT-based device, thanks to the heat dissipation effect granted by the built-in fins. Besides, the addition of oriented polymer films interconnects, contracting when above their glass transition temperature, allowed a single substrate two-dimensional (2D) TE device to self-fold into a three-dimensional (3D) hexagonal honeycomb structure, with built-in fins, contactlessly and autonomously. The demonstrated shape-programmed kirigami-inspired scalable TE device paves the way for realising self-powered applications comprising hundreds of TE legs with both inorganic (e.g., Bi2Te3) and organic (e.g. CNT veils) TE materials and integrated heat sinks

Design and characterization of hybrid III–V concentrator photovoltaic–thermoelectric receivers under primary and secondary optical elements

Lattice-matched monolithic triple-junction Concentrator Photovoltaic (CPV) cells (InGa(0.495)P/GaIn(0.012)As/Ge) were electrically and thermally interfaced to two Thermoelectric (TE) Peltier module designs. An electrical and thermal model of the hybrid receivers was modelled in COMSOL Multiphysics software v5.3 to improve CPV cell cooling whilst increasing photon energy conversion efficiency. The receivers were measured for current-voltage characteristics with the CPV cell only (with sylguard encapsulant), under single secondary optical element (SOE) at x2.5 optical concentration, and under Fresnel lens primary optical element (POE) concentration between x313 and x480. Measurements were taken in solar simulators at Cardiff and Jaén Universities, and on-sun with dual-axis tracking at Jaén University. The hybrid receivers were electrically, thermally and theoretically investigated. The electrical performance data for the cells under variable irradiance and cell temperature conditions were measured using the integrated thermoelectric module as both a temperature sensor and as a solid-state heat pump. The performance of six SOE-CPV-TE hybrid devices were evaluated within two 3-receiver strings under primary optical concentration with measured acceptance angles of 1.00o and 0.89o, similar to commercially sourced CPV modules. A six-parameter one-diode equivalent electrical model was developed for the multi-junction CPV cells with SOE and POE. This was applied to extract six model parameters with the experimental I-V curves of type A receiver at 1, 3 and 500 concentration ratios. Standard test conditions (1000W/m2, 25oC and AM1.5G spectrum) were assumed based on trust-region-reflective least squares algorithm in MATLAB. The model fitted the experimental I-V curves satisfactorily with a mean error of 4.44%, and the optical intensity gain coefficient of SOE and POE is as high as 0.91, in comparison with 0.50-0.86 for crossed compound parabolic concentrators (CCPC). The determined values of diode reverse saturation current, combined series resistance and shunt resistance were similar to those of monocrystalline PV cell/modules in our previous publications. The model may be applicable to performance prediction of multi-junction CPV cells in the future

Formulation Pre-screening of Inhalation Powders Using Computational Atom–Atom Systematic Search Method

The synthonic modeling approach provides a molecule-centered understanding of the surface properties of crystals. It has been applied extensively to understand crystallization processes. This study aimed to investigate the functional relevance of synthonic modeling to the formulation of inhalation powders by assessing cohesivity of three active pharmaceutical ingredients (APIs, fluticasone propionate (FP), budesonide (Bud), and salbutamol base (SB)) and the commonly used excipient, α-lactose monohydrate (LMH). It is found that FP (−11.5 kcal/mol) has a higher cohesive strength than Bud (−9.9 kcal/mol) or SB (−7.8 kcal/mol). The prediction correlated directly to cohesive strength measurements using laser diffraction, where the airflow pressure required for complete dispersion (CPP) was 3.5, 2.0, and 1.0 bar for FP, Bud, and SB, respectively. The highest cohesive strength was predicted for LMH (−15.9 kcal/mol), which did not correlate with the CPP value of 2.0 bar (i.e., ranking lower than FP). High FP–LMH adhesive forces (−11.7 kcal/mol) were predicted. However, aerosolization studies revealed that the FP–LMH blends consisted of agglomerated FP particles with a large median diameter (∼4–5 μm) that were not disrupted by LMH. Modeling of the crystal and surface chemistry of LMH identified high electrostatic and H-bond components of its cohesive energy due to the presence of water and hydroxyl groups in lactose, unlike the APIs. A direct comparison of the predicted and measured cohesive balance of LMH with APIs will require a more in-depth understanding of highly hydrogen-bonded systems with respect to the synthonic engineering modeling tool, as well as the influence of agglomerate structure on surface–surface contact geometry. Overall, this research has demonstrated the possible application and relevance of synthonic engineering tools for rapid pre-screening in drug formulation and design