Melt electrospinning today: An opportune time for an emerging polymer process

Life at Low Reynolds Number

A lamp (600) comprising a solid state light emitter (450), the lamp being an A lamp and providing a wall plug efficiency of at least 90 lumens per Watt. Also, a lamp (400) comprising a solid state light emitter (450) and a power supply, the emitter being mounted on a heat dissipation element (420), the dissipation element being spaced from the power supply. Also, a lamp, comprising a solid state light emitter and a heat dissipation element that has a heat dissipation chamber, whereby an ambient medium can enter the chamber, pass through the chamber, and exit. Also, a lamp(10), comprising a light transmissive housing (12) at least one solid state lighting emitter and a first heat dissipation element. Also, a lamp comprising a heat sink comprising a heat dissipation chamber. Also, a lamp comprising first and second heat dissipation elements. Also, a lamp comprising means (74) for creating flow of ambient fluid.

Heat sinks and lamp incorporating same

Systems and methods that integrate audio capabilities within a display. A multilayered arrangement of dielectric and conductive layers can form a transducer that is integrated into the display. The dielectric layer can subsequently be charged (e.g., a biased voltage) and subject to a voltage to produce distortions and/or deflections of the dielectric layer, to produce acoustic waves that are audible to a user.

Display with integrated audio transducer device

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1106&context=coolingpubs

Enhancement of external forced convection by ionic wind

Thermal management of microelectronics with electrostatic fluid accelerators

Forced air cooling with rotary fans is the most popular cooling solution for electronic products. However, increasing heat generation in microelectronics, and the demand for ever smaller portable devices, has resulted in heat fluxes and form-factors that push the limits of conventional rotary fan-based air cooling technology. Electrohydrodynamic (EHD) ionic wind pumps offer an attractive alternative to fans. In this technique, applying a voltage to a sharp electrode ionizes nearby air molecules, which are then propelled by the electric field transferring momentum to neutral air molecules, generating bulk airflow and cooling. The fundamental principles of this technology have been investigated theoretically and experimentally. However, few real world applications have been produced to date due to technical challenges such as device miniaturization, high voltage generation, electromagnetic interference (EMI), and reliability. This paper discusses the successful integration of an EHD cooling system into a laptop computer. The stock rotary fans in the laptop cooling system were removed and directly replaced with EHD blowers. Airflow and thermal performance measurements, both at the device and system level are presented.

Electrohydrodynamic (EHD) cooled laptop

Electrostatic air propulsion is a promising technology with such potential applications as energy-efficient ventilation, air sterilization, cooling of electronics, and dehumidification. The challenges of existing designs include the need to increase air speed, backpressure, energy efficiency, and heat exchange capability. The ultimate goal of this direction of research is to create multi-channel energy efficient ionic pumps. In the described project, a single cell analysis is conducted in this study as a building block of future designs. This paper presents the numerical simulation and experimental results of electrostatic fluid accelerators. This study was conducted for the purpose of optimizing device characteristics through the control of the electric field distribution. Simulations were performed for multiple collector electrode voltage distributions. A method to quantify the change in pump performance between different voltage distributions is presented. The influence of space charge on pump performance is also discussed. A significant improvement of air velocity generated by optimized electrostatic fluid accelerators has been achieved using the proposed approach.

Design and optimization of electrostatic fluid accelerators

Existing thermal-management methods for electronics do not meet the technology needs and remain a major bottleneck in the evolution of computing, sensing, and information technology. The decreasing size of microelectronic components and the resulting increasing thermal output density require novel cooling solutions. Electrostatic fluid accelerators (EFAs), also known as electrohydrodynamic ionic wind pumps, have the potential of becoming a critical element of electronic thermal-management solutions. In order to take full advantage of EFA-based thermal management, it is essential to miniaturize EFA technology. This paper demonstrates the successful operation of a mesoscale microfabricated silicon EFA. Several cantilever structures fabricated in bulk silicon with radii of tip curvature ranging from 0.5 to 25 mum are used as the corona electrode. The device was fabricated using the combination of deep reactive ion etching (DRIE) and reactive ion etch (RIE) microfabrication processes. Forced convection cooling is demonstrated using infrared imaging, showing a 25degC surface temperature reduction over an actively heated substrate. The fabrication and test results of a mesoscale microfabricated EFA are presented in this paper.

Miniaturization of Electrostatic Fluid Accelerators

Classic thermal management solutions for microelectronics are becoming inadequate and there is an increasing need for fundamentally new approaches. Electrohydrodynamic ionic wind pumps, also known as electrostatic fluid accelerators (EFA), have the potential for becoming a critical element in electronics thermal management solutions. As the EFA field continues to evolve, developing new EFA-based technologies will require accurate models that can help predict pump performance metrics, such as air velocity profile, back pressure, and cooling effectiveness. Many previous modeling efforts only account for electrostatic interactions. For truly accurate modeling, however, it is important to include effects of fluid dynamics and space charge diffusion in charge transport. The modeling problem becomes especially challenging for the design and optimization of EFA devices with greater complexity and smaller dimensions. This paper presents a coupled physics finite element model (FEM) using a complete EFA charge transport model including charge diffusion and fluid dynamic effects. A cantilever EFA structure is modeled and analyzed for forced convection cooling. Numerical modeling predicts maximum air velocities of approximately 4 m/s and a maximum convection heat transfer coefficient of 280 W/(m2K) for the cantilever EFA structure investigated. Preliminary experimental results for a microfabricated cantilever EFA device for forced convection cooling are also discussed.

Nels Jewell-Larsen

Papers

Thermal management of microelectronics with electrostatic fluid accelerators

Electrohydrodynamic (EHD) cooled laptop

Design and optimization of electrostatic fluid accelerators

Miniaturization of Electrostatic Fluid Accelerators

CFD analysis of electrostatic fluid accelerators for forced convection cooling