- Thin-Film Superlattice Thermoelectric Devices for Energy Harvesting and Thermal Management

2012 ◽  
pp. 431-450
Keyword(s):  
Thin Film ◽  
Energy Harvesting ◽  
Thermal Management ◽  
Thermoelectric Devices

scholarly journals Capillary-Limited Evaporation From Well-Defined Microstructured Surfaces

2013 ◽  
Author(s):  
Solomon Adera ◽  
Rishi Raj ◽  
Evelyn N. Wang
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Phase Change ◽  
Thermal Management ◽  
Latent Heat ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Microstructured Surfaces ◽  
Latent Heat Of Vaporization

Thermal management is increasingly becoming a bottleneck for a variety of high power density applications such as integrated circuits, solar cells, microprocessors, and energy conversion devices. The performance and reliability of these devices are usually limited by the rate at which heat can be removed from the device footprint, which averages well above 100 W/cm2 (locally this heat flux can exceed 1000 W/cm2). State-of-the-art air cooling strategies which utilize the sensible heat are insufficient at these large heat fluxes. As a result, novel thermal management solutions such as via thin-film evaporation that utilize the latent heat of vaporization of a fluid are needed. The high latent heat of vaporization associated with typical liquid-vapor phase change phenomena allows significant heat transfer with small temperature rise. In this work, we demonstrate a promising thermal management approach where square arrays of cylindrical micropillar arrays are used for thin-film evaporation. The microstructures control the liquid film thickness and the associated thermal resistance in addition to maintaining a continuous liquid supply via the capillary pumping mechanism. When the capillary-induced liquid supply mechanism cannot deliver sufficient liquid for phase change heat transfer, the critical heat flux is reached and dryout occurs. This capillary limitation on thin-film evaporation was experimentally investigated by fabricating well-defined silicon micropillar arrays using standard contact photolithography and deep reactive ion etching. A thin film resistive heater and thermal sensors were integrated on the back side of the test sample using e-beam evaporation and acetone lift-off. The experiments were carried out in a controlled environmental chamber maintained at the water saturation pressure of ≈3.5 kPa and ≈25 °C. We demonstrated significantly higher heat dissipation capability in excess of 100 W/cm2. These preliminary results suggest the potential of thin-film evaporation from microstructured surfaces for advanced thermal management applications.

scholarly journals FINITE ELEMENT SIMULATION OF MEMS PIEZOELECTRIC ENERGY SCAVENGER BASED ON PZT THIN FILM

2019 ◽  
Vol 20 (1) ◽  
pp. 90-99
Author(s):  
Aliza Aini Md Ralib ◽  
Nur Wafa Asyiqin Zulfakher ◽  
Rosminazuin Ab Rahim ◽  
Nor Farahidah Za'bah ◽  
Noor Hazrin Hany Mohamad Hanif
Keyword(s):  
Thin Film ◽  
Energy Harvesting ◽  
Output Voltage ◽  
Energy Harvester ◽  
Maximum Output Power ◽  
Vibration Energy ◽  
Maximum Output ◽  
Vibration Energy Harvesting ◽  
Piezoelectric Energy ◽  
The World

Vibration energy harvesting has been progressively developed in the advancement of technology and widely used by a lot of researchers around the world. There is a very high demand for energy scavenging around the world due to it being cheaper in price, possibly miniaturized within a system, long lasting, and environmentally friendly. The conventional battery is hazardous to the environment and has a shorter operating lifespan. Therefore, ambient vibration energy serves as an alternative that can replace the battery because it can be integrated and compatible to micro-electromechanical systems. This paper presents the design and analysis of a MEMS piezoelectric energy harvester, which is a vibration energy harvesting type. The energy harvester was formed using Lead Zicronate Titanate (PZT-5A) as the piezoelectric thin film, silicon as the substrate layer and structural steel as the electrode layer. The resonance frequency will provide the maximum output power, maximum output voltage and maximum displacement of vibration. The operating mode also plays an important role to generate larger output voltage with less displacement of cantilever. Some designs also have been studied by varying height and length of piezoelectric materials. Hence, this project will demonstrate the simulation of a MEMS piezoelectric device for a low power electronic performance. Simulation results show PZT-5A piezoelectric energy with a length of 31 mm and height of 0.16 mm generates maximum output voltage of 7.435 V and maximum output power of 2.30 mW at the resonance frequency of 40 Hz. ABSTRAK: Penuaian tenaga getaran telah berkembang secara pesat dalam kemajuan teknologi dan telah digunakan secara meluas oleh ramai penyelidik di seluruh dunia. Terdapat permintaan yang sangat tinggi di seluruh dunia terhadap penuaian tenaga kerana harganya yang lebih murah, bersaiz kecil dalam satu sistem, tahan lama dan mesra alam. Manakala, bateri konvensional adalah berbahaya bagi alam sekitar dan mempunyai jangka hayat yang lebih pendek. Oleh itu, getaran tenaga dari persekitaran lebih sesuai sebagai alternatif kepada bateri kerana ia mudah diintegrasikan dan serasi dengan sistem mikroelektromekanikal. Kertas kerja ini  membentangkan reka bentuk dan analisis tenaga piezoelektrik MEMS iaitu salah satu jenis penuaian tenaga getaran. Penuai tenaga ini dibentuk menggunakan Lead Zicronate Titanate (PZT-5A) sebagai lapisan filem tipis piezoelektrik, silikon sebagai lapisan substrat dan keluli struktur sebagai lapisan elektrod. Frekuensi resonans akan memberikan hasil tenaga maksima, voltan tenaga maksima dan getaran jarak maksima. Mod pengendalian juga memainkan peranan penting bagi menghasilkan tenaga yang lebih besar. Reka bentuk yang mempunyai ketinggian dan panjang berlainan juga telah diuji dengan menggunakan bahan piezoelektrik yang sama. Oleh itu, projek ini akan menghasilkan simulasi piezoelektrik MEMS yang sesuai digunakan bagi alat elektronik berkuasa rendah. Hasil simulasi menunjukkan dengan panjang 31 mm dan ketinggian 0.16 mm, piezoelektrik PZT ini menghasilkan voltan maksima sebanyak 7.435 V dan tenaga output maksima 2.30 mW pada frekuensi resonans 40 Hz.

Thin-film thermoelectric devices with high room-temperature figures of merit

2010 ◽  
pp. 120-125 ◽  
Author(s):  
Rama Venkatasubramanian ◽  
Edward Silvola ◽  
Thomas Colpitts ◽  
Brooks O'Quinn
Keyword(s):  
Thin Film ◽  
Room Temperature ◽  
Thermoelectric Devices ◽  
Figures Of Merit
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