White Papers
Using Numerical Methods to Study the Effects Opening Ratio Made to Temperature Field in Micro-Desktop
This research uses the advanced simulation tool FloTHERM to study the effects of different opening ratios of the front panel to temperature field in the micro-desktop. Based on the studies, the best opening ratio with better cost performance and lower temperature is selected. Simulation results match experimental data well. Micro-desktop is a new smaller volume product with higher integration, which leads to smaller space for internal components and higher flow resistance inside. Therefore, the opening ratio of the front panel strongly influences the flow from internal fan at specific speed. Hence, this will further determine surface temperature distribution of important components and product performance. However, a larger opening ratio might also cause problems to structural strength and safety. This paper calculates flow fields and temperature fields inside the enclosure at different opening ratios, evaluates correlation between opening ratio and temperature of important components under different ambient temperatures, and selects the best solution where the system operates the most cost effectively. The simulation results are compared with experimental data to verify the validity of simulation calculation.
What They Didn’t Teach You in Engineering School About Heat Transfer
Using Computational Fluid Dynamics (CFD) is no longer relegated to the realm of the specialist. A new class of CFD analysis software, ‘Concurrent CFD’, is proving to be highly effective at performing heat transfer analysis, enabling mechanical engineers to accelerate key decisions at their workstations and without the need for CFD specialists. Embedded into the MCAD environment, this intuitive process allows designers to optimize a product during the design stages reducing manufacturing costs across a wide range of mechanical designs and systems.
State of the Art in Solid State Lighting Thermal Design
Unlike incandescent lighting that relies on heat to cause a filament to glow and produce light as hot black body, light emitting diodes (LEDs) are semiconductors and as such must be kept cool. When LEDs produce light, heat is a by-product. Heat generated in an LED increases its temperature. As the LED’s temperature increases, the light output decreases, the light changes color, and the lifetime of the LED reduces. Temperature adversely affects both the functional performance of the LED and its longevity. As a consequence, thermal management has become the most predominant issue in solid state lighting (SSL) design.
State of the Art in LED Thermal Characterization
Using the JEDEC standard static test method for transient thermal measurements in accordance with JESD51-14 and CIE 127-2007 has increased the level of accuracy in light-emitting diodes (LEDs) thermal characterization. These higher standards have resulted in increased customer confidence and market share. In compliance with these standards, the Mentor Graphics T3Ster system can complete more than 100 LED thermal measurements in a single day, and it is the most accurate. The T3Ster post-processing software fully supports the latest thermal testing standard (JEDEC JESD51-14) for junction-to-case thermal resistance measurement. This paper discusses the importance of more accurate thermal characterization to the rapidly evolving marketplace and how the T3Ster and TERALED systems are meeting this challenge for lighting manufacturers and their customers.
Thermal transient measurement of high power bipolar transistors: chances and challenges
Transient thermal testing becomes more and more important for discrete power transistors (BJTs), IGBTs and MOSFETs. While reaching proper power levels is relatively simple for the two latter, measuring BJTs is more challenging. Existing standards such as the JEDEC JESD51 and MIL-STD-750 give general guidelines on their transient measurements, i.e. powering and transient recording. However, the typical realization of the standard needs two high current power supplies with fast switching capabilities. Furthermore, BJTs operate as high frequency amplifiers in the circuit scheme needed for thermal testing, which may cause unwanted oscillations. This paper proposes an exact realization of the existing standards with a more cost effective instrumentation and better stability. Also a small add-on to the T3Ster line facilitating the standard measurements is presented in a case study.
Optical Characterization of Power LED
Besides their electrical properties the optical parameters of LEDs also depend on junction temperature. For this reason thermal characterization and thermal management play important role in case of power LEDs, necessitating both physical measurements and simulation tools. The focus of this paper is a combined electrical, thermal and optical characterization of power LED assemblies. In terms of simulation a method for board-level electrothermal simulation is presented, for measurements a combined thermal and radiometric characterization system of power LEDs and LED assemblies is discussed.
Optimizing Gas Mixing Processes with CAD-Embedded Engineering Fluid Dynamics Simulation
Best practices for CFD analysis in gas mixing with new CAD-embedded tools.
Understanding electronic IP: common issues and how to find them
Using IP blocks in designs requiring DO-254 compliance is becoming more popular as a way to reduce costs and schedules. However, the use of IP comes with its own problems and pitfalls. A good methodology to better screen this IP before its usage can significantly reduce unexpected problems and lower risk, especially on safety critical designs. The most important soft IP screening technologies are automatic formal check and clock domain crossing analysis. This paper will provide a background explanation of IP, including: what types exist in the market; caveats to their usage; and suggestions to better analyze IP before it is used in a design, thus lowering risk and improving product safety. (Note: This paper does not address IP compliance issues. For more information on that topic, please refer to the DO-254 User Group paper "Use of Intellectual Property (IP) Cores in Airborne Electronic Hardware".
The ROI of Concurrent Design with CFD
Research from Aberdeen's Q1 2011 business review has found that the top strategy for manufacturers, reported by 46%, is to improve business execution. What does this mean for new product development? A look at Aberdeen's October 2010 "NPD - the 2011 Growth Imperative: Optimizing Speed and Cost in New Product Development" report reveals the top challenges that must be addressed to accomplish this.
What They Didn’t Teach You in Engineering School About 3D Pressure Drop Analysis
Computational Fluid Dynamics (CFD) analysis is no longer a discipline reserved only for highly trained practitioners. A new class of CFD analysis software known as “Concurrent CFD” is proving to be greatly effective at performing pressure drop analysis, enabling mechanical engineers to accelerate key decisions at their workstations, without the need for CFD specialists. Embedded into the MCAD environment, this intuitive process allows designers to optimize a product during the design stages, reducing manufacturing costs across a wide range of mechanical designs and systems.
Beer Fridge: A Personal Journey
Mini-fridges, commonly filled with beer and the occasional moldering sandwich, have become a ubiquitous fixture in college dorm rooms and office break areas. But for some reason they never seem to cool their contents as well as their full-size cousins in the kitchen. This paper, based on a series of blog entries, presents a light-hearted look at the problem and offers a solution. In doing so, it demonstrates some practical thermal analysis methods using Mentor Graphics FloTHERM and proves that thermal simulation can help engineers design better products for consumers.