b'Geek Hub | Engineer InnovationT=300.00sSelected GoalsC 300 ter five minutes of heating250Figure 1: Model of an200 face plot of egg afegg frying on a CPU in150 300Simcenter FloTHERM XT 200 250 Figure 3: Temperature sur100 25 25 texture onto the board. This allowed 0 50 75 100 150 the footprints of the board Figure 2: Temperature against time for egg cooled CPU accurately against the image.Time components to be positioned Geek Hub | Engineer InnovationAn excessively detailed board is not Solving complex thermal models withy for this model as we are Engineer Innovation | Geek Hub CFD requires a lot of processing powernecessarand a CPU under full load generates aonly interested in the CPU temperature. To do this, the model fair amount of heat. But can you cooky that may alter needs to include the major sources of an egg on it? Search online and youy around can find videos of people attempting toheat and any geometrGeek Hub cook on their processors, but howllthe flow of air around critical This time.Frying an Egg on a CPU! effective as a cooling solution is this?components. The geometrthe CPU, such as the CPU socket, needs By James Forsyth, Engineering intern, Mentor, a SiemensBefore you throw away yourtunityto be much more detailed as this has a conventional heatsink and fan, in favory and a two-of a multifunctional omelette, we significant effect on heat transfer by investigate what CFD in Simcenterconduction. The CPU itself is modeled Flotherm XT software can predictwith accurate geometrabout the fate of your PC if you do so. resistor network assembly thermal model, based on an Intel Corey Business i3-4130 as a representative mid-Model range desktop processor. Typical As a student intern at Mentor, ated bymaximum Tjunc and Tcase are Siemens Business I get the opporto create and play with interesting and90C and 72C. The geometrunusual thermal models made in thefar from the CPU, such as the I/O y basic projectts, can be modeled as simple software. For this concept, I star porcuboids that will present an comprising two cuboids and a cylinder creating a ver obstacle to air flow on that edge to model a motherboard, processorof the board. Additional detail and egg. Then I did some research would just prolong the solver standard dimensions for motherboards,computation time with diminutiveGeek Hub | Engineer InnovationCPU thermal design power (TDP),improvement in accuracy.thermal data for eggs.y simple model, I wasOne consideration is that the egg able to test things rapidly, get a roughLimitationsUsing this ver cannot quite be simplified to a feel for the range of temperatures andmaterial with thermal63evaluate how feasible the concept wasproperties dependent on temperature, which I then created a more detailed model, to model. ting a board usingSimcenter Flotherm XT is ADeasily capable of modeling. ting by impor For instance, apply heat to a FLOEDA Bridge, a tool in Simcenter star block of aluminum and that y to be produced from anenergy will all eventually be Flotherm XT that allows 3D C transferred to the ambient air intuitive 2D EDA environment. Using a geometr CPU cooler radial heatsink and fan. topographical image of aOnce solved, this gave a junction representative mITX motherboard andtemperature of 65.1C after five a selection of known dimensions, I wasminutes of the CPU being under full able to accurately scale the image as aload at 54W with the system approaching equilibrium. Selected GoalsThe passive cooling of the egg cannot the white; thermal conductivities ofConclusion C 600.550-0.558 W/(m K) for the yolk andtedmatch the forced convection of theFigure 5: Board with egg replaced with stock CPU cooler 500.389-0.407 W/(m K) for the whitestock cooler. An egg-based cooling (decreasing with temperature). Thesolution could only keep the CPU300tionactual values used in the model werebelow the maximum 90C Tjunc if theedu/~mcclemen/581Thermal.html40 250as it cools. Do the same to an egg andbased on a moving average of repor CPU performance were throttled down[accessed April 2015] 30 150 200ted to theexperimental data.. to 10W TDP, so there are only possible75 100 Timenot all of the energy will be transferredapplications in lower powerC. Nmeth, K. Horvth, . Drobecz,20 0 25 50to the ambient; cooking an egg is anying away heat,L. Friedrich, K. Psztor-Huszr, C. Engineer Innovation | Geek Hub endothermic process and a propor Another factor not considered in theenvironments with plenty oftainlyBalla. Calorimetric study of model is water in the egg heating up toventilation. With the requirement of of the energy will be conver steam which rises, carr frequently swapping out the egg, Ifacechanges induced by preservativesFigure 7: Temperature against time for stock change in chemical enthalpy of the eggthough this is in small enoughcant see this catching on. If the aim isin liquid egg products. Polishcooled CPUas it cooks. quantities compared to the flow ofto cook eggs though, CPUs cer Journal of Food and Nutrition So the question is: how significant issurrounding air that it can be ignoredproduce enough heat to do so; withSciences, 2010, Vol.60(4)y. The specificfor now. thermal throttling, the processor acts this lost cooking energy to our model?A. Laca, B. Paredes, M. Daz. as a thermostatically controlled surWell, after some research andThese two modeling limitations meanat around 90C, sufficient to cook on. IfThermal behaviour of lyophilized 62 Geek Hub | Engineer Innovation enthalpy to denature the egg proteinsthat the results are likely to be a slightying pan instead. egg yolk and egg yolk fraction. calculations, not ver you value your computer, maybe during cooking is around 2.7 J/g for eggoverestimation of the temperaturesconsider buy a fr Jan, Vol.102(1)white and around 1.0 J/g egg yolk,[3,4]while the egg is still cooking, giving aJournal Of Food Engineering, 2011 worst-case scenario. This can often beReferencesso for an average 50 g egg, the total ntel Corporation, 2014. ARK | beneficial; if the worst-case scenario isI Intel Core i3-4130 Processor (3MJ. Coimbra, A. Gabas, L. Minim, E. energy required is only around 80J.formance should be superior. Cache, 3.40 GHz) [online]. http:// Garcia-Rojas, V. Telis, J. Telis-This energy would contribute to a totalwithin thermal design constraints, theRomero. Density, heat capacity and drop in CPU temperature ofactual per ark.intel.com/products/77480/ thermal conductivity of liquid egg approximately 6C, but this removal ofIntel-Core-i3-4130-Processor-3M- products. Journal of Food heat can only happen once per egg.Above 65C, the white begins toCache-3_40-GHz [accessed AprilEngineering, 2006, Vol.74(2) nCompare this to the 54 W TDP of thecoagulate and above 70C the yolk2015]solidifies. Once solid and cooked, the CPU under heavy load; after a fewegg is a much poorer heatsink; it is lessJ. McClements, University ofT=300.00sminutes of egg cooking, the heatthermally conductive and convectionMassachusetts, 2001. Thermal dissipated is of the order of 10 kJ andwithin the egg no longer occurs, it isAnalysis of Foods [online]. http://the protein denaturation can onlyless dense due to water loss, and air/ people.umass.Mike had to create another simulationmitigate a negligible fraction of this. steam gaps are formed underneath the with a lid to see how this changed theegg, insulating the CPU causing more results. We expected the temperatureThe majority of the heat supplied endsheat to accumulate. Modeling the egg to rise, but we had to wait to see if thisup, well, heating the egg. The eggsas always liquid gives a best-caseT=300.00shigh water content gives it physical would be a drastic increase." properties similar to waterslightlyscenario above 70C.When Mike realized there was a lidhigher densities of 1130 kg/m3 for theResultsfacey, selected theyolk and 1133 kg/m3 for the white;tunately, the CPU junction65missing from the model and the airspecific heat capacities of 3.55-3.60 J/ Unforare cool enough to eliminate the risk ofwas escaping through the top, he went(kg K) for the yolk (increasing withtemperature exceeds 90C within six injury. Many times the designback into the geometr temperature) and 2.55-2.75 J/(kg K) forseconds, at which point the CPU clock face feels tooopen plane and with a few quick clickswould throttle down to reduce theface plot of stock cooled CPUrequirements for the outer sur created a lid to close the model at thethermal power and prevent damage to y innovativetemperature are limited by how hot they high and unrealisticFigure 8: Sury and helpsurface feels. If a sur top. In an intermediate simulation, hethe systemless than ideal for a having to deal with a prosthetic legwarm, the end user could interpret thisobtained ver d defined some ofcooling solution. The egg would also as a malfunctioning or poorly designedtemperatures. As he was making atiesburn and catch fire. y before! Debbie found ver AD example andquick simulation, he The central location of the CPU on the ways to explain the geometr unit. the solid components as an insulator Engineer Innovation | Geek Hub visualize the aim of the project (Figureview ts mean limited cold AD andMike took a GrabC material. He also experimented bytiesboard and the large obstacles to air per putting a heatsink on the PCB, and forT=300.00s1). sformed some modifications until itts was neglected.Figure 4: Over flow in the neighboring memor ticle plot showing air flow through stock coolerlooked more like the physical board. Hethis comparison the material proper DIMMS and I/O porWith the information gathered, Miketed intoFigure 7: Paralso applied some scaling features,for some of the par tant. Theair can passively flow over the hot egg used a model found on GRABC because the initial unit was smaller.Now that the top of the leg is closed,by natural convection. Even adjusting modified it according to Debbie the influence of the material proper t. the results for the modeling limitations descriptions. Simcenter FLOEFD with the Simcenterbecomes more impor discomfor described earlier, there is simply The IDF file was impor should not cause any burns or faces) werecombination of the closed top withinsufficient cooling.Flotherm FloEDA Bridge so that the Once the first version was useable,boundary conditions (materials, heatinsulator material, caused the highThe information that can be gathered Mike shared this model with Johntemperatures. Once this was realized, aFor comparison, a new project Wilson who created the PCB. John issources and radiative sur is invaluable, without having to build AD, Johncreated automatically, see Figure 3.simulation was run for both cases withmultiple prototypes or having toconfiguration was created with the egg the Electronics Product Specialist at ting from MC The ambient conditions were set tothe leg defined as standard stainlessredesign later on in the design process. substituted for a standard Intel stock Mentor, A Siemens Business. typical values of 20C and 1.01 bar.steel. The maximum temperature is Gravity is enabled because it is cooledalmost equal in both cases, it shows faces show theonly a very small difference. The openwww.limbcare.orgted with an image and with theby natural convection.Rather than star version is 0.1C cooler. What does thisFor more information:star yflowmean? Most of the heat is convecting help of Debbie, determined the approximate scales of the board andThe colored sur and radiating from the PCB to the outerDebbie Searle Blog: y/higher power dissipation components.temperature distribution on the PCB.https://bit.ly/2JJCztVpowered there is a need to develop aaround these components. It is causedReferencesWith electronics that are batter The arrows illustrate the air enclosure.y, putting on a lid and by the natural convection, whichIn summar https://grabcad.com/librar ticle plot, showing air flow around egg and CPUsolution that meets the functionalmeans the heated air moves upwardsenclosing the casing makes minimalsbelow-knee-prosthesis-1 nrequirements with the lowest powercausing air circulation in this area. impact. The maximum temperaturesFigure 4: Parconsumption possible. In thesereached in either case is 38C. The situations the critical IC componentsThe air is escaping out through the top,maximum advised temperature in a64are well within their temperaturebut as our physical example has a lid,consumer product is around 41C. So at requirements (reliability of electronicsa little over body temperature, Debbieare strongly related to both peakleg, even while working at its hardest, temperature cycling). Thermal design operating temperatures and often involves ensuring that any73Figure 2: Board created faces that may be touched 67exposed surFigure 3: Boundary conditions of the PCB Figure 5: Temperature distribution on the PCB Figure 7: Comparison of the two variants72'