Q2 A You Are Designing The Thermal Management Of A New Cpu In A Pc The Cpu Produces Heat Equal To The Last Two Digits 1 (82.92 KiB) Viewed 35 times
Q2 A You Are Designing The Thermal Management Of A New Cpu In A Pc The Cpu Produces Heat Equal To The Last Two Digits 2 (82.92 KiB) Viewed 35 times
Q2 A You Are Designing The Thermal Management Of A New Cpu In A Pc The Cpu Produces Heat Equal To The Last Two Digits 3 (82.92 KiB) Viewed 35 times
Q2) a) You are designing the thermal management of a new CPU in a PC. The CPU produces heat equal to the last two digits of your matriculation number plus 10 (For example, if your matriculation number is 1234567, the CPU produces 77 W of heat). What is the maximum thermal resistance that can exist between the between the CPU and the 22 °C outside environment in order to avoid thermal runaway? [2] b) As a first approximation, you assume the CPU is connected to the surrounding environment by a block of material with cross sectional area 2 cm x 2 cm and length of 20 cm. Is it possible to cool the CPU from a) above if the material is i) copper (conductivity = 385 W/m K) or ii) Aluminium (conductivity=205 W/m K)? [2] c) You decide the approximation in b) above is too simplistic and choose to employ a heatsink to cool the CPU. Draw a thorough thermal resistance network that describes a CPU, connected to a heatsink in contact with the surrounding environment. You should include values for any temperatures and thermal resistances taken from a) and b) above. You should also indicate any unknown resistances, including what heat transfer mechanism they originate from. [5] d) Using the information contained within the ENG3032 lecture notes, calculate the efficiency of a heatsink fin using the following properties: heat transfer coefficient of fin = 50 W/m² K, fin material is copper with thermal conductivity = 390 W/m K. The fin thickness in mm is equal to the last two digits of your matriculation number plus 1 and its length in mm is equal to the last three digits of your matriculation number plus 100 (For example, if your matriculation number is 1234567, the fin width is 68 mm and its length is 667 mm). In 400 words or fewer, explain whether you feel this is a good efficiency. What could you change to improve the value and do all of these changes automatically mean a heatsink will be effective at cooling a component? [6] e) A critical aspect of a heatsink is its 'spreading resistance. However, this underlying concept is equally valid in many other thermal-conduction scenarios. In no more than 500 words, describe another situation where the same processes are at play. Select your example from day-to-day life, such as one found during cooking or heating a house. Highlight the parallels with 'spreading resistance' including what factors must be considered when altering it? You should also explain whether a high spreading resistance is desirable or not in your example. [5]
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