Ch 4. Energy Analysis Multimedia Engineering Thermodynamics Steady-flowProcess Steady-flowDevices (1) Steady-flowDevices (2) Steady-flowDevices (3) Unsteady-flowProcess
 Chapter 1. Basics 2. Pure Substances 3. First Law 4. Energy Analysis 5. Second Law 6. Entropy 7. Exergy Analysis 8. Gas Power Cyc 9. Brayton Cycle 10. Rankine Cycle Appendix Basic Math Units Thermo Tables Search eBooks Dynamics Statics Mechanics Fluids Thermodynamics Math Author(s): Meirong Huang Kurt Gramoll ©Kurt Gramoll

 THERMODYNAMICS - CASE STUDY Introduction Cooling Computer by a Fan The engineering computer lab is planning to discard some old computer parts this summer. Alex plans to build a computer by himself using those parts but is worried about the cooling capacity of the fan he obtained since the electronic components of a computer can only work under a specific temperature range. For the given fan, he needs to determine how many printed circuit boards (PCBs) he can use in the computer before it overheats. What is known: Each PCB dissipates 10 W of power The air enters the box at 20 oC and 1 atm The temperature at the exit can not exceed 32 oC The power of the fan is 20 W. CPU and other components other than PCBs dissipates 60 W of power The flow rate of the fan is 0.01 kg/s Questions How many PCBs can he install in this computer? Approach Method 1: Consider the whole enclosure as a control volume. Method 2: Consider the air as control volume A and the fan, the CPU, and PCBs as control volume B.