Ch 3. First Law of Thermodynamics th Multimedia Engineering Thermodynamics Conservationof Mass Conservationof Energy Solids andLiquids Ideal Gas
 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 How Window Air Conditioner Works Click to View Movie (92 kB) Lee is a new AME student at the University of Oklahoma. He rents a small apartment which has a window air conditioner. Lee spends most of his time at school, hence he only wants to run the air conditioner when he is at home. But he is worrying that it will take too long for the room temperature to reach the temperature setting. Also, he is interested in knowing how much heat will be released to the ambient during the cooling process. What is known: Coefficient of performance (the ratio of the heat removed from the room to the net work required for the air conditioner) of the air conditioner COP = 2.5 Power input of the air conditioner= 900 W Room temperature Troom = 90oF Temperature setting of the air conditioner Tsetting = 75 oF 10 kJ heat needs to be removed for the temperature of the room to go down 1 oF Questions How long time will it take to cool the room down to the temperature setting? How much heat will be released to the ambient? Approach Take the window air conditioner as a system The energy balance equation is: (Qin - Qout ) + (Win - Wout) + (Emass,in -Emass,out) = ΔEsystem