1. Transient Heat Transfer of Automobile A/C System Prepared by: Jason Hixson, Don Scott, and Michael Hickey December 2, 2005 UTC ENCH 435

2. Objectives Perform material and energy balance. Observe pseudo steady-state transient behavior.

3. A/C Schematic Recycled AirCooled Air R-134a M 2,T 2 M 1, T 1 M 3,T 3 M 4,T 4 R-134a

4. Variables & Assumptions Entrance temperature Exit temperature Fan speed setting Velocity Engine RPM Time Fan Speed Setting C p =.24 BTU/lb*R H 3 =7.39 BTU/lb H 4 =100.9 BTU/lb T 3 =T 4 =40 °C Vent area=19.4 in 2 Cab volume=81 ft 3 m 1 =m 2 m 3 =m 4

5. Energy and Material Balance: Air Side: ∆H=m 2 *C p (T 2 -T 1 ) ∆H=UA ∆T lm Refrigerant Side: ∆H=m 3 (H 4 -H 3 ) m 3 =m 4

6. Setting 2 Setting 3 Setting 4 Setting 1 Setting 2 Setting 3 Setting 4 600 RPMs 2000 RPMs

7. 600 RPMs 2000 RPMs

8. 600 RPMs

9. 2000 RPMs 600 RPMs

10. 2000 RPMs 600 RPMs

11. 2000 RPMs

12. RECOMMENDATIONS 1.Look at measuring the power used by the system do determine impact on battery and alternator performance. 2.Look at the systems impact on gas mileage while running.

13. QUESTIONS COMMENTS