1. Learning Psychrometrics and Sensors measuring T and RH方煒
台大生機系教授
Wei Fang, Ph.D., Professor
Dept. of Bio-Industrial Mechatronics Engineering,
National Taiwan University

2. Analog Dry Bulb Temperature sensor

3. Analog Dry and Wet Bulb Temperature

4. Digital Dry Bulb Temperature reader

5. Infra-red Dry Bulb Temperature

6. Thermal Imager http://us.fluke.com/usen/products/CategoryTI/

8. Sensing element

9. Dry and wet Bulb Temperature sensors in Weather station and greenhouse

10. RH = f(Tdb, Twb)
Patm = kPa

11. Tdb and RH Sensors

12. Tdb and RH data logger

13. Day/Night trends of T and RH

14. High T coexist with Low Hum.午夜 中午 溫度 濕度

15. High humid Env.
Low T, High RH
High T, Low RH

16. Forced ventilation

17. Evaporative cooling
Fogging

18. Evaporative cooling
Pad and Fan system

19. Approach to release thermal stress

20. Beware of the side effect.
Approach to release thermal stress
Beware of the side effect.

21. Psychrometric Chart

24. Process: from one state to another

27. Human comfort zone

28. Animal comfort zone – T only
Productivity
Dry bulb temperature

29. Impact of T and RH on milk production of cows
82.49
64.65
63.39
68.47
72.32
76.68
64.31
65.05
75.73
79.96
63.7
87.09
90.09
88.06
86.01
82.09
84.21
82.36
THI>85, no recovery
Adapted from ASHRAE Fundamentals, 1999

30. Reduction of milk vs. Temperature-Humidity Index (THI)
Adapted from ASHRAE Fundamentals, 1999

31. Milk Production=f(HD74, HA80S)
MP = – * HD74 – * HA80S
Where,
MP: Milk production (in kg/day/cow)
21.48: daily production (in kg) per cow in normal weather condition
HD74: total hrs of THI > 74 for previous 4 days
HA80S: square of total hrs of THI > 80 for previous day
Linvill and Pardue (1992)

32. THI lines on Psychrometric chart

33. More about Psychrometric chart
Following contents, created by the author, are available from DSpace at UVM.
Tutorial for digital psy chart
Digital psychrometric chart software

34. The End