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Learning Psychrometrics and Sensors measuring T and RH

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. Analog Dry Bulb Temperature sensor. Analog Dry and Wet Bulb Temperature. Digital Dry Bulb Temperature reader.

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Learning Psychrometrics and Sensors measuring T and RH

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  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://www.landinst.com/infrared/products/thermal_imaging/tp8_portable_imager.htm http://us.fluke.com/usen/products/CategoryTI/ http://www.landinst.com/infrared/products/thermal_imaging/guide_M4_thermal_imager.htm

  7. Sensing element

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

  9. RH = f(Tdb, Twb) Patm = 101.325 kPa

  10. Tdb and RH Sensors

  11. Tdb and RH data logger

  12. Day/Night trends of T and RH

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

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

  15. Forced ventilation

  16. Evaporative cooling Fogging

  17. Evaporative cooling Pad and Fan system

  18. Approach to release thermal stress

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

  20. Psychrometric Chart

  21. Process: from one state to another

  22. Human comfort zone

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

  24. Impact of T and RH on milk production of cows 82.49 64.65 72.32 63.39 68.47 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

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

  26. Milk Production=f(HD74, HA80S) MP =21.48 – 0.051 * HD74 – 0.0099 * 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)

  27. THI lines on Psychrometric chart

  28. 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

  29. The End

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