learning psychrometrics and sensors measuring t and rh
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
Learning Psychrometrics and Sensors measuring T and RH 方煒
台大生機系教授
Wei Fang, Ph.D., ProfessorDept. of Bio-Industrial Mechatronics Engineering, National Taiwan University
Analog Dry Bulb Temperature sensor
Analog Dry and Wet Bulb Temperature
Digital Dry Bulb Temperature reader
Infra-red Dry Bulb Temperature
Thermal Imager
http://us.fluke.com/usen/products/CategoryTI/
http://www.landinst.com/infrared/products/thermal_imaging/tp8_portable_imager.htm
http://www.landinst.com/infrared/products/thermal_imaging/guide_M4_thermal_imager.htm
Sensing element
Dry and wet Bulb Temperature sensors in Weather station and greenhouse
RH = f(Tdb, Twb)
Patm = 101.325 kPa
Tdb and RH Sensors
Tdb and RH data logger
Day/Night trends of T and RH
High T coexist with Low Hum.
午夜 中午 午夜
溫度
濕度
High humid Env.
Low T, High RH High T, Low RH
Forced ventilation
Evaporative cooling
Fogging
Evaporative cooling
Pad and Fan system
Approach to release thermal stress
Approach to release thermal stress
Beware of the side effect.
Psychrometric Chart
Process: from one state to another
Human comfort zone
Animal comfort zone – T only
Dry bulb temperature
Pro
duct
ivity
Impact of T and RH on milk production of cows
THI>85, no recovery
Adapted from ASHRAE Fundamentals, 1999
75.73 79.96 63.765.0572.3268.4763.39 76.68
90.0987.09
88.06
64.31
64.6582.49
86.0182.09
82.3684.21
Reduction of milk vs. Temperature-Humidity Index (THI)
Adapted from ASHRAE Fundamentals, 1999
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 wea
ther condition– HD74: total hrs of THI > 74 for previous 4 days– HA80S: square of total hrs of THI > 80 for previous d
ay Linvill and Pardue (1992)
THI lines on Psychrometric chart
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
The End