# Tutorial for Psyc0226 Wei Fang, Ph.D., Professor

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Tutorial for Psyc0226 Wei Fang, Ph.D., Professor
Dept. of Bio-Industrial Mechatronics Engineering National Taiwan University Software last updated: 2002/02/26 Tutorial last updated: 2003/11/28

Capability of Psyc0226 Allow alteration on atmospheric pressure
Provide handy PsyTables Totally 11 tables are available Provide PsyCharts State calculation: besides AtmP, values of 2 independent states are required to calculate others Process calculation: find differences between 2 states More process calculation: Evaporative cooling Vapor pressure deficit on leaf

More message of the selected cell
Abbreviations of thermodynamic properties of moist air used in Psyc0226 Tdb: dry bulb Temp. RH : relative humidity Twb: Wet bulb Temp. Tdp: dew point Temp. AH : absolute humidity SV : specific volume Hfg: Saturated DOS: degree of Saturation Pws: saturated vapor pressure Pw: vapor pressure More message of the selected cell

Block in red defined as Psychart window

Set the Atmospheric pressure is the first step

Handy PsyTables

Totally 11 PsyTables

1. Define the ranges 2. Set the intervals 3. List the values

Table 1: Twb = f(Tdb, RH) Twb RH (50 – 100%)and Tdb (20 – 44 oC)

Wet Bulb Depression is the limit of evaporative cooling methods.
Table 2: WBD = f(Tdb,RH) WBD Wet Bulb Depression is the limit of evaporative cooling methods.

Table 3: RH = f(Tdb,Twb) RH Twb (20 – 44 oC) and Tdb (20 – 44 oC)

Table 4: VPD of air

VPD=Pws@Tdb – Pw@Tdb AHD=Sat.AH@Tdb – Sat.AH@Tdp
VPD/AHD of air

Table 5: VPD’ of air

VPD’=Pw@Twb – Pw@Tdb AHD’=Sat.AH@Twb – Sat.AH@Tdp
VPD’/AHD’ of air

Psycharts Evaporative cooling process calculation
Besides atmospheric pressure, values of 2 independent states are required to derive others find differences between 2 states Evaporative cooling process calculation Vapor pressure deficit on leaf

State Calculation

Independent Properties (IP)
Twb RH Tdp AH SV H hfg DOS Pws Pw Tdb IP Any pair of IP can be the given values to derive others.

One click in Psychart window using left button of the mouse can define a state

Process Calculation

Use mouse to define 2 states
To define 2nd state, change from ‘Inactive’ to ‘Active’ first. Click in the Psychart window at the selected state or click on the crosshair region to move along constant lines or curves. Click on ‘Cal.’ to calculate the difference.

Move along prefix lines or Curves
Constant Twb Constant Tdb Constant RH Constant Tdp, Pw, AH Constant Tdp, Pw, AH Constant RH Constant Tdb Constant Twb

A process with sensible heat gain

Process: between states
Sensible Heating (3->4) Sensible Cooling (4->3) Humidification (4->5) Dehumidification (5->4) Heating (3->5, 3->1) Cooling (5->3, 1->3) Air Mixing (1, 2->3) Evaporative Cooling，Drying (1->2, 1->3) Combination of above (1->2->3->4->5)

Evaporative cooling process

Enter ‘Tdb after pad’ or ‘pad efficiency’ to derive others followed by a Click on ‘Draw’ icon.
WBD

Temperature drop after passing through pad (ΔT)
ΔT = WBD of outdoor x Efficiency of the pad T T- ΔT

Vapor pressure deficit (VPD)
Enter Leaf temperature, then click on Draw icon. VPD

Other user friendly designs

Lines and curves can be visible or hidden by (de)selecting related icons

Zoom in & out

Labels in Psychart window can be hidden by de-select the Unit label icon

The state user defined in the psychart window using left button of the mouse will be placed in the center of the psychart window if the Centralize icon was selected. This option is set inactive by default.

Enjoy playing with Digital Psychart
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