Tutorial for Psyc0226

Wei Fang, Ph.D., ProfessorDept. of Bio-Industrial Mechatronics Engineering

National Taiwan University

Software last updated: 2002/02/26Tutorial last updated: 2003/11/28

Capability of Psyc0226

Allow alteration on atmospheric pressure

Provide handy PsyTablesTotally 11 tables are available

Provide PsyChartsState calculation: besides AtmP, values of 2 independent states are required to calculate othersProcess calculation: find differences between 2 statesMore process calculation:

Evaporative cooling Vapor pressure deficit on leaf

Abbreviations of thermodynamic properties of moist air used in Psyc0226

1. Tdb: dry bulb Temp. 2. RH : relative humidity3. Twb: Wet bulb Temp.4. Tdp: dew point Temp.5. AH : absolute humidity 6. SV : specific volume7. Hfg: Saturated 8. DOS: degree of Saturation9. Pws: saturated vapor pressure10. 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

User friendly 3-step design in PsyTable

1. Define the ranges

3. List the values

2. Set the intervals

Table 1: Twb = f(Tdb, RH)

RH (50 – 100%)and Tdb (20 – 44 oC)

Twb

Table 2: WBD = f(Tdb,RH)

WBD

Wet Bulb Depression is the limit of evaporative cooling methods.

Table 3: RH = f(Tdb,Twb)

Twb (20 – 44 oC) and Tdb (20 – 44 oC)

RH

Table 4: VPD of air

VPD/AHD of air

VPD=Pws@Tdb – Pw@TdbAHD=Sat.AH@Tdb – Sat.AH@Tdp

Table 5: VPD’ of air

VPD’/AHD’ of air

VPD’=Pw@Twb – Pw@TdbAHD’=Sat.AH@Twb – Sat.AH@Tdp

PsychartsBesides 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 IP IP IP IP IP IP 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

1. To define 2nd state, change from ‘Inactive’ to ‘Active’ first.

2. Click in the Psychart window at the selected state or click on the crosshair region to move along constant lines or curves.

3. Click on ‘Cal.’ to calculate the difference.

Move along prefix lines or Curves

Constant Tdp, Pw,

AH

Constant Twb

Constant RH

Constant Twb

Constant Tdp, Pw,

AH

Constant RH

Constant Tdb

Constant Tdb

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)

VPD

Enter Leaf temperature, then click on Draw icon.

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 PsychartPlease send us information regarding found bugs.

Mail to : weifang@ntu.edu.tw