This document discusses fundamentals of adiabatic dryer systems. It defines key terms like bone dry mass and explains the relationships between dryer feed, product, and capacity. Mass and energy balance equations are presented for analyzing dryer processes. Sample exam problems are provided to calculate air required for drying, dryer capacity based on air flow rate and conditions, and heat supplied to remove a given amount of moisture.

1. AIR CONDITIONING and VENTILATION SYSTEMS
NME 515
Dryer Fundamentals
Engr. Charlton Inao, ME
TESDA TVET NC Level 3 RAC-CRE Certified
1

2. The Basic Dryer
with Sample Board Exams
Engr . Charlton Inao

3. Adiabatic Dryer

4. Fundamental Considerations
❑ Unless otherwise specified drying
operation is always adiabatic saturation
(WB=C)
❑ Dryer capacity is always referred to the
products(P) unless otherwise specified

5. Questions Normally Asked
In Drying Systems
1) Dryer feed/product relationships
2) Capacity of Fan in the Dryer
3) The required heat or steam flow input of
the dryer

6. Feed or Product
◼ Principle: Bone Dry Mass (BDM) is constant
BDMF=BDMP
Equation
Where :
F= mass flow rate of feed, kg/s, pound per minute, pounds per hour
P = mass flow rate of product in kg/s, pound per minute,lpm

7. Derivation: BDM of Feed
FEED

8. Derivation: BDM of Product

9. Notes to remember
❑ Ma= dry air, not humid air
❑ Psychrometric chart shall not be used if
the pressure is not atmospheric
❑ Psychrometric chart is based on standard
air,
1 atm
❑ Dry Air= total air- humid air
❑ Ma = dry air

10. FAN CAPACITY

11. Material Balance: Dryer

12. Revisit Diagram
Entry of Air After Heater,Fan Zone,Dryer
Entry After Dryer
SH1=SH2

13. Material Balance: mass
balance
◼ Min = M out
Note:
Put fan after the heater if not
specified
Hfg=hg-hfs

14. Psychrometric chart (SI units)

16. Psychrometric chart (English
units)

17. STEAM REQUIREMENT
◼ Process Analysis : Heater
◼ Qdryer= M(Δh)

18. D-9 BP OCTOBER , 1990
Wet material containing 215% moisture (dry
basis) is to be dried at the rate of 1.5 kg/sec in
a continuous dryer to give a product
containing 5% moisture (wet basis). The
drying medium consists of air heated to 373 K
and containing water vapor equivalent to a
partial pressure of 1.40 kPa. The air leave the
dryer at 310 K and 70% saturated. Calculate
how much air will be required to remove the

19. D-11 BP OCTOBER , 1981
A continuous dryer is supplied with air at 21 deg.C dry bulb and 16
deg.C wet bulb heated to 75 deg.C. It enters the heating coils at a
velocity of 366 m/min and the size of the circular duct is 183 cm.
The condition of the air leaving the dryer is 43 deg.C dry bulb and
70% relative humiidity. The moisture content of the entering
material is 24% while the moisture content of the leaving material is
8%.
Calculate:
◼ [1] Amount of moisture evaporated
◼ [2] Capacity of dryer
◼ [3]Heat supplied to the dryer

20. Illustration