1. Dissertation Report on
“A COMPARATIVE EXPERIMENTAL STUDY OF THERMAL PERFORMANCE
OF THREE SOLAR AIR HEATERS HAVING DIFFERENT ABSORBER AREA’’
In partial fulfillment for the award of degree of
MASTER OF TECHNOLOGY
In
MECHANICAL ENGINEERING
With specialization
ENERGY ENGINEERING
Centre of excellence, Solar energy research and utilization
1
SURESH GYAN VIHAR UNIVERSITY
JAIPUR
BY
VIKAS KUMAR
Guided By
Mr. HARI KUMAR SINGH

2. INTRODUCTION 2
 Solar air heaters are unique type of heat interchange that absorb and
converts solar radiant energy into heat.
 The main focus is on the use of Renewable energy.
 It is pollution free device and very much environment friendly.
 It provide a healthy environment with low cost air heating.
Basically solar air heaters are classified in the following
two categories:
a. Air heaters with porous absorbers and
b. Air heater with non porous absorber
 Ceof
 solar collector and the cost of equipment is very less as compare to

3. PROBLEM FORMULATION
3
 In earlier year the entire world has become more and more dependent on
fossil fuels such as coal , oil and natural gas.
 These resources are limited and it is created by natural processes over
millions of years.
 The whole world focusing on Shortage of fuel and emphasizes the need
for alternate energy sources.
 The Solar energy is one of the low cost and easily available energy
source in the world.
 Solar energy is most pollution-free and limitless source

4. OBJECTIVE 4
 To compare the thermal efficiency of three different solar air heaters, type-
I, type II and type III respectively.
 To investigate the effect of mass flow rate in thermal efficiency of solar air
heater.
 To show aluminum wire mesh and aluminum fins ensure more air flow
above and below the absorber plates, generate the turbulence and decrease
the dead zones in the collector.
 To prove solar air heater as potential device for harnessing energy from the
sun.

5. MATERIALS & METHODS 5
Components of solar air heater:
The main component of solar air heater are following:-
The casing or container
Insulation
Absorber plate
Cover plate
Fan
Stand

6. The casing or container 6
 It is made by strong plywood box.
 The thickness of plywood was 12mm.
 The internal dimension of box was 1476mm×726mm×186mm
Casing of plywood box
 It is made by strong plywood box.
 The thickness of plywood was 12mm.
 The internal dimension of box was 147686

7. Insulation
7
 The thermo Cole and aluminum sheet were used (Scientific name
Polystyrene) for insulating the plywood box from sides and bottom.
 The insulation is necessary for the solar air heater for minimizing the heat
loss from sides and bottom of the collector box.
Thermo Cole for insulation

8. Absorber plate
8
 The aluminum sheet of 22 gauge thickness were used for absorber plate.
 The sheet was painted by black dark rubber coating for absorbing heat
and provides durability.
absorber plate before coated absorber plate after coated

9. Cover plate 9
 The two normal transparent window glass cover of 5 mm thickness were
used for cover plate.
 The length of glass cover was 1474 mm and width was 723 mm so that it
could sit over container box.
 Thermal conductivity of glass is 0.96W/m K
Glass cover used for solar air heater

10. Fan 10
The two computer exhaust fan of 12v each were used to force the air
through the collector.
It was connected by voltage divider to regulate and maintain the speed
of fans.
Fans used for inlet of solar collector

11. Stand
11
 The SAHs stand were making by 260
slope shape rectangular stand to
sit the SAHs.
stand for holding SAHs at an angle

12. Measuring instruments 12
Following measuring instruments used for experiment:
LM-35 temperature sensor
Digital (TENMARS TM- 207)
Digital anemometer (METRAVI AVM-05)
alcohol thermometer
Magnetic base

13. Magnetic bas for measuring tilt angle of SAHsDigital anemometer (METRAVI AVM-05)
Digital solar power meter (TENMARS TM- 207)
LM-35 temperature sensor
13

14. Technical specification of
measuring instruments
LM-35
Model- LM-35
Accuracy
0.5 ensured
Temp. operating
-55o
C to 150o
C
Operating from
4V to 30V
Less than
60 Aᵤ
Solar power
meter
Model – LM-100
Accuracy
-3% to 3% at 2854K
Range
20 to 2000 foot
candles
Resolution
0.01 fc/lux
Temperature
-10 o
C to 55o
C
Sensor
Silicon Photodiode
Alcohol
thermometer
Accuracy
1 o
C
Range
-10 to 100 o
C
Organic liquid
Mercury
Glass used
Normal
14

15. Experimental set-up
15
In this experiment following three types of solar air heaters were employed:
1. Simple single pass solar air heater (Type I)
2. Single pass solar air heater having aluminum
wire mesh (Type II)
3. Single pass SAHs having aluminum fins (Type
III)

16. 16
Outlook representation of simple single
pass SAHs (Type I)
Absorber plate for Type III SAHs

17. 17Type II Type III
Aluminum wire mesh used in absorber plate
of Type II SAHs
Aluminum fins inserting on absorber plate of
Type III SAHs

18. Calculation 18
The thermal efficiency of all three types, I, type II and type III solar air
heaters, were calculated using equation :
η = Cṁ p (Ta, out – Ta, in)/I Ac
Where, ṁ = mass flow rate (kg/s)
Cp = Specific heat of air at constant pressure (kJ/kg K)
Ta, out = Temperature of air at outlet
Ta, in = Temperature of air at inlet
I = Solar radiation (W/m2
)
Ac = Surface area of the collector (m2
)

19. 19Energy
losses
1/U = 1/ha + dx1 / k1 + dx2 /k2
Where,
dx1 = Thickness of thermo Cole
dx2 = Thickness of plywood
k1 = Thermal conductivity of thermo Cole
k2 = Thermal conductivity of plywood
ha = Convective heat transfer coefficient for air
Q = UA∆T
Qtotal = Qsides + Qtop + Qbottom
Qtotal = 98.88 Watt
Total losses from Sun = 21600 kJ
Total gain = 20318 kJ

20. RESULT & DISCUSSIONS
20
Simple single pass solar air heater (Type I) at exit air
velocity is 4.20 m/s on May 30, 2015
1. The highest daily solar flux is obtained as 965 W/m2.
2. Daily mean solar flux is measured as 800 W/m2
.
3. The difference between the exit and inlet temperature is measured by 33°C.

21. Thermal efficiency 21
 The mean thermal efficiency is calculated as 42.02%.

22. Single pass solar air heater having aluminum wire mesh
(Type II) at exit air velocity is 4.20 m/s on June 05,2015 22
 The highest daily solar flux is obtained as 995 W/m2
.
 Daily mean solar flux is measured as 805 W/m2
.
 The mean thermal efficiency is calculated as 43.26%.
 The difference between the mean daily exit and inlet temperature is
measured as 31°C.

23. Single pass solar air heater having aluminum fins
(Type III) at exit air velocity is 4.20 m/s on June 15,
2015
23
 The highest daily solar flux is obtained as 1025 W/m2
.
 Daily mean solar flux is measured as 871 W/m2
.
 The mean thermal efficiency is calculated as 41.44%.
 The difference between the mean daily exit and inlet temperature is
measured as 33°C.

24. Thermal efficiency comparison among
Type I and Type II 24
Thermal efficiency comparison among
Type I and Type III

25. Thermal efficiency comparison graph of Type I,
Type II and Type III solar air heaters at exit air
velocity 4.20 m/s
25

26. CONCLUSIONS
26
 Single pass solar air heaters having aluminum fins higher thermal efficiency
compare to single pass solar air heaters and single pass SAHs with aluminum
wire mesh.
 Single pass solar air heater with aluminum wire mesh and aluminum fins has
improved thermal efficiency as wire mesh and fins increase the heat transfer
area.
 The maximum mean thermal efficiency obtained as 46.12% in single-pass
solar air heater with aluminum fins (Type III) at exit air velocity 4.20 m/s.
 The maximum peak thermal efficiency obtained as 46.12% in single-pass
solar air heater with aluminum fins (Type III) at exit air velocity 4.20 m/s.
 The wire mesh and fins or obstacles guarantee a superior air flow above and
below the absorber plates, generate the turbulence and decrease the dead
zones in the collector.

27. 27