This document presents information about utilizing solar energy for heating water. It discusses the benefits of solar energy over fossil fuels, describes the key components and processes of passive and active solar water heating systems, and outlines different types of solar collectors including flat plate, evacuated tube, parabolic dish, parabolic trough, and linear Fresnel collectors.

1. Presented by :
• Shehryar Ahmad
• Hamza Saleem
• Aqib Jah Temuri
• Sidra Salahuddin
• Mariam Gul
• Sana Masood
D-14-CH-39
D-14-CH-57
D-14-CH-33
D-14-CH-117
D-14-CH-73
D-14-CH-53
DEPARTMENT OF CHEMICAL ENGINEERING

2. UTILISATION OF SOLAR
ENERGY FOR HEATING
WATER

3. INTRODUCTION :
Solar water heating is a well established, highly
effective and pollution free process for heating water
that can be used through out the country for various
applications.
 It also minimizes the consumption of fossil fuels for
heating water.
 Reduces the emission of unwanted gases.

4. Why Solar Energy is better than Fossil Fuels?
 Fossil fuels = Pollution. That is a fact that we are all aware
of.
 Unlike solar powered energy, fossil fuels are non-
renewable resources. Not only do they take years to form,
but the rate of use is far greater than the rate of formation.
 In addition to being non-renewable, fossil fuels also
produce around 21.3 billion tons of CO2 each year.
According to scientists and environmentalists, CO2 is our
global warming contributor that causes the average
surface temperature of the Earth to rise.

5. SOLAR COLLECTOR:
A solar collector is a device, used to capture or
concentrate sun thermal energy and transfers this heat
energy to the water or other fluid which can be used
for various purposes as follows;
 Industrial Purposes.
 Domestic Purposes.
 Residential Purposes.

6. PROCESS OF THE SOLAR WATER HEATING:
The process of solar water heating is carried out in the
solar water heaters.
There are mainly two processes for water heating
through solar energy;
1. Passive water heating
2. Active solar water heating.

7. PASSIVE WATER HEATING:
Passive water heating system
involves no moving parts (no any
external source required to
circulate the water). Passive solar
water heaters work on the
principle of convection, in which
hot water rises and cold water
sinks within the tank in a
continual process as long as there
is sunlight available the process is
also called Thermosiphon solar
water heating.

8. ACTIVE WATER HEATING
solar water heating in this
system the water is
circulated forcedly
through external source
(pumps are used for
circulation). The water is
circulated through pump
in the solar collector and
then stored in the hot
water storage tank.

9. DIRECT V.S. INDIRECT HEATING SYSTEM
 Direct solar water heating systems pass potable water
through the thermal collector that eventually flows
directly to the desired application (No heat exchanger is
required).
 Indirect Heating System works similarly to direct models
but rather than ‘directly’ heating the water in the solar
collectors, a special fluid with anti-freeze properties is
heated. This fluid transfers the heat to the water by heat
exchanger when it drains back into the tank.

10. TYPES OF SOLAR COLLECTORS:
There are mainly two types of solar collectors classified
on the basis of the nature of materials and their
geometrical shapes.
1. Non-concentrating Collectors.
2. Concentrating Collectors.

11. NON-CONCENTRATING COLLECTORS:
The stationary or non-concentrating collectors are
permanently fixed in position and do not track the sun and
can be further subdivided into two types.
 Flat-plate collectors
 Evacuated tube collectors
They are used to achieve low to medium temperatures.

12. FLAT-PLATE COLLECTOR:
 Flat plate collectors
easily attain
temperatures of 60 to
100ºC.
 Highly transparent
polymer films insulation
can be used to attain
temperature up to
125ºC.
 Double glazed flat plate
collectors filled with
inert gas also increases
its efficiency.

13. COMPONENTS OF SOLAR COLLECTOR:
1. Absorber Plate : Made of any material, which will rapidly
absorb heat from sun’s rays and quickly transfer that heat to the
tubes or fins attached in some manner, which produces a good
thermal bond.
2. Tubes or Fin : For conducting or directing the heat transfer
fluid from the inlet header or duct to the outlet.
3. Glazing : This may be one or more sheets of glass or a
diathermanous (radiation transmitting) plastic film or sheet.
4. Thermal Insulation : This minimizes downward heat losses
from the plate.
5. Cover Strip : To hold the other components in position and
make it all Water tight.
6. Container or Casing : This surrounds the foregoing
components and keeps them free from dust, moisture, etc.

14. EVACUATED TUBE COLLECTOR:
 ETC use rows of glass tube, each
of which contains a heat pipe
collector with a heat transfer fluid
surrounded by a vacuum which
greatly reduces heat losses.
 It provides temperatures up to
120°c
 More suitable for use in cold
climates.
 With the use of inert gas or ultra-
high vacuum, temperature can be
increased up to 150°c.

15. PARTS OF EVACUATED TUBE COLLECTOR:
 The ETC solar collector is comprised of four main parts:
 Evacuated Tube (ET): Absorbs solar energy and converts it to
usable heat. A vacuum between the two glass layers insulates
against heat loss. The Heat Transfer Fin helps to transfer heat
to the Heat Pipe.
 Heat Pipe (HP): Copper vacuum pipe that transfers the heat
from within the ET up to the manifold.
 Manifold: Insulated box containing the copper header pipe.
The header is a pair of contoured copper pipes with dry connect
sockets that the heat pipes plug into.
 Mounting Frame.

17. CONCENTRATING COLLECTORS:
 Concentrating collectors use mirrored surfaces to concentrate the
sun's energy on an absorber called a receiver.
 Concentrators perform best when pointed directly at the sun. To do
this, these systems use tracking mechanisms to move the collectors
during the day to keep them focused on the sun. Single-axis
trackers move east to west; dual-axis trackers move east and west
and north and south.
 They can achieve temperatures up to 400°C.
They can be further divided into three types.
1. Parabolic Dish Collectors.
2. Linear Parabolic Trough Collectors.
3. Linear Fresnel Collectors.

18. PARABOLIC DISH COLLECTOR:
 The collector collects the solar
energy coming directly from the sun
and concentrates or focuses it on a
small area. The resultant solar beam
has all of the power of the sunlight
hitting the dish but is concentrated
in a small area so that it can be more
efficiently used.
 Glass mirrors reflect ~92% of the
sunlight that hits them.
 The dish structure must track the
sun continuously to reflect the beam
into the thermal receiver.

19. PARABOLIC TROUGH COLLECTOR:
 Because of their parabolic shape,
troughs can focus the sun at 30 to
60 times its normal intensity on a
receiver pipe located along the
focal line of the trough.
 Synthetic oil captures this heat as
the oil circulates through the
pipe, reaching temperatures as
high as 390°C (735ºF).
 The hot oil then goes through a
heat exchanger to produce steam.

20. Linear Fresnel Collector:
 Linear Fresnel reflector
approximate the parabolic shape
of trough system but using long
rows of curved mirrors to reflect
the sun´s rays onto a downward-
facing linear, fixed receiver.
 The main advantage is that their
simple design of flexibly bent
mirrors and fixed receivers
requires lower investment costs
and facilitates direct steam
generation, eliminating the need
for heat transfer fluids and heat
exchangers.