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Fabrication and analysis of passive type Solar Water Heating System. The system is manufactured in the workshop of Quaid-e-Awam University of Engineering,Science and Technology for fulfillment of my Bachelor Engineering Degree. The system was successful by which good results ontained in winter season through thermosiphon water heating process with 40% efficiency.
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2/5/2011 1
1. Introduction to the Solar Water Heating
2. Process of the solar water heating
3. Objective of our Project
4. Solar Water Heating in Pakistan5. Types of solar water heating system
6. Fabrication of passive solar water heating system
7. Our project (Passive solar water heating system)
8. Experimental results
9. Benefits of solar water heating system
10.Applications of solar water heating system
2/5/2011 3
Solar water heating is a well establish, highly effective, pollution
free technology for domestic water that can be used through the
country for various applications. The solar water heater capture
the sun’s heat in the form of discrete packets of photons, that sun
heat is utilised in the system for heating the water, the system
recieves sun’s heat by the solar flat-plate collector and transfers
that heat to the water.
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Collection: solar radiation is captured by
solar colllector.
Transfer: circulation fluids transfer this
energy to a storage tank, circulation can be
natural (thermosiphon system) or forced,
using a circulator (low head pump)
Storage: hot water is stored untill it is
needed at a later time in a mechanical
room, or on the roof in case of a
thermosiphon system.
Collection of solar energyCollection of solar energy
TransferTransfer
2/5/2011 5
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, passive water heating and active solar water heating.
Passive, as the name implies, 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.2/5/2011 6
Active 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.
Passive and active solar water heating systems.2/5/2011 7
The principle object of designing the passive solar water
heater is to study, analysis, evaluate and fabricate a system of
water heating by utilization of solar energy for domestic use.
The project involves both economical and technical viability
of the whole system, the theoretical evaluation were to be
arrived through spot studies.
The fabrication was carried out with the help of raw materials
which are easily and cheaply available in local markets. 2/5/2011 8
2/5/2011 9
Solar water heating technology is quite mature but its use in
Pakistan has been quite limited so far mainly because of inability
of market development and absence of governmental support and
subsidized gas price.
A number of public sector organizations are actively working on
the development of solar water heaters that have now started
gaining popularity particularly in the northern mountainous regions
due to cold weather and limited and difficult supply of natural gas
in these areas.
Solar water heating systems represent the most common application
of solar energy at the present time.
There are basically two types of water heating systems:
1.Natural circulation systems or Passive solar water heating system
Direct passive solar water heating
Indirect passive solar water heating
1.Forced circulation or Active solar water heating system.
Direct active solar water heating systems
Indirect active solar water heating systems
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The principle of natural circulation
just like boiling the water In a flat
bed collector in cold water flows to
the collector.
it gets warm by sunshine and flows
upward as it becomes lighter than
cold water and stored in the tank
which can be used directly.
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Direct passive solar water heating
Direct passive solar water heating systems
take water from the household water supply to
circulate between the collector and tank.
When water warms up, convection causes it to
rise and flow towards the storage tank.
The term ‘direct’ means the water to be used
by building occupants is run directly through
the solar collector.
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Indirect passive solar water heating
In indirect or closed loop systems the heat transfer fluid is treated
water, a refrigerant, or a non-freezing liquid such as an anti-freeze
solution, hydrocarbon oil, or silicone.
2/5/2011 13
Forced circulation or active solar
water heating system is one where
the exchange fluid is forcedly
pumped from the storage tank
through the collectors and back
into the tank.
An electric pump is used to
circulate the water from the
collector.2/5/2011 14
Direct active solar water heating systems
An active direct solar water heater is
a pump-driven system that uses solar
energy to heat potable water directly.
Water from the storage tank is
pumped into the solar collector under
the moderation of a controller.
2/5/2011 15
Indirect active solar water heating
systems
In an active indirect system, the pump
controls the flow of the heat transfer
fluid, not the potable water itself.
The heat transfer fluid is heated by the
sun, then sent through a coil that either
wraps around the bottom of the water
heater or inside the water heater.
2/5/201116
Passive solar water heating systems heat water using only the
energy of the sun. However these are;
1. more reliable and long lasting than active solar heating systems
2. lack of moving, electrical parts
3. They are less expensive
4. But less efficient
2/5/2011 17
Fabrication of passive solar water heating system includes the
following components,
Flat-plate collector
Storage tank
Piping for water circulation
Supporting stand
2/5/2011 18
Flat-plate collectorFlat-plate collector
Supporting standSupporting stand
Storage tankStorage tank
Piping for water circulationPiping for water circulation
For constructing these components, the proper material
selection is very much necessary which needs the study of
material properties
Flat-plate collector A solar collector is a special kind of heat exchanger that
transforms solar radiant energy into heat. Flat plate collectors easily attain temperatures of 60 to 100ºC
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The main components of a flat plate solar collector are:
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 fins, 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 loss 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.2/5/2011 20
STORAGE TANK
The storage tank is used to accumulate the hot water for service
or end use.
for designing the storage tank, a number of factors usually must
be considered (such as the properties of the material used, the
induced stresses, elastic ability, the cost of fabrication etc.)
Length Dia Ratio
Most economically method of construction of cylinder is to keep
the length to diameter of vessel between 2 and 5.
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length-dia ratio should be kept minimum in order to have
minimum surface area so that heat losses can be prevented,
hence we take length-dia ratio as;
L / d = 2
L = 2d
STORAGE TANK INSULATION
Storage heat loss cause a significant drop in system
performance, therefore need for thermal insulation tank is
dispensable.
Commonly the material used for insulation is glass wool.2/5/2011 22
SUPPORTING STAND / FRAME
The supporting stand for collector
and tank is made up of iron angles
resting on legs which are also made
up of iron rods.
A simple structure of mild steel
sheet is fabricated so as to provide
the storage tank upper height and the
collector at inclination exposed to
the sun.
2/5/2011 23
2/5/2011 24
Passive solar water heating system
Storage tankStorage tank
Flat-plate collectorFlat-plate collector
Supporting standSupporting stand
This type of system will need no pump, and water will circulate
the effect of density, through the collector tubes.
In this type of system collectors are placed below the level of
storage tank, water from storage tank will flow into the
collector and on heating the density will decrease.
Water having less density will lift upward and will makes room for
the colder water from the tank thus the loop will be completed.
2/5/2011 25
Our project passive solar water heating system consists of the
following components;
1. Flat-plate collector
2. Hot water storage tank
3. Supporting stand for collector and storage tank
4. Controlling devices (valves and cocks)
CAPACITY OF THE PROJECT
The capacity of the project is 20 U.S gallons of water which is
suitable for domestic use of one person, which can be utilized for
bathing, washing cloths and vessels.
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Capacity of solar water heating system basically involves
determining the total collector area and the storage volume.
Collector area
The collector area is 0.76 m2
Storage volume
The capacity of the project is 75 liters.
2/5/2011 27
The passive solar water heating system was fabricated in
workshop of university, simple manufacturing processes are
employed which helps in limiting the difficulties.
Components to be fabricated
Following components are required for passive solar water heater.
1. Flat-plate collector
2. Hot water storage tank
3. Supporting stand
2/5/2011 28
1. Flat-plate collector
The flat-plate collector was fabricated in the mechanical Engineering department workshop.
1. Specification of the Flat-plate collector
Length of collector = 3.5 feet / 1.066 m
Width of the collector = 2.5 feet / 0.76 m
Length of absorber plate = 1.016 m
Width od absorber plate = 0.71 m
Material for absorber plate = aluminum foil
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Thermal conductivity of absorber plate = 237 W·m−1·K−1
Density of absorber plate material = 2.7 kg/m3
Plate thickness 18 gauges
Diameter of riser tubes = 9 mm
Tube center-to-center distance = 2.5 inches
Number of tubes = 10
Diameter of header pipes = 0.5 inches
Insulating material used = glass wool
Density of insulating material = 200 kg/m3
2/5/2011 30
1. Pictures of fabricating the collector
2/5/2011 31
Hot water storage tank
In the fabrication of hot water storage tank steel sheet is used.
The sheet is rolled by the roller machine to bring it into shell
shape.
Both ends of shell are sealed by a round tray shape hold to a
proper size.
Finally tank is placed in casing sell, the gap between the storage
and casing shell is filled by the glass wool as an insulating
medium.
The capacity of the storage tank is 75 liters.2/5/2011 32
Supporting stand
The supporting stand for collector and tank is made up of iron
angles iron rods, the legs are made by iron rods and base by the
iron angles.
2/5/2011 33
COST OF THE FABRICATION OF PROJECT
S/NO Component cost
1 Flat-plate collector 9090 rupees
2 Storage tank 3255 rupees
3 Supporting stand 2545 rupees
4 Piping and mountings 900 rupees
5 Total cost 15790 Rupees
2/5/2011 34
Experimental study was conducted during the month of
December
The passive solar water heating system tested to investigate its
performance in terms of the water heating through solar
energy.
We took twenty readings in five corresponding different days
and different timings in a day from morning to noon.
2/5/2011 35
The experimental results include following parameters.
1. Solar radiation in W/m2
2. Humidity in percentage
3. Atmospheric temperature in centigrade
4. Inlet cold water temperature in centigrade
5. Outlet hot water temperature in centigrade
6. Difference in temperature in centigrade
2/5/2011 36
INSTRUMENTS USED FOR RESULTS
Following instruments were used for getting the readings of the result parameters:
1. Light meter HD2302.02. Digital Thermometer KT2013. Humidity Temperature meter MS 6503
2/5/2011 37
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Light meter HD2302.0
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Digital thermometer KT201
2/5/2011 40Humidity temperature meter MS 6503
RESULTS AND DISCUSSION 1st day results on 13th Dec 2010
2/5/2011 41
Time Inlet Temp:
T 1˚C
Outlet Temp:
T 2 ˚C
Diff: in Temp:T ˚C
Atm. Temp:T ˚C
HumidityMax:% RH
Solar Radiation
W/m2
9:30 am 16.4 38.7 22.3 21.4 41% 700 W/m2
11:00 am
20 75 55 25 39% 846 W/m2
12:30 pm
22.5 79 56.5 22.5 41% 980 W/m2
2:00 pm 23.5 87.7 64.2 27.3 35.1% 773 W/m2
Total average
20.6 ˚C 70.1 ˚C 49.5 ˚C 24.05 ˚C 39.025% RH
824.75 W/m2
Graph of the Dec 13th 2010 results
2/5/2011 42
TOTAL AVERAGE RESULTS OF THE PROJECT
DAY Inlet Temp:
T 1˚C
Outlet Temp:
T 2 ˚C
Diff: in Temp:T ˚C
Atm. Temp:T ˚C
HumidityMax:% RH
Solar Radiation
W/m2
13 Dec 2010
20.6 70.1 49.5 24.05 39 824.75
14 Dec 2010
24.075 75.35 51.2 26.3 37.05 787.75
15 Dec2010
23.6 76.675 53.07 22.3 44.5 766
20 Dec 2010
24.6 77.45 52.85 24.55 43.4 775
21 Dec 2010
27.75 74.5 51.75 24.55 42.75 793.75
Total average
24.125 ˚C 74.815 ˚C 51.674 ˚C 24.35 ˚C 41.245% RH
789.45 W/m2
2/5/2011 43
GRAPH OF THE TOTAL PROJECT AVERAGE RESULTS
2/5/2011 44
We can save over 50% on our energy bill for domestic hot water.
The fuel we use to heat our water (the sun) is free. We are protected from future fuel shortages and price
increases. Solar water heaters do not pollute the environment. We avoid carbon dioxide, nitrogen oxides, sulphur dioxide and
other air pollutants created when electricity or solid fuel is used to heat water.
2/5/2011 45
Solar energy is extremely safe and clean.(It is ideal for allergy sufferers and those with chemical sensitivity.)
We avoid storing tanks of highly flammable material in our house.
We avoid fuel odors and reduce electromagnetic fields in or around our home.
Virtually no maintenance, repair work or cleaning is required.
• We are choosing a socially aware and environmentally responsible energy source
2/5/2011 46
Following are the applications of solar water heating;
A. Domestic applications
B. Commercial applications
C. Industrial applications
2/5/2011 47
From the practical of fabrication and analysis of passive solar water heating system, we have learned that how to design the solar water heater for domestic use and other purposes where the hot water is required.
The system works on the solar energy which is free of cost and is a renewable source of energy.
the use of renewable energy is the need of today’s world due to increasing the environmental concerns by the use of non renewable energy resources such as natural gas, oil and coal.
• On the basis of above mentioned experimental observation it is concluded that:
Fabricated passive solar water heating system was satisfactory. From the practical of system we achieved good experimental
results.2/5/2011 48
2/5/2011 49
Any Queries / Questions
