DESIGN AND FABRICATION OF SOLAR WATER HEATER
TEMPERATURE CONTROL SYSTEM
ABSTRACT
Using solar energy is the best way to combat global warming and pollution
problems . It is the best alternative for fossil fuels since they are non renewable
source of energy. The solar water heater requires little initial investment and
serves for many years free of cost since it uses sun's energy . The problem with
solar water heaters is that , initially 10- 15 liters of water should be drained out to
get hot water . This water is wasted sometimes . During summer season , the water
is too hot and manual mixing through mixers do not provide accurate mixing and
desired temperature of water cannot be achieved. Our research work proposes an
idea of temperature control system for solar water heater . In this system the user
can select the temperature range of the hot water . If the cold water comes through
the pipe it shall be diverted to cold water tank and if too hot water comes out of
the pipe, it's temperature shall be lowered by mixing it with cold water . The
system shall fully automate the mixing process and shall provide the user with
water according to the temperature range selected.
INTRODUCTION
Solar Water Heating (SWH) is the process of converting sunlight into renewable
energy to heat water using a solar thermal collector. Solar water heating systems
comprise of various technologies that are increasingly used worldwide. Solar
energy is diurnal and seasonal in nature. Solar energy can be used for heating water
/ air for any process applications and generating electricity using photovoltaics.
Solar Domestic Hot Water System is not entirely new. In 19th century, black
painted metal tanks filled with water were used to absorb solar energy. It had the
disadvantage of rapid loss of its heat because it had no insulation. In 1891,
Clarence Kemp patented by adding a metal panel to the tank in order to improve
the efficiency of the solar tank. In 1909, William Bailey started selling day and
night solar water heater with a coiled pipe collector inside a glass covered box and
a separate insulated indoor waterstorage tank mounted above the collector thereby
allowing hot water circulation by natural convection. By 1960s, simple solar water
heater with a basin and top glass cover were used in large numbers in Japan. Usage
of Solar Water Heaters increases globally to meet out the energy crisis, deficit and
increase in cost of fossil fuels. This attempt to utilize renewable solar energy also
reduces the carbon emission into the atmosphere. A solar water heater unit consists
of components such as solar collector, storage tank, heat exchanger, circulation
pump, connecting pipe lines etc. The solar collector transforms the solar radiation
into thermal energy. The following are the advantages of flat plate collectors
Simple construction and relatively low cost, and there is no mechanism for
tracking the diurnal motion of sun, both direct and diffuse radiation are used which
is very important owing to the fact that approximately 40% of the total radiation is
diffuse radiation.
TYPES OF SOLAR WATER HEATERS
The two major types of collectors are Non-concentrating /Flat Plate Collectors
(FPC) and concentrating (parabolic /cylindrical) collectors. FPC is the most
effective and simplest of solar energy collection for low temperature applications,
and concentrating types are used for high temperature applications like solar
furnace, etc. The technology of heating water using solar energy is used
successfully for large scale process heat applications in industries and small scale
for domestic needs in order to preserve fuel reserves and avoid using high grade
electrical energy for heating. A Conventional Solar water heater is provided with a
solar collector and storage device separately. A compact Solar Water Heater is
provided with a storage device well below the collector as an integrated unit
thereby minimizing the material usage, space and consequently cost. A compact
Integrated Collector – Storage type Flat Plate 3 Solar Water Heater (ICSFPSWH)
has its own disadvantage of poor retention of heat during night. There is a lot of
scope for improving the performance of solar water heaters by optimizing different
design parameters.
Our research mainly focuses on producing a prototype model and simulating it .
The system shall consist of hot water tank and cold water tank . The system is
provided with lcd and 4* 4 keypad to select temperature range . The user can select
the temperature range and system shall deliver water within selected range . The
system shall consume very less power and can be installed with current day solar
water heaters. The system shall not only save water it shall improve solar water
heating technology.
PROBLEM STATEMENT
In Order to get hot water from solar water heater , the cold water should be
drained off first . This water goes waste sometimes . The solar water heaters
do not have any feedback system and the user cannot get water of desired
temperature. During summer season, the water is heated too much and
manual mixers do not provide required water temperature . The current day
solar water heater need a feedback system for them to deliver hot water
which the user requires .
OBJECTIVES
•
To develop a feedback and temperature control system for solar water
heaters and improve their efficiency.
• To design a reliable technology for solar water heaters and contribute
towards use of green energy.
• To select suitable components required for the system to work efficiently.
• To design an algorithm for the system to deliver water with temperature
requested by the user .
• To test the protype for the designed algorithm and record the results.
LITRATURE SURVEY
[1]Deshmukh Nisha, Diwate Shraddha, Mane Nikhil , Padule Sunil and Gaikwad
Nitin
Volume: 04 Issue: 03 | Mar -2017
Title -SOLAR TRACKING AND MONITORING SYSTEM FOR SOLAR
WATER HEATER
In the above research work a sun tracking system is used track the sun's position
and capture maximum radiation to produce maximum power as possible . The
harvested power was used to detect percentage of water in the solar water heater
tank . The system used solonoid value to draw water from the tank . The
temerature was set to 50 degree celcius . When the water attained 50 degree the
solenoid valve was activated and the water used to came down automatically .
[2]P.P.Patil et al, 2015 deals with design consideration of the solar water heaters to
obtain hot water for the domestic and industrial applications. Design of solar water
heating system is important to assure maximum benefit to the users, so they
concentrate and analyze absorber plate materials, absorber and glazing coating
along with the changes in the design.Designing a solar water system involves
appropriate selection of each component of the desired capacity and location of
installation for solar water heater to produce hot water. Various factors and
correlations for design of collector, storage tank and insulating material are briefly
discussed. Constructional element of a flat plate solar collectors and operational
characteristics are clearly defined and shows its importance to get better thermal
performance.
[3]L.Chilambarasan et al, 2018 worked on helical internal grooved solar flat plate
collectors to enhance their conversion efficiency by reducing heat loss from the
collector surface. In an experiment conducted in three ways, case-I: plain tube,
case –II: internal groove with 0.43 pitch and case-III: internal grooved with 0.44
pitches. Every case analyzes with two identical mass
flow rates of 0.01 Kg/sec and 0.015 Kg/sec. According to their conclusions
•
For plain tube, efficiency increased with the increasing mass flow rate. At
the same, efficiency is to be increased 7% for increasing solar intensity by
5% at a higher mass flow rate.
•
For grooved tube (pitch-0.43) increasing efficiency from 8% to 20% than
that of plain tubes.
•
For grooved tube (pitch-0.44) increasing efficiency from 8% to 22% with
increasing mass flow rate.
From the above mentioned work grooved absorber tube collectors, always produce
more outlet water temperature than that
of plain tubes. Changing internal grooved pitch makes the changes on the
efficiency.
[4](K.Balaji et al,2015) focused on thermodynamics analysis of a solar flat plate
water heater using an extended surface absorber tube. He studied the effect of with
and without extended surface by using a data acquisition system. Fluid flow
parameter factor such as friction factor and non- dimensional numbers are
analyzed. Open loop solar collector with and without extended surface are
constructed same frame and orientation towards the south with tilt angle of 13oC
according to the topographical conditions. To resist the heat loss provided
insulation material. The selection of fins geometry based on circumference and the
contact surface.
Assumption
•
Properties of absorbent remain constant at all point.
• Heat transfer process is to be a steady state
•
Potential and kinetic energies are neglected
• The system always be a chemical equilibrium
• There is no mass loss inside the system
[5]S saravanan et al, 2016 experimental investigation on the flat plate solar water
heater with glass as an absorber material to check the thermal performance of
difference absorbent such as absorber black painted clear toughened glass plate
sandwich type (ABPCTG), absorbent tinted toughened glass plate sandwich type
(ATTG) and absorber galvanized iron plate with pipe (AGI) were used as an
absorbent material. performance of flat plate solar collector declines over the year
due to scale formation in water passage and reduce the heat transfer probably It
lead to poor system performance so toughened glass absorber is to be investigated
to overcome this problem. Two toughened glass is used to make ABPCTG, clear
glass placed top and bottom is frosted glass on one side for painting purpose has
been used for investigation. Here, 2mm glass strip placed in between them to water
flow passage. Clear and tinted glasses used to make ATTG. The three identical
experimental set up with different absorber material are conducted the comparative
analysis throughout maximum solar intensity.
[6]S. S. Pawar, Chinmay Karandekar, Gaurav More, Shubham Khule and Raj
Bansode
Volume: 09 Issue: 07 | July 2022
DESIGN OF SOLAR PARABOLIC TROUGH WATER HEATER
In the above research work a solar parabolic was designed , developed and tested .
The water was fed at the inlet and outlet temperature was measure at different
intervals of time .The parabolic was construsted using reflective material . The
incident ray of the sun was diverted towards the tube and the water was heated .
The performance of the instrument was tested and analysed .
COMPONENTS USED
1. 20*20 MM MILD STEEL SQUARE PIPE .
The hollow pipe is used to construct the frame of the simulation setup .
2.PLASTIC CONTAINERS
The containers are used to simulate solar water heater and cold water tank .
3. MIXING TANK
The mixing tank is constructed from 6 inch pvc pipe . The tank shall be provided
with inlet and outlet valve and shall then be installed in the simulation setup.
4. 12 SOLENOID WATER VALVE
A solenoid valve is an electromechanically operated valve.
Solenoid valves differ in the characteristics of the electric current they use, the
strength of the magnetic field they generate, the mechanism they use to regulate
the fluid, and the type and characteristics of fluid they control. The mechanism
varies from linear action, plunger-type actuators to pivoted-armature actuators and
rocker actuators. The valve can use a two-port design to regulate a flow or use a
three or more port design to switch flows between ports. Multiple solenoid valves
can be placed together on a manifold.
Solenoid valves are the most frequently used control elements in fluidics. Their
tasks are to shut off, release, dose, distribute or mix fluids. They are found in many
application areas. Solenoids offer fast and safe switching, high-reliability, long
service life, good medium compatibility of the materials used, low control power
and compact design.
SOLONOID VALVE
The solonoid valve is used to control the flow of the liquids .
5.12 VOLT WATER PUMP
A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by
mechanical action, typically converted from electrical energy into hydraulic
energy.
Mechanical pumps serve in a wide range of applications such as pumping water
from wells, aquarium filtering, pond filtering and aeration, in the car industry for
water-cooling and fuel injection, in the energy industry for pumping oil and natural
gas or for operating cooling towers and other components of heating, ventilation
and air conditioning systems. In the medical industry, pumps are used for
biochemical processes in developing and manufacturing medicine, and as artificial
replacements for body parts, in particular the artificial heart and penile prosthesis.
12 VOLT PUMP
The 12 volt pump is used to pump water from mixing tank to the cold water tank .
6.ARDUINO UNO MICROCONTROLLER:A microcontroller (MCU for microcontroller unit) is a small computer on a single
VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs
(processor cores) along with memory and programmable input/output peripherals.
Program memory in the form of ferroelectric RAM, NOR flash or OTP ROM is
also often included on chip, as well as a small amount of RAM.
SPECIFICATIONS:Microcontroller :ATmega328
Operating Voltage :5V
Input Voltage (recommended): 7-12V
Input Voltage (limits) :6-20V
Digital I/O Pins :14 (of which 6 provide PWM output)
Analog Input Pins: 6
DC Current per I/O Pin :40 mA
DC Current for 3.3V Pin :50 Ma
Flash Memory :32 KB (ATmega328) of which 0.5 KB used by bootloader
SRAM :2 KB (ATmega328)
EEPROM :1 KB (ATmega328)
Clock Speed :16 MHz
ARDUINO UNO
7. 16*2 LCD DISPLAY
LIQUID CRYSTAL DISPLAY
A liquid-crystal display (LCD) is a flat-panel display or other electronically
modulated optical device that uses the light-modulating properties of liquid
crystals combined with polarizers. Liquid crystals do not emit light directly,
instead using a backlight or reflector to produce images in color or monochrome.
LCDs are available to display arbitrary images (as in a general-purpose computer
display) or fixed images with low information content, which can be displayed or
hidden. For instance: preset words, digits, and seven-segment displays, as in a
digital clock, are all good examples of devices with these displays. They use the
same basic technology, except that arbitrary images are made from a matrix of
small pixels, while other displays have larger elements. LCDs can either be
normally on (positive) or off (negative), depending on the polarizer arrangement.
For example, a character positive LCD with a backlight will have black lettering
on a background that is the color of the backlight, and a character negative LCD
will have a black background with the letters being of the same color as the
backlight. Optical filters are added to white on blue LCDs to give them their
characteristic appearance.
LCD
The lcd display is used to provide graphical user interface .
8. 4*3 KEYPAD
A keypad is a block or pad of buttons set with an arrangement of digits, symbols,
or alphabetical letters. Pads mostly containing numbers and used with computers
are numeric keypads. Keypads are found on devices which require mainly numeric
input such as calculators, television remotes, push-button telephones, vending
machines, ATMs, point of sale terminals, combination locks, safes, and digital
door locks.
4*3 KEYPAD
The keypad is used to provide input to the system .
9.TEMPERATURE SENSOR
DS18B20 digital temperature sensor works on a single bus and it has 64-bit ROM
to store the serial number of component. It can get quite a few DS18B20 sensors
connected to a single bus in parallel. With a microcontroller, you can control so
many DS18B20 sensors that are distributed around a wide range. So the sensor is
widely used in these fields, including HVAC environmental control, temperature
detection of building, instrument and machine, and process monitoring and control.
The number of sensors in the parallel connection cannot be over 8; otherwise,
brownout will happen and the signal transmission will turn to be unstable. As a
result, multi-point temperature measurement will fail.
Working Voltage: 3V~5.5V
Detected Temperature Range: -55°C~+125°C (-67°F~+257°F) deviation ±2°C ,10°C~+85°C deviation ±0.5°C
DS18B20 SENSOR
The temperature sensor is used to detect the tempertaure in the mixing tank . The
input values for microcontroller is obtained from it .
10. RELAY
A relay is an electrically operated switch. It consists of a set of input terminals for
a single or multiple control signals, and a set of operating contact terminals. The
switch may have any number of contacts in multiple contact forms, such as make
contacts, break contacts, or combinations thereof.Relays are used where it is
necessary to control a circuit by an independent low-power signal, or where several
circuits must be controlled by one signal. Relays were first used in long-distance
telegraph circuits as signal repeaters: they refresh the signal coming in from one
circuit by transmitting it on another circuit. Relays were used extensively in
telephone exchanges and early computers to perform logical operations.
The traditional form of a relay uses an electromagnet to close or open the contacts,
but relays using other operating principles have also been invented, such as in
solid-state relays which use semiconductor properties for control without relying
on moving parts. Relays with calibrated operating characteristics and sometimes
multiple operating coils are used to protect electrical circuits from overload or
faults; in modern electric power systems these functions are performed by digital
instruments still called protective relays.
Latching relays require only a single pulse of control power to operate the switch
persistently. Another pulse applied to a second set of control terminals, or a pulse
with opposite polarity, resets the switch, while repeated pulses of the same kind
have no effects. Magnetic latching relays are useful in applications when
interrupted power should not affect the circuits that the relay is controlling.
RELAY MODULE
The relay module is used to turn on/off the solonoid valve and pump.
11. BUCK CONVERTER
A buck converter (step-down converter) is a DC-to-DC power converter which
steps down voltage (while stepping up current) from its input (supply) to its output
(load). It is a class of switched-mode power supply (SMPS) typically containing at
least two semiconductors (a diode and a transistor, although modern buck
converters frequently replace the diode with a second transistor used for
synchronous rectification) and at least one energy storage element, a capacitor,
inductor, or the two in combination. To reduce voltage ripple, filters made of
capacitors (sometimes in combination with inductors) are normally added to such a
converter's output (load-side filter) and input (supply-side filter).
Switching converters (such as buck converters) provide much greater power
efficiency as DC-to-DC converters than linear regulators, which are simpler
circuits that lower voltages by dissipating power as heat, but do not step up output
current.
Buck converters can be highly efficient (often higher than 90%), making them
useful for tasks such as converting a computer's main (bulk) supply voltage (often
12 V) down to lower voltages needed by USB, DRAM and the CPU (1.8 V or
less).
BUCK CONVERTER
The buck converter is used to reduce the 12 volt of the battery to 5 volts so as to
provide power to the circuit elements .
BILL OF MATERIALS
SL NO
COMPONENTS
QUANTITY
AMOUNT
1
20*20 MS PIPE
6 KG
630
2
25 LITER CONTAINERS
2 PC
1120
3
6 INCH PVC PIPE
1 FT
180
4
END CAPS
2 PC
200
5
SOLENOID VALVES
3 PC
1350
6
12 VOLT PUMP
1 PC
290
7
12 VOLT BATTERY
1 PC
900
8
1/ 2 INCH PIPE
2 METER
250
9
BUCK CONVERTER
1 PC
180
10
ARDUINO UNO
1 PC
900
11
DS18B20 SENSOR
1 PC
120
12
4*3 KEYPAD
1 PC
135
13
LCD WITH I2C CIRCUIT
1 PC
480
14
DIGITAL THERMOMETER
1 PC
300
METHODOLOGY
The simulation setup consists of a hot water tank which represents the solar water
heater and a cold tank which represents the overhead cold water tank . The system
also has a mixing tank which evaluates the water temperature before providing it to
the user . The hot water and cold water flows into the mixing tank through
solenoid operated valves . The cold water from the mixing tank shall be sent back
to cold water tank by using a pump. The user can access the evaluated water
through an outlet that is controlled by solenoid operated valve .
The system is provided with lcd and keypad for the user to input temperature range
. The system is also provided with a digital thermometer to get the hot water
temperature in the hot water tank .
Initially the user has to turn on the system . The system prompts the user to input
the temperature range. The user has to enter the required temperature . Now the
inputted value is stored in the system there are three different cases based on the
temperature inputted by the user .
Case 1. Hot Water temperature below input temperature
In this case all valves are shut and only hot water valve is opened . The cold water
coming initially from the water heater is drained and pumped to cold water tank
until the water temperature coming from hot water tank is equal to input
temperature.
Case 2. Hot Water temperature equal to input temperature
In this case all valve are shut except for hot water tank valve and user outlet valve .
The water coming from hot water tank directly flows to the user outlet.
Case 3. Hot Water temperature greater than input value .
In this case all the valves are shut except for cold water tank valve . The system
mixes the hot water with cold water to match its temperature with input
temperature value , once the value matches the input value , the user outlet value is
opened . After this the cold water valve is shut and hot water valve is opened. The
process of mixing and calibrating is continued . The entire process happen within
seconds and the user is provided with conineous supply of water .
ISOMETRIC VIEW
FRONT VIEW
TOP VIEW
SIDE VIEW
FINAL ASSENMBY 2D DRAFTINGS
SCHEMATIC DIAGRAM
MATHEMATICAL CALCULATIONS
CONSTRUCTION
• Initially the 20*20 mm mild steel square pipes are cut using disc cutter.
• It is welded to form the frame of the simulation setup .
• The hot water tank and cold water tank is installed at the top of the frame .
• The mixing tank is installed below the hot and cold tanks .
• The hot water outlet and cold water outlet is connected to the mixing tank
through solenoid operated valve .
• The outlet of the mixing tank is connected to user outlet through solenoid
valve .
• The other outlet of the mixing tank is connected to cold water tank through
pump.
• The set up is wired with circuit elements and finally coded using arduino
IDE.
ADVANTAGE
•
The system shall reduce water wastage.
• The user can obtain required temperature of the water with one touch of a
button.
• The system consumes very less power and does not require frequent
maintainance.
• The system improves the solar water heating technology and makes it more
reliable.
DISADVANTAGE
•
The system shall require external power supply if we want to pump the
water to over head tank situated in elevated heights.
• The clogging problems may arise due to silt and sedimentation.
APPLICATIONS
•
The system can be used with present day solar water heater for obtaining
required water temperature.
EXPECTED OUTCOME
• The current designs that do not provide water according to the user's
temperature requirement shall be improvised.
• The water wastage problems shall be solved by introducing the proposed
method .
• The manual mixing problems that are encountered in the current day designs
shall be trouble shooted.
FUTURE SCOPE
• The proposed method can be inbuilt in current day designs.
• The power to run the system can be obtained from solar panels and the
dependency on external power supply can be cut off.
• The system can be provided with an alternative tank to divert cold water and
this water can be used to wash vehicles/ clothes outside the house.
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