Report on Solar Water Heater

Report on Solar Water Heater

Abstract:- Solar water heater is a system which is used to heat the water with the help of solar energy. Solar energy is an important source of renewable energy (unconventional energy).

Solar water heater is eco friendly, easy to use installation and economic when setup whole system, in the presence of sun light collector start working and after some time, water is heated.

Solar water heater uses in hotels, hospitals, hostels, bathing, industrial application etc.

Solar water heater is used to solve conventional resources like coal, electricity, diesel, gas etc. but it is not able to do fast work and it cannot work in the absence of sun light this is drawback of this solar water heater.

Key words:- Solar Energy Collector, Storage Tank, Insulated Pipe, Pump

Introduction:- A solar water heater is a device which provides hot water for bathing, washing, cleaning, etc using solar energy. Solar hot water system turns cold water into hot water with the help of sun’s ray.

In solar water heater collector is used to collect solar energy , insulated tanks are used to store hot water pump is used to pumped the cold water through collector (hot water)

Type of collector:-

1.       Flate Plate Collector

2.       Evacuated tube collector

Flate Plate Collector:-  Flate plate collector is used to absorbed solar radiation. Which consist of an insulated outer metallic box. Covered on the top with glass sheet. Inside there are blankeried metallic absorber sheets with built in riser tubes to carry water.  The absorber absorb the solar radiation and transfer the heat to the flowing water . These collectors are metallic type and longer life.

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Evacuated Tube Collector:- These collectors are made of glass which can be easily broken in nature.

Note:- Systems are installed with or without heat exchanger and pump or without pump. System without pump is known as forced circulation system. Thermo –syphon system also called  Natural convention.

Insulated Storage Tanks:

1.       Purpose:-  A hot water storage tank is a water tank that is used for storing hot water for space heating or domestic use.

2.       Materials:- Mild steel or steel (p=7850 kg/, k= 47.6 w/m°c)

3.       Insulation:- The most common type of water heater blanket is fiberglass insulation with a vinye film on the outside.

Properties of fiberglass

1.       Lightweight

2.       Resistance to corrosive attacks

3.       Low thermal conductivity

4.       High strength

Properties of Vinyl

1.       It is resistant to moisture and humidity

2.       It is very strong

3.       It is low cost material

4.       It is easily recycled

Insulated Pipes

1.       Purpose:- To transport fluid to the low header of the collector (cold water) to the top of the storage tank ( hot water).

2.       Materials:- Galvanized iron sheet

3.       Properties:- Tough and strong, easily worked, long life

Pump

In solar water heater, pressure pump is used to pump cold water from the source the solarizer tank.

System Control

Purpose  :- To protect the system from damage and for efficient working

ü  Sensor

ü  Control valve

ü  Maintain height between top and the collector to the bottom of the storage tank (0.3-0.4)m to avoid reserve flow during height ( in case of natural convention).

Types of solar water heating system

These are two types:-

1.       Closed loop system

2.       Open loop system

Closed Loop System

In the closed loop system , heat exchanger are installed to protect the system from hard water obtained bore wells or freezing temperature in the cold regions.

Open Loop System

There are two types:-

1.       Natural circulation system (thermosyphon):- in this system, water flow without pump.

2.       Forced circulation system:- in this system, water flow using pump.

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Working:-  As sun light strikes the collector, the water inside it is heated. If circulated pump is regulated by PV collector panels), PV collector panels is activated by sun light. The DC motor pump moves water from the tank through the collector and back to the tank.  If the circulating pump is regulated by an electronic differential collector, a sensor at the bottom of the tank activate the circulating pump. When water temperature above (15-20 °f) the cold water.

This process is continues till collector outlet is about 5°f higher than that in the bottom of the tank. If temperature difference decreases further than pump shuts off automatically by collector time is also set by operator to operate during radiation is available to heat the portable water. During insufficient sun light or high hot water demand, a backup electrical element in the storage tank heats the water check valve prevents heat loss when pump is off.

Heat Storage in the System

Q = M. C. (T1-T2)

Where

ü  Q= Heat storage in water(watt)

ü  M= Mass flow (kg/sec)

ü  C= Specific heat of water (4.18 kj/kg°c )

ü  T1= Hot water temperature (°c)

ü  T2= Cold water temperature (°c)

Collector Area:-

ü  Actual average insulation = Solar average insulation * collector efficiency

ü  Collector Area = Total heat required for water heating/ Average insulation available

Protect Against Freezing;-

v  Collector may be designed to be drained during time when they are not operating or when freezing is a possibility.

v  Antifreezing solution (Ethylene glycol) can be used in the collector with heat exchanger to transfer energy to the water.

v  The collector may be covered with movable insulation.

v  The operating of the electric heat strips attached to the absorber.

Application of SWHS

Ø  Solar water heating systems are used in hotels, hospitals, houses, bathing and various industrial applications etc.

Advantage of SWHS

ü  These systems use solar energy which is a free and renewable sources of energy.

ü  These systems has low maintainance cost.

ü  Simple to construct and install.

ü  No running cost.

ü  It saves time and high grade from of electric energy.

ü  Required low temperature up to 100 °C can be achieved by SWHS.

Disadvantage of SWHS

ü  Freezing problem

ü  Electrical or gas required during winter period.

ü  They require excellent overheating and freeze protection.

Conclusion

v  SWHS gives free cost of energy.

v  Cheaper cost as compare to other heating system.

v  Due to Constraints. On energy availability, it is most suitable.

v  Keep the environment clean.

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