Solar.pptx

What’s Solar Energy?  Sun is basic source of energy for earth. Solar energy is

available in form of Electromagnetic radiation.  Sun is large sphere of very hot gases, heat being

generated by the various fusion reaction in it.  The sun generates an approximately 1.1*1020 kwh energy

in every second.  Solar energy Originates with the thermonuclear fusion

reactions occurring in the sun. Prof Ronak Doshi

•Represents the entire electromagnetic radiation (visible light, infrared, ultraviolet, and radio waves). •This energy consists of radiant light and heat energy from the sun.

•Out of all energy emitted by sun only a small fraction of energy is absorbed by the earth. •Just this tiny fraction of the sun’s energy is enough to meet all our power needs.

Prof Ronak Doshi

Prof Ronak Doshi

How much solar energy?

The surface receives about 47% of the total solar energy that reaches the Earth. Only this amount is usable. Prof Ronak Doshi

•

•

Using present solar techniques some of the solar energy reaching the earth is utilized for generating heat, electricity etc…. Even then the energy demand met by using solar energy is very less. Fossils 1st Qtr Bio-fuels 2nd Qtr

3rd Qtr Hydro-based Nuclear 4th Qtr

SOLAR(0.8%) Windmills Prof Ronak Doshi

Sun Radiation  The radiated beam from the sun reaching the earth could

be of two types.  

Direct radiation Diffuse radiation

Prof Ronak Doshi

Solar Constant • The solar constant is defined as the total energy received from the sun per unit time ,on a surface of unit area kept perpendicular to the radiation, in space just outside the earth's atmosphere when the earth is at its mean distance from the sun. • Solar constant have approximately value is 1367 W/m2. (World Radiation Center)

Prof Ronak Doshi

Prof Ronak Doshi

 The solar radiation intensity falling on a surface is called

irradiance or isolation and is measured in W/m2 or kW/m2. The solar constant can be used to calculate the irradiance incident on a surface perpendicular to the Sun’s rays outside and the Earth’s atmosphere on any day of the year (i.e. as the distance between the Sun and Earth changes thought the year):

 Where:

I0 = extraterrestrial (outside the atmosphere) irradiance on a plane perpendicular to the Sun’s rays (W/m2), ISC = the solar constant (1367 W/m2), n = the day of the year such that for January the 1st n = 1. Prof Ronak Doshi

Direct or Beam Radiation  Solar radiation that has not been absorbed or

scattered and reaches the ground directly from the sun is called "direct(or Beam) radiation".

Prof Ronak Doshi

• Diffuse Radiation: The diffuse radiation is that solar radiation received from the sun after its direction has been changed by reflection and scattering by the atmosphere.

• Total or Global Radiation: The total solar radiation received at any point on the earth's surface is the sum of the direct and diffuse radiation.

Prof Ronak Doshi

Prof Ronak Doshi

Extraterrestrial radiation Solar radiation incident on the outer atmosphere of the earth is called extraterrestrial radiation.

Prof Ronak Doshi

Prof Ronak Doshi

Terrestrial radiation  It is the radiation on the earth’s surface after the

solar radiations have traversed through the layer of atmosphere.

Prof Ronak Doshi

Irradiance, W/m2:  The rate at which radiant energy is incident on a surface,

per unit area of the surface.  The symbol G is used for solar irradiance, with appropriate subscripts for beam, diffuse or total.

Prof Ronak Doshi

Irradiation, J/m2 : The incident energy per unit area on a surface, found by integration of irradiance over a specified by time, usually an hour a day.

Prof Ronak Doshi

Air mass:  A term called air mass (AM) is often used as a measure of the distance traveled by beam radiation through the atmosphere before it reaches a location on the earth's surface. The air mass is the ratio of the path of the sun's rays through the atmosphere to the length of path when the sun is at zenith.  The zenith is an imaginary point directly "above" a particular location.

Prof Ronak Doshi

Prof Ronak Doshi

 Solar Radiation Measurement: Measurement of solar radiation are

important because of cooling & heating applications. Experimental determination of the energy transferred to a surface by solar radiation required instruments which will measure the heating effect of direct solar radiation & diffuse radiation. Three basic type of instruments are employed for solar radiation measurement:  1) Pyrheliometer : This is used for measuring solar radiation from the

sun & from a small portion of the sky around the sun(beam radiation) at normal distance.  2) Pyranometer : An instrument for measuring total hemispherical solar (beam+diffuse) radiation, usually on a horizontal surface. If shaded from the beam radiation by a shade ring, it measures diffuse radiation.  3) Sunshine recorder : It is used to measure hours to bright sunshine. The hours of bright sunshine that is the time in which solar disc is visible is of use in estimating the long term averages of solar radiation. Prof Ronak Doshi

Pyranometer

Prof Ronak Doshi

 The instrument’s radiation-sensing element has basically the same structure

as that of a thermoelectric pyrheliometer.  Another similarity is that the temperature difference derived between the

radiation-sensing element (the hot junction) and the reflecting surface (the cold junction) that serves as a temperature reference point is expressed by a thermopile as an thermo electromotive force.  Major Component Are:    

Black Surface Glass Dome Thermopile Supporting stand

 difference are as follows:  1) Several pairs of thermocouples are connected in series to make a

thermopile that detects the temperature difference between the black and white radiation-sensing surfaces. Prof Ronak Doshi

 2) The temperature difference between two black radiation-

sensing surfaces with differing areas is detected by a thermopile.  3) The temperature difference between a radiation-sensing

surface painted solid black and a metallic block with high heat capacity is detected by a thermopile. The thermopile generates a thermopile emf which proportional to the radiations absorbed.  This thermo emf is calibrated in terms of the received radiation

. This will measure the global radiation.  If only the diffusion radiation is to be measured the direct

radiation is blocked by a shield. So only th e diffusion radiation will be incident on surface. Hence the thermo emf will be proportional to the diffusion radiation

Prof Ronak Doshi

Pyrheliometer

Prof Ronak Doshi

 Three pyrheliometers have been in wide-spread use to measure normal

incident beam radiation : i) The angstrom Pyrheliometer ii) The abbot silver disc Pyrheliometer iii) Eppley pyrheliometer: The angstrom Pyrheliometer:  In the instrument a sensor is towards the sun, the sensing surface is normal to the line joining the sun to the receiver & only radiation from the sun & a narrow annuals of the sky is received by the sensor.  In this pyrheliometer a thin blackened shaded manganin (size 20*20*0.1 mm) is heated electrically until it is at the same temperature as a similar strip which is exposed to solar radiation. It is shown schematically. Under steady state conditions (both strips at identical temperature) the energy used for heating is equal to the absorbed solar energy. Prof Ronak Doshi

Angstrom Pyrheliometer

Prof Ronak Doshi

Prof Ronak Doshi

 The Abbot silver disc Pyrheliometer:

The sensing element is a silver disk measuring 28 mm in diameter with a thickness of 7 mm that is painted black on its radiation-receiving side. It has a hole from the periphery toward the center to allow insertion of the bulb of a high-precision mercury-in-glass thermometer. Prof Ronak Doshi

 To maintain good thermal contact between the disk and the bulb,

the hole is filled with a small amount of mercury. It is enclosed outside by a heat-insulating wooden container.  The stem of the thermometer is bent in a right angle outside the wooden container and supported in a metallic protective tube.  A cylinder with diaphragms inside is fitted in the wooden container to let direct solar radiation fall onto the silver disk. There is a metallic-plate shutter at the top end of the cylinder to block or allow the passage of solar radiation to the disk.  During the measurement phase, the disk is heated by solar radiation and its temperature rises. The intensity of this radiation is ascertained by measuring the temperature change of the disk between the measurement phase and the shading phase with the mercury-in-glass thermometer. Prof Ronak Doshi

 Sunshine Recorder:It is a device that records the amount of sunshine at a

given location. The results provide information about theweather and climate of a geographical area. This information is useful in meteorology, science, agriculture, tourism, and other fields. There are two basic types of sunshine recorders. One type uses the sun itself as a times scale for the sunshine readings. The other type uses some form of clock for the time scale.

Prof Ronak Doshi

Sunshine Recorder

Prof Ronak Doshi

 This instrument is used to measure the hour of bright

sunshine in a day.  Suns beam is focussed to a point by a spherical glass which acts as a convex lens. A graduated paper strip is placed at the focal point. Due to the heating effect of the focussed beam, a burn mark is produced on the paper. The graduation on the paper is done as per the hour of the day.  As sun moving during the day the burn marks at the focal point is produce continuously on the paper strip.  At the end of the day a continuous burn mark with varying intensities of burn can be seen on the paper depicting the sunshine hour.

Prof Ronak Doshi

 The duration of bright sunshine in a day is measured by means of

a sunshine recorder.  The sun’s ray are focused by a glass-sphere to point on a card strip held in a groove in a spherical bowl mounted concentrically with the sphere.  Whenever there is a bright sunshine ,the image formed is intense enough to burn a spot on the card strip. through the days the sun moves across the sky, the images move along the strip. Thus a burnt space whose length is proportional to the duration of sunshine is obtained on the strip.

Prof Ronak Doshi

Application of solar energy  Solar water heating  Solar Air heating  Solar Dryers

 Solar Distillation  Solar thermal power plants  Photovoltaic

Prof Ronak Doshi

Why Solar Water Heating? Electricity or natural gas water heating

Solar Water Heating

Pay 100% of hot water heating bill

Eliminate up to 80% of bill

Surrender to continued rising energy costs

Enjoy a constant increasing savings in nontaxable income

Add zero equity to your home

Increase home’s investment

value

through

Profit from an income Make monthly payments for hot water with opportunity that produces no return on investment positive cash flow

your

generation a monthly

Contribute to air pollution and add heavy Utilize a safe, free, non-polluting energy toxic metals into the air and water source—the sun Prof Ronak Doshi

Types of solar water heating system The solar water heating systems are of two categories: 1) Natural circulation or thermo-syphon solar water heaters 2) Forced circulation solar water heating system i)Direct or open loop system ii) Indirect or closed loop system Prof Ronak Doshi

Natural Circulation SWHS  As water from the lower of

the tank enter into collector plate heated up and rises in the copper tube column.  Hot water enter at the top of the storage tank via upper header of the collector.

Prof Ronak Doshi

Prof Ronak Doshi

 Collection: solar radiation is captured by

solar colllector.

Collection of solar energy

 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. Prof Ronak Doshi

Transfer

Basic Components of SWHS  Flat plate collector  Insulated water storage tank  Well insulated pipes connecting flat plate collector

and to the storage tank  Auxiliary heater ( for cloudy days)

Prof Ronak Doshi

Flat Plate collector It is a device which is used to convert solar energy into thermal energy & consists of the following components: Absorber Transparent cover Insulation Tubes, Fins Frame

Prof Ronak Doshi

Insulated water storage tank Purpose: A hot water storage tank (also hot water tank, thermal storage tank) is a water tank that is used for storing hot water for space heating or domestic use

Material: Mild steel or Steel Insulation: The most common type of water heater blanket is fiberglass insulation.

Prof Ronak Doshi

Properties of fiberglass  lightweight;  tight structure ;  resistance to corrosive attacks;

 superior shock and wear resistance;  cheap maintenance in service;

Prof Ronak Doshi

Insulated pipes Purpose- To transport fluid to the lower header of the collector (cold water) to the top of the storage tank (hot water). Material- Galvanized Iron sheet. Properties>This material is tough and strong, > It can be fairly easily worked (bent or formed), > It lasts a long time, too, because the zinc coating (the galvanizing) inhibits corrosion quite well. Prof Ronak Doshi

Auxiliary heater ( for cloudy days) Purpose:  An auxiliary heater is attached in the tank to provide supplement heat during cloudy days.  Freezing protection during winter season.  Act as heat exchanger.

Prof Ronak Doshi



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. Prof Ronak Doshi

ACTIVE-OPEN LOOP SOLAR WATER HEATING SYSTEMS

Prof Ronak Doshi

ACTIVE-CLOSE LOOP SOLAR WATER HEATING SYSTEMS

Prof Ronak Doshi

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. Prof Ronak Doshi

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. Prof Ronak Doshi

 2. Solar Dryers  It is estimated that 20% of the food production is wasted

during the post harvest period. the agricultural product losses are due to spillage ,contamination ,attack by birds & insects, attack of rodents during harvesting & storage of food. The drying or dehydration process removes the moisture of material in thin layers on open ground. It helps in easy transport of food products due to reduced weight caused by moisture loss. Drying of seeds prevents the germination & growth of fungi & bacteria.

Disadvantage of natural sun drying:  1) No control over drying rate & non-uniform drying.  2)Discolouration, nutritional changes, loss of germination.  3)Too slow drying may cause growth of fungi & bacteria.  4)Moisture content cannot be controlled. Prof Ronak Doshi

 Types of Solar dryers  1. Natural convection or direct type solar dryers (

cabinet dryers)  2. Forced circulation solar dryers  - Direct gain type  - Indirect gain type

Prof Ronak Doshi

SOLAR DRYER Natural convection or direct type solar dryers ( cabinet dryers)

Ventilation Holes

Door

Tray to Keep Food

Thermal Insulation

Prof Ronak Doshi

Forced circulation solar dryers 1. Direct gain type

Glass Cover

Plastic Sheet

Door

Tray to Keep Food

Hot Air

Fresh Air Prof Ronak Doshi

2. Indirect gain type

Hot Air Feed

Solar Collector

Dehydrator

Rock Storage Tank

Dry Product

Exhaust

Brower Fresh Air Prof Ronak Doshi

Prof Ronak Doshi

Prof Ronak Doshi

Prof Ronak Doshi

Solar Distillation  Process that removes impurities & contaminants  How?  Heat water to point of vaporization  Water vapor condenses on cooler surfaces

 Condensate runs off into collection bin

Prof Ronak Doshi

 Fresh water is basic need for sustenance of human

life. The availability of fresh water from rivers, lakes and ponds.  The solar energy can be utilised to convert the saline water into distilled water. This water can be used both for drinking as well as clean water in automobile, battery, industries etc.  The device which is used to convert saline water into pure water by using solar energy is called still.

Prof Ronak Doshi

 The saline water is supplied to basin by filter.  A overflow pipe allows the excess water to flow out

from the basin.  The top of basin is covered with air tight transparent cover. The cover is roof like and the slop is provied towards a collection trough.

Prof Ronak Doshi

3. Solar Distillation

Prof Ronak Doshi

Condensed Water Drop Glass Cover

Filler

Evaporation

Saline Water

Over Flow Pipe Prof Ronak Doshi

Insulation

 Solar Distillation:  Fresh & clean water is the basic need for sustenance life & their



  

 

prosperity. Pollutant discharge, bathing & washing. This solar energy can be converted the saline water into distilled water. This water being potable, it can be used for both drinking as well for requirement of clean water in automobile, battery & industries. The device which is used to convert saline water into pure by using solar energy is called solar still, generally known as “Basin type solar still”. Description: Basin Liner: it is a shallow basin covered with black surface. Overflow Pipe: Allows excess water outside the basin. Transparent Cover: covered with a sloping air tight glass or plastic. The performance of a solar still is represented in terms of liters of water produced per day per square meter of basin area(l/m2/day). Prof Ronak Doshi

 η= (m*Δh)/H

m=mass of distilled water; Δh=enthalpy change of inlet cold water to water vapour; H=Intensity of solar radiation.

Prof Ronak Doshi

Types of Solar Still

 Various design of solar still are being developed with

Minor variations in various countries some of solar stills are given below. 1. Double sloped symmetrical still with basin divided into two bays 2. Single sloped glass solar still 3. V trough type solar still 4. Solar still with plastic inflated cover 5. Wick type solar still

Prof Ronak Doshi

Types of Solar Still Double sloped symmetrical still with basin divided into two bays Glass Cover Basin 1

Basin 2

Condensed Water Channel

V trough type solar still Plastic Roof

Prof Ronak Doshi

Wick type solar still Saline Water Inlet

Glass Cover

Black Fabric

Condensed Water

Thermal Insulation

Saline Water Outlet

Prof Ronak Doshi

 Solar still with plastic inflated cover

Plastic Cover

Basin

Prof Ronak Doshi

Solar Heating of Building  Various methods have been developed for solar

heating of space. Each method basically involve the collection of solar energy and its storage.  Space heating classified as:  1) Passive System  2) Active System

Prof Ronak Doshi

 Solar Heating & cooling of buildings:  various methods have been developed for solar heating of

space.

 1)Passive System: In this system the collection, storage

& distribution of solar energy is done by natural means for transport of energy by convection, radiation & conduction ,such systems do not use any electrical or mechanical power & any other electrical controls.

 2)Active System: In active solar space heating system,

the solar energy is collected by solar collectors or either by water or air. This energy is then storage materials either in the form of sensible heat or latent heat or in chemical reaction. Prof Ronak Doshi

What is Passive Heating? Passive heating : -refers to technologies or design features used to heat buildings without power consumption. -building design attempts to integrate the principles of physics into building exterior envelope to: *speed up heat transfer into a building Transport of energy by  Convection  Radiation  Conduction Prof Ronak Doshi

 Solar Passive Heating system:

This system is south facing concrete or stone or brick wall 10cm to 20cm thick called Trambay wall. This wall is designed for thermal storage & its outer surface is black pointed in order to increase the absorption energy.

Prof Ronak Doshi

Passive Space Cooling using ventilation:

Prof Ronak Doshi

Active Space heating System:  It requires some basic components:  1) A solar radiation collector which heats a fluid. A fluid

used may be water or air depending upon the design of the system.  2) A storage device to store heat for use at night & on cloudy or rainy day.  3) A distribution system to supply heat where ever required.

Prof Ronak Doshi

 Hot water Space Heating System:  The cold water from storage tank is pumped to

solar collector by pump A. Hot water from storage tank is pumped by pump B & it is supplied to the heat exchanger where it transfers the heat to the cold air from the building.  The cold water after transfer of heat is returned to storage tank 7 the hot air from heat exchanger is supplied to the building for space heating.  An auxiliary heater is provided if the hot water from storage tank is not at desired temperature on cloudy days. Prof Ronak Doshi

Prof Ronak Doshi

 Active Hot Air heating System:

Prof Ronak Doshi

Solar Based LiBr – H2O Vapour Absorption System for Space Cooling

Prof Ronak Doshi

SOLAR POWER PLANT

 Commonly used cycle for solar thermal power plants:1. Stirling cycle:- It consists of two constant volume

process and two isothermal process during which the heat addition and heat rejection processes take place. 2. Brayton cycle:- It consists of two constant pressure processes for heat addition and heat rejection and two adiabatic processes. 3. Ranking cycle:- It used in conventional thermal power plant can be applied to thermal power plant. The system is most commonly used. The efficiency of power plant based on brayton cycle and rankine cycle is lower than stirling cycle. Prof Ronak Doshi

 Advantage and disadvantage of solar thermal

power plants over conventional thermal power plant Advantage: Saves costly and depleting fossil fuels  Pollution free  Do not require fuel transportation  Can be installed far away fuel sources and in remote areas.

Prof Ronak Doshi

Disadvantage: Cost of power generation is high  Need stand by power  Need very large collector area for installation  Cannot supply continuous electrical power  Only suitable where favorable sun shine conditions are available  Low thermal efficiency  Need thermal storage system Prof Ronak Doshi

SOLAR POWER PLANT 1. Low Temperature Solar Power Plant  A) Low Temperature Flat Plat Collector Solar power Plant  B) Solar Pond Electric Power Plant 2. Medium Temperature Solar Power Plant

3. High Temperature Solar Thermal Power Plant  A) Solar Thermal Power Plant using dish Collectors  B) Central tower Receiver Power Plant using Heliostats Prof Ronak Doshi

Low Temperature Solar Power Plant  The low temperature solar power plant use the

working fluid temperature in the range of 60 to 100 C which can be obtained using flat plate type collectors or by solar ponds. The efficiency of such plants is only 2% to 3%.  The working fluid used in such plants are the fluids having low boiling temperatures at atmospheric pressure. The fluids used are refrigerant R -11 , butane gas etc.

Prof Ronak Doshi

Low Temperature Flat Plat Collector Solar power Plant

Prof Ronak Doshi

Solar Pond Electric Power Plant

Prof Ronak Doshi

Medium Temperature Solar Power Plant  These system employ an array of parabolic trough

concentrating collector spread over a large area. The general range of working temperature are between 250 to 400 C  Parabolic in line focusing type collector are used and generally preferred because of low cost and require sun tracking in one plane only as compared to paraboloied concentrating collector having higher cost and require sun tracking in two planes.  The system works on rankine cycle. The schematic diagram of a medium temperature solar power plant using in line parabolic trough concentrators is shown in fig. Prof Ronak Doshi

Prof Ronak Doshi

High Temperature Solar thermal Power plants:  For efficient utilizstion of solar heat energy into

electrical energy the working fluid has to be supplied at high temperature.  Large solar thermal plants can be built in the capacity of 50 MW to 200 MW.  Such plants use paraboloidal dish collactors or heliostats.  These system have high thermal efficiency.

Prof Ronak Doshi

Central tower receiver power plant using heliostats

Prof Ronak Doshi

Prof Ronak Doshi

Prof Ronak Doshi

Prof Ronak Doshi

Prof Ronak Doshi

Stirling cycle:  In Stirling cycle, Carnot cycle’s compression and

expansion isentropic processes are replaced by two constant-volume regeneration processes.  During the regeneration process heat is transferred to a thermal storage device (regenerator) during one part and is transferred back to the working fluid in another part of the cycle.  The regenerator can be a wire or a ceramic mesh or any kind of porous plug with a high thermal mass (mass times specific heat). The regenerator is assumed to be reversible heat transfer device. Prof Ronak Doshi

Brayton cycle:  The combustion process is replaced by a

   

constant-pressure heat-addition process from an external source, and the exhaust process is replaced by a constantpressure heat-rejection process to the ambient air. 1-2 Isentropic compression (in a compressor) 2-3 Constant-pressure heat addition 3-4 Isentropic expansion (in a turbine) 4-1 Constant-pressure heat rejection Prof Ronak Doshi

 Rankine Cycle  Many of the impracticalities associated with the

Carnot cycle can be eliminated by superheating the steam in the boiler and condensing it completely in the condenser.  The cycle that results is the Rankine cycle, which is the ideal cycle for vapor power plants. The ideal Rankine cycle does not involve any internal irreversibilities.

Prof Ronak Doshi

Passive Heating  Building with window facing in northern hemisphere.

This system has south facing concrete or stone or brick wall which is called trambay wall.

 This wall is designed for thermal storage and its outer

surface is black pointed. The entire wall is covered by one or two sheets of glass with an air gap about 10 cm or more.

 The store wall provided with vents A and Bat the top and

bottom of the wall. This is for circulation of hot and cold air. Prof Ronak Doshi

 Due to solar radiation air in airgap is heated and flow

from A and cool air from living space through bottom vent B replace it.  Controlling the air flow through vents by shutters.

Prof Ronak Doshi

Passive Cooling  The passive solar cooling system uses the principle of

chimney.  The air between the glass cover and south wall gets heated due to solar radiation .  This heated air rises up and it moves out of the ducts provided at the top of glass covers. This heated air is replaced by cool air from the surroundings which enetrs from the bottom air vent.

Prof Ronak Doshi

Active Space Heating  Active Space heating System: It requires some basic componenets:  1) A solar radiation collector which heats a

fluid. A fluid used may be water or air depending upon the design of the system.  2) A storage device to store heat for use at night & on cloudy or rainy day.  3) A distribution system to supply heat where ever required. Prof Ronak Doshi

Hot Water Space Heating system  Hot water Space Heating System: The cold

water from storage tank is pumped to solar collector by pump A. Hot water from storage tank is pumped by pump B & it is supplied to the heat exchanger where it transfers the heat to the cold air from the building.  The cold water after transfer of heat is returned to storage tank 7 the hot air from heat exchanger is supplied to the building for space heating.  An auxiliary heater is provided if the hot water from storage tank is not at desired temperature on cloudy days Prof Ronak Doshi

Active Hot air Heating system  It consist of array of solar collectors, rock bed storage

system, auxillary heater, blowers and other controls. Thermal energy is transported from array of solar collectors to cold air supplied by the blower.  The damper can be adjusted to supply excess hot air to the storage tank and remainder is supplied to the building for space heating.  Auxillary heating system augments the supply of hot air when the heat supplied by the collectors or storage is not sufficient. Prof Ronak Doshi

 Three way valves are used by pass the storage tank

when solar heat is not avilable in sufficient quantitiy during cloudy days.

Prof Ronak Doshi

Solar Based Li Br – H2O Vapour absorption system for space cooling  This system utilize the low grade heating energy  





produced by the solar collector to produce cold. This sysetm consist of 1) Absorber: the function of absorber is to absorb refrigerant vapour by its weak solution in suitable absorbent. 2)Pump: Its function is to raise the pressure of rich solution received from the absorber upto condenser pressure. 3)Generator: help to enrgy suppled and the left over weak solution is used for recycling. Prof Ronak Doshi