HOT WATER @ ZERO ENERGY CONSUMPTIONHOT WATER @ ZERO COST

HOT WATER @ LIFE

a solar water heater projection by centre for application of renewable energy

EMAIL : CARE@CARE‐INDIA.COM  WEBSITE : HTTP://WWW.CARE‐INDIA.COM

SOLAR WATER HEATERSSOLAR WATER HEATERS

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HOT WATER @ ZERO ENERGY CONSUMPTIONHOT WATER @ ZERO COSTHOT WATER @ LIFE erg

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HOT WATER @ LIFE

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Environmental benefitsA SWH of 100 litres capacity can prevent emission of 1.5 tonnes of carbon dioxide peryear .a Life : 15‐20 years

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Approximate cost :Rs.15000‐ 20,000 for a 100 litres capacity system and Rs.110‐150 per installed litre forhigher capacity systemso

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Payback period :when electricity is replaced 3‐4 yearswhen furnace oil is replaced 4‐5 yearswhen coal is replaced 5‐6 yearsre fo

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when coal is replaced 5 6 years

Fuel Savings :A 100 litres capacity SWH can replace an electric geyser for residential use and saves1500 units of electricity annually.n o

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Avoided uitility cost on generationThe use of 100 SWHs of 100 litres capacity each can contribute to a peak load saving of100 KW.

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AVERAGE SOLAR INSOLATION DATA

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Insolation (from Latin insolare, to expose tothe sun) is the total amount of solarradiation energy received on a given surface

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area during a given time. It is also called solarirradiation and expressed as "hourlyirradiation" if recorded during an hour or "dailyirradiation" if recorded during a day. The unit

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recommended by the World MeteorologicalOrganization is the megajoule per square metre(MJ/m2) or joule per square millimetre(J/mm2)re fo

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An alternate unit of measure is the Langley (1thermochemical calorie per square centimeteror 41,840 J/m2). Practitioners in the business

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of solar energy may use the unit watt-hour persquare metre (Wh/m2). If this energy is dividedby the recording time in hours, it is then adensity of power called irradiance, expressed in

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Solar Hot Water System turns cold water into hot water with the help ofsun’s rays.Around 60 deg. – 80 deg. C temperature can be attained depending on solarradiation weather conditions and solar collector system efficiencyw

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radiation, weather conditions and solar collector system efficiencyHot water for homes, hostels, hotels, hospitals, restaurants, dairies,industries etc. Can be installed on roof‐tops, building terrace and openground where there is no shading, south orientation of collectors and over‐h d t k b SWH t

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head tank above SWH systemSWH system generates hot water on clear sunny days (maximum), partiallyclouded (moderate) but not in rainy or heavy overcast dayOnly soft and potable water can be used Stainless Steel is used for small

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tanks whereas Mild Steel tanks with anticorrosion coating inside are usedfor large tanksSolar water heaters (SWHs) of 100‐300 litres capacity are suited fordomestic application.

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Larger systems can be used in restaurants, guest houses, hotels, hospitals,industries etc.

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• A Solar Water Heater comprises of an array of solarcollectors to collect solar energy and an insulatedt k t t h t t B th t d t hw

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tank to store hot water. Both are connected to eachother.

• During the day time, water in solar collectors getsheated which is either pumped or flown

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automatically on thermo syphon principle to thestorage tank.

• Hot water then stored in the tank can be used forvarious applications.re fo

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• Either by gravity flow or forced circulation, waterfrom the cold‐water tank enters the solar tank andfills it up The cold water from the solar tank in turnflows in the bottom header pipe of the absorber,n o

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and into the copper tubes , until all the absorbertubes and the header at the top of the absorber arefull. The heated water being lighter than the coldwater rises and via the top header pipe of theerg

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p p pabsorber, flows into the top of the solar tank.

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• Two types of Solar Water Heatersare available; one based on flat platecollectors and the other based on

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evacuated tube collectors. Flat platecollector (FPC) based systems are ofmetallic type and have longer life ascompared to Evacuated tubeo

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pcollector (ETC) based systembecause ETCs are made of glasswhich are of fragile( can be easilyb k d t d) i t

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broken or destroyed) in nature.• Both these systems are available

with and without heat exchanger.They can also work with and withoutn of renew

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ypump. Systems without pump areknown as thermo syphon systemsand those with pump are known asf d i l ti t

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• The solar radiation is absorbed by Flat Plate Collectors which consist of an insulatedouter metallic box covered on the top with glass sheet.

• Inside there are blackened metallic absorber (selectively coated) sheets with built in

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channels or riser tubes to carry water.• The absorber absorbs the solar radiation and transfers the heat to the flowing water.

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• Evacuated Tube Collector is made ofdouble layer borosilicate glass tubesevacuated for providing insulation.

• The outer wall of the inner tube is coatedergy

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• The outer wall of the inner tube is coatedwith selective absorbing material.

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Purpose‐ To transport fluid to the lower header of the collector (cold water) to the topof the storage tank (hot water).

Material‐ Galvanized Iron sheet. 

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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.o

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qPROPERTIES OF GLASS WOOLUSED as insulation material for pipe connection• Density : 10‐100 kg/m³• Average fiber dia. : 5.5 µmre fo

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g 5 5 µ• Water content : ≤ 1%• Shrinking temperature:   ≥ 250 °C • Thermal conductivity: 0.038–0.06 w/mºK • Non combustible in naturen o

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Non combustible in nature

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FIBERGLASS VINYL

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• Lightweight;• Tight Structure ;

ResistanceToCorrosive Attacks;

•Vinyl is resistant to moisture and humidity; •It is a very strong and durable o

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;• Superior ShockAndWear Resistance;• CheapMaintenance In Service;• DamageAnd Breakage Resistance;

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It is a very strong and durable plastic material•Vinyl can be manufactured in variety of colors, both re fo

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• At Temperatures Below Zero It Doesn’tBecome SlipperyOr CoveredWith Ice;

• Hardly Bendable Material;LowThermal Conductivity

transparent and solid;•It is low cost material•It can easily be recycled.

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• LowThermal Conductivity .

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• On cloudy days also, if it is for a day or two, you still get warm water as water 

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gets heated due to diffused radiation available in the atmosphere.

• The system, however, is either connected to an electric geyser in the o

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g yhouse or an electrical back‐up is provided in the storage tank of the system which is switched on when ater is not s fficientl  hot

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water is not sufficiently hot• So, you get hot water all the time even 

on rainy days.An auxiliary heater is attached in then of renew

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ytank to provide supplement heatduring cloudy days.Freezing protection during winterseasonerg

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Collector Area

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Average solar insolation: 5000 kcal/m² dayCollector efficiency: 30 %Hot water demand per day: 100 litresTape water temperature: 15 ˚Cw

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, g ( )m= mass flow (kg/second)c = Specific heat of water(1 kcal/kg ˚C or

4.187 KJ/kg ˚ k)T1= Hot water temperature (˚C)

ape ate te pe atu e 5 C

Hot water temperature: 55 ˚C

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( )T2= Cold water temperature (˚C)

Specific heat of water = 1 kcal/kg˚c

ACTUAL AVG.INSOLATION AVAILABLE =  SOLAR AVG. INSOLATION* COLLECTOR EFFICIENCY

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= 1500 kcal/m² day= 5000×30/100Specific heat of water 1 kcal/kg c

Q= 100×1×(55‐15)40 10² k l

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= 40×10² kcal

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Purpose: A hot water storagetank (also hot water tank, thermalt t k h t t th lw

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storage tank, hot water thermalstorage unit, heat storage tank) is awater tank that is used for storinghot water for space heating oro

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p gdomestic useMaterial: Mild steel orSteel(Density:7850 kg/m³,Thermal cond cti it 6 /m ºc)

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Thermal conductivity: 47.6 w/m ºc)Insulation:The most common type ofwater heater blanket is fiberglassinsulation with a vinyl film on then o

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MATERIAL PROPERTIES

Epoxy, air dry Cost-effective, corrosion resistant coating

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Epoxy, thermal cure Excellent impact resistance, plus corrosion and abrasion resistance

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Molybdenum disulfide Friction protection for high pressure loads

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a solar • Best suited for colder climates, an indirect system pumps heat‐transfer fluids (usually a non‐w

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, y p p ( ytoxic propylene glycol‐water antifreeze mixture) through collectors, and then transfers theheated fluid from the collectors to a storage tank. Heat exchangers transfer the heat from thefluid to the household water stored in the tanks. Water stored within the tank is then heatedh th fl id th h h t h l t d i id th t t k A tif

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when the fluid passes through a heat exchanger located inside the storage tank. Antifreezefluid is used to prevent collector piping from freezing and allow for the maximum transfer ofheat from the solar collector to the storage tank. Many indirect system designs alsoincorporate an external heat exchangerre fo

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p g• in warmer climates, direct systems are more commonly used. The direct system circulates

potable water directly through the solar collector into the storage tank. In other words, thewater that is used in the house is the same water that has circulated through the solar

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collector. These systems incorporate various strategies to control the operation of thecirculating pump, which can include photovoltaic or differential controllers.

• Passive direct systems are also used in warmer climates. The unique characteristic of thesesystems is that they do not use pumps or other electrical components, thereby providing aerg

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y y p p p , y p gsimple and reliable system. The most common passive systems are the thermosiphon (seediagram below) and integral collector storage systems. Indirect thermosiphon systems couldalso be used in colder climates.

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A thermosiphon solar water heater requires neither pump nor controller. Cold water fromthe city water line flows directly to the tank on the roof. Solar heated water flows from the

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the residence.

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Purpose: To protect the system from damage and for efficient working.•Sensor ( In case of forced circulation system)• Control valveerg

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y •Maintain the height between top of the collector to the bottom of the storage tank 0.3 ‐0.4 m to avoid reverse flow during night( in case of natural convection system).

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p• No or negligible running cost.• Almost maintenance free.• Cost is low and economically competitive with electric water heating system.

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• It saves time and high grade form of electric energy.• Required low temperature up to 100o C can be achieved by simple flat plate 

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gFreezing problem

• No big problems related to this.

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Environmental benefitsA SWH of 100 litres capacity can prevent emission of 1.5 tonnes of carbon dioxide peryear a Life : 15‐20 yearsw

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year .a Life : 15 20 years

Approximate cost :Rs.15000‐ 20,000 for a 100 litres capacity system and Rs.110‐150 per installed litre forhigher capacity systemso

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Payback period :when electricity is replaced 3‐4 yearswhen furnace oil is replaced 4‐5 yearswhen coal is replaced 5 6 years

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when coal is replaced 5‐6 years

Fuel Savings :A 100 litres capacity SWH can replace an electric geyser for residential use and saves1500 units of electricity annually.n o

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1500 units of electricity annually.

Avoided uitility cost on generationThe use of 100 SWHs of 100 litres capacity each can contribute to a peak load saving of100 KW.erg

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a solar • A 100 lpd system (2 sq m of collector area) installed in a home can save 4‐6 units ofw

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• A 100 lpd system (2 sq.m of collector area) installed in a home can save 4‐6 units ofelectricity/day depending on the place of installation & hot water use. On anaverage it could be taken as 5 units/day. Maximum average saving with 300 cleardays, therefore, could be taken as 1500 units/year.

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• Assuming 300 days of solar hot water use in Bangalore and 150 days in Delhi, thesavings could be 1500 & 750 units per year respectively i.e. replacement of a 2 KWelectric geyser working for 2 ½ hours in a day. Considering all parts of the countryand maximum installations in areas where hot water requirement is more during theyear average saving could be taken as 1200 units/year/100 lpd system

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year, average saving could be taken as 1200 units/year/100 lpd system.

• 1 million such systems installed will be able to save 1200 million units ofelectricity/year A 100 lpd system (2 sq.m of collector area) installed in an industrycan save around 140 litres of diesel in a year.n o

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can save around 140 litres of diesel in a year.

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• 1 system of 100 lpd can replace an electric geyser of 2 KW capacity in a home. 1 millionsuch systems will replace 1 million geysers of 2 KW capacity each in homes.

Assuming that at least 50% of geysers are switched on at a time this will have aojec

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Assuming that at least 50% of geysers are switched on at a time, this will have apeak load shaving of 1000 MW.

CO2 Reduction• A 100 lpd system on an average saves up to 1500 units of electricity/yr. To generate thatmuch of electricity from a coal based power plant 1 5 tone of CO2 /year is released inre fo

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much of electricity from a coal based power plant, 1.5 tone of CO2 /year is released inatmosphere. One million solar water heating systems installed in homes will , therefore,also result in reduction of 1.5 million tone of CO2 emission in atmosphere.

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