Universidad Anáhuac México

Solar Water Heater With Copper Pipeline

Anier Isabel Peña Fajardo ID: 00244390 Lizbeth Martínez Patatuchi ID: 00226848

Ingeniería de la Energía

Isabel Lascurain Gutiérrez

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Index

Index 2

Introduction 2

Solar Thermal 3

Types of water heaters 4

Operation and Installation 5

Installation Images 6

Costs 9

Advantages and Disadvantages 10

Why copper? 10

Results 12

Solar Thermal in Mexico 13

Efficiency 14

Applications in Mexico 15

Conclusions 16

References 16

Introduction Solar thermal energy is used to heat water or other fluids, and can also power solar cooling systems. They differ from solar photovoltaic (PV) systems, which generate electricity rather than heat. Solar thermal energy has been used for centuries by the harnessing of solar energy for heating and drying. More recently, in a wide variety of thermal processes, solar energy has been developed for power generation, water heating, mechanical crop drying and water purification among others. The primary uses for solar thermal systems in rural locations are water heating for domestic use and swimming pools; heating of buildings; and evaporative processes (such as distillation and dryers) for agriculture. All of these processes require an operating temperature of less than 100oC; therefore the solar energy flux is enough to elevate the working fluid to the required temperature without needing to concentrate the sun's energy (ie. using mirrors or lenses). There are three main types of solar hot water panels: Evacuated tube, glazed flat panel, and unglazed flat panel. Each of these types of panels have different operating conditions where they have better efficiency than the others.

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In this case we are based on glazed flat panels, which are better for domestic hot water heating, also they are recommended for moderate climates. Glazed flat-plate collectors are insulated, weatherproofed boxes that contain a dark absorber plate under one or more glass or plastic (polymer) covers (Anónimo, Solar Direct, s/f). To make this project we are using plastic cover in order to reduce costs since we want to focus on low-income places so it will have a higher availability. Also we made this with copper which can be found naturally in all plants and animals. Also copper is a ductile metal found in nature well known for its electrical conductivity and its use for construction and plumbing purposes. Objectives

● Create a solar water heater with low cost materials in order to focus it in low income places ● Generate conscious about the use of clean energy sources ● Analyse the advantages and disadvantages of solar water heaters ● In order to the experimental work, register the changes in the project ● Focus this project mainly in communities with not many resources or opportunities

Solar Thermal Solar thermal technology uses the sun’s energy, rather than fossil fuels, to generate low-cost, environmentally friendly thermal energy. This energy is used to heat water or other fluids, and can also power solar cooling systems. Solar thermal systems differ from solar photovoltaic (PV) systems, which generate electricity rather than heat (Anónimo, s/f). Solar thermal technology comes in many shapes and sizes, and is used in a wide variety of commercial applications. Commonly seen types of solar thermal systems include:

➔ Domestic Hot Water (DHW) systems

These include active and passive glycol systems (both closed and open loop), as well as drainback systems

➔ Swimming Pool/Hot Tub-Heating Systems

There are closed loop glycol and drainback varieties

➔ Space Heating Systems (radiant)

Usually attached to a DHW system

➔ Combi Systems

Combination of any of the above How does they work?

1. Solar thermal collectors (panels) on a roof, shade structure or other location absorb solar energy.

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2. Solar fluid circulated through the collectors by a low-energy pump delivers heat to a water storage tank.

3. When users need hot water, the solar-heated water in the storage tank pre-feeds the primary water-heating system.

4. When pre-fed with the solar hot water, the boiler or water heater is either not activated, or activated for less time than if there were no solar hot water system.

Types of water heaters There are different types of solar heaters (passive direct system, active direct system and active indirect system), our project is based on a solar heater with passive direct system: The graph shows the simplicity of the system. It should be noted that systems which do not withstand high pressure (for example those with simple vacuum tubes) require an additional pressure limiter. There are equipment of very different sizes from 80 liters to several thousand liters for example for hotels. With a good finish and good materials (for example stainless steel) can last more than 15 years with very little maintenance. Small systems for one or two people and cheap (which is not necessarily the best investment) cost approximately from $ 6,000.00 pesos plus installation.

Image 1: Passive direct system for a solar thermal water heater. SEENERGY MEXICO. Energía solar térmica. http://www.seenergymexico.com/energia-solar-termica.php

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Our system is based on a passive direct system with some changes:

Image 2: Diagram of our system. Made in SketchUp. Lizbeth Martínez Patatuchi. 2017

Unlike a heater with passive direct system our model does not return heated water to the water tank. This is because our system does not have the same capacity and efficiency as a conventional water heater, instead the water outlet of our model reaches the user directly.

Operation and Installation “They consist of an absorber panel – generally a painted metal, such as copper – attached to copper pipes where water or a heat transfer liquid passes through. This is encased in a metal frame, surrounded by thick insulation to help retain the collected heat, and protected by a sheet of glass or plastic, which also provides an insulating air space. Flat panels are typically designed with an unsealed enclosure. This can make them prone to condensation over time, which can result in corrosion. However, this largely does not impact the actual performance of a flat panel unless corrosion results, and is mainly a cosmetic downfall. Flat panel collectors are more sensitive to sun angle, and may require the use of racking systems, or other elevations to maximize their production. Also flat panel collectors are best for users in southern climates or for northern seasonal homes only used during the summer”,(Anónimo, Solar Panels Plus, 2014). Steps to create our solar water heater:

1. Cut the copper tubes, for our project we use seven 50 cm long tubes & seven 8 cm long tubes

2. Weld the copper tubes in order to create a serpentine connection 3. Paints the wood base of black so that the heat concentrates more 4. Add to the base the black plastic that is going to work as an absorber 5. Cut two holes in the base for the entranceway and the water way out

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6. Put the pipeline in the base and take one tube out for the water entranceway and the other in the way out

7. Place the plastic on top of the base 8. Introduce a thermometer on top of the base

For illustrative examples, check the following section of “Installation Images”.

Installation Images

For the installation of our solar water heater it is necessary to know two important points: the latitude of the place where it is desired to install and to where the north is. Having these two data we can know the inclination and direction that our heater must have to operate more effectively. Using the compass of our cell phone we were able to determine where the north and south are and the latitude of our position.

Image 3: Latitude and direction given by our cell phone. Screenshot. 2017

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The recommended tilt ( ) in general is the latitude of the place plus 10 degrees (minimum) or 15 θ degrees (maximum).

Image 4: Diagram to calculate height. Made in Keynote. Lizbeth Martínez Patatuchi. 2017

In order to achieve the proper inclination, it is necessary to calculate to what distance ( ) the H upper part of the collector must be found with respect to the floor, the formula to obtain it is:

ong SinθH = l * (Where is the desired inclination angle).θ

Because it is North latitude, the solar collector should be oriented to the South. If it is South latitude, the collector faces north. Since we obtained the direction and latitude of our location it is necessary to follow these steps to continue the installation:

1. With the help of the compass, the heater must be pointed south. 2. Mexico City is at latitude 19º so that the slope of the collectors should be between:

and min 0ºθ = 3 max 5ºθ = 3 0º 5º3 < θ < 3

considering the minimum angle for the equator of 15° for the convection to be performed and at most 45° for the extremes near the poles.

3. To obtain the height that our collector needs, we will use the indicated formula and the angles obtained from the previous analysis (knowing that the length of our collector is long=70cm).

min ong in(θmin) 0cm in(30º) 5cmH = l * S = 7 * S = 3 max ong in(θmax) 0cm in(35º) 0.15cmH = l * S = 7 * S = 4

5cm 0.15cm3 < H < 4

Now we know that our collector should be pointing south with a slope between 29º and 34º, this means that the height of our system should be between 35cm and 40cm with respect to the floor.

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Elements of a common solar heater

Image 5: Flat plate collectors,. (Strathclyde, 2010)

● Inlet connection: it is the part where water enters the copper pipe ● Flow tubes: elements that allow the flow of water and which in turn keep it warm ● Absorber plate: absorbs solar radiation and converts it to heat, or, in a solar photovoltaic

device, the material that readily absorbs photons to generate charge carriers (free electrons or holes)

● Enclosure: to protect the base of the solar heater ● Insulation: prevents loss of accumulated heat in the solar collector and improves

absorption efficiency ● Glazing frame: it helps to transmit the temperature to the flow tubes

Below is a diagram of the elements of our solar water heater:

Image 6: Elements of our solar heater. Made in SketchUp. Lizbeth Martínez Patatuchi. 2017.

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The following list the elements of our system with their respective purposes:

● Copper tube: It is the means by which water is transported and heated. Copper conducts heat easily, is tough and easy to handle.

● Wood base: It supports the whole system and has a simple inclination mechanism. ● Transparent plastic: It covers the entire system. The plastic helps the interior to warm and

keep the heat inside. ● Absorbent plastic: Maintains and propagates heat throughout the interior. ● Black paint: Attract solar radiation into the system. The oil-based paint protects the wood

and produces a more effective heat exchange.

Costs One of the important points of these systems is the cost of materials and installation. To realize a cost visualization different types of heaters were quoted in the Mexican distributor Solemex.

Image 7: Solemex price list of solar heaters. Solemex.

http://www.solemex.mx/?gclid=CjwKEAjws-LKBRDCk9v6_cnBgjISJAADkzXe6vond2Uf5v6CWIcCjDjQNDuzIFNFN8q1Trh79kxofRoChwnw_wcB

As you can see in the picture the prices vary depending on the capacity and size of the heater. The prices are different in each company and there are even some that include the service of installation free. Cost is usually the primary consideration, but in this case, since we want to focus our project on areas with low resources we need to reduce material costs and facilitate the installation of the system.

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The table below shows the materials with their respective costs for the realization of our system:

Material Approximate cost (pesos)

Half-inch copper tube $179.00

Copper connectors $19.50

Water faucet $56.00

Solder (lead & tin) $85.00

Wood base $420.00

Transparent plastic $26.99

Absorbent plastic $59.99

Black paint $155.00

Paint brush $16.50

Total: $1017.98 Table 1: Material and costs for this project.

Advantages and Disadvantages -Advantages

● Saves your money - Reduces your monthly utility costs ● Saves the environment - Reduces fossil fuel consumption ● Reduce the use of water ● It is easy to find all materials in order to do lot of solar water heaters ● Its use is not restricted to low-income communities ●

-Disadvantages ● It doesn’t heat water as a normal heater ● It depends 100% of sun ● It takes much more time to heat a certain quantity of water than a normal heater ● It is not automated

Why copper? Copper is an elemental nutrient that is needed to maintain good health. In fact, it can be found naturally in all plants and animals. The metallic form of copper can also be found in our environment as it occurs naturally, so its cost is not as high as other metals. To highlight copper is a ductile metal found in nature. It is well known for its electrical conductivity. It is a valuable material for construction and, therefore, is widely used in the construction and plumbing industries.

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Copper vs Plastic The plastic is an economical material that facilitates the energy saving thanks to "its low weight, its great benefits and its high insulating power". According to the Spanish Confederation of Employers of Plastics, these characteristics make it a regular option for the pipes that are located in public buildings, homes and workplaces. . Copper is an economical, lightweight, durable, elastic material - it can be curved in cold recyclable in its entirety and frequently in plumbing, gas and heating installations. It is proven that it does not lose its qualities over time, even after being recycled. According to the Spanish Copper Information Center, "it maintains its physicochemical properties and the same performance" after its reuse. . Like plastics, copper does not suffer from corrosion, its internal walls are smooth, it withstands fire and great pressures, it does not deform in the extreme heat and offers a good protection against the contaminants of the domestic water supply: "they allow to inhibit the growth of bacteria, viruses and fungi, thus contributing to improving the quality of the water we drink, "says the Center Protection of health.. Also copper minimizes the potential for legionella to appear and does not cause migration of harmful substances into the water. Royal Decree 140/2003, which establishes sanitary criteria for the quality of water for human consumption, requires that the maximum legal copper content in tap water is 2 mg / l, the amount of Copper that is recommended to consume daily (Anónimo, s/f) Comparison There are three main types of solar hot water panels: Evacuated tube, glazed flat panel, and unglazed flat panel. Each of these types of panels have different operating conditions where they have better efficiency than the others. Although the following analysis shows that on average in Vancouver’s environmental conditions for residential systems, it is important to check the difference between each solar heater and understand that it doesn’t matter the place where the analysis has been done but the comparisons of each one.

Image 8: Efficiencies comparison of the three types of solar water

heaters.http://www.vrec.ca/faqs/what-best-type-solar-panel-term-performance/

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Results To analyze the behavior of our solar water heater 7 measurements were made during 1 hour at different times of day during the days 3 and 4 July. The results were the following:

Table 2: First Measurement 3 of July.

Table 3: Second Measurement 4 of July.

We try to make the measurements during the hours where sunlight is most effective to be able to notice the operation of our system. The following charts show the behavior of our solar heater:

Graph 1 & 2: Behavior of the collector during the day.

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Table 4: Total Average of the system.

The temperature of the environment was between 17ºC to 21ºC with a partly cloudy sky. The final temperature generated by our heater was affected by the weather. The days of the measurements (June 3 and 4) were cloudy and there were only a few lapses with direct sunlight towards the collector. However our system worked better than we expected even in a cloudy and low temperature day. The initial temperature given by the faucet was an average of 20ºC and after one hour the final temperature generated by the solar heater was about 45ºC.

Solar Thermal in Mexico Mexico’s solar resources are among the best in the world, far superior to those of Germany and Spain. Experts rank the quality of Mexico's solar thermal resources among the world's best. In terms of photovoltaic resources, the country has significant advantages:

● Average Global Horizontal Irradiation (GHI) is approximately 5 kWh/m2/day, the energy equivalent of 50 times Mexico's annual national electricity generation

● 70% of the territory has GHI values greater than 4.5kWh/m2 ● Just 0.06% of the Mexican national territory would be sufficient to generate the overall

electricity consumption of Mexico in 2005 according the GTZ report "Nichos de mercado para sistemas fotovoltaicos en conexión a la red eléctrica de México" (June 2009).

Image 9: Global horizontal solar radiation, obtained by (Oseguera, 2010)

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Two facts emerge from the Solar Energy Sector study:

● Northern Mexico's Direct Normal Insolation is equivalent to the best in the U.S. Southwest and in the North African deserts

● Assuming a net system efficiency of 15%, a square of 25 km in Chihuahua or in the Sonora desert would be sufficient to supply all of Mexico's electricity (based on information provided by Energy Department and GTZ (2009) at the "Renewable Energy for Sustainable Development in México" study).

Solar power in all its forms amounts today to less than one percent of Mexico's energy matrix, according to CSP Today. For all its potential, utility-scale concentrated solar power (CSP) remains very much in its infancy. But Sonora wants to grow up fast (Oseguera, 2010).

Efficiency It is the most economical energy. The initial investment (which depends on the size of the equipment) will offer you free hot water for more than 90% of the year, for more than 20 years without problems. Every sunny or semi-sunny day of the year you will take advantage of the sun's energy to have hot water at home. The efficiency of the collectors depends in addition to their quality, solar radiation and other factors, essentially the difference in temperature between the environment and water in the collectors. The heated water is always kept in well insulated tanks that can save the temperature for the next day. Good insulation is of paramount importance for the efficiency of the entire system. For Mexico, these water heating systems are ideal. Due to the intense solar radiation in much of the country, simple systems at affordable prices are sufficient for the vast majority of the population. On average, they are amortized in less than five years. Contrary to common belief, they also operate on the coast with prolonged periods of fog or in winter, where they significantly reduce (and with more sophisticated systems eliminate) expenses for heating water.

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Applications in Mexico

Image 10: Solar irradiation worldwide, obtained by (Soto, 2016)

Despite this, Greenpeace Mexico, points out that in the country this resource is little used. So there are not so many applications.. According to CONUEE (“Comisión Nacional para el Uso Eficiente de la Energía”), in our country there are several barriers that have limited the use of solar energy for water heating, among which is the distrust of potential users and buyers. That is why, for several years, the institutions in charge work to establish a regulatory framework that ensures users an adequate quality in the systems and their facilities.

Image 11: Different applications of solar water heaters in Mexico, obtained by (Soto, 2016)

Also as it was said in Mexico the passive direct system dominates the market. There are several national companies that produce these heaters with flat panels.

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Conclusions By realizing this type of solar heater we could noticed that not invested so much time nor a high amount of money, which helps us to fulfill one of the objectives that is to approach it to communities with few resources because as the theory says, there are places where solar heaters are used for domestic routines or in agriculture. In the same way analyzing the advantages, the disadvantages and the results, we can say that it is functional to have a solar water heater of this type because it reaches a high degree of temperature and also the water consumption would be better controlled ; however, the pipe should be longer to obtain a greater amount of water which make us spend a little more of money. As the theory says, copper is a material that we can easily find, and through this project we prove that it is an economic material and also conducts the heat well enough to heat the necessary water. Finally we hope that it will be a project with greater application not only in Mexico but throughout the world, because its realization is easy and you would obtain many benefits with it, mainly the protection of the environment and to provide resources to communities that do not have them.

References Anónimo. (2014). Solar Panel Plus. Obtenido de

http://www.solarpanelsplus.com/all-about-solar/evacuated-tubes-or-flat-plates/ Anónimo. (2014). Solar Panels Plus. Obtenido de

http://www.solarpanelsplus.com/all-about-solar/evacuated-tubes-or-flat-plates/ Anónimo. (s/f). Solar Direct. Obtenido de Bringing renewable technology down to earth:

http://solardirect.com/solar/panels.html#waterflat Anónimo. (s/f). SunWater Solar. Obtenido de Solar Thermal:

http://sunwatersolar.com/solar-thermal/what-is-solar-thermal Oseguera, O. (07 de June de 2010). gtm. Obtenido de A Wood Mackenzie Bussiness:

https://www.greentechmedia.com/articles/read/sunny-mexico-an-energy-opportunit Energy Opportunities in Rural Locations:

http://www.esru.strath.ac.uk/EandE/Web_sites/09-10/Rural_renewables/Oppotunities.html

Strathclyde, U. o. (2010). Small Scales Renewables in Rural Locations. Obtenido de Solar

Soto, A. B. (14 de March de 2016). PROFECO. Obtenido de Calentadores solares de agua. Usa la energía solar a tu favor: https://www.profeco.gob.mx/encuesta/brujula/bruj_2016/bol325_calentadores_solares.asp

Moises Becerra Pérez. Calentador Solar de Efecto Invernadero. Tecnodesarrollos. http://tecnodesarrollos.com.mx/CalentadorSolar.html

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Solemex. Calentadores Solares. http://www.solemex.mx/?gclid=CjwKEAjws-LKBRDCk9v6_cnBgjISJAADkzXe6vond2Uf5v6CWIcCjDjQNDuzIFNFN8q1Trh79kxofRoChwnw_wcB

SEENERGY MEXICO. Energía Solar Térmica. http://www.seenergymexico.com/energia-solar-termica.php

Emilio Alvarez Peimbert. Inclinación que debe tener el colector. 26/03/2012. http://micalentadorsolar.com/wiki/index.php/Inclinacion_que_debe_tener_el_colector

SAUVONS LA TERRE. Instalar calentador solar de agua. http://sauvonslaterre.com/es/SAVE-THE-WORLD-News/80-Easynetwork-deal/1429-orientation-and-tilt-angle-of-solar-water-heaters

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