Ground Source Cooling System Report 68q1k

CHAPTER 1 INTRODUCTION Closed Loop Ground Source Cooling Systems use the relative constant temperature of the ground water to regulate the temperature of a home or building efficiently. The system does not create heat through combustion of fuel or ing electricity through resistors, it moves heat from the house or building to the ground for cooling. This system does not use any fluid or gas refrigerant. One of the main reasons that so many people dismiss the idea of using geothermal energy in their homes is because they think it is simply too expensive. This is actually a common misconception, and many people can actually save a lot of money by switching to geothermal home heating and cooling. The truth is that a geothermal heat pump system is quite inexpensive to operate, but it will cost a considerable amount to have it installed. The earth absorbs almost 50% of all solar energy and remains a nearly constant temperature of 10°C to 22°C depending on geographic location. Working with an underground loop system, geothermal heating or cooling systems utilize this constant temperature to exchange energy between the house and the earth as needed for cooling and heating. Ground source cooling system is cost effective because it uses energy efficiently.

Figure 1: Layout of A Ground source cooling system 1

1.1 GROUND SOURCE COOLING VS. CONVENTIONAL AIR CONDITIONING SYSTEM

Fig 2: Ground source cooling system

Vs.

Fig 3: Conventional air conditioning system

Nearly all conventional residential and light commercial buildings use refrigerant type air conditioning systems for cooling the interior space. These units all have the familiar outdoor condenser units. Variations include packaged heating/cooling units and air source heat pumps. All use outside air to cool the refrigerant, while rejecting heat into the surrounding air. These units will be referred to as "air source" equipment. Comparisons between Ground source cooling system and conventional air source units are convoluted because of the sharp decrease in efficiency of air source equipment as a function of outside air temperature. Manufacturers of air source equipment are quick to post impressive EER (Energy Efficiency Ratio) and SEER (Seasonal Energy Efficiency Ratios) numbers on their "high efficiency" models, but a closer examination of the actual performance data shows that these lofty numbers do not correlate well under realistic installed conditions. A typical example of a 3-ton air source unit shows manufacturer's EER as 12.0. However, a closer look at performance values yields a calculated EER value of 10.5, at rated conditions. This would represent a daytime temperature of about 32.2°C. When the outside temperature rises to 37.7°C, the air source EER drops to 9.2, which represents a reduction in efficiency of 12%. If outside temperature rises to 43.3° C, the air source EER drops even further to 7.7, which represents a reduction in efficiency of 27%. This means that the unit is requiring 27% more electricity to yield the same cooling.

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1.2 TYPES OF GROUND SOURCE COOLING SYSTEMS 1.2.1 Closed Loop Geothermal Systems The most typical geothermal installation utilizes a closed loop system. In a closed loop system, a loop of piping is buried underground and filled with water that continuously circulates through the system. There are four major types of closed loop geothermal systems like horizontal loops, vertical loops, slinky coils and pond loops.

Figure 4: Types of Geothermal Systems

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1.2.1.1 Horizontal Geothermal Ground Loop System If adequate soil or clay based land is available, horizontal geothermal ground loops are typically one of the more economical choices. In horizontal geothermal ground loops, several hundred feet of five to six feet deep trenches are dug with a backhoe or chain trencher. Piping is then laid in the trench and backfilled. A typical horizontal ground loop will be 400 to 600 feet long for each ton of heating and cooling. Because of the amount of trenching involved, horizontal ground loops are most commonly used for new construction. Finally, because horizontal geothermal ground loops are relatively shallow, they are often not appropriate for areas with extreme climates such as the North or Deep South.

Figure 5: Horizontal Geothermal Ground Loop System 4

1.2.1.2 Vertical Geothermal Ground Loop System When extreme climates, limited space or rocky terrain is a concern, vertical geothermal ground loops are often the only viable option. This makes them popular for use on small lots and in retrofits. In vertical geothermal ground loops, a drilling rig is used to drill 150 to 300 foot deep holes in which hairpin shaped loops of pipe are dropped and then grouted. A typical vertical ground loop requires 300 to 600 feet of piping per ton of heating and cooling. Vertical loops are typically more expensive than horizontal loops, but are considerably less complicated than drilling for water. Less piping is also required for vertical geothermal ground loops as opposed to horizontal loops as the earth temperature is more stable at depth.

Figure 6: Vertical Geothermal Ground Loop System 5

1.2.1.3 Slinky Coil Geothermal Ground Loop System Slinky coil geothermal ground loops are gaining popularity, particularly in residential geothermal system installations. Slinky coil ground loops are essentially a more economic and space efficient version of a horizontal ground loop. Rather than using straight pipe, slinky coils, as you might expect, use overlapped loops of piping laid out horizontally along the bottom of a wide trench. Depending on soil, climate and your heat pumps run fraction, slinky coil trenches can be anywhere from one third to two thirds shorter than traditional horizontal loop trenches. Slinky loops are used to reduce the heat exchanger per foot trench requirements but require more pipe per ton of capacity. This pipe is coiled like a slinky, overlapped and laid in a trench. Two-pipe systems may require 200-300 feet of more pipe per ton of nominal heat exchange capacity. The trench length decreases as the number of pipes in the trench increases or as slinky overlap increases

Figure 7: Slinky Coil Geothermal Ground Loop System

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1.2.1.4 Geothermal Pond Loop System If at least a 1½ acre by 8 ft deep pond or lake is available on your property, a closed loop geothermal system can be installed by laying coils of pipe in the bottom of a body of water. However, a horizontal trench will still be needed to bring the loop up to the home and close the loop. Due to the inherent advantages of water to water heat transfer, this type of geothermal system is both highly economical and efficient. In specific situations, where an open loop system cannot be applied to a nearby body of water, a closed loop system may be the best choice. Just like the other closed loop systems, an environmentally friendly coolant is circulated through the closed piping except the exchanging medium is water instead of the earth. Bodies of water, like earth are thermal masses and hold the same thermal inertia as the earth does, so at the same depth, the body of water will provide very similar constant temperatures as the earth. Pond loop configurations are generally slinky like in nature and extend a minimum of 6 to 8 feet below the the lowest water level to assure proper heat exchange.

Figure 8: Pond Loop Geothermal Ground Loop System

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1.2.2 Open Loop Geothermal System With open geothermal ground loops, rather than continuously running the same supply of water through the system, fresh water from a well or pond is pumped into and back out of the geothermal unit. Both an abundant source of clean water and an adequate runoff area are required for a successful open loop system. Typically, the entering water temperature of an open loop system is approximately 6 degrees higher than a closed loop system. Higher entering water temperatures can lead to improved efficiency of the geothermal system. Water sources with high levels of salt, chlorides or other minerals can cause premature system failure or inefficient operation. While double well designs can be economical, use of open geothermal ground loops is generally discouraged and even prohibited in some jurisdictions. Water quality is key to an open loop design as mineral content and acidity can quickly damage geothermal units. Also, improper installation or runoff management of an open loop geothermal system can result in ground water contamination or depleted aquifers.

Figure 9: Open Loop Geothermal System 8

1.3 BENEFITS OF GROUND SOURCE COOLING SYSTEM The main benefits of ground source cooling system is to provide a Year round comfort, Energy efficiency, Long lasting system, Noise reduction, Comfort and an Eco-friendly system. 1.3.1 Year Round Comfort One benefit of having a ground source cooling system installed is that it is the only home comfort system you will need. While its name might suggest otherwise, a ground source cooling system can cool the house effectively, meaning that you will not need to invest in any type of air conditioning system to compliment it. Once your ground source cooling system is in place, you will be assured a comfortable indoor environment all year long. 1.3.2 Energy Efficiency Ground source cooling system are also very energy efficient. Because they do not actually have to generate heat, when compared to the outdoor unit of a split air conditioning system. They run on very little electricity. While the actual amount that you will save annually by switching to ground source cooling system will vary depending on what you were paying before, you will be hard pressed to find any type of home cooling system that is cheaper. When you use geothermal energy, you are depending on an energy source that you, quite literally, do not have to pay for. 1.3.3 Long Lasting Compared to many of the more traditional home cooling systems, ground source cooling systems are remarkably long lasting. While a typical air conditioning system may last somewhere between 15 and 20 years, the pipes installed with a ground source cooling system will be good for 50 years or more. Basically, that means that you will probably never have to worry about replacing your home cooling system again when you switch to ground source cooling system. And that makes your initial investment seem even more reasonable. Safe, secure & solid, ground source cooling system do not use fossil fuels, they create no rust, rot or corrosion.

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1.3.4 Noise Reduction As they have no outside condensing units (such as those in air conditioners), there's no noise outside the home. Ground source cooling system are so quiet inside of a house that s may not be aware they are operating. 1.3.5 Comfort Ground source cooling system deliver consistent temperatures. Modern fans efficiently mix air from all corners of the house but it maintains the same room temperature whereas ground source cooling system draws fresh air from the atmosphere and cools the air. This creates a more even temperature throughout your home and requires less energy to balance previously hot and cold areas. 1.3.6 Eco-Friendly As ground source cooling system does not use any type of refrigerants there is no harm caused to the environment in the form of global warming and depletion of ozone layer. The coolant used here is water which is easily available in nature and is cheaper compared to other coolants. Coolants are usually used with additives, like corrosion inhibitors and antifreeze. Antifreeze is a solution of a suitable organic chemical (most often ethylene glycol, diethylene glycol, or propylene glycol) but such additives are not necessary in ground source cooling system.

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CHAPTER 2 LITERATURE REVIEW Building cooling may be provided by circulating water directly between the ground loop heat exchanger and chilled ceilings or beams. In this system, the heat extracted from the ground for heating is replaced during the cooling season. This paper presents a simulation methodology for GSHP systems, and examines a potential system for a five-story office building in Newcastle. A building simulation model is used to provide hourly building heating and cooling loads for a typical meteorological year. The system simulation is then used to predict system performance and long-term temperature response of the ground. Energy consumption for this system is compared to that of a conventional system with condensing gas boilers and vapor compression refrigeration.

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Surface water or pond systems use different heat transfer mechanisms than vertical and horizontal loop systems. Ponds gain heat from solar radiation, convection from air (when the air is warmer than the water) and ground conduction. The ground conduction is dominant in winter, particularly with frozen lakes. Cooling is mostly accomplished by evaporation at the surface with some radiant and convective heat transfer. Evaporation is dependent on the surface temperature of the water, the wind speed and the ambient wet bulb. At night, radiant heat transfer to a cool dark sky can provide significant cooling. For instance, up to 50 Btu/ft² of cooling will occur from a lake that is 25°F cooler than the sky on a clear night.

Figure 10: Pond Loop System 11

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2.1 BRIEF GEOTHERMAL HISTORY Heat is a form of energy and geothermal energy is, literally, the heat contained within the Earth that generates geological phenomena on a planetary scale. The thermal energy of the Earth is therefore immense, but only a fraction could be utilized by mankind. So far utilization of this energy has been limited to areas in which geological conditions permit a carrier (water in the liquid phase or steam) to ‘transfer’ the heat from deep hot zones to or near the surface, thus giving rise to geothermal resources; innovative techniques in the near future, however, may offer new perspectives in this sector.

Figure 11: The Earth's Crust, Mantle, And Core. Top Right: A Section Through The Crust And The Uppermost Mantle 12

In many areas of life, practical applications precede scientific research and technological developments, and the geothermal sector is a good example of this. In the early part of the nineteenth century the geothermal fluids were already being exploited for their energy content. A chemical industry was set up in that period in Italy (in the zone now known as Larderello), to extract boric acid from the boric hot waters emerging naturally or from specially drilled shallow boreholes. The boric acid was obtained by evaporating the boric waters in iron boilers, using the wood from nearby forests as fuel. In 1827 sco Larderel, founder of this industry, developed a system for utilising the heat of the boric fluids in the evaporation process, rather than burning wood from the rapidly depleting forests.

Figure 12: The “Covered Lagoon” Used In The First Half Of The 19th Century In The Larderello Area, Italy, To Collect The Hot Boric Waters And Extract The Boric Acid

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Exploitation of the natural steam for its mechanical energy began at much the same time. The geothermal steam was used to raise liquids in primitive gas lifts and later in reciprocating and centrifugal pumps and winches, all of which were used in drilling or the local boric acid industry. Between 1850 and 1875 the factory at Larderello held the monopoly in Europe for boric acid production. Between 1910 and 1940 the low pressure steam in this part of Tuscany was brought into use to heat the industrial and residential buildings and greenhouses. Other countries also began developing their geothermal resources on an industrial scale. In 1892 the first geothermal district heating system began operations in Boise, Idaho (USA). In 1928 Iceland, another pioneer in the utilization of geothermal energy, also began exploiting its geothermal fluids (mainly hot waters) for domestic heating purposes. By 1904 the first attempt was being made at generating electricity from geothermal steam; again, it was to take place at Larderello (Figure 13).

Figure 13: The Engine Used At Larderello In 1904 In The First Experiment In Generating Electric Energy From Geothermal Steam, Along With Its Inventor, Prince Piero Ginori Conti The success of this experiment was a clear indication of the industrial value of geothermal energy and marked the beginning of a form of exploitation that was to develop significantly from then on. Electricity generation at Larderello was a commercial success. By 1942 the installed geothermoelectric capacity had reached 127,650 kWe. Several countries were soon to follow the example set by Italy. In 1919 the first geothermal wells in Japan were drilled at Beppu, followed in 1921 by wells drilled at The Geysers, California, USA. In 1958 a small geothermal power plant began operating in New Zealand, in 1959 another began in Mexico, in 1960 in the USA, followed by many other countries in the years to come. 14

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2.2 ENVIRONMENTAL IMPACT During the 1960s, when the environment was healthier and human beings were less aware of any threat to the earth, geothermal energy was still considered a 'clean energy'. There is actually no way of producing or transforming energy into a form that can be utilised by man without making some direct or indirect impact on the environment. Even the oldest and simplest form of producing thermal energy, i.e. burning wood, has a detrimental effect, and deforestation, one of the major problems in recent years, first began when ancestors cut down trees to cook their and heat houses. Exploitation of geothermal energy also has an impact on the environment, but there is no doubt that it is one of the least polluting forms of energy.

2.3 PRESENT AND FUTURE The thermal energy present in the underground is enormous. A group of experts has estimated (Table 7) the geothermal potential of each continent in of high and lowtemperature resources (International Geothermal Association, 2001).

Table 1: World-Wide Geothermal Potential (IGA, 2001)

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If exploited correctly, geothermal energy could certainly assume an important role in the energy balance of some countries. In certain circumstances even small-scale geothermal resources are capable of solving numerous local problems and of raising the living standards of small isolated communities. The data reported by Fridleifson (2003) give some idea of the role played by geothermal energy with respect to other renewable energy sources: of the total electricity produced from renewables in 1998, i.e. 2826 TWh, 92% came from hydro power, 5.5% from biomass, 1.6% from geothermal, 0.6% from wind, 0.05% from solar, and 0.02% from tidal. Biomass constitutes 93% of the total direct heat production from renewables, geothermal represents 5% and solar heating 2%.

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CHAPTER 3 SCOPE OF PROJECT

This project has been designed and established with a closed pond loop ground source cooling system so as to have a future alternative to traditional heating, and air conditioning systems. This project deals with a detailed study of various types of ground source cooling system and development of a closed pond loop system. An attempt has been made to develop a miniature model to study on ground source cooling system and their effects. Detailed study reveals important components of the system being Radiator, Copper pipes, Pump, Fan and a Tank containing water. A miniature model has been developed with the help of the above said components and study the effects of the cooling system with the help of a temperature sensing device is carried out. An analysis of the assembled cooling system was carried out and the important parameters which affect the cooling system were studied.

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CHAPTER 4 COMPONENT DETAILS The ground source cooling system requires three primary components; copper pipes, a liquid pump, Coolant and a radiator (heat transfer device). A loop field can be installed horizontally or vertically as convenient.

4.1 TYPES OF MATERIALS FOR PIPING 4.1.1 Copper pipe In a closed loop system the fluid is circulated through the looped copper pipes. In this system there is no direct interaction between the fluid and the earth only heat transfer across the copper pipe. The amount of vertical or horizontal loop required is a function of the ground formation thermal conductivity, deep earth temperature, and heating and cooling power needed, and also depends on the balance between the amount of heat rejected to and absorbed from the ground during the course of the year. A rough approximation of the soil temperature is the average daily temperature for the region.

Figure 14: Copper Pipe 18

4.1.2 Aluminium Pipe

Figure 15: Aluminium Pipe

Physically, chemically and mechanically aluminium is a metal like steel, brass, copper, zinc, lead or titanium. It can be melted, cast, formed and machined much like these metals and it conducts electric current. In fact often the same equipment and fabrication methods are used as for steel. Aluminium is a very light metal with a specific weight of 2.7 g/cm3, about a third that of steel. For example, the use of aluminium in vehicles reduces dead-weight and energy consumption while increasing load capacity. Its strength can be adapted to the application required by modifying the composition of its alloys. Aluminium is an excellent heat and electricity conductor and in relation to its weight is almost twice as good a conductor as copper. This has made aluminium the most commonly used material in major power transmission lines. Aluminium is ductile and has a low melting point and density. In a molten condition it can be processed in a number of ways. Its ductility allows products of aluminium to be basically formed close to the end of the product’s design. Aluminium is 100 percent recyclable with no downgrading of its qualities. The re-melting of aluminium requires little energy only about 5 percent of the energy required to produce the primary metal initially is needed in the recycling process.

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4.1.3 Fiberglass Fiberglass also called glass reinforced plastic is a lightweight, extremely strong, and robust material. Although strength properties are somewhat lower than carbon fiber and it is less stiff, the material is typically far less brittle, and the raw materials are much less expensive. Its bulk strength and weight properties are also very favorable when compared to metals, and it can be easily formed using molding processes. The plastic matrix may be epoxy, a thermosetting plastic (most often polyester or vinylester) or thermoplastic. Common uses of fiberglass include boats, automobiles, baths, hot tubs, water tanks, roofing, pipes, cladding, casts and external door skins. Fiberglass is an immensely versatile material which combines its light weight with an inherent strength to provide a weather resistant finish, with a variety of surface textures.

Figure 16: Fibreglass

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4.1.4 Galvanized Iron Pipe (GI) Galvanized metal has a zinc coating on it to protect it from rust. The zinc will corrode before the iron, and unlike rust, the zinc oxide will not fall off the pipe so forms a protective coating on the base metal. Unlike tin plating when the zinc coating is scratched the base metal is still protected because the zinc will oxidize easier than the iron, where tin will actually accelerate the rusting of iron if oxygen can get to it. Galvanized pipe can be welded or cut with a torch, however the fumes given off by the zinc should not be inhaled as they are poisonous. These pipes are widely used for conveying raw water & distribution of treated water in majority of rural water supply schemes, where the requirement of water is less. Mostly medium quality GI pipes are used. These pipes are cheap, light in weight and easy to handle and transport and easy to . Their sizes vary from 15mm to 150mm.

Figure 17: GI Pipe

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4.2 HEAT EXCHANGER (RADIATOR) The radiator is designed to dissipate the heat that the coolant has absorbed from the system. Radiators are filled with tubes that the coolant es through. The fan carries heat off of the radiator. A radiator is a type of heat exchanger. It is designed to transfer heat from the hot coolant that flows through it to the air blown through it by the fan. Most modern cars use aluminum radiators. These radiators are made by brazing thin aluminum fins to flattened aluminum tubes. The coolant flows from the inlet to the outlet through many tubes mounted in a parallel arrangement. The fins conduct the heat from the tubes and transfer it to the air flowing through the radiator. The tubes sometimes have a type of fin inserted into them called a turbulator, which increases the turbulence of the fluid flowing through the tubes. If the fluid flowed very smoothly through the tubes, only the fluid actually touching the tubes would be cooled directly. The amount of heat transferred to the tubes from the fluid running through them depends on the difference in temperature between the tube and the fluid touching it. So if the fluid that is in with the tube cools down quickly, less heat will be transferred. By creating turbulence inside the tube, all of the fluid mixes together, keeping the temperature of the fluid touching the tubes up so that more heat can be extracted, and all of the fluid inside the tube is used effectively.

Figure 18: Radiator

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4.2.1 Types of Radiators 4.2.1.1 Water-Air convective cooling radiator These Radiators are used for cooling internal combustion engines, chiefly in automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating plants or any similar use of such an engine.

Figure 19: Water-Air Convective Radiator

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To cool down the engine, a coolant is ed through the engine block where it is heated, is fed into the inlet tank of the radiator, which distributes the coolant across the radiator core, then cools down as it circulates through the radiator tubes to the opposite tank, the cold coolant is fed back to the engine, and the cycle repeats. This coolant is usually water-based, with addition of glycols to prevent freezing and other additives to limit corrosion, erosion and cavitation, but may also be an oil. The first engines used Thermosyphon to circulate the coolant, however nowadays all engines but the smallest ones use a pump. As it circulates through the tubes, the coolant transfers its heat to the tubes which, in turn, transfer the heat to the fins that are lodged between each row of tubes. The fins then release the heat to the ambient air. Fins are used to greatly increase the surface of the tubes to the air, thus increasing the exchange efficiency.

Figure 20: Car Engine Bay, With Radiator In Front

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4.2.1.2 Type Radiator Radiators are available in heights of 12, 20, 24 inches and 15 ¾ -78 ¾ inches wide. The output ranges from 2,800-16,000 Btu/hr. A Radiators has the capability of replacing up to 29 feet of baseboard. There are 6 separate options for connections making the desired location of the radiator extremely versatile.

Figure 21: Type Radiator

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4.2.1.3 Column Type Radiator

Figure 22: Column Type Radiator

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4.2.1.4 Radiators Used In Computer Motherboards As electronic devices become smaller, the problem of dispersing waste heat becomes more difficult. Tiny radiators known as heat sinks are used to convey heat from the electronic components into a cooling air stream. Heat is transferred to the air by conduction and convection, a relatively small proportion of heat is transferred by radiation owing to the low temperature of semiconductor devices compared to their surroundings.

Figure 23: A ive Heatsink On A Motherboard

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4.3 MONOBLOCK PUMP These are single phase capacitor start and run, 2 pole design pump used for clear water free from mud, grit etc. For domestic application and as a booster pump to fill the overhead tank for multi storage buildings. Pump is fitted with a non return valve, which does not allow water to return in the duct on line, thereby delivering the water instantaneously when the pump is switched on. Ball Bearing sealed on both sides take the entire load with ample factor of safety and additional lubrication in not required.

Figure 24: Monoblock Pump The pump is available in three different bodies namely: Aluminium die-cast body, Cast iron body and Steel body.

Specifications Head

9m

Drive

0.06 kw

Voltage

230-50Hz

RPM

2800

Amp

0.6 Table 2: Pump Specification 28

4.3.1 Types of Pumps 4.3.1.1 Centrifugal Pump A centrifugal pump is a rotodynamic pump that uses a rotating impeller to create flow by the addition of energy to a fluid. Centrifugal pumps are commonly used to move liquids through piping. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diff or volute chamber (casing), from where it exits into the downstream piping. Centrifugal pumps are used for large discharge through smaller heads. Most centrifugal pumps are not self-priming. In other words, the pump casing must be filled with liquid before the pump is started, or the pump will not be able to function. If the pump casing becomes filled with vapors or gases, the pump impeller becomes gas-bound and incapable of pumping. To ensure that a centrifugal pump remains primed and does not become gas-bound, most centrifugal pumps are located below the level of the source from which the pump is to take its suction. The same effect can be gained by supplying liquid to the pump suction under pressure supplied by another pump placed in the suction line.

Figure 25: Cutaway View Of Centrifugal Pump

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4.3.1.2 Axial Flow Pump

An axial flow pump or AFP is a common type of pump that essentially consists of a propeller in a pipe. The propeller can be driven directly by a sealed motor in the pipe or mounted to the pipe from the outside or by a right-angle drive shaft that pierces the pipe. The main advantage of an AFP is that it can easily be adjusted to run at peak efficiency at low-flow/high-pressure and high-flow/low-pressure by changing the pitch on the propeller. These pumps have the smallest of the dimensions among many of the conventional pumps and are more suited for low heads and higher discharges. An application example of an AFP would be transfer pumps used for sailing ballast. In Power Plants they are used for pumping water from a reservoir, river, lake or sea for the refrigeration line. In chemical industry, they are used for the circulation of large masses of liquid, such as in evaporators and crystallizers. In sewage treatment an AFP is often used for internal mixed liquor recirculation (i.e. transferring nitrified mixed liquor from aeration zone to denitrification zone).

Figure 26: Axial Flow Pump

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4.4 COOLANT (WATER) The most common coolant is water. Its high heat capacity and low cost makes it a suitable heat-transfer medium. It is usually used with additives, like corrosion inhibitors and antifreezes. Antifreeze, a solution of a suitable organic chemical (most often ethylene glycol, diethylene glycol, or propylene glycol) in water, is used when the water-based coolant has to withstand temperatures below 0°C, or when its boiling point has to be raised. Very pure demonized water, due to its relatively low electrical conductivity, is used to cool some electrical equipment, often high-power transmitters. Heavy water is used in some nuclear reactors; it also serves as a neutron . Thermal Properties of Water: 1) Maximum density at 4oC - 1,000 kg/m3 2) Freezing temperature - 0oC (Official Ice at 0oC) 3) Boiling temperature - 100oC 4) Latent heat of melting - 334 kJ/kg 5) Latent heat of evaporation - 2,270 kJ/kg 6)

Critical temperature - 380 - 386oC

7)

Critical pressure - 221.2 bar

8)

Specific heat capacity water - 4.187 kJ/ kgK

9)

Specific heat capacity ice - 2.108 kJ/ kgK

10) Specific heat capacity water vapor - 1.996 kJ/ kgK 11) Thermal expansion from 4oC to 100oC - 4.2x10-2 12) Bulk modulus elasticity - 2.15 x 109 (Pa, N/m2)

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4.4.1 Types of Coolants A coolant is a fluid which flows through a device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. An ideal coolant has high thermal capacity, low viscosity, low cost, non-toxic and chemically inert, neither causing nor promoting corrosion of the cooling system. Some applications also require the coolant to be an electrical insulator. 4.4.1.1 Gases Air is a common form of a coolant. Air cooling uses either convective airflow (ive cooling) or a forced circulation using fans. Hydrogen is used as a high-performance gaseous coolant. Its thermal conductivity is higher than all other gases, it has high specific heat capacity, low density and therefore low viscosity, which is an advantage for rotary machines susceptible to windage losses. Hydrogen-cooled turbogenerators are currently the most common electrical generators in large power plants. Inert gases are used as coolants in gas cooled nuclear reactors. Helium has a low tendency to absorb neutrons and become radioactive. Carbon dioxide is used in Magnox and AGR reactors. Steam can be used where high specific heat capacity is required in gaseous form and the corrosive properties of hot water are ed for. 4.4.1.2 Molten Metals and Salts Liquid fusible alloys can be used as coolants in applications where high temperature stability is required, e.g. some fast breeder nuclear reactors. Sodium (in sodium cooled fast reactors) or sodium-potassium alloy NaK are frequently used; in special cases lithium can be employed. Another liquid metal used as a coolant is lead, in e.g. lead cooled fast reactors, or a lead-bismuth alloy. Some early fast neutron reactors used mercury. For certain applications the stems of automotive poppet valves may be hollow and filled with sodium to improve heat transport and transfer. For certain applications the stems of automotive poppet valves may be hollow and filled with sodium to improve heat transport and transfer.

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4.4.1.3 Liquid Gases Liquefied gases are used as coolants for cryogenic applications, including cryo-electron microscopy, overclocking of computer processors, applications using superconductors or extremely sensitive sensors and very low-noise amplifiers. Liquid nitrogen, which boils at about -196 °C (77K), is the most common and least expensive coolant in use. Liquid air is used to a lesser extent, due to its liquid oxygen content which makes it prone to cause fire or explosions when in with combustible materials (see oxyliquits). Lower temperatures can be reached using liquefied neon which boils at about -246 °C. The lowest temperatures, used for the most powerful superconducting magnets, are reached using liquid helium. Liquid hydrogen at -250 to -265 °C can also be used as a coolant. Liquid hydrogen is also used both as a fuel and as a coolant to cool nozzles and combustion chambers of rocket engines. 4.4.1.4 Nanofluids An emerging and new class of coolants are nanofluids which consist of a carrier liquid, such as water, dispersed with tiny nano-scale particles known as nanoparticles. Purpose-designed nanoparticles of e.g. CuO, alumina, titanium dioxide, carbon nanotubes, silica or metals (e.g. copper, or silver nanorods) dispersed into the carrier liquid that enhances the heat transfer capabilities of the resulting coolant compared to the carrier liquid alone. The enhancement can be theoretically as high as 350%. The experiments however did not prove so high thermal conductivity improvements, but found significant increase of the critical heat flux of the coolants. 4.4.1.5 Solids In some applications, solid materials are used as coolants. The materials require high energy to vaporize, this energy is then carried away by the vaporized gases. This approach is common inspaceflight, for atmospheric re-entry shields and for cooling of rocket engine nozzles. The same approach is also used for fire protection of structures, where ablative coating is applied. Dry ice and water ice can be also used as coolants, when in direct with the structure being cooled. Sublimation of water ice was used for cooling the space suits of astronauts in the Project Apollo.

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CHAPTER 5 WORKING Closed Vertical Loop Ground Source cooling systems work on a different principle than an ordinary air conditioning system, and they require little maintenance or attention. With Ground Source cooling systems, there's no need to create heat, hence no need for chemical combustion at the building. Instead, the Earth's natural energy is utilized and system is installed below the surface of the ground or submersed in a pond or lake. Fluid circulating in the loop carries cool water to the radiator and air is ed through the radiator which in turn creates cool air and this cool air is spread inside the room with the help of the fan. In summer, the process is to cool the home. Excess heat is drawn from the home, expelled to the loop, and absorbed by the Earth. Ground Source cooling systems provide cooling in the same way that a refrigerator keeps its contents cool, by drawing heat from the interior, not by injecting cold air.

Figure 27: Working Of A Ground Source Cooling System In principle, the ground source cooling system functions like a air conditioning system, to capture and move heat between indoors and out. Ground source cooling system, in contrast, transfer heat through long loops of liquid-filled pipe buried in the ground.

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5.1 DRAWING PLAN

Figure 28: Drawing Plan of a Vertical Loop Ground Source Cooling System

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5.2 MODEL PHOTOGRAPHS

Thermal Sensors

Radiator and Fan Assembly

Figure 29: Radiator and Fan Assembly

Thermal Sensors

Figure 30: Side View of Radiator Showing Thermal Sensors 36

Temperature Indicator

Switch

Figure 31: Temperature Indicator and Switch

Water Outlet

Pump

Water Inlet

Figure 32: Pump

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Figure 33: Radiator

Figure 34: Side View of the Radiator 38

Radiator

Temperature Indicator

Pump

Source

Stand

Figure 35: Miniature Model of Ground Source Cooling System

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5.3 HOW IT WORKS In cooling mode, hot air is removed by absorbing it into the ground. It can be realized by using the ground loop pipes mechanism. Theoretically, the ground underneath line almost will not be influenced by the surface temperature condition. Therefore, loop pipes that also contain a refrigerant (it is usually pumped through tubing) can be functioned as well to remove the warm energy in the room with cooler energy from the ground (the ground’s temperature is relatively cooler or lower than the surface temperature during summer). This mechanism process is also familiar called as direct exchange. In addition, there are two popular methods in the geothermal cooling mode, 

Water to water methods that usually use the liquid spread system and



Water to air mechanism (requiring a liquid coolant).

5.3.1 Water to water method Water to water ground source system can be used to produce either hot water or chilled water from the ground loop. The water produced by the water to water unit can be used to either heat or cool the ventilation air as required. Water to water units avoid the use of natural gas to directly condition the ventilation air. However, compressor work is required in cooling mode, so they are not as efficient as a air conditioning system arrangement. They are, however, generally less expensive. 5.3.2 Water to air mechanism Water to air ground source system can be either hot air or cooled air from the ground loop. This system also avoid the use of natural gas to directly condition the ventilation air. Air is circulated in this system with the help of a fan and a radiator in which water is circulated through the radiator. This method is used in the undertaken project.

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In heating mode, the ground loop system is used as medium of water that pumped from the ground. The natural hot water from the ground (the ground’s temperature is relatively higher or hotter than the surface temperature during winter) then will be transferred into compressor that will be heated once again (by using not too high energy) and then through the heat exchanger and finally will be released into the room radiantly to heat the air inside of the room. Another advantage is that there's no need for a noisy outdoor fan to move air through the compressor coils. Ground source cooling system units simply pump liquid, so they can be placed indoors, safe from the elements.

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5.4 WORKING PRINCIPLE OF THE MODEL The constructed miniature model works on the principle of a closed pond loop system. A pond is a body of water shallow enough to rooted plants. Many times plants grow all the way across a shallow pond. Water temperatures in ponds and lakes during summer months is not uniform from top to bottom. Three distinct layers develop: The top layer stays warm at around 65–75 degrees F (18.8–24.5 degrees C). The middle layer drops dramatically, usually to 45–65 degrees F (7.4– 18.8 degrees C). The bottom layer is the coldest, staying at around 39–45 degrees F (4.0–7.4 degrees C). Since light does not penetrate to the bottom, photosynthesis is limited to the top layer. Because of the warmer waters and more plentiful food supply, almost all creatures spend the summer months in the upper layer. In cold climates, most ponds and lakes are large enough so that they don't freeze solid. During the winter months some creatures hibernate in the bottom of the ponds this is mainly because the temperature at the bottom is warmer when compared to the topmost layer.

Figure 36: Temperature Distribution in Ponds 42

5.5 TEMPERATURE DISTRIBUTION ACROSS INDIA

Figure 37: Temperature Distribution Across India

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5.6 OBSERVATIONS Sl no.

Source

Observed temperature in ◦C

1

Inlet temp of heat exchanger

28

2

Outlet temp of heat exchanger

32

3

Room temperature

33

4

Temperature outside room

34

5

Outlet air temperature from heat exchanger

27

Table 3: Experimental Observation

5.7 CALCULATIONS 5.7.1 Heat transfer rate between radiator and room air As per forced convection fluid ing through the tube of a heat exchanger follows the Newton’s law of cooling (1) = 13.1 X (0.3625 X 0.425)X(305– 301) =13.1 X (0.3625 X 0.425)X 4 =8.0728 Watts

Where, Q is the convective heat flow rate (watt), A is area exposed to heat transfer (m2), tout = temp at outlet of heat exchanger (K), tin= temp at inlet of heat exchanger (K), h = heat transfer coefficient (W/m2K).

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5.7.2 Heat transfer rate between pipe and earth Since conduction s essentially due to random molecular motion, the concept is termed as microform of heat transfer is usually referred to as diffusion of energy. Conduction is prescribed by Fourier law,

(2) 2

= 50 X (0.0125) X 0.785 X 0.5 =0.003067 Watt

Where, Q is the conduction heat flow rate (watt), A is area exposed to heat transfer (m2), tout = temp at outlet of pipe (K), tin= temp at inlet of pipe (K), k = thermal conductivity (W/mK).

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5.7.3 Calculating Indoor Temperature and Humidity Loads Calculating Sensible And Latent Heat From People, Lights, Electric Equipment, Machines. Indoor climate is influenced by 

Sensible and latent heat from persons, lights, machines and electrical equipment and industrial processes



Pollution and gases from persons, building materials, inventory and industrial processes

The most important sources influencing the indoor climate may be summarized to 

Sensible And Latent Heat From People



Sensible Heat From Lights

5.7.3.1 Sensible and Latent Heat From People Sensible heat from persons are transferred through conduction, convection and radiation. Latent heat from persons are transferred through water vapor. The sensible heat influence on the air temperature and latent heat influence the moisture content of air. The heat transferred from persons depends on activity, clothing, air temperature and the number of persons in the building.

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5.7.3.2 Sensible Heat From Lights Heat transferred to the room from the lights can be calculated as Hl = Pinst K1 K2

(3)

Where, Hl = heat transferred from the lights (W), Pinst = installed effect (W), K1 = simultaneous coefficient, K2 = correction coefficient if lights are ventilated. (1 for no ventilation, 0.3 - 0.6 if ventilated). The table below can be used to estimate heat load from lights. (The manufacturer’s datasheets should be checked for details)

Illumination (lux) Installed effect (W) 200

400

600

800

1000

Incandescent lamp

38

75

110

145

180

Fluorescent tubes

15

25

36

48

60

Table 4: Sensible Heat Readings For Light Lux is an SI unit of illumination which is measure by a lux meter.

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Normal Illumination of Rooms:

Office Activity

Illumination (lux)

Normal work

200

PC work

500

Archive

200

Drawing work, normal

500

Drawing work, detailed

1000

Table 5: Normal Illumination of Rooms

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CHAPTER 6 ADVANTAGES AND DISADVANTAGES OF GROUND SOURCE COOLING SYSTEM

6.1 ADVANTAGES  Ground source cooling system use far less electricity than traditional air conditioning systems.

 Ground source cooling system have few moving parts, so they are highly reliable.  Failures are rare and minimal maintenance is required, other than regular forced air system maintenance (fan, filters) and some maintenance on the water loop in open loop systems due to mineral and sediment in the water. 

Unlike central air conditioning systems, Ground source cooling systems have no parts outside. There is no wear and tear on an outdoor condenser. You do not need to worry about leaves, plants, or dirt getting onto the condenser fan. There is no risk of vandalism.

 Ground source cooling systems can last far longer than most air conditioning systems. 

Ground source cooling systems create no noise outside the home, and almost no noise inside.



Geothermal is a renewable source of energy for heating, cooling, and air conditioning. There is no pollution caused by home geothermal systems; even in an open loop water system that is properly designed, the small amount of heat extracted from your home during the hot weather cooling system is not enough to cause any adverse effects on flora or fauna.

 Ground source cooling systems do not contribute to global warming.

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6.2 DISADVANTAGES



The disadvantages of Ground source cooling systems are up-front costs, disturbances to your land during installation, environmental risks of direct exchange systems, legal conformance risks relating to open loop systems, and maintenance issues relating to open loop systems.

 The installation type that causes the most disruption to your landscape is a horizontal installation, either in standard loops or in a Slinky configuration. This is because of the long, wide, and deep (6-10 feet) trenches needs to be dug. 

They use copper pipes to circulate the coolant, and copper pipes buried under ground can easily corrode over time, leading to leaks that are hard to locate and almost impossible to fix.

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CHAPTER 7 SUMMARY

7.1 HIGHLIGHTS OF THE WORK

The main highlight of this project is the study and development of a miniature model of an eco-friendly ground source cooling system and the demonstration of the working concepts of the model. A detailed analysis of the developed model and the study of effects of ground source cooling system in a known enclosed area has been carried out. Use of Geothermal energy which is a renewable source of energy for heating, cooling and air conditioning systems that work by exchanging heat with the earth has been studied in detail. No pollution caused by the ground source cooling systems and its effects on flora or fauna have been stressed in this project. Finally the work done in this project helps provide a clean, economical, efficient and an alternate way of cooling homes.

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7.2 CONCLUSIONS The utilization of Ground source cooling systems for heating and cooling benefits the environment. People receive lower operating and maintenance costs, a higher operating efficiency, an outstanding system reliability and lifetime, substantial noise reduction and safety, and improved indoor air quality and comfort. Utilities benefit by an increased market share, reduced electrical demand, and improved load factor during summer. Last, but not least, the environment benefits by lower carbon dioxide emission and less acid rain. Ground source cooling systems conserve natural resources by providing climate control very efficiently, thus also lowering emissions. Therefore in order to protect the eco system and for the preservation of the planet such friendly and safe measures have to be undertaken.

7.3 AWARDS

Campus Innovation Awards – 2012 at College of Engineering, Pune Categories

1. Jury Award

–

1st BEST in Mechanical Engineering.

2. Social Selection Award

–

Most Popular in Mechanical Engineering.

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CHAPTER 8 COST ESTIMATION

SL NO.

COMPONENTS

PRICE (Rs.)

1.

Temperature Indicator with Channel

2,600/-

2.

Thermal Sensors

750/-

3.

Thermometer

350/-

4.

Radiator

5,500/-

5.

Table

1,250/-

6.

Pump

1,450/-

7.

Fan

1,250/-

8.

Miscellaneous

1,850/-

Total

15,000/-

Table 6: Cost Estimation

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REFERENCES

RESEARCH PAPERS

[1]. Spitler, J.D. and C. Underwood, “ Application of Direct Cooling Ground Source Heat Pump Systems”,

Proceedings of ASHRAE-CIBSE Conference, Edinburgh, Scotland,

September 24-26, 2003.

[2]. Mcquay International, American society of

heating, Air-Conditioning and

refrigeration Engineers Inc. “ Design Of Geothermal Systems For Commercial and Institutional Buildings”, Fort Wayne, IN, 2002. [3]. Fridleifsson, I.B., Geothermal energy for the benefit of the people, “Renewable and Sustainable Energy Reviews 5”, 299-312, 2001. [4]. International Geothermal Association, Report of the IGA to the UN Commission on Sustainable Development, Session 9 (CSD-9), New York, April, 2001. BOOKS Heat and Mass Transfer………………………………………….by D. S. Kumar, 2001 Basic thermodynamics …………………………………………..by M.K.Muralidhara, 2001 Applied Thermodynamics………………………………………..by R.K.Hegde, 1999 Refrigeration and Air Conditioning………………………….......by Ananthanarayan, 1998 WEBSITES http://en.wikipedia.org/wiki/Geothermal_heat_pump http://www.vollmer-engineering.co.uk/cooling/ground-source-cooling/ http://www.yoakumdrilling.com/groundsource.html http://www.engineeringtoolbox.com/air-conditioning-systems-t_39.html http://water.usgs.gov/software/ground_water.html http://www.engineeringtoolbox.com/cooling-heating-efficiency-d_410.html http://www.engineeringtoolbox.com/cooling-heating-equations-d_747.html http://www.engineeringtoolbox.com/heat-condenser-evaporator-d_881.html

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ACKNOWLEDGEMENT A satisfaction that accompanies the accomplishment of any task would be incomplete without the mention of people who helped to make it possible. It is our duty to thank all those who have been inspiring and ive towards this project. Firstly, we would like to thank and express our sincere gratitude to our principal, Dr. M. S. INDIRA, for her and allowing us to carry out our project. We also express our gratitude towards Mr. KHALIQUE EJAZ AHMED, our internal guide who has played an integral part in guiding and boosting our morale at every step of the way, to bring out our potential. We express our heartfelt gratitude towards our beloved HOD Dr. D. N. SHIVAPPA, whose enthusiasm and would be ed with great iration. Finally we would like to thank all our parents and friends for their belief and during our times of hardship, without which we would not be where we are today.

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