geothermal_energy_systems_final.ppt

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Geothermal Energy Systems Presented by: Mansi Bedi Prerna Sharma M.Arch, I Sem. Contemporary Technology

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Geothermal Energy Geothermal Energy is heat (thermal) derived from the earth (geo). It is the thermal energy from the earth's core, which is stored in the rock in the earth's crust. Definition Applications Advantages Renewable Environment friendly Sustainable Cost effective Worldwide use of Geothermal Energy for Direct use Source: www.geofund.info/uploads/images/geofund%20images/geothermal_energy_utilization.JPG Limitations: Not every area has accessible geothermal sources. Green house gases emission. Localized Depletion Hot water spring Geothermal Power Plant

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Geothermal Energy Systems Systems that utilizes the thermal energy stored in earth. Principle Earth behaves as a huge collector-cum-storage medium. Beyond 4 m depth earth temperature remains constant ( equal to mean air temperature at surface), since it absorbs only 50% of all solar energy Ways of tapping Geothermal Gradient Source: http://www3.uakron.edu/geology/Foos/Energy/1geot9.gif&imgrefur

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Architectural practice of using earth against building walls. Passive solar & sustainable architecture. Definition Direct coupling- earth envelopes Earth berming In-hill construction Underground/fully recessed construction Typology Taking advantage of the earth as a thermal mass. Offering extra protection from the natural elements Energy savings Efficient use of land in urban settings Shelters have low maintenance requirements Advantages Water seepage Internal condensation Bad acoustics Poor indoor air quality. Requires heavier construction than conventional building techniques Limitations Earth sheltering In-hill construction Earth berming underground/fully recessed Cross-section

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An active technique that applies geothermal energy in required purposes using ground source exchange. Indirect coupling – Geothermal exchange systems Components Working

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The earth connection is where heat transfer between the GSHP system and the soil occurs. Components – Ground loop system Types

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Central heating and/or cooling system that pumps heat to or from the ground Components – Geothermal heat pump Classification Desuper heater Absorption heat pump Air to air Water to water

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Components – Geothermal heat pump Working Cooling Mode Heating mode It consists of-

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Components – Heat Transfer Fluid & Distribution system It is the refrigerant that circulates throughout the loop The decision to use water or antifreeze in the loop system depends on a number of factors, such as the type of loop system installed and local conditions. Most residential geothermal systems use conventional ductwork to distribute hot or cold air and to provide humidity control. A few systems use water-to-water heat pumps with one or more fan-coil units, baseboard radiators, or under-floor circulating pipes. Properly sized, constructed, and sealed ducts are essential to maintain system efficiency. Ducts must be well insulated and, whenever possible, located inside of the building's thermal envelope). Working systems Distribution system

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Summary- Geothermal Exchange Systems Vertical ground loop system Vertical pipe connected to heat pump Heat pump

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Summary- Geothermal Exchange Systems

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Comparative with conventional systems

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Comparison with conventional systems Advantages Disadvantages Architectural Advantages

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Practical applications in India The Indian Context In India ground sink temperature remains between 20-25˚C. Enough load temperature is not available. Practical use merely limited to precooling fresh air to be used by conventional air-conditioning system. The system may be effective in peak summers and winters but fails in monsoon. Refrigerant- based dehumidifiers/ chillers need to be used in addition. Not extensively used in India. Largest project in India using geo- exchange system is a hotel under construction in Udaipur. It would employ open well system. Involves using lake water to pre cool ambient air and dumping it to well.* * Source Mr. Nirmal C. Gupta, Gupta Consultants & Associates.

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A passive technique consisting of a tunnel for passage of calculated amount of air for the purpose of HVAC of a space using natural heat of the earth, 4 m below the earth surface. Also known as ground- coupled heat exchanger or earth- tube heat exchanger. Used for either partial or full cooling and/or heating of facility ventilation air Indirect coupling – Earth Air Tunnel Types Space to be conditioned Surface Overview Principle Uses constant air temperature below 4 m of earth’ surface. Air blown through long cement of metal tubes buried in earth. Heat Dissipated through surface contact. Conditioned air supplied to space Earth Air Tunnel 4 m Open System Space to be conditioned Surface U bend Earth Air Tunnel Closed System Space to be conditioned Surface Earth Air Tunnel Combination System

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Indirect coupling – Earth Air Tunnel Components Working Schematics Earth Air Tunnel

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Indirect coupling – Earth Air Tunnel Efficiency Efficiency of EAT

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Indirect coupling – Earth Air Tunnel Advantages Limitations

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Indirect coupling – Earth Air Tunnel Entire Scheme and passive factors effecting it

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Practical application in India TNI Neemrana Campus EAT used for P.G. hostels and Academic block. Tunnels cool outside air from 44/360C to 280C. 18 tunnels to handle 2 Lac CFM Each Tunnel 90m long to handle 12000 CFM -18000 CFM 8 air change/Hrs. in Peak Summer and 3 air change/Hrs. during Monsoon & Winter Displacement Ventilation for Proper Air Circulation Special AHUs for recooling & Dehumidifying air for each Tunnel.

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Indirect coupling – Earth Air Tunnel RETREAT, Gual Pahari EAT used for south block living quarters. Tunnels cool outside air from to 30-280C. 4 tunnels to handle 6,000CFM Each Tunnel 70 m with 70 cm dia. 4 fans 2 HPeach force air in. Solar chimney force air out. Supplemented by 10 TR dehumidifier and chillers.

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Bibliography Special Thanks to: MR. NIRMAL C. GUPTA, PROPRIETOR, GUPTA CONSULTANTS AND ASSOCIATES AR. JEEWAN KAPUR, ARCHIGROUP ARCHITECTS Energy efficient buildings in India, by Mili Majumdar, TERI, India, Ministry of Non-conventional energy sources, pg. 115 Performance evaluation and energy conservation potential of earth air tunnel system coupled with non air- conditioned building : Building & environment by, Kumar, R. Ramesh, S. Kaushik Geothermal heat pumps: a guide for planning & installing by Karl Ochsner, Earthsean Publishers , U.K. Books Referred: www. Wikipedia.com www.indiaarchitectureinfo.com Websites: