design of earth air tunnel to conserve energy_ final
TRANSCRIPT
DESIGN OF EARTH AIR TUNNELS TO CONSERVE ENERGY
Presented by: APURVA ANAND
10-MARC-01M.ARCH.(BUILDING
SERVICES)
Direct
Industrial & Domestic heatingHVAC
GreenhousesIndire
ctElectricity generation
GEOTHERMAL ENERGY DEFINITION
• 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.
APPLICATIONS
ADVANTAGES
• Renewable
• Environment friendly
• Sustainable
• Cost effective
LIMITATIONS:
• Not every area has accessible geothermal sources.
• Green house gases emission.
• Localized Depletion
Hot water spring
Geothermal Power Plant
GEOTHERMAL ENERGY SYSTEMSSystems that utilizes the thermal energy stored in earth. PRINCIPLE
• Earth behaves as a huge collector-cum-storage .
• Beyond 4m 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 energy
indirect coupling
Earth air tunnel
Geothermal
exchange systems
direct coupling
earth envelope
Geothermal Gradient
Earth sheltering
In-hill construction
Earth berming
underground/fully recessed
DEFINITION
• Architectural practice of using earth against building walls.
• Passive solar & sustainable architecture.
TYPOLOGY
• Earth Berming
• In-hill construction
• Underground/fully recessed construction
ADVANTAGES
• 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
LIMITATIONS
• Water seepage
• Internal condensation
• Bad acoustics
• Poor indoor air quality.
• Requires heavier construction than conventional building techniques
DIRECT COUPLING- EARTH ENVELOPES
OVERVIEWAn active technique that applies geothermal energy in required purposes using ground source exchange. It is the refrigerant that circulates throughout the loop.
Ground Loop system Heat Transfer fluid Heat Pump Air distribution
system
COMPONENTS
WORKING
Circulation of fluid through pipes buried in
ground
Exchange of heat either-way ( from fluid to earth
or vice-versa)
Electrically driven concentrates this energy
& release it at desired temperature
Distribution through various distribution
systems
INDIRECT COUPLING – GEOTHERMAL EXCHANGE SYSTEMS
OVERVIEW• 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
Earth Air Tunnel
Open loop
System
Closed Loop
System
Combination system
PRINCIPLE• Uses constant air
temperature below 4 m of earth’ surface.
• Air blown through long tubes buried in earth.
• Heat Dissipated through surface contact.
• Conditioned air supplied to space
Space to be conditioned Surface
Earth Air TunnelOpen System
Space to be conditioned
Surface
Closed System
Space to be conditioned
Surface
Earth Air Tunnel
Combination System
Inlet
Inline fan
(optional)
Filter
concrete/plastic coated metal/ plastic coated with
antimicrobial layer
tubes,hume pipes and
tunnels with ceramic tile
Outlet
Blower
Air Handling
Unit (optional
)
Air distributi
on system
Air exhaust
system
COMPONENTS
WORKINGFresh Air sucked in
through inlet.Inlet air filtered
(mechanically/ natural filters)Air passed through the
length of tunnel. Heat gained/ lost through
surface contact Conditioned air supplied
to AHUAHU contains evaporative coolers(summers)/dehumi
difiers (monsoons)/ chillers/cooling pads.
Air Distribution, circulation and re-
circulation of return airAir Exhaust through solar
chimneys/ exhausts
Schematics Earth Air Tunnel
INDIRECT COUPLING – EARTH AIR TUNNEL
Efficiency
Surface Area available for
contact
Length of tube(80
M)Diameter of tube(4-24 inch)
Soil TypeClayey Soil is most
effective. Sandy soil is least
Season Works best in dry summer and winters
Soil ConditionsDepth of
water table
Depth of tunnel
Surface conditions Shady, sunlit, wet,
dry, combination
INDIRECT COUPLING – EARTH AIR TUNNEL
ADVANTAGESCost saving(operational phase-upto 70%)
Reduces air pollution
Energy saver
Reduces green house gases
100% fresh air without recirculation
Retrofit
Durable
Low Noise
High installation costs
Cumbersome Installation
Subject to climate
Need add-ons to achieve effective conditioning
Large space required
Not every area has accessible geothermal sources.
Long payback period
LIMITATIONS
INDIRECT COUPLING – EARTH AIR TUNNEL
STUDY I- RETREAT, GUAL PAHARI
• EAT used for south block living quarters.
• Tunnels cool outside air and maintains a comfortable temperature of 22-26oC inside.
• 4 tunnels to handle 6,000CFM
• Each Tunnel 70 m with 70 cm dia.
• 4 fans 2 HP each force air in.
• Solar chimney force air out.• Supplemented by 10 TR
dehumidifier and chillers.
PRACTICAL APPLICATION IN INDIA
ENERGY CONSERVATION
STUDY II-CINEMA HALL IN JODHPUR, CHOPASANI ROAD, JODHPUR
PRACTICAL APPLICATION IN INDIA
Exit Verandah, 1.8 M Wide &35.36 M Long
East wall, there are no windows or ventilators. The east side has extended foyers and A recessed entrance with an overhang of 1.75 M which reduces the solar load on this wall
The projector room projects out at a height of 3 M X 2 M.
The north, south and east walls contribute very little to the heat load of the conditioned space. The overhang provided for these walls reduces the solar load.
STUDY II-CINEMA HALL IN JODHPUR, CHOPASANI ROAD, JODHPUR
PRACTICAL APPLICATION IN INDIA
Roof is made of asbestos sheet, supported on beams. Acts as an air cavity to circulate the cooled air available through a wind tower.
Total heat gain - 218 KW = 218 x 3412 BTU = 7,43,816 BTUTherefore 61 TR is the HVAC load.After introducing the passive techniques and earth air tunnel the HVAC load was reduced to 23 TR.
Almost 70% reduction in energy consumption
Area Volume Temperature U value Thermal gain/loss
Item (m2) (m3) (°C) (W/m2 °C) (W)Roof (without treatment) 1800 — 53.48
-27 = 26.48
3.53 168 253.9 Roof (with treatment) 1800 — 33.9- 27 = 6.9
3.53 43 842.6 West wall 344.3 — 43.75 - 27 = 16.75 3.5 20 184.6North wall 11 743.34 — 41.75-27 = 14.75 1.86 20 385.3East wall 344.3 — 41.75 -27= 14.75 3.5 17 774.5South wall 11 743.04 — 41.75-27= 14.75 1.86 20 385.3Doors 45 — 41.75-27 = 14.75 0.5 331.9Floor 1537.92 — 33.75 -27 = 6.75 4.42 45 883.8Ventilation — — 6.75 0.28 227.3Infiltration — 19 839.16 — — 57 220Occupancy (a) 806 (No.) — — — 75 60 450
Occupancy (b) 806 (No.) — — — 55 ( - )44330
Light (a) 1500W — — — 1.25 1875Light (b) 1000 W — — — — 1250Appliances 15 770W — — — — 15880
Length of EAT- 40 m Dia of hume pipes- .7 m Humidity is added by the
fresh air inlets covered with wet gunny bags at the wind tower.
STUDY III- ONGC- RAJIV GANDHI URJA BHAWAN VASANT KUNJ, NEW DELHI
PRACTICAL APPLICATION IN INDIA
OVERVIEW Client ONGC. Architect Hafeez Contractor. Site Area- 36,340 Sqm. G+5 Structure with two basements Built Up Area- 46,900 Sqm HVAC Load- 3100 TR.
GREEN AND ENERGY EFFICIENT FEATURES
Use renewable energy such as geothermal energy, solar energy to reduce power consumption
Ensure roof / wall insulation to reduce load on HVAC. Use high efficiency and HFC based chillers for reducing environmental degradation due to
carbon & NOX emissions
Use energy modeling before construction so that complete building performance is known and can be optimized at the design stage itself
Use CO2 sensors monitoring air quality to enhance benefits to occupants Use building material with high recycled content. Use certified wood & high-performance glass. Use double skin external wall.
STUDY III- ONGC- RAJIV GANDHI URJA BHAWAN, VASANT KUNJ, NEW DELHI
PRACTICAL APPLICATION IN INDIA
To cater the requirement of the building HVAC load a Hume pipe is being laid at the depth of 8 m from the natural ground level covering a running length of about 1000 m.
This pipe is having a diameter of 880 mm and at the corners where the 90o turn is required, is being connected to each other using the 3mm thick mild steel plates.
As the Hume pipe is running all along the basement retaining wall so to avoid the infiltration into the walls through the condensation part of the pipe a gap of 1350 mm has been maintained between the walls and the pipes.
STUDY III- ONGC- RAJIV GANDHI URJA BHAWAN, VASANT KUNJ, NEW DELHI
PRACTICAL APPLICATION IN INDIA
From the primary pipe secondary pipes are connected which consequently connects the earth air tunnels to the seven AHUs planned at the various points of the basement layout.
The Hume pipes are resting over the 1:2:4 R.C.C. bases so as to avoid deflection from the pressure exerted by the soil
To cater the humidity requirement in hot and dry summer days two fan towers are incorporated with the mist sprays have been assimilated into the designing parameters which in later stage will act as a landscape feature to the site.
STUDY III- ONGC- RAJIV GANDHI URJA BHAWAN, VASANT KUNJ, NEW DELHI
PRACTICAL APPLICATION IN INDIA
As the Hume pipes territory ends on the outward portion of the basement retaining walls the rest of the distance covered by the cool air to the AHUs is undertaken with the help of ducts placed at the ceiling level.
At the intersection the air filters and the dampers are also proposed to enhance the indoor air quality and to minimize the noise created by the change in the cross sectional area from the Hume pipe to the duct
The tunnel can be constructed using any type of pipe ,concrete ,masonry etc, thickness of
tunnel wall should be as less as possible for faster heat exchange The pipe diameter should preferably be between 3-6” Pipes of lower diameter would require a
larger flow velocity and more pressure to ensure same volumetric supply of cool air.
Adjacent pipes shall have minimum gap of 2 times of the diameter of each pipe. The pipe overlay ground should preferably be left loose or covered with lawn/foliage. Shade
on the ground would be even better.
CONCLUSIONS
The blower should be used with Variable Frequency Drive(VFD)
In case of space constraints the vertical air shaft can also be used. In dry ambient conditions, use of water mist/spray in the tower before supplying air to rooms/AHU is suggested.
The depth should be 4 meters below the ground level for nearly constant ground temperature characteristics..
The length of the tunnel should be limited between 60-
70meters for optimum results.
BIBLIOGRAPHY
No.
Title Author Publisher
1) RENEWABLE ENERGY: SOURCES FOR FUELS AND ELECTRICITY
LAURIE BURNHAM (EXECUTIVE EDITOR)
ISLAND PRESS
2) GEOTHERMAL RESOURCES: AN ENERGY ALTERNATIVE
HARSH K. GUPTA ELSEVIER SCIENTIFIC PUBLISHING COMPANY
3) ENERGY CONSERVATION IN A CINEMA HALL UNDER HOT AND DRY CONDITION
A. K. SINGH, G. N. TIWARI, N. LUGANI AND H. P. GARG
‘DEVELOPMENT ALTERNATIVES, B-32, TARA CRESCENT, QUTAB INSTITUTIONAL AREA, NEW MEHRAULI ROAD
SECONDARY SEARCH
TERTIARY SEARCH http://www.worldbank.org/html/fpd/energy/geothermal/index.htm http://www.geothermie.de/egec-geothernet/ci_prof/europe/italy/italy_data.pdf http://gibsonhomebuilders.com/masterbuildershow/2008/07/08/earth-sheltered-homes http://en.wikipedia.org/wiki/Geothermal_energy http://www.eai.in/ref/ae/geo/geo.html http://www.thefullwiki.org/Earth_warming_tubes http://www.geos.iitb.ac.in/geothermalindia/pubs/geoweb.htm