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EARTH AIR TUNNEL HEAT EXCHANGER

Submitted to Dr. Vashimanth Sharma

Submitted bySumitabh TiwariSai Goutham Golive

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Table of Contents

1. Earth Air Tunnel Heat Exchanger coupled with a solar air heating duct 2. Hybrid Earth Air Tunnel Heat Exchanger3. Coupled Cooling system with EATHE Exchanger and Solar Chimney 4. Integrated EATH-Evaporative Cooling system in Hot and Dry Climate

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EARTH AIR TUNNEL HEAT EXCHANGER COUPLED WITH A SOLAR AIR HEATING DUCT During winter, fresh cold air needs to be warm up before supplying

to the buildings, thus consuming more energy.

To reduce high grade energy consumption of conventional active heating systems, earth air tunnel heat exchanger (EATHE)system is used as alternative.

Soil temperature, at a depth of about 10 feet or more, stays fairly constant throughout the year and is approximately equal to the average annual ambient air temperature.

The ground can, therefore, be used as a heat source for heating in winter.

Cold outdoor air is sent into the earth air tunnel heat exchanger. When air flows in the earth air tunnel, heat is transferred from the earth to the air. As a result, the air temperature at the outlet of the earth air tunnel heat exchanger is much higher than that of the ambient.

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The outlet air from the earth air tunnel can be directly used for space heating if its temperature is high enough.

Alternatively, the outlet air may be heated further by associating air conditioning machines and solar air heating duct. Both of the above uses of earth air tunnel heat exchanger can contribute to reduction in energy consumption.

The main advantages of the system are its simplicity, high preheating potential, low operational and maintenance costs, saving of fossil fuels and related emissions.

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The EATHE coupled with a solar air heating duct.

A U-shaped made of galvanized iron has been used as a solar air heating duct having top and lateral wall exposed to solar energy.

Inlet of duct was connected to the outlet pipe of EATHE by means of T-socket and outlet of duct was also connected at the exit of EATHE pipe at suitable position.

The exterior surface of the entire duct was painted black so as to absorb most of the solar radiation falling on it.

Dampers were provided at the inlet and exit of solar air heating duct as well as at the exit of EATHE pipe, to regulate the flow of air.

Heated air coming out of EATHE pipe can be made to flow through solar air heating duct for further heating.

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HYBRID EARTH AIR TUNNEL HEAT EXCHANGER

In the area with very hot weather temperature in summer like Ajmer the condenser temperature and pressure are increased considerably which consequently increases the power consumption of the air conditioner due to the increase in the pressure ratio.

Increasing condenser temperature also decreases cooling capacity.

In order to increase the performance of air conditioner in this situation, one of the best solutions is decreasing the condenser temperature.

Reducing the condenser temperature reduces the pressure ratio across the compressor which results into reduction in power consumption.

The temperature of the condenser tubes can be reduced by cooling them down with the help of cold air form the EATHE.7

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It comprises of long horizontal cylindrical PVC pipe buried at a depth in a flat land with dry soil.

Inlet of EATHE is connected to a single phase, variable speed motorized blower having maximum speed of 2800 rpm and maximum flow rate of 0.0945 m3/s through a vertical pipe.

The air from the ambient was forced to move through the earth air

pipe system with the help of blower.

Velocity of air through the pipe can be varied by changing the speed (rpm) of the blower with the help of an auto transformer.

window air conditioner has been used as an active cooling system.

Air from the EATHE was supplied to the condenser coils of the air conditioner using well insulated wooden boxes provided on the outer casing of the air conditioner.

To reduce peak power, as well as save energy we use hybrid earth air tunnel heat exchanger.9

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Coupled Cooling system with EATHE Exchanger and Solar Chimney [2]

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Coupled Cooling system with EATH Exchanger and Solar Chimney(contd.)

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The air inside the solar collector is heated up as the solar radiation strikes the solar collector 

Hence, the hot air migrates from the solar collector to chimney bottom and rises to the top of the chimney.

As the system components are tightly connected, the hot air migration creates a pressure difference and draws the ambient air through the EAHE.

As the warm ambient air travels through the EAHE tube, it cools down due to the heat exchange process that occurs with the underground soil, providing a fresh cool air draft to the test facility building.

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Integrated EATH-Evaporative Cooling system in Hot and Dry Climate [1]

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Integrated EATHE and cooler(contd.)

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Integrated EATHE and cooler(contd.)

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REFERENCES

1. Sanjeev Jakhara, Rohit Misrab, Vikas Bansalc, M.S. Soni Thermal performance investigation of earth air tunnel heat exchanger coupled with a solar air heating duct for northwestern India.2. Rohit Misraa, Vikas Bansala, Ghanshyam Das Agarwala, Jyotirmay Mathur, Tarun Aseri , Thermal performance investigation of hybrid earth air tunnel heat exchanger3. Vikas Bansal, Rohit Mishra, Ghanshyam Das Agarwal performance analysis of integrated earth–air-tunnel-evaporative cooling system in hot and dry climate Energy and Buildings 47 (2012) 525–5324.Haorong Li, Yuebin Yu, Fuxin Niu, Michel Shafik, Bing Chen, performance of a coupled cooling system with earth to air heat exchanger and solar chimney. Renewable Energy, Volume 62, February 2014, Pages 468-477

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