Effects of Parameters on Performance of Earth Air Heat Exchanger System (Eahe): A Review (original) (raw)
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Journal of Engineering and Sustainable Development, 2018
The earth to air heat exchangers (EAHE) is effective passive cooling and heating techniques for buildings. This paper studies numerically the effect of some design and environmental parameters (moist content of soil, pipe material and thickness of pipe wall) on the overall performance of EAHE system. Three types of soil were selected (dry soil, moist soil and saturated soil) with two pipe materials PVC and steel and three thicknesses of pipe wall (2, 3 and 6 mm). This numerical study has been done for summer and winter seasons according to the weather conditions for Nasiriyah city in southern of Iraq. First the built numerical model was validated against experimental model and the results of comparison showed good agreement. After the validation the overall performance of EAHE system with selected parameters was analyzed with ranges of air velocity, inlet temperature and pipe length of 50 m. The simulated results showed that the very moist or saturated soil gives the best overall pe...
PERFORMANCE ANALYSIS OF EARTH TUBE HEAT EXCHANGER
This study performs an analysis of Earth Tube Heat Exchangers used to improve the efficiency of heating, ventilation, and air conditioning (HVAC) systems. ETHE can be used in either a heating or cooling mode by taking advantage of a " near constant " ground temperature. The " near constant " ground temperature can be used as either a heat sink to remove heat to cool a building, or as a heat source to heat a building. The outlet temperature of air was determined by using effectiveness of ETHE (ε) which is a function of number of transfer units (NTU). The effectiveness of earth–air heat exchanger is determined by the dimensionless group NTU. The all analysis based on cooling test because of in winter session ETHE was not prepared for input parameter. ETHE is made of 19.22 m long PVC pipe of 10.6 cm nominal diameter and 3 mm wall thickness. ETHE is buried 2 m deep below surface. Ambient air is pumped through it by a 125w blower. The analysis based on the values of normal speed of air flow (1.8, 3.5, 5 m/s) and static mean temperature of air in three consecutive summer months March,April,May were (32.2, 37.8, 40.3 0 C) respectively at inlet obtained from experimental set‐up installed at Bhopal (Central India). At higher outlet velocity and maximum temperature difference, the system is most efficient to be used.
A Review on Earth-Air Heat Exchanger
2018
The demands of cooling energy & the thermal comfort requirements are rapidly increasing day by day due to global warming effect. The temperature of earth at a certain depth about 1.5 m to 3 m the temperature of ground remains nearly same throughout the year. This temperature remains more than the outside temperature in winter season and lowers than the outside temperature in summer season. The earth air heat exchanger is the possible approach to reduction of heat loss and for the thermal comfort improvement. Earth air heat exchanger or earth tube heat exchanger is a device used to produce heating effects in winter and cooling effects in summer using the ground or soil as a source or sink. When ambient air is drawn through buried pipes, the air is cooled in summer and heated in winter, before it is used for ventilation. The earth air heat exchanger can full fill in both purposes heating in winter and cooling in summer. This paper focus on the effects of various parameters on performa...
The earth to air heat exchangers (EAHE) is effective passive cooling and heating techniques for buildings. This paper studies numerically the effect of some design and environmental parameters (moist content of soil, pipe material and thickness of pipe wall) on the overall performance of EAHE system. Three types of soil were selected (dry soil, moist soil and saturated soil) with two pipe materials PVC and steel and three thicknesses of pipe wall (2, 3 and 6 mm). This numerical study has been done for summer and winter seasons according to the weather conditions for Nasiriyah city in southern of Iraq. First the built numerical model was validated against experimental model and the results of comparison showed good agreement. After the validation the overall performance of EAHE system with selected parameters was analyzed with ranges of air velocity, inlet temperature and pipe length of 50 m. The simulated results showed that the very moist or saturated soil gives the best overall performance of EAHE system compare with other soils, Furthermore there is no significant effect of pipe material and wall thickness on the overall performance.
Experimental Analysis of Earth Air Heat Exchanger (EAHE) Systems in Different Laying Arrangements
The present world energy scenario indicates that the conventional energy sources are depleting and per capita energy consumption is indication of living standard of a nation so, it becomes very important to find and explore nonconventional energy sources to meet the energy requirement of the society. The nonconventional energy sources are better option of clean and sustainable energy. This kind of energy is, at principle, inexhaustible and can be found and exploited equally well on the planet. The increased need for thermal comfort, the rising cost of energy consumption and environmental issues have made alternative and hybrid techniques and methods very attractive. Earth tubes, also called earth-air heat exchangers (EAHX) offer the possibility of reducing use of nonrenewable energy in ventilation and air conditioning systems and provide good indoor air quality for the conditioned environments. The following conclusion is made on the basis of experimental investigation done on Earth Air Heat Exchanger: The average Temperature rise from inlet to outlet is from 3 to 7°C in both series and parallel arrangements,Nusselt Number in parallel connection for different Reynolds Number is higher than the Nusselt number in series connection,Nusselt number in parallel connection varies from (19 to 24) and (18 to 22) in series connection, COP of the parallel connection is higher than the COP of series for the Reynolds number greater than 30000.
2016
This study performs an analysis of Earth Tube Heat Exchangers used to improve the efficiency of heating, ventilation, and air conditioning (HVAC) systems. ETHE can be used in either a heating or cooling mode by taking advantage of a "near constant" ground temperature. The "near constant" ground temperature can be used as either a heat sink to remove heat to cool a building, or as a heat source to heat a building. The outlet temperature of air was determined by using effectiveness of ETHE (ε) which is a function of number of transfer units (NTU). The effectiveness of earth-air heat exchanger is determined by the dimensionless group NTU. The all analysis based on cooling test because of in winter session ETHE was not prepared for input parameter.
Experimental and analytical studies of earth–air heat exchanger (EAHE) systems in India: A review
Renewable and Sustainable Energy Reviews, 2013
This is the property of earth that at a depth of about 1.5 to 2 m, the temperature of ground remains almost constant throughout the year. This constant temperature is called earth's undisturbed temperature which remains higher than surface temperature of earth in winter season and vice versa in summer. For effective utilization of heat capacity of earth, the earth-air heat exchanger (EAHE) has to be designed. The EAHEs are considered as an effective passive heating/cooling medium for buildings. This is basically a series of metallic, plastic or concrete pipes buried underground at a particular depth through which the fresh atmospheric air flows and gets heated in winter and supplied to the building if at sufficiently high temperature and vice versa in summer. Till date many researchers have carried out a number of studies in designing, modeling and testing of EAHEs systems. This paper reviews on the experimental and analytical studies of EAHE systems around the world but the studies are mainly focused on EAHE systems at the Indian universities as of the end June, 2012.
Performance analysis of earth–pipe–air heat exchanger for winter heating
Energy and Buildings, 2009
Earth-pipe-air heat exchanger (EPAHE) systems can be used to reduce the cooling load of buildings in summer. A transient and implicit model based on computational fluid dynamics was developed to predict the thermal performance and cooling capacity of earth-air-pipe heat exchanger systems. The model was developed inside the FLUENT simulation program. The model developed is validated against experimental investigations on an experimental set-up in Ajmer (Western India). Good agreement between simulated results and experimental data is obtained. Effects of the operating parameters (i.e. the pipe material, air velocity) on the thermal performance of earth-air-pipe heat exchanger systems are studied. The 23.42 m long EPAHE system discussed in this paper gives cooling in the range of 8.0-12.7 8C for the flow velocities 2-5 m/s. Investigations on steel and PVC pipes have shown that the performance of the EPAHE system is not significantly affected by the material of the buried pipe (pipe). Velocity of air through the pipe is found to greatly affect the performance of EPAHE system. The COP of the EPAHE system discussed in this paper varies from 1.9 to 2.9 for increase in velocity from 2.0 to 5.0 m/s. ß
Heat Transfer—Asian Res., 2019
To reduce energy consumption, the earth-to-air heat exchanger (EAHE) is a suitable technique for cooling and heating buildings. This paper studies numerically the effect of some design parameters (pipe diameter, inlet condition, pipe length, and outlet condition) on the overall performance of the EAHE system. Four diameters of the EAHE pipe (2, 3, 4, and 6 in) are studied and this numerical study has been done for summer and winter seasons for Nasiriyah city in southern Iraq. First, the built numerical model was validated against the experimental model, and the results of comparison showed a good consensus. After the validation and by using computational fluid dynamics modeling, the overall performance of the EAHE system with all pipe diameters was analyzed with ranges of air velocity, DBT or inlet temperature, and a pipe length of 50 m. The simulated results showed that the EAHE system with 6 in pipe diameter has the best values of overall performance, but from the thermal performance point of view, the 2 in pipe diameter is more suitable. K E Y W O R D S computational fluid dynamics, earth-to-air heat exchanger system, geothermal energy, numerical investigation, thermal performance Heat Transfer-Asian Res. 2019;1-25. wileyonlinelibrary.com/journal/htj
Parametric and experimental study on thermal performance of an earth–air heat exchanger
International Journal of Energy Research, 2006
In the present paper a quasi-steady state mathematical model is developed to predict the outlet air temperature and monthly heating and cooling potentials of an earth–air heat exchanger. Monthly values of heating and cooling potentials are estimated by rigorous experimentation throughout the year for composite climate of New Delhi. The uncertainty values are calculated for each month; for December the value is 4.9%. It is observed that there is an 8.9 and a 5.9°C temperature rise and fall during winter and summer due to the earth–air heat exchanger buried at a depth of 1.5 m underground. The correlation coefficient, root mean square of percentage deviation, reduced chi-square and mean bias error have been computed for each month. The values are 1, 3.0%, 0.8 and −0.63 for December. Statistical analysis shows that there is fair agreement between theoretical results and experimental observations for each month. Monthly values of heating and cooling potentials have also been predicted for other climatic conditions in India namely Jodhpur, Chennai, Mumbai and Kolkata. Copyright © 2005 John Wiley & Sons, Ltd.