Numerical study of earth-to-air heat exchanger for three different climates

Ramírez-Dávila, L.; Xamán, J.; Arce, J.; Álvarez, G.; Hernández-Pérez, I.

doi:10.1016/j.enbuild.2014.02.073

Cited by 71 publications

(28 citation statements)

References 29 publications

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“…The convergence criterion was stablished 10 −10 for all the unknown variables. More details of the methodology used, it was presented in a previous study [24]. To ensure the accuracy of the numerical results, a grid independence study was done for the maximum Reynolds number considered in this study (1500).…”

Section: Methodsmentioning

confidence: 99%

“…The same effect is also obtained by increasing the soil thermal conductivity. Bojic et al proposed a model for multi-pipes but in the study a 1-D model was used to compute the temperature of the ground [16].Recently, Ramírez-Dávila et al presented the numerical study of conjugate heat transfer in 2-D between the pipe and the soil[24]. The authors used a correlation to compute the convective heat transfer between the air and the soil, so more realistic conditions were assumed in this study.…”

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confidence: 98%

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Pseudo transient numerical study of an earth-to-air heat exchanger for different climates of México

Xamán

Hernández-López

Alvarado-Juárez

et al. 2015

Energy and Buildings

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 98%

Pseudo transient numerical study of an earth-to-air heat exchanger for different climates of México

Xamán

Hernández-López

Alvarado-Juárez

et al. 2015

Energy and Buildings

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“…Several experimental and/or numerical studies on the EAHX cooling performances in hot climate, such as one of Marrakech (Morocco), have been performed through the world [9][10][11][14][15][16][17][18][19][20][21]. All of these studies concluded on the very interesting performances of the EAHX for air cooling, although these performances depend on many parameters, in particular the soil properties and the local climate.…”

Section: Experimental Projects and Guidelinesmentioning

confidence: 99%

Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate

Khabbaz

Benhamou

Limam

et al. 2016

Energy and Buildings

109

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Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate, Energy and Buildings http://dx.doi.org/10. 1016/j.enbuild.2016.04.071 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. 3 ABSTRACT This work deals with an experimental and numerical study of an Earth-to-Air Heat Exchanger (EAHX) for air cooling, connected to a residential building located in Marrakech (Morocco) which climate is a hot semi-arid one. The EAHX consists of three parallel PVC pipes of 72 m length each and 15 cm inside diameter, buried at 2.2-3.2 m depth. Each pipe is equipped with a fan, which blows treated air into the building. The experimental study consists of summer monitoring of the EAHX via measurements of air temperature and humidity throughout the exchanger, as well as at its inlet and outlet to the building for two fixed values of the airflow rate. The experimental results show that the EAHX is a good semipassive system for air refreshment, as the recorded blown air temperature into the building is quasi-constant at 25 °C with air humidity around 40%, even though the outside temperature reaches more than 40 °C. Furthermore, the reduction of daily and annual air temperature amplitudes is characterized by an exponential drop as a function of pipe length. The characteristic length is found to be around 20m and 70m respectively for the daily and annual air temperature amplitudes reduction. Moreover, it is shown that the design guidelines from literature cannot straightforwardly be applied to an EAHX which is subject to meteorological disturbance from the upper surface and/or which is not operated all year round, for which numerical simulation with a validated models remains necessary. 1 EXPERIMENTAL AND NUMERICAL STUDY OF AN EARTH-TO-AIR HEAT EXCHANGER FOR AIR COOLING INOn the other hand, dynamic simulations of the EAHX using TRNSYS software (TYPE 460) were performed with one pipe or three pipes continuously running. Good agreement was found between the simulation and experimental results. Simulation results show that the EAHX can perform a maximum drop of air temperature as high as 19.5 °C and 18.3 °C respectively for an EAHX with one and three pipes. The achieving specific cooling capacity is 58 W/m 2 (one pipe) and 55 W/m 2 (three pipes) obtained for air temperatures of 25 °C and 26 °C respectively, at the EAHX outlet and 44.6 °C at its inlet.

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“…In Equations (3) to (8), b is constant dependent on the type of soil, D v is the diffusion coefficient of water vapour in air (m 2 /s), f() is the fractional volume of gas-filled pores (f() =  s - K s is the saturated hydraulic conductivity (m/s),  is the tortuosity factor for diffusion of gases in soil,  s is the saturated matric potential or capillary pressure (m),  s is the saturated volumetric moisture content (m 3 /m 3 ) and  v is the density of water vapour (kg/m 3 ).…”

Section: Model Equationsmentioning

confidence: 99%

“…Al-Ajmi et al [6] showed that an EAHX could potentially reduce cooling energy demand by 30% over the peak summer season for a typical house in a hot and arid climate in Kuwait. The thermal behavior of EAHXs has also been studied for a unique building called 'Casa Ventura' in Brazil [7] and for buildings under three different climatic conditions in Mexico [8]. Because EAHX systems alone are often insufficient to meet the thermal comfort requirements in summer conditions, Misra et al [9] used a hybrid EAHX to enhance the efficiency of an air conditioner in India whereas Bansal et al [10] integrated an evaporative cooler with an EAHX to minimise the use of an air conditioner.…”

Section: Introductionmentioning

confidence: 99%

Dynamic interactions between the ground heat exchanger and environments in earth–air tunnel ventilation of buildings

Gan

2014

Energy and Buildings

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Earth-air tunnel ventilation is an energy efficient method of preheating or cooling of supply air to a building. The purposes of this study are to investigate the performance of earth-air heat exchangers under varying soil and atmosphere conditions and the interactions between the heat exchanger and environments. A computer program has been developed for simulation of the thermal performance of an earth-air heat exchanger for preheating and cooling of supply air, taking account of dynamic variations of climatic, load and soil conditions. The program solves equations for coupled heat and moisture transfer in soil with boundary conditions for convection, radiation and evaporation/condensation that vary with the climate both at the soil top surface and inside the heat exchanger. The importance of dynamic interactions between the heat exchanger, soil and atmosphere is illustrated from the comparison of the heat transfer rates through the heat exchanger. The predicted heat transfer rate varies with operating time and decreases along the passage of air in the heat exchanger. Neglecting the interactions would significantly over-predict the heat transfer rate and the amount of over-prediction increases with operating time.

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Numerical study of earth-to-air heat exchanger for three different climates

Cited by 71 publications

References 29 publications

Pseudo transient numerical study of an earth-to-air heat exchanger for different climates of México

Pseudo transient numerical study of an earth-to-air heat exchanger for different climates of México

Experimental and numerical study of an earth-to-air heat exchanger for air cooling in a residential building in hot semi-arid climate

Dynamic interactions between the ground heat exchanger and environments in earth–air tunnel ventilation of buildings

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