Transient analysis based determination of derating factor for earth air tunnel heat exchanger in summer

Misra, Rohit; Bansal, Vikas; Agrawal, Ghanshyam Das; Mathur, Jyotirmay; Aseri, Tarun Kumar

doi:10.1016/j.enbuild.2012.11.001

Cited by 35 publications

(12 citation statements)

References 22 publications

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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%

“…Most of these models are based on finite differences. Some of them are limited to the description of only one ""typical"" pipe [14,18,[28][29][30][31]. Others deal with several parallel running pipes, with or without possibility to treat more complicated cases than steady state flow rate, homogenous and laterally adiabatic soils, or sole sensible heat exchange [32][33][34][35].…”

Section: Modelsmentioning

confidence: 99%

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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

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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Section: Experimental Projects and Guidelinesmentioning

confidence: 99%

Section: Modelsmentioning

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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“…However, heat and moisture transfer in shallow soil surrounding a heat exchanger is neither axi-symmetric normal to the pipe nor varying uniformly along the pipe for long term operation due to the influence of daily and seasonal climatic variations and interactions between soil and the heat exchanger. For more realistic simulation, therefore, numerical solution of a three-dimensional model is required and this type of numerical heat transfer model has been developed or applied by a number of researchers [17][18][19][20][21] to predict the performance of EAHXs. Both analytical and numerical models allow parametric analysis to be performed such as air and soil properties and pipe size but the numerical model would also enable additional parameters such as non-uniform soil properties and pipe configurations to be analysed.…”

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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“…Misra et al, (2013) conducted an exhaustive parametric analysis on the performance of earth air heat exchanger (EAHX) also analyzed how in continuous operation performance degrades and devised a term "derating factor" to relate this degradation. Their results show a variation of 0 % to 64 % in derating factor which is caused by choosing different parameters like air velocity, pipes dimensions, depth, soils thermal conductivity [6].…”

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confidence: 99%

Design, Construction and Performance Evaluation of Earth -to -Air Heat Exchanger for Room Cooling in Sokoto, Nigeria

2017

IJASRE

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Tropical climate is characterised by high ambient temperatures and solar radiation, a combination of these factors causes thermal discomfort in buildings. With the rapid increase in population and economic growth of countries in the tropical regions, it is becoming inevitable that passive and low energy strategies must be used as suitable alternatives. Earth air heat exchanger (EAHX) is a subterranean ventilation system that explores soil temperature below the surface to pre-cool or pre-heat ventilation air. Performance of the earth air heat exchanger varies with climatic and soil condition of the area. In this research paper, an Earth air heat exchanger (EAHX) was designed, constructed and installed at

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Transient analysis based determination of derating factor for earth air tunnel heat exchanger in summer

Cited by 35 publications

References 22 publications

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

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

Design, Construction and Performance Evaluation of Earth -to -Air Heat Exchanger for Room Cooling in Sokoto, Nigeria

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