Numerical‐analytical study of earth‐air heat exchangers with complex geometries guided by constructal design

Nunes, Bruna Rodrigues; Rodrigues, Michel Kepes; Rocha, Luíz Alberto Oliveira; Labat, Matthieu; Lorente, Sylvie; Santos, Elizaldo Domingues dos; Isoldi, Liércio André; Biserni, Cesare

doi:10.1002/er.7157

Cited by 13 publications

(2 citation statements)

References 43 publications

(124 reference statements)

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“…The study concludes that a high air flow velocity affects the thermal performance, primarily during cooling, and that reducing the separation between tubes from 1 m to 0.50 m can reduce land area requirements for EAHE pipes by approximately 50%. Nunes et al [11] presented an EAHE's analyticalnumerical model. The study focused on three performance indicators: minimizing airflow pressure drop, soil volume occupation, and thermal potential.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Hybrid Numerical Analytical Approach of an Earth-to-Air Heat Exchanger

Aissaoui,

Rouag,

Belloufi

et al. 2023

Annals of West University of Timisoara - Physics

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The primary goal of this paper is to assess the thermal behaviour of Earth-to-Air Heat Exchanger (EAHE) under continuous operation mode during the cooling period in warm climatic conditions. An experimental setup was conducted in Biskra University (Algeria) to test the ability to use EAHE as an alternative solution to conventional air conditioning systems. Besides, a transient numerical approach for the flowing air within the EAHE was developed using energy balance equations, discretised by the implicit finite differences method and solved by Thomas method. Furthermore, the transient temperature profile of the soil around the EAHE was investigated in order to determine the adiabatic radius of the soil as a function of the duration of operation. In this context, a transient semi-analytical model was integrated to the air model to estimate the transient EAHE’s performance deterioration. This deterioration is produced by the thermal saturation of the soil, which is influenced by the heat released from the air inside the pipe. Results showed that continuous operation for a duration of four days has minimal impact on the outlet air temperatures due to the implementation of night purging. Furthermore, the design and thermal efficiency of the EAHE are impacted by factors such as higher air velocity and reduced soil thermal conductivity.

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Section: Introductionmentioning

confidence: 99%

Experimental and Hybrid Numerical Analytical Approach of an Earth-to-Air Heat Exchanger

Aissaoui,

Rouag,

Belloufi

et al. 2023

Annals of West University of Timisoara - Physics

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show abstract

“…Studies have investigated optimizing multiple ducts, airflow uniformity, spacing, depth, and inlet duct angle [15][16][17][18]. The application of constructal design for geometric investigation of EAHE also show promise to reduce soil volume occupation and promise to reduce P t [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Maximizing Efficiency of Earth-Air Heat Exchangers with Galvanized Blocks

Domingues

Ramalho

Fernando

2023

DDF

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Earth-air heat exchangers (EAHE) consist of buried ducts and a ventilation system, which require minimal electricity, making them a cost-effective and sustainable solution for improving the thermal conditions of built environments. To enhance the efficiency of the EAHE system and optimize its use of the soil's thermal potential, we employed a galvanized block with a cross-sectional area of 1.5 m2 around the duct. The simulations conducted in this study used climatic data from Viamão, a city in southern Brazil, and demonstrated the effectiveness of this strategy. The galvanized block increased the thermal conductivity of the soil region and enabled the EAHE system to utilize higher quantities of thermal energy. The first part of the work highlights the importance of block coupling in improving thermal efficiency and the two potentials of EAHE systems. We also introduce a new method for calculating EAHE efficiency throughout the year. We name it maximum efficiency because it measures how much thermal potential an EAHE installation can extract from the highest amount available in the soil during the year. Subsequently, we conducted simulations of ducts at different depths to evaluate their performance. Our results showed that annual efficiencies increased significantly with the addition of the galvanized block. We also found how the installation depth impacts the thermal potentials. Specifically, we obtained almost 4.0°C and 3.8°C for the (annual RMS) soil and EAHE thermal potentials, respectively, at 3.5m.

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Geometrical investigation of cooling channels with two alternated isothermal blocks under forced convective turbulent flow

Feijó

Fragassa

Teixeira

et al. 2022

Continuum Mech. Thermodyn.

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The present work performs a numerical analysis of the geometrical investigation of a two-dimensional channel with two alternated isothermal rectangular blocks subjected to turbulent forced convective flows. Constructal Design associated with Exhaustive Search is used to investigate the influence of the geometry of the isothermal blocks over the performance of the cooling convective flows in a multi-objective viewpoint, i.e., considering the pressure drop and heat transfer rate. The time-averaged equations of continuity, momentum, and energy conservation are solved with the finite volume method. The k–$$\omega $$ ω shear stress transport model is used for the closure of turbulence. The effect of the two proposed degrees of freedom, the height/length ratio of the two blocks ($$H_{1}/L_{1}$$ H 1 / L 1 and $$H_{2}/L_{2})$$ H 2 / L 2 ) , is analyzed in relation to the proposed objectives. Regarding the thermal purpose, the geometry with the highest insertion into the channel led to the best performance, while the opposite configuration led to the best fluid dynamic performance. This behavior was similar to that previously found in the literature for forced convective laminar flows. For a multi-objective perspective, the use of technique for order preference by similarity to ideal solution indicated that asymmetric blocks led to the best multi-objective performance when both performance indicators had the same weight.

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Numerical‐analytical study of earth‐air heat exchangers with complex geometries guided by constructal design

Abstract: Significant advancements in developing earth-air heat exchanger models have been detected in the past several decades. It is worth mentioning that this type

Cited by 13 publications

References 43 publications

Experimental and Hybrid Numerical Analytical Approach of an Earth-to-Air Heat Exchanger

Experimental and Hybrid Numerical Analytical Approach of an Earth-to-Air Heat Exchanger

Maximizing Efficiency of Earth-Air Heat Exchangers with Galvanized Blocks

Geometrical investigation of cooling channels with two alternated isothermal blocks under forced convective turbulent flow

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