The state of art on the applications, technology integration, and latest research trends of earth-air-heat exchanger system

Agrawal, Kamal Kumar; Misra, Rohit; Agrawal, Ghanshyam Das; Bhardwaj, Mayank; Jamuwa, Doraj Kamal

doi:10.1016/j.geothermics.2019.05.011

Cited by 55 publications

(24 citation statements)

References 83 publications

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“…Simulation tools were developed, including most recently Choi et al and Katsura et al 4,5 both for heating and cooling modes. While many research topics were identified in the EAHE technology, it was observed in Agrawal et al 6 that the geometry of the EAHE was poorly studied and remained the same most of the time, that is, one or multiple parallel straight pipes buried at a constant depth. However, much complex arrangements can be found for similar systems.…”

Section: Introductionmentioning

confidence: 99%

Improving the performances of earth air heat exchangers through Constructal design

2019

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Summary Earth to air heat exchanger (EAHE) is a well‐known technique used to preheat or precool outdoor air before blowing it into a building. However, its geometry is often very simple as it consists in one or multiple straight pipes, while more complex arrangements can be found in heat exchangers design. In this paper, we explore the advantage of designing an EAHE as a network through the Constructal law point of view. A methodology is first proposed to design a single pipe EAHE when the need is defined in terms of cooling power, overall efficiency and enthalpy difference between the inlet air and the ground. Next, the single pipe EAHE is used as a reference for designing a tree‐shaped network under the constraint of identical fluid volume and cooling power. The geometrical features are allowed to change for the different branches of the network. The network coefficient of performance is found to increase significantly with the bifurcation level, illustrating the superior performances of the network. This approach was found to be robust as the improvements were not depending on the cooling demand or the environmental conditions. However, further work is needed to move from this theoretical result to practical considerations.

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Section: Introductionmentioning

confidence: 99%

Improving the performances of earth air heat exchangers through Constructal design

2019

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“…However, not only sensible heat transfer-but also latent heat exchange-has to be taken into account when air precooled in a GAHE is fed to HVAC installations [12].The GAHE concept and design continues to be studied, optimized and developed. The current state of knowledge and the most recent developments have been presented in several review articles [13][14][15]. Some authors have investigated selected aspects of GAHE design and operation.…”

mentioning

confidence: 99%

“…The GAHE concept and design continues to be studied, optimized and developed. The current state of knowledge and the most recent developments have been presented in several review articles [13][14][15]. Some authors have investigated selected aspects of GAHE design and operation.…”

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confidence: 99%

Operation of a Tube GAHE in Northeastern Poland in Spring and Summer—A Comparison of Real-World Data with Mathematically Modeled Data

Skotnicka-Siepsiak

2020

Energies

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The article analyzes a ground-to-air heat exchanger (GAHE) for a mechanical ventilation system in a building. The heat exchanger’s performance was evaluated in northeastern Poland between May and August of 2016, 2017, and 2018. In spring and summer, the GAHE can be theoretically used to precool air for HVAC systems. The aim of the study was to compare the real-world performance of GAHE with its theoretical performance determined based on the distribution of ground temperature and the temperature at the GAHE outlet modeled in compliance with Standard PN-EN 16798-5 1:2017-07. The modeled values differed considerably from real-world data in May and June, but the model demonstrated satisfactory data fit in July and August. In all years, the modeled average monthly air temperature at the GAHE outlet was 8.3 °C below real-world values in May, but the above difference was only 1.1 °C in August. The developed mathematical model is simple and easy to use, and it can be deployed already in the preliminary design stage. It does not require expensive software or expert skills. However, this study revealed that the model has several limitations. The observed discrepancies should be taken into account when modeling the performance of a GAHE.

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“…Depending on the heat-transfer rate and energy quantity, the heat-transfer efficiency is dependent on the input air temperature, air flow rate, tube materials, geometrical dimensions of tubes, buried depth, soil temperature, and soil thermal properties. According to the research results in the latest studies, UAT systems are characterized with the building energy-saving potential and the improvement of indoor thermal comfort [26,27].To quantitatively investigate the impact of geometrical and operating parameters on the system performance, researchers have mainly focused on the development of mathematical models to accurately predict the thermal and energy performances [28,29]. The commonly used mathematical models can be classified as the steady-state model and dynamic models based on the temperature variation of surrounding soil outside buried tubes with operation time [30].…”

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confidence: 99%

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confidence: 99%

Study on a Dynamic Numerical Model of an Underground Air Tunnel System for Cooling Applications—Experimental Validation and Multidimensional Parametrical Analysis

et al. 2020

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The underground air tunnel system shows promising potentials for reducing energy consumption of buildings and for improving indoor thermal comfort, whereas the existing dynamic models using the computational fluid dynamic (CFD) method show computational complexity and are user-unfriendly for parametrical analysis. In this study, a dynamic numerical model was developed with the on-site experimental calibration. Compared to the traditional CFD method with high computational complexity, the mathematical model on the MATLAB/SIMULINK platform is time-saving in terms of the real-time thermal performance prediction. The experimental validation results indicated that the maximum absolute relative deviation was 3.18% between the model-driven results and the data from the on-site experiments. Parametrical analysis results indicated that, with the increase of the tube length, the outlet temperature decreases with an increase of the cooling capacity whereas the increasing/decreasing magnitude slows down. In addition, the system performance is independent on the tube materials. Furthermore, the outlet air temperature and cooling capacity are dependent on the tube diameter and air velocity, i.e., a larger tube diameter and a higher air velocity are more suitable to improve the system's cooling capacity, and a smaller tube diameter and a lower air velocity will produce a more stable and lower outlet temperature. Further studies need to be conducted for the trade-off solutions between air velocity and tube diameter for the bi-criteria performance enhancement between outlet temperature and cooling capacity. This study proposed an experimentally validated mathematical model to accurately predict the thermal performance of the underground air tunnel system with high computational efficiency, which can provide technical guidance to multi-combined solutions through geometrical designs and operating parameters for the optimal design and robust operation.Energies 2020, 13, 1236 2 of 20 environmental concerns [4,5]. The contradiction between the daily increased energy demand and the energy shortage calls for the necessity to deploy renewable energy [6][7][8][9] and to reduce the dependence on fossil fuels. In order to reduce the reliance on traditional fossil fuels without sacrificing economic and social development, the deployment of large-scale renewable energy systems (such as heating, cooling, and electric systems) has become one of the most promising solutions to reduce the building energy consumption and to cover the building demand [10,11]. Depending on the renewable energy sources, the renewable energy systems can be classified into solar-driven [12][13][14][15][16][17], wind-driven, and geothermal-driven energy systems. Compared to the instability in temporal distribution and the unevenness in spatial distribution of solar and wind resources, the geothermal energy shows promising potentials in terms of the abundant resource distribution, the stability of energy supply, the simplicity of system designs and operations, and so on....

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The state of art on the applications, technology integration, and latest research trends of earth-air-heat exchanger system

Cited by 55 publications

References 83 publications

Improving the performances of earth air heat exchangers through Constructal design

Improving the performances of earth air heat exchangers through Constructal design

Operation of a Tube GAHE in Northeastern Poland in Spring and Summer—A Comparison of Real-World Data with Mathematically Modeled Data

Study on a Dynamic Numerical Model of an Underground Air Tunnel System for Cooling Applications—Experimental Validation and Multidimensional Parametrical Analysis

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