Thermal-hydraulic characteristics of an earth air heat exchanger: An experimental analysis

IF 9 1区工程技术 Q1 ENERGY & FUELS

Energy Pub Date : 2024-11-08 DOI:10.1016/j.energy.2024.133766

Emad M.S. El-Said

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引用次数: 0

Abstract

The pipe layout design has a great effect on the thermal-hydraulic characteristics of earth air heat exchanger (EAHE) systems. So, in the current study proposed four new buried pipe design configurations; low to high to low, high to low to high, spiral, and circular, in addition to the straight or uniform for comparison. These five configurations are tested and analyzed experimentally depending on the thermo-hydraulic performance for summer cooling requirements with variation of Re in the range of 18041–40843. The results show that changing the uniform design of the EAHE with fixed pipe length enhances both the heat transfer process and pressure loss values. At the same operating conditions, the circular design has the best performance compared to the other ones. For all pipe shapes, the cooling effect increases with the increase of air Re. The thermal-hydraulic performance of the circular design pipe is higher than that of the other pipe designs. The highest coefficient of performance (COP) average values that can be obtained at Re = 18041 is 3.05 for circular shape and enhances by 48.08 % compared to uniform shape. The effectiveness of EAHE with circular shape is improved by about 3.52 % compared to uniform shape at Re = 18041. Spiral design is optimum design based on the Nu value which reaches about 48 with enhancement 12.56 % and 0.34 % compared to uniform and circular shapes respectively, at Re = 40843. The hydrothermal performance factor is highest in the case of circular shape with value about 21.9 at Re = 21257. By increasing Re, the drawbacks of the increasing in the total entropy generation are reflected negatively on the exergy efficiency. The specific cost of the circular shape at Re = 40843 is the optimum value by about 0.7 $/W. Spiral and circular shapes have a decrease of CO₂ emissions less than uniform shape by percentage varied from 2.93 % to 13.84 % for decrease in the Re from 21257 to 40843. It is concluded that using EAHE with four new shapes is highly efficient in increasing cooling capacity and energy consumption in buildings.

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土空气热交换器的热液压特性：实验分析

管道布局设计对土风换热器（EAHE）系统的热工水力特性有很大影响。因此，本研究提出了四种新的地埋管设计配置：低到高到低、高到低到高、螺旋和圆形，此外还有直管或均匀管供比较。根据夏季制冷要求的热工水力性能，对这五种配置进行了实验测试和分析，Re 变化范围为 18041-40843 。结果表明，改变管道长度固定的 EAHE 的均匀设计可提高传热过程和压力损失值。在相同的运行条件下，圆形设计与其他设计相比性能最佳。对于所有形状的管道，冷却效果都随着空气 Re 的增加而增加。圆形设计管道的热液压性能高于其他管道设计。在 Re = 18041 时，圆形管道的最高性能系数（COP）平均值为 3.05，比均匀形状的管道提高了 48.08%。在 Re = 18041 时，圆形 EAHE 的效率比均匀形状提高了约 3.52%。在 Re = 40843 条件下，根据 Nu 值，螺旋形设计是最佳设计，其 Nu 值约为 48，与均匀形和圆形相比，分别提高了 12.56 % 和 0.34 %。在 Re = 21257 时，圆形的水热性能系数最高，约为 21.9。随着 Re 值的增加，总熵产生量增加的缺点会对放热效率产生负面影响。在 Re = 40843 时，圆形的具体成本是最佳值，约为 0.7 美元/瓦。当 Re 值从 21257 降至 40843 时，螺旋形和圆形比均匀形的二氧化碳排放量减少了 2.93 % 至 13.84 %。由此得出结论，使用四种新形状的 EAHE 能够高效地提高建筑物的制冷能力和能耗。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Energy 工程技术-能源与燃料

CiteScore

15.30

自引率

14.40%

发文量

审稿时长

14.2 weeks

期刊介绍： Energy is a multidisciplinary, international journal that publishes research and analysis in the field of energy engineering. Our aim is to become a leading peer-reviewed platform and a trusted source of information for energy-related topics. The journal covers a range of areas including mechanical engineering, thermal sciences, and energy analysis. We are particularly interested in research on energy modelling, prediction, integrated energy systems, planning, and management. Additionally, we welcome papers on energy conservation, efficiency, biomass and bioenergy, renewable energy, electricity supply and demand, energy storage, buildings, and economic and policy issues. These topics should align with our broader multidisciplinary focus.