Experimental measurements and CFD simulation of a ground source heat exchanger operating at a cold climate for a passive house ventilation system

Flaga-Maryańczyk, Agnieszka; Schnotale, Jacek; Radoń, Jan; Wąs, Krzysztof

doi:10.1016/j.enbuild.2013.09.008

Cited by 58 publications

(31 citation statements)

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“…Few studies concern the analysis of horizontal air ground heat exchangers. In [14] the experimental measurements and numerical simulation of an air ground source heat exchanger operating at a cold climate for a passive house ventilation system were reported. Figure 1 shows the behavior of the outside air temperature and the ground temperature varying the depth along year 2002 by a climatic station located in the city of Lecce (Italy).…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamic Modeling of Horizontal Air-Ground Heat Exchangers (HAGHE) for HVAC Systems

et al. 2014

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Abstract:In order to satisfy the requirements of Directive 2010/31/EU for Zero Energy Buildings (ZEB), innovative solutions were investigated for building HVAC systems. Horizontal air-ground heat exchangers (HAGHE) offer a significant contribution in reducing energy consumption for ventilation, using the thermal energy stored underground, in order to pre-heat or pre-cool the ventilation air, in winter and summer, respectively. This is particularly interesting in applications for industrial, commercial and education buildings where keeping the indoor air quality under control is extremely important. Experimental measurements show that, throughout the year, the outside air temperature fluctuations are mitigated at sufficient ground depth (about 3 m) because of the high thermal inertia of the soil, the ground temperature is relatively constant and instead higher than that of the outside air in winter and lower in summer. The study aims to numerically investigate the behavior of HAGHE by varying the air flow rate and soil conductivity in unsteady conditions by using annual weather data of South-East Italy. The analysis shows that, in warm climates, the HAGHE brings a real advantage for only a few hours daily in winter, while it shows significant benefits in the summer for the cooling of ventilation air up to several temperature degrees, already by a short pipe. OPEN ACCESSEnergies 2014, 7 8466

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Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamic Modeling of Horizontal Air-Ground Heat Exchangers (HAGHE) for HVAC Systems

et al. 2014

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“…The operation of HGHE has been studied in several research papers. Flaga-Maryanczyk et al [8] presented comparable results between experimental measurements and numerical simulation of HGHE operation at a cold climate for a passive house ventilation system. CFD simulation performed by Tarnawski et al [9] shows that straight HGHE in GSHP system offers relatively low thermal degradation of the ground environment, lower cost of heating and cooling, and higher operating efficiency than electric resistance heating or ASHP system.…”

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confidence: 80%

Analysis of Short Time Period of Operation of Horizontal Ground Heat Exchangers

2015

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Ground source heat pump (GSHP) systems have been proven to have higher efficiency compared to conventional air source heat pump systems for space heating and cooling applications. While vertical ground heat exchangers (GHE) are favorable in GSHP installation, this type of configuration requires higher capital costs as opposed to horizontal configuration. Numerical simulation has been used to accurately predict the thermal performance of GHE. In this paper, numerical analysis of thermal performance for slinky horizontal GHE loops in different orientations and operation modes is discussed. It was found that the loop orientation is not so important due to the little effect it has on thermal performance. While the mean heat exchange rate of copper loop increases 48% compared to HDPE loop, the analysis supports the common claim that heat exchange rate is predominantly limited by the thermal conductivity of the ground. With the same amount of circulation work, the mean heat exchange rate increases by 83%-162% when operated in parallel loops operations. The performance in these operations can be further optimized to 10%-14% increase when spacing between adjacent loops was provided. The spacing helps to minimize interference of heat flow that would penalize the overall thermal performance. OPEN ACCESSResources 2015, 4 508 Keywords: ground source heat pump; ground heat exchangers; numerical simulation; horizontal; slinky IntroductionGround source heat pump (GSHP) systems have been proven to have higher efficiency compared to conventional air source heat pump (ASHP) systems for space heating and cooling applications. This is due to the relatively stable subterranean temperature in which GSHP systems exploit to extract and reject heat, whereas ASHP systems are exposed to large fluctuation in ambient temperature and climate conditions. GSHP installations do not require large cooling towers, or can be coupled with one for greater efficiency. Hence, their running costs are lower than ASHP systems. Garber et al. [1] suggest that potential savings from a GSHP system largely depend on projected HVAC system efficiencies and gas and electricity prices. The risk analysis performed shows that a full-size GSHP with auxiliary back up is potentially the most economical system configuration.The thermal performance of GSHP depends on many parameters such as short-term weather variations, seasonal variations, moisture content of soil, and thermal conductivity of soil among others that would affect the temperature of ground [2]. GSHP systems extract and reject heat by means of ground heat exchangers (GHE). GHE can be generally classified into two widely installed closed-loop types, which are vertical and horizontal configurations. Vertical GHE are pipes installed vertically in boreholes typically 15-120 m deep. Meanwhile, pipes are laid and buried in trenches 1-2 m deep in horizontal ground heat exchangers (HGHE) installations. Vertical GHE, commonly installed where availability of land area is scarce, provides high and steady thermal perfo...

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“…Flaga-Maryanczyk et al (67) conducted a study in Sweden which examined a passive ventilation system which integrated a run-around system using a ground source heat pump as the heat source to warm incoming air. A schematic of the design is shown in Figure 14.…”

Section: Application Of Run-around Systemsmentioning

confidence: 99%