Heat Transfer Performance of the Underground CO 2 Pipe in the Direct Expansion Ground Source Heat Pump

Gao, Yuefen; Cheng, Yongzhao; Nan, Shanshan

doi:10.1016/j.egypro.2017.03.989

Cited by 12 publications

(2 citation statements)

References 2 publications

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“…They assessed the pressure, temperature, and quality variations of the CO 2 along the U-pipe. Gao et al (2017) established a borehole model to analyze the heat transfer between the refrigerant and the soil for a direct-expansion CO 2 GSHP. They studied the influence of shank spacing (center-to-center U-pipe distance), soil and backfill thermal conductivity, CO 2 inlet temperature, and CO 2 mass flow rate.…”

Section: Progress In Gshps Using Co2mentioning

confidence: 99%

Progress in ground-source heat pumps using natural refrigerants

Skye

2018

International Journal of Refrigeration

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Natural refrigerants are attractive candidates for replacing the high Global-Warming- Potential fluorinated refrigerants used in ground-source heat pumps (GSHPs). This paper presents a comprehensive survey on GSHPs using CO2, NH3, water, and hydrocarbons. We compared the refrigerants’ thermodynamic properties, analyzed their performance in brine-to-air and brine-to-water GSHPs, and discussed recent progress in their use in GSHPs. Studies of CO2 were the most common due to its favorable properties, covering advanced cycles, direct-expansion, secondary fluid, and hybrid GSHPs. Though with toxicity concerns, NH3 was the second most studied, including vapor-compression GSHPs for heating, absorption-type GSHPs to eliminate ground imbalance, and hybrid compression-absorption GSHPs to widen the operating temperature range. A few studies evaluated water as a refrigerant for absorption-type GSHPs, including applications for solar cooling, ground imbalance, and district heating. Propane was the only hydrocarbon considered for GSHPs, including analyses on refrigerant charge, performance analysis, and propane as a secondary fluid.

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Section: Progress In Gshps Using Co2mentioning

confidence: 99%

Progress in ground-source heat pumps using natural refrigerants

Skye

2018

International Journal of Refrigeration

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“…At present, a relatively few studies is reported on DX-GSHP. The available theoretical researches have mainly focused on numerical methods to simulate the GHE and study the effect of different parameters on the system performance (Ghazizade and Ameri, 2018;Yuefen, et al 2017;Mastrullo 2014;Austin and Sumathy, 2011, Eslami Nejad, et al 2014. The modeling of transient behavior of GHE and the surrounding ground is somehow complex and only few transient models are available in the literature (Beauchamp, et al 2013;Rousseau, et al 2015;Eslami Nejad et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Carbon dioxide evaporation process in direct expansion geothermal boreholes

Badache¹,

Eslami²,

Bastani³

et al. 2018

Proceedings of the IGSHPA Research Track 2018

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The impact is even more significant in direct expansion GSHP (DX-GSHP) systems as the refrigerant used in the heat pump also acts as the heat transfer fluid for the GHE. In this study, several experiments were carried out to investigate the performance of GHEs in a carbon dioxide (CO2) DX-GSHP. The evaporation of CO2 in the GHE was studied under various mass flow rates and number of active boreholes. For this purpose, a transcritical CO2 DX-GSHP test facility was built and fully equipped at CanmetENERGY-Varennes research laboratory. It was found that a partial two-phase flow regime along the GHE decreases the performance compared to the full two-phase flow and it has to be avoided for more efficient DX-GSHP systems.

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