Laboratory investigation on the use of thermally enhanced phase change material to improve the performance of borehole heat exchangers for ground source heat pumps

Lyne, Yi; Paksoy, Halime; Farid, Mohammed

doi:10.1002/er.4522

Cited by 24 publications

(5 citation statements)

References 25 publications

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“…Changing the physical state is crucial for the proper implementation of these materials, which is why attention should be focused on the phase change temperature (PCT). It is recommended to use several PCM materials with different PCT to cover a greater operating temperature range, i.e., heating and cooling periods [140]. The term PCM corresponds to a wide variety of materials categorized into organic, inorganic, solid-solid, and hygroscopic materials.…”

Section: Backfill and Grouting Materialsmentioning

confidence: 99%

Application and Design Aspects of Ground Heat Exchangers

et al. 2021

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With the constant increase in energy demand, using renewable energy has become a priority. Geothermal energy is a widely available, constant source of renewable energy that has shown great potential as an alternative source of energy in achieving global energy sustainability and environment protection. When exploiting geothermal energy, whether is for heating or cooling buildings or generating electricity, a ground heat exchanger (GHE) is the most important component, whose performance can be easily improved by following the latest design aspects. This article focuses on the application of different types of GHEs with attention directed to deep vertical borehole heat exchangers and direct expansion systems, which were not dealt with in detail in recent reviews. The article gives a review of the most recent advances in design aspects of GHE, namely pipe arrangement, materials, and working fluids. The influence of the main design parameters on the performance of horizontal, vertical, and shallow GHEs is discussed together with commonly used performance indicators for the evaluation of GHE. A survey of the available literature shows that thermal performance is mostly a point of interest, while hydraulic and/or economic performance is often not addressed, potentially resulting in non-optimal GHE design.

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Section: Backfill and Grouting Materialsmentioning

confidence: 99%

Application and Design Aspects of Ground Heat Exchangers

et al. 2021

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“…Bottarell et al [8,9] adopted the numerical simulation to study the effect of adding PCM to backfill materials on the heat transfer performance of horizontal buried pipe heat exchanger, and the results showed that PCM could slow down the soil temperature rise and improve the heat pump performance. Lyne et al [10] discussed the effects of soil, PCM, and graphite PCM backfill materials with high conductivity on the temperature of heat exchange boreholes, and the results showed that PCM could reduce the soil temperature fluctuation. Yang et al [11][12][13] tested and simulated the energy storage and heat transfer characteristics of PCM-backfilled buried heat exchangers, and the results showed that in both summer and winter, PCM backfilling could improve the energy storage performance, reduce the variation range of soil temperature outside the boreholes, enhance the recovery rate of soil temperature, and decrease the heat effect radius of borehole.…”

Section: Introductionmentioning

confidence: 99%

Development of a Phase Change Backfill Material with High Heat Capacity and High Thermal Conductivity Used for Ground Source Heat Pumps

Chen

Luo

Pei

et al. 2023

International Journal of Energy Research

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To solve the problems of phase change materials (PCM) including low thermal conductivity and easy washout and loss after liquefaction in current studies on borehole backfill materials, capric acid-lauric acid/expanded graphite (CA-LA/EG) PCM admixture with high thermal conductivity and high heat capacity was developed by using expanded graphite as the carrier. The PCM admixture is mixed with original sands (drilling debris) to make phase change backfill materials (PCBM). When the PCM backfilling is applied, the key issue is to dissipate the large amount of heat stored as latent heat in boreholes to the surrounding formation in time; otherwise, serious heat accumulation would be induced. Numerical simulation of application of the PCBM in multiple intermittent operation cycles was conducted when the admixture percentages and thermal conductivities are different. The result shows that compared with conventional low-conductivity PCM admixtures and ordinary backfill sands such as drilling debris, the CA-LA/EG admixture can mitigate the temperature fluctuation in borehole and improve its heat exchange rate. The heat exchange rate was increased by 11.6% when 30% of CA-LA/EG admixture was added. However, the improvement declined as the number of operation cycle increased, so the intermittent operation mode is suggested to match the PCBM application since the heat in borehole should be dissipated in time to reserve storage capacity in the next operation cycle and continuously utilize the high heat capacity of the PCM.

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“…They reported a substantial increase in heating COP of 4.6 for GSHP system against 3.1 for the VRF system, while the cooling COP was enhanced to 3.3 from 2.1. A research has been conducted to investigate the inclusion of high conductivity phase change material (PCM) in the borehole heat exchanger of a GSHP to reduce the borehole length required and improve its COP 20 . Results from their experiments revealed that the maximum COP values of a GHSP calculated assuming an ideal reversed Carnot cycle for cooling mode showed an increase of approximately 81% with PCM and by 112% with graphite enhanced PCM.…”

Section: Introductionmentioning

confidence: 99%

A comparison of ground and air source heat pump performance for domestic applications: A case study in Perth, Australia

Aprianti

Tan

Diu

et al. 2021

Intl J of Energy Research

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This paper aims to assess the efficacy and practical feasibility of implementing a ground source heat pump (GSHP) vis-à-vis an air source heat pump (ASHP) for domestic applications. The outcomes of this comparison are based on monitoring each of those systems installed in two near identical adjacent houses in Perth, Western Australia. The former house has an open-loop groundwater system. There is one family in each house whose operational requirements of the air conditioning system were independent. Data collected from both houses over 2 years was used to determine the cooling capacities delivered and coefficient of performance (COP), as a function of seasonal variations of ambient conditions. It was observed that the COP of the GSHP system was higher than that of the ASHP system for both heating and cooling. Further, these two performance parameters were independent of ambient conditions in the former whereas they show a perceivable ambient dependent trend in the latter.

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Laboratory investigation on the use of thermally enhanced phase change material to improve the performance of borehole heat exchangers for ground source heat pumps

Cited by 24 publications

References 25 publications

Application and Design Aspects of Ground Heat Exchangers

Application and Design Aspects of Ground Heat Exchangers

Development of a Phase Change Backfill Material with High Heat Capacity and High Thermal Conductivity Used for Ground Source Heat Pumps

A comparison of ground and air source heat pump performance for domestic applications: A case study in Perth, Australia

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