Determination of optimum geothermal Rankine cycle parameters utilizing coaxial heat exchanger

Mokhtari, Hamid; Hadiannasab, Hasti; Mostafavi, M.; Ahmadibeni, Ali; Shahriari, Behrooz

doi:10.1016/j.energy.2016.02.067

Cited by 58 publications

(18 citation statements)

References 30 publications

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“…Since 00', several authors (i.e. Kujawa et al 2006;Wang et al 2009;Taleghani 2013;Akhmadullin and Tyagi 2014;Mokhtari et al 2016;Renaud et al 2019) are studying the use of the deep borehole heat exchanger (DBHE), or WellBore Heat eXchanger (WBHX) as is named by Nalla et al (2005), and 3 pilot tests have been realized (Kohl et al 2002;Morita et al 1992). The feasibility of geothermal energy production via the DBHE has been demonstrated, though the heating effectiveness of this type of closed-loop plants is much lower than conventional plants, due to the pure conductive heat extraction.…”

Section: Introductionmentioning

confidence: 99%

Producing geothermal energy with a deep borehole heat exchanger: Exergy optimization of different applications and preliminary design criteria

Alimonti

Conti

Soldo

2021

Energy

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This paper aims at proposing fast and plain design tools to evaluate the best energy application for deep borehole heat exchangers, exploiting geothermal resources. Exergy efficiency has been chosen as a performance index. Five possible utilization solutions have been analyzed: district heating, adsorption cooling, ORC power production, a thermal cascade system, and combined heat and power configuration. An extensive sensitivity analysis on source characteristics and well geometry has been performed to find the design criteria that ensure the maximum exergy performance.Results show that configurations involving district heating are recommended for exclusive power production. If optimized, district heating exergy efficiency can reach values in the range 40 % -50 % when a geothermal source at the well bottom is lower than 300 °C. For higher values, the combined heat and power production is a preferable choice, reaching an exergy efficiency of up to 60 %. Design charts are also provided to read first-attempt values of the well operative temperatures and flow rate to maximize exergy efficiency for each utilization layouts.

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Section: Introductionmentioning

confidence: 99%

Producing geothermal energy with a deep borehole heat exchanger: Exergy optimization of different applications and preliminary design criteria

Alimonti

Conti

Soldo

2021

Energy

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“…The main obstacles to the growth of the geothermal sector are the costs and risk related to exploration and drilling phases, and the absence of social consensus among the population. An interesting solution proposed by several authors since 2000, i.e., [2][3][4][5][6][7], is the use of a zero-mass extraction device. The plant is a coaxial heat exchanger made of steel (Figure 1), which avoids all the risks (corrosion, scaling, subsidence, vapour emissions, micro-seismicity) and the costs related to the extraction and reinjection of brine.…”

Section: Introductionmentioning

confidence: 99%

“…It includes the classification of resources with exergy [25][26][27] the exergy analysis of geothermal power plants [23,[28][29][30], and the low enthalpy applications (ground source heat pumps, district heating and cooling, and thermal storage), see [31][32][33][34][35]. The literature regarding the deep borehole heat exchanger reports only a few works [6,18,36] that include a thermodynamic assessment based on exergy balance: all of them analyze a DBHE connected to an organic Rankine cycle plant.…”

Section: Introductionmentioning

confidence: 99%

Selecting the Optimal Use of the Geothermal Energy Produced with a Deep Borehole Heat Exchanger: Exergy Performance

Alimonti

Conti

Soldo

2020

The First World Energies Forum—Current and Future Energy Issues

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The geothermal sector has a strength point with respect to other renewable energy sources: the availability of a wide range of both thermal and power applications depending on the source temperature. Several researches have been focused on the possibility to produce geothermal energy without brine extraction, by means of a deep borehole heat exchanger. This solution may be the key to increase the social acceptance, to reduce the environmental impact of geothermal projects, and to exploit unconventional geothermal systems, where the extraction of brine is technically complex. In this work, exergy efficiency has been used to investigate the best utilization strategy downstream of the deep borehole heat exchanger. Five configurations have been analyzed: a district heating plant, an absorption cooling plant, an organic Rankine cycle, a cascade system composed of district heat and absorption chiller, and a cascade system composed of the organic Rankine plant. District heating results in a promising and robust solution: it ensures high energy capacities per well depth and high exergy efficiency. Power production shows performances in line with typical geothermal binary plants, but the system capacity per well depth is low and the complexity increases both irreversibilities and sensibility to operative and source conditions.

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“…They found that the sensitive parameter analysis indicates that casing geometry will strongly affect the heat transfer between the geothermal well and the surrounding rocks. Mokhtari et al [11] found that when evaluating the pressure drop and thermal efficiency of the heat exchanger, the diameter ratio of the inner to outer pipe is very important. Their results showed that the optimal diameter ratios for pressure drop minimization and thermal efficiency maximization are 0.675 and 0.353, respectively.…”

Section: Introductionmentioning

confidence: 99%

“…To extract more heat from subsurface reservoir, low boiling point organic fluids with high heat-to-electricity efficiency are often used as working fluid mostly in ORC plants. Mokhtari et al [11] investigated four organic fluids (R123, R134a, R245fa, R22) often used as working fluids in geothermal power plants. They found that R123 has the most desirable characteristics in comparison with other working fluids.…”

Section: Introductionmentioning

confidence: 99%

Geothermal Power Production from Abandoned Oil Reservoirs Using In Situ Combustion Technology

Zhu

Liu

et al. 2019

Energies

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Development of geothermal resources on abandoned oil reservoirs is considered environmentally friendly. This method could reduce the rate of energy consumption from oil fields. In this study, the feasibility of geothermal energy recovery based on a deep borehole heat exchanger modified from abandoned oil reservoirs using in situ combustion technology is investigated. This system could produce a large amount of heat compensated by in situ combustion in oil reservoir without directly contacting the formation fluid and affecting the oil production. A coupling strategy between the heat exchange system and the oil reservoir was developed to help avoid the high computational cost while ensuring computational accuracy. Several computational scenarios were performed, and results were obtained and analyzed. The computational results showed that an optimal water injection velocity of 0.06 m/s provides a highest outlet temperature of (165.8 °C) and the greatest power output of (164.6 kW) for a single well in all the performed scenarios. Based on the findings of this study, a geothermal energy production system associated with in situ combustion is proposed, specifically for economic reasons, because it can rapidly shorten the payback period of the upfront costs. Modeling was also performed, and based on the modeling data, the proposed technology has a very short payback period of about 4.5 years and a final cumulative net cash flow of about $4.94 million. In conclusion, the present study demonstrates that utilizing geothermal resources or thermal energy in oilfields by adopting in situ combustion technology for enhanced oil recovery is of great significance and has great economic benefits.

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Determination of optimum geothermal Rankine cycle parameters utilizing coaxial heat exchanger

Cited by 58 publications

References 30 publications

Producing geothermal energy with a deep borehole heat exchanger: Exergy optimization of different applications and preliminary design criteria

Producing geothermal energy with a deep borehole heat exchanger: Exergy optimization of different applications and preliminary design criteria

Selecting the Optimal Use of the Geothermal Energy Produced with a Deep Borehole Heat Exchanger: Exergy Performance

Geothermal Power Production from Abandoned Oil Reservoirs Using In Situ Combustion Technology

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