Improvement in Heat Transfer in Hydrocarbon and Geothermal Energy Coproduction Systems Using Carbon Quantum Dots: An Experimental and Modeling Approach

Villada Y. Giraldo L.J. Estenoz D. Riazi M. Ordoñez J. Taborda E.A. Bastidas M. Franco C.A. Cortés F.B.
June 2025 Multidisciplinary Digital Publishing Institute (MDPI)

Nanomaterials
2025 #15 Issue 12

The main objective of this study is to improve heat transfer in hydrocarbon- and geothermal-energy coproduction systems using carbon quantum dots (CQDs). Two types of 0D nanoparticles (synthesized and commercial CQDs) were used for the formulation of nanofluids to increase the heat transfer from depleted wells for the coproduction of oil and electrical energy. The synthesized and commercial CQDs were characterized in terms of their morphology, zeta potential, density, size, and heat capacity. The nanofluids were prepared using brine from an oil well of interest and two types of CQDs. The effect of the CQDs on the thermophysical properties of the nanofluids was evaluated based on their thermal conductivity. In addition, a mathematical model based on heat transfer principles to predict the effect of nanofluids on the efficiency of the organic Rankine cycle (ORC) was implemented. The synthesized and commercial CQDs had particle sizes of 25 and 16 nm, respectively. Similarly, zeta potential values of 36 and 48 mV were obtained. Both CQDs have similar functional groups and UV absorption, and the fluorescence spectra show that the study CQDs have a maximum excitation–emission signal around 360–460 nm. The characterization of the nanofluids showed that the addition of 100, 300, and 500 mg/L of CQDs increased the thermal conductivity by 40, 50, and 60 %, respectively. However, the 1000 mg/L incorporated decreased the thermal conductivities of the nanofluids. The observed behavior can be attributed to the aggregate size of the nanoparticles. Furthermore, a new thermal conductivity model for CQD-based nanofluids was developed considering brine salinity, particle size distribution, and agglomeration effects. The model showed a remarkable fit with the experimental data and predicted the effect of the nanofluid concentration on the thermal conductivity and cycle efficiency. Coupled with an ORC cycle model, CQD concentrations of approximately 550 mg/L increased the cycle efficiency by approximately 13.8% and 18.6% for commercial and synthesized CQDs, respectively.

carbon quantum dots , coproduction , decarbonization , geothermal energy , renewable energy , simulation , thermal conductivity

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Grupo de Investigación Fenómenos de Superficie Michael Polanyi, Departamento de Procesos y Energía, Facultad de Minas, Universidad Nacional de Colombia, Sede Medellín, Medellín, 050034, Colombia
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional del Litoral, Santa Fe 3000, Güemes, 3450, Argentina
School of Mining and Geosciences, Nazarbayev University, Astana, 010000, Kazakhstan
Center for Advanced Power Systems, Department of Mechanical Engineering, FAMU-FSU College of Engineering, Energy and Sustainability Center, Florida A&M University-Florida State University, Tallahassee, 32310, FL, United States
Grupo Destacar, Universidad de La Guajira, Km 5, vía Maicao, Riohacha, 440002, Colombia

Grupo de Investigación Fenómenos de Superficie Michael Polanyi
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
School of Mining and Geosciences
Center for Advanced Power Systems
Grupo Destacar

10 лет помогаем публиковать статьи Международный издатель

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