Transcritical Carbon Dioxide Research Articles

Exergy analyses and optimization of a single flash geothermal power plant combined with a trans-critical CO2 cycle using genetic algorithm and Nelder–Mead simplex method

Compared with conventional fossil fuel sources, geothermal energy has several advantages. The produced geothermal energy is safe for the environment and suitable for meeting heating power needs. Because the hot water used in the geothermal process can be recycled and used to generate more steam, this energy is sustainable. Furthermore, the climate change does not affect geothermal power installations. This study suggests a combined power generation cycle replicating using the EES software that combines a single flash cycle with a trans-critical carbon dioxide cycle. The findings demonstrate that, in comparison to the BASIC single flash cycle, the design characteristics of the proposed system are greatly improved. The proposed strategy is then improved using the Nelder–Mead simplex method and Genetic Algorithm. The target parameter is exergy efficiency, and the three assumed variable parameters are separator pressure, steam turbine outlet pressure, and carbon dioxide turbine inlet pressure. The system’s exergy efficiency was 32.46% in the default operating mode, rising to 39.21% with the Genetic Algorithm and 36.16% with the Nelder–Mead simplex method. In the final step, the exergy destruction of different system components is calculated and analyzed.Graphical

Energy, Exergy, and Economic (3E) Analysis of Transcritical Carbon Dioxide Refrigeration System Based on ORC System

This paper used the energy, exergy, and economic analysis of a carbon dioxide (CO2) transcritical two-stage compression system based on organic Rankine cycle (ORC) waste heat recovery technology. When the intermediate pressure and high-pressure compressor outlet pressure were changed, respectively, this study simulated the change in system energy efficiency by adding the ORC for waste heat recovery, calculated the ratio of exergy loss of each component, and performed an economic analysis of the coupled system. The results show that adding waste heat recovery can effectively increase the energy efficiency of the system, and among all components, the heat exchanger had the largest exergy loss, while the evaporator had the highest capital investment and maintenance costs.

Thermodynamic analysis of a transcritical CO[formula omitted] heat pump integrating a vortex tube

A thermodynamic model is used to analyze a transcritical carbon dioxide heat pump cycle integrating a vortex tube. The objective is to prove that a vortex tube is beneficial in raising heat pump efficiency. The novelty of the current work lies in implementing a sophisticated thermodynamic model of the vortex tube operating with carbon dioxide at high pressures or in a two-phase state. However, for all other components of the heat pump, a commercial library (TIL) associated with the Dymola software is used to simulate the system. A transcritical carbon dioxide conventional heat pump model is validated to determine the feasibility of implementing the TIL library. Then, the vortex tube heat pump is analyzed to test the heat pump performance and the effect of different parameters under various operating conditions. Of the parameters discussed, the hot exit pressure of the vortex tube and the desuperheater glycol mass flow rate are the most effective parameters on the desuperheater heating capacity and the overall coefficient of performance. Meanwhile, the hot exit pressure significantly controls the desuperheater glycol exit temperature, yet, with limitation. On the other hand, the variation of the cold mass fraction shows insignificant changes in the desuperheater glycol exit temperature. The final conclusion is that the heating coefficient of performance of the vortex tube heat pump is improved by a maximum of 43.7% when compared to that of the conventional heat pump.

Multi-variable study/optimization of a novel geothermal-driven poly-generation system: Application of a soft-computing intelligent procedure and MOGWO

Due to the operational conditions of flash-binary geothermal cycles, it is difficult to design a multiple heat recovery technique for its waste heat. To address this deficiency and reuse its waste heat in different stages, this study proposes a novel poly-generation model considering parallel and series waste heat recovery. The prime target is to maintain the temperature and enthalpy level of the waste heat from each stage to another and provide a unified framework, leading to producing the main required products. The model comprises a transcritical carbon dioxide Rankine cycle, a desalination subsystem, a single-effect absorption refrigerator, and a low-temperature electrolyzer. To this end, a multi-aspect feasibility study is conducted from energy, exergy, and economic viewpoints, and a multi-criteria optimization is applied in four different scenarios using an artificial neural network in tandem with a multi-objective grey wolf optimization. The most suitable state of operation of each optimized scenario and the efficient scenario is defined through the TOPSIS approach. It was found that the most influential parameter affecting the performance metric was the geothermal water inlet temperature. Besides, the second scenario, i.e., exergy efficiency/total investment cost rate, resulted in the best state of operation. Finally, the optimum objective functions were gauged at 29.59% and 72.72 $/h, respectively. In this situation, the optimum net output power, cooling load, freshwater production rate, and hydrogen production rate were equal to 1666.0 kW, 1029.0 kW, 146.4 m3/day, and 1967.0 m3/day, respectively. Besides, the sustainability index and levelized cost of products were obtained to be 2.11 and 0.0602 $/kWh.

Optimization of a Single Flash Geothermal Power Plant Powered by a Trans-Critical Carbon Dioxide Cycle Using Genetic Algorithm and Nelder-Mead Simplex Method

The usage of renewable energies, including geothermal energy, is expanding rapidly worldwide. The low efficiency of geothermal cycles has consistently highlighted the importance of recovering heat loss for these cycles. This paper proposes a combined power generation cycle (single flash geothermal cycle with trans-critical CO2 cycle) and simulates in the EES (Engineering Equation Solver) software. The results show that the design parameters of the proposed system are significantly improved compared to the BASIC single flash cycle. Then, the proposed approach is optimized using the genetic algorithm and the Nelder-Mead Simplex method. Separator pressure, steam turbine output pressure, and CO2 turbine inlet pressure are three assumed variable parameters, and exergy efficiency is the target parameter. In the default operating mode, the system exergy efficiency was 32%, increasing to 39% using the genetic algorithm and 37% using the Nelder-Mead method.

Ionic liquid screening and performance optimization of transcritical carbon dioxide absorption heat pump enhanced by expander

Absorption technologies show great potential in utilizing renewable energy and waste heat. In this study, novel CO2/ionic liquid (IL) mixtures are investigated to overcome the shortcomings of conventional working fluids. To screen the optimum ILs for a transcritical CO2/IL absorption heat pump (TsCO2-AHP), the absorption cycle models using 34 IL species are established to estimate the cycle performance. Within the selected candidates, [OMIM][Tf2N] yields the best cycle performance. For imidazolium-based ILs with different anions, the coefficient of performance (COP) is in the order of [Tf2N] > [C(CN)3] > [OTF] > [DCA] ≈ [PF6]. [EMIM][C(CN)3] yields the highest heat transfer coefficient of 0.520 kW/(m2·K) due to its better transport properties compared to other candidates. The high-side pressure optimization is conducted to maximize the COP. At the generator temperature of 138 °C, the COP of CO2/[OMIM][Tf2N] reaches the highest 0.2614 with the optimum Phigh of 10.289 MPa. By equipping an expander, the COP of the TsCO2-AHP is improved by 11.9% because of a larger cooling capacity and less electricity consumption. The main objectives are contributing novel potential working fluids, optimizing the cycle parameters, as well as selecting the best-performance CO2/IL mixture for improved development of absorption technologies.

Impact of a thermoelectric subcooler heat exchanger on a carbon dioxide transcritical refrigeration facility

To improve the performance of vapour compression refrigeration cycles, the inclusion of a thermoelectric subcooler for low-medium power units has been the focus of recent studies due to its robustness, compactness and simplicity of operation. In thermoelectric systems, it has been demonstrated that the heat exchangers used in the hot and cold side of the thermoelectric modules have a critical impact in the performance of the system. This influence has not yet been studied for thermoelectric subcooling systems in vapour compression cycles. This work, for the first time, evaluates the impact that the heat exchangers of a thermoelectric subcooler, included in a transcritical carbon dioxide refrigeration cycle, have, in the performance of the refrigeration cycle. The influence is quantified in terms of: optimum working conditions, coefficient of performance and cooling capacity. The results show that, through an optimization of the heat exchangers of the thermoelectric subcooler, the performance improvements on the coefficient of performance using this technology are boosted from 11.96 to 14.75 % and the upgrade in the cooling capacity of the system rises from 21.4 to 26.3 %. Moreover, the optimum gas-cooler working pressure of the system is reduced and the optimum voltage supplied to the thermoelectric modules increases.

The potential of transcritical cycles based on CO[formula omitted] mixtures: An exergy-based analysis

This paper focuses on the thermodynamic comparison between pure supercritical Carbon Dioxide and blended transcritical Carbon Dioxide power cycles by means of a thorough exergy analysis, considering exergy efficiency, exergy destruction and efficiency losses from Carnot cycle as main figures of merit. A reference power plant based on a steam Rankine cycle and representative of the state-of-the-art (SoA) of Concentrated Solar Power (CSP) plants is selected as base-case. Two different temperatures of the energy (heat) source are considered: 575 °C (SoA) and 725 °C (next generation CSP).Compared to SoA Rankine cycles, CO2 blends enable cycle exergy efficiency gains up to 2.7 percentage points at 575 °C. At 725 °C, they outperform both SoA and pure CO2 cycles with exergy efficiencies up to 75.3%. This performance is brought by a significant reduction in the exergy destruction across the compression and heat rejection process rounding 50%. Additionally, it has been found that the internal condensation occurring inside the heat recuperator for those mixtures with a large temperature glide improves recuperator exergy efficiency, supporting the use of simpler layouts without split-compression. Finally, CO2 blends exhibit lower cycle exergy efficiency degradation than pure sCO2 in the event of an increase in the design ambient temperature.

Thermodynamic investigation of a single flash geothermal power plant powered by carbon dioxide transcritical recovery cycle

The use of new energy sources, such as geothermal energy, is rapidly expanding worldwide, and it is a viable alternative to fossil fuels. This paper proposes a geothermal power generation system (combined single flash geothermal cycle with transcritical carbon dioxide recovery cycle). To improve system performance, a recuperator is used to recover some of the heat loss. The proposed system simulation is performed in EES software and then validated by previous research. The proposed system is analyzed from the perspective of energy and exergy. The effects of the proposed system separator pressure, carbon dioxide turbine inlet pressure and carbon dioxide condenser outlet temperature on energy efficiency, exergy efficiency and system net power output have been investigated. Findings show that the proposed system in recovery mode has a net power output of 401.40 kW, energy efficiency of 53.6 percent, and exergy efficiency of 46.32 percent, which are significantly higher than the basic mode’s values of 149.9 kW, 2.39 percent, and 12.12 percent, respectively.

A combined cooling and power transcritical CO2 cycle for waste heat recovery from gas turbines

• A combined cooling and power cycle working with CO 2 is proposed for waste heat recovery from a gas turbine. • Efficiencies of the combined system and its COP are evaluated for three configurations (simple, split and cascade) versus different cycle parameters. • Although the split configuration has the highest net power generation at high and moderate heat source temperatures, in the case of low temperature waste heat from the gas turbine (less than 420 °C), net power of the simple cycle surpasses and the split cycle gives the lowest net power. • The split configuration yields the highest thermal efficiency between the three investigated configurations except at low condenser pressures. • The split cycle has a slight supremacy in heat recovery efficiency at intermediate and high gas turbine exhaust temperatures. This supremacy persists over all the investigated cycle parameters. • For low CO 2 mass fractions into the refrigeration part, cascade configuration has the highest COP. • For high CO 2 mass fractions into the refrigeration part, simple configuration has the highest COP. • The split cycle is the most efficient configuration regarding the total system efficiency. Hence, it can be selected as the candidate cycle configuration for further optimization in a future study. A transcritical carbon dioxide (T-CO 2 ) cycle is analyzed for waste heat recovery from a gas turbine. The cycle is proposed to produce combined power and cooling using carbon dioxide as a single pure working fluid. Simple, cascade and split cycle configurations are compared for power generation using a recuperator while a low-temperature loop is added for the cascade and split cycles. In a previous report in the literature the power generation part alone was presented for the three configurations and it was concluded that the split cycle can produce the highest power among the three systems. Here, the same configurations are studied combined with a compression refrigeration cooling effect with the same working fluid, and a parametric study is conducted. The power cycle is a T-CO 2 cycle which absorbs the waste heat from a gas turbine. The effect of different parameters like cooling load, splitters mass fractions, turbine pressure and condenser pressure are investigated and a comparison between the three configurations are demonstrated. It is shown that, for instance, in case of higher temperatures of gas turbine exhaust the split configuration has the highest net power production while using gas turbine exhaust flow of temperatures less than 420 °C the simple configuration produces the maximum output power. From the cooling perspective, for values of turbine inlet pressure higher than 222 bar, abs. the cascade cycle indicates the best cooling performance while the split one takes this position at lower turbine inlet pressures.

Thermo-economic analysis and optimization of a cascade transcritical carbon dioxide cycle driven by the waste heat of gas turbine and cold energy of liquefied natural gas

• A cascade transcritical CO 2 cycle is proposed to recover waste heat and cold energy. • The cascade transcritical CO 2 cycle is condensed by LNG at different pressures. • The effects of thermodynamic parameters on the system performance are studied. • The maximum exergy efficiency is 49.24% according to the optimization result. In this paper, a cascade transcritical carbon dioxide cycle is proposed to utilize the waste heat of gas turbine and the cold energy of liquefied natural gas (LNG). In the proposed system, the carbon dioxide of the bottom cycle and the top cycle are condensed at different pressures by LNG. Meanwhile, the LNG absorbs heat from carbon dioxide at different temperatures, leading to smaller temperature difference. The detailed models are established and the simulation results are discussed from the viewpoints of thermodynamics and economics. Under the design condition, the exergy destruction of the low-pressure condenser is the largest, followed by the high-pressure condenser. The investment cost of the high-temperature turbine is the highest. The exergy efficiency of the proposed cascade transcritical CO 2 cycle first rises then drops as the split ratio and the pressure of high-pressure condenser increase. Moreover, the system exergy efficiency would increase as the inlet temperature of high-temperature turbine rises and decrease as the pressure of low-pressure condenser rises. Finally, the optimization results indicate that the maximum exergy efficiency of the proposed cascade transcritical carbon dioxide cycle is 49.24%. The net power output of the optimal case is 15.53 MW, which is 6.14 MW higher than the reference system.

Off-Design Modeling and Operational Optimization of Trans-Critical Carbon Dioxide Heat Pumps

Abstract Industrial heat pumps, and specifically those using carbon dioxide (CO2) as a refrigerant, can play a key role in the decarbonization of the heating and cooling sector, due to their low global warming potential, toxicity and flammability. However, challenges arise when dealing with the modeling and optimization of CO2 heat pumps under different operating conditions. We address this challenge by presenting a modeling and optimization tool to predict and optimize the operation of heat pumps in off-design conditions. The tool improves on the current state-of-the-art in several ways. First, it describes a novel thermodynamic cycle, which features higher performance than conventional heat pumps. Also, it is based on a mathematical model that describes accurately the behavior of CO2 across a wide range of thermodynamic conditions, especially near its critical region, and takes into account effects of motor-cooling, leakages and performance limits. Furthermore, it maximizes the coefficient of performance (COP) of the heat pump via an accurate and computationally efficient optimization problem. The capabilities of the model are illustrated by looking at different typical heat pump applications based on real-world projects within the heating and cooling sector. Different case studies are considered, showing how the heat pump is optimally operated during the year to maximize its COP while meeting the varying boundary conditions.

Transcritical carbon dioxide heat pump cycle: Validation and comparison of one-dimensional models of ejector with independent data sets

Two typical 1-D homogeneous equilibrium models from the literature (constant and variable pressure mixing models) were used to study the ejector expansion transcritical CO 2 heat pump cycle. A sensitivity analysis was performed to study the impact of the isentropic efficiency of the compressor and of each component of the ejector on the overall system performance. Two groups of independent experimental data from the literature were used to validate the two models. It was found that the cycle performance was more sensitive to the isentropic efficiency of the compressor than that of the individual components of the ejector. With appropriate input value of the compressor efficiency, both 1-D models accurately predicted the ejector outlet pressure and vapor quality. However, for the ejector entrainment ratio and cycle COP, the deviations were more than 50 %. These deviations can be significantly minimized to 10 % by eliminating the imbalance occurring in the system operation using a data post-processing method to correct the pseudo steady state in the real operation system. By comparing the simulation results of the two models, it has been shown that there is minor difference on the prediction accuracy. The research can serve as a practical reference for the operation of two-phase-flow ejector expansion transcritical heat pump cycle, and can also provide an insight and orientation for the subsequent optimization of 1-D ejector numerical models. • Two 1-D homogeneous equilibrium models of the ejector are experimental validated. • Neglecting the pressure variation during the mixing has no significant impact. • The liquid imbalance is a predominant source of the modeling deviation. • An innovative data post-processing method is proposed. • The system performance is more sensitive to the compressor isentropic efficiency.

Transcritical carbon dioxide cycle as a way to improve the efficiency of a Liquid Air Energy Storage system

The article deals with the subject of energy storage. This important issue relates to the ongoing transformation toward renewable energy sources. Liquid Air Energy Storage (LAES) is a mechanical energy storage technology that is suitable for large-scale energy storage. The article presents a method to increase the efficiency of LAES by coupling it with the transcritical carbon dioxide cycle. To this end, the paper presents a numerical analysis of two Kapitza LAES systems with the transcritical CO2 cycle: in parallel and subsequent mode. In both cases, maximizing CO2 pressure contributes to greater overall efficiency. It is only profitable to direct residual heat to the CO2 cycle. In contrast, lowering the air temperature prior to expansion in hopes of providing a greater amount of heat to the CO2 cycle actually delivers worse results. Parallel system implementation can add 5–6% to storage efficiency, depending on other factors. In comparison, the subsequent system only adds some 3.5%–5% to storage efficiency.

Performance assessment of an experimental CO[formula omitted] transcritical refrigeration plant working with a thermoelectric subcooler in combination with an internal heat exchanger

Regulations in the refrigeration sector are forcing the transition to low global warming potential fluids such as carbon dioxide in order to decrease direct greenhouse gases emissions. Several technologies have arisen over the past years to compensate the low performance of the transcritical carbon dioxide vapour compression cycle at high ambient temperatures. For low–medium power units, the inclusion of a thermoelectric subcooler or an internal heat exchanger have been proven as effective solutions for enhancing the coefficient of performance. However, the combination of a thermoelectric subcooler and an internal heat exchanger working simultaneously is yet to be explored theoretically or experimentally. This work presents, for the first time, an experimental transcritical carbon dioxide refrigeration facility that works simultaneously with a thermoelectric subcooler and with an internal heat exchanger in order to boost the cooling capacity and coefficient of performance of the refrigeration system. The experimental tests report improvements at optimum working conditions of 22.4% in the coefficient of performance and an enhancement in the cooling capacity of 22.5%. The 22.4% increase in coefficient of performance would result in a decrease of energy consumption along a reduction of the greenhouse gases emissions. The proposed combination of a thermoelectric subcooler and an internal heat exchanger outperforms each of the technologies on their own and presents itself as a great controllable solution to boost the performance and reduce the greenhouse gasses emissions of transcritical carbon dioxide refrigeration cycles.

Exergy destruction characteristics of a transcritical carbon dioxide two-stage compression/ejector refrigeration system for low-temperature cold storage

Cold storage is an irreplaceable part of food cold chain. In the present study, a novel transcritical carbon dioxide two-stage compression/ejector refrigeration system for low-temperature cold storage is proposed to freeze and refrigerate food. Also, a combination of conventional and advanced exergy methods is adopted to evaluate the exergy destruction characteristics inside the system. According to the advanced exergy method, 69.88% of the exergy destruction is endogenous, which suggesting that exergy destruction of the system is primarily contributed to the irreversibility of components themselves, meanwhile, the interactions between components are not very close. Among all components, the high-pressure compressor possesses the most tremendous avoidable endogenous exergy destruction, indicating that it has the maximum potential for optimization. And the rest of the improved order is the ejector, low-pressure compressor, evaporator, gas cooler and intercooler, while the high-pressure and low-pressure expansion valves have the lowest priority for optimization. Remarkably, there is a significant discrepancy between the conclusions obtained from these two exergy methods. Furthermore, the system was also found to have a COP of 0.42 under the actual operating condition and 0.62 under the unavoidable operating condition. The impacts of the ejector and compressor efficiencies, as well as discharge and intermediate pressure upon theoretical exergetic performance of the system are considered. The system exergy efficiency is respectively increased by 5.78%, 36.2% and 50% as the ejector, low-pressure and high-pressure compressor efficiencies ranging from 0.5 to 0.9. In addition, there exists an optimal intermediate pressure of 4.25 MPa and an optimal discharge pressure of 8.75 MPa from the perspective of system exergy efficiency.

Experimental demonstration of comminution with transcritical carbon dioxide cycles

A new comminution technology that can reduce energy consumption when compared to traditional grinding of rock is presented. The process is based on pulverization driven by transcritical CO2 cycles, resulting in tensile fracture inside the particle rather than compression from outside. Tensile strength of many rocks is approximately 10 times lower compared to compressive strength offering significant potential for saving energy. In this apparatus, comminution can occur over multiple cycles to enhance rock breakage without extracting and refeeding rock between cycles. The test rig depicts test conditions to capture and to recycle the CO2.Limestone is utilized as an example material in a lab-scale experimental apparatus. Within the apparatus, the temperature and pressure are raised to supercritical conditions. A rapid release of the CO2 into a decompression chamber results in an expansion of supercritical CO2 inside the pores and fractures rock from tension instead of compression. Results show a significant fraction of the limestone is comminuted in three consecutive CO2 pressure cycles. A majority of the resulting particles exhibit larger fragments from 5 mm to 13.2 mm. 6.2% of the feed material was directly transferred to fine material <300 μm without many intermediate progeny particles. Initial results indicate a larger ratio of the pressure before and after burst, and longer soak times aid pulverization. A single rock is also analyzed, where it is noted that breakage occurs along visible fractures, and this behavior is noted over consecutive cycles.

Experimental evaluation of a transcritical CO[formula omitted] refrigeration facility working with an internal heat exchanger and a thermoelectric subcooler: Performance assessment and comparative

The use of carbon dioxide in transcritical state has become one of the most used solutions to comply with the F-Gas directive and reduce greenhouse gases emissions from refrigeration systems at high ambient temperatures. For low-medium power units, the commonly used solutions to improve the efficiency such as the ejector, multiple compressor arrangements, mechanical subcooler, etc., add complexity and increase the cost of the refrigeration facility, which is not ideal for small units. In this low-medium power range, two technologies stand out to increase the performance of a carbon dioxide transcritical cycle: the internal heat exchanger and the thermoelectric subcooler. This study brings a complete research in which both solutions have been tested in the same experimental transcritical carbon dioxide refrigeration facility under the same working conditions. It focuses on the real performance of both systems and discusses the strengths and weaknesses of using an internal heat exchanger or a thermoelectric subcooler. The results show that the thermoelectric subcooler outperforms the internal heat exchanger in both the coefficient of performance and the cooling capacity while also being a more controllable and flexible solution.

Evaluation of the performance and economy for a hybrid energy storage system using hydrogen and compressed carbon dioxide as the energy carrier

A green concept of hybrid energy storage system with hydrogen and compressed carbon dioxide as the energy carrier has been proposed in this paper. The integration of the two energy storage methods leads to a hybrid efficient storage way, which can have higher energy density and lower pressure tank volume compared to the compressed carbon dioxide, and has higher energy storage efficiency compared with the hydrogen one. The ratio of the two energy storage is determined by the hydrogen consumption way. In this paper, the hydrogen fueled gas turbine with carbon dioxide as the working fluid (Allam cycle) is used for large amounts of the hydrogen consumption, and the mass flow rate ratio of hydrogen and CO2 is 0.0048 at the design point. The combined system can be used for inter-regional power dispatching, peak and frequency modulation and so on. A basic system form is firstly introduced, and the round trip efficiency (RTE) and levelized cost of electricity (LCOE) are 42.41% and 0.2075 $/kWh at the design point, respectively. In addition, two improved types are proposed. The effect of key parameters, including the CO2 compressor outlet pressure, the CO2 compressor inlet pressure and the CO2 mass flow rate, on the system performance is performed. The multi-objective optimization is also conducted. The comparison reveals that the improved form-I performs with a lower LCOE and a weaker RTE. In contrast, the improved form-II owns a better RTE but a higher LCOE. It can be concluded that the improved form-I can improve the economic performance of the energy storage system through the optimization of the compressed carbon dioxide high pressure storage subsystem. And the improved form-II can enhance the thermodynamic performance by adding the transcritical carbon dioxide cycle branch. Potential solutions to improve the system economic performances are also discussed and the results indicate that technology development, subsidies and electricity market transaction premium would be beneficial for the large-scale promotion of the system in practical.

Experimental validation and development of an advanced computational model of a transcritical carbon dioxide vapour compression cycle with a thermoelectric subcooling system

The inclusion of a thermoelectric subcooler as an alternative to increment the performance of a vapour compression cycle has been proved promising when properly designed and operated for low-medium power units. In this work, a computational model that simulates the behaviour of a carbon dioxide transcritical vapour compression cycle in conjunction with a thermoelectric subcooler system is presented. The computational tool is coded in Matlab and uses Refprop V9.1 to calculate the properties of the refrigerant at each point of the refrigeration cycle. Working conditions, effect of the heat exchangers of the subcooling system, temperature dependent thermoelectric properties, thermal contact resistances and the four thermoelectric effects are taken into account to increment its accuracy. The model has been validated using experimental data to prove the reliability and accuracy of the results obtained and shows deviations between the ± 7% for the most relevant outputs. Using the validated computational tool a 13.6 % COP improvement is predicted when optimizing the total number of thermoelectric modules of the subcooling system. The computational experimentally validated tool is properly fit to aid in the design and operation of thermoelectric subcooling systems, being able to predict the optimal configuration and operation settings for the whole refrigeration plant. • Transcritical CO2 vapour compression cycle with thermoelectric subcooling. • Advanced computational model to predict optimal operation settings of the system. • Validation of the model using experimental data with deviations between the ±7%. • Computational optimization of the number of modules in a thermoelectric subcooler. • 13.6% COP improvement using the hybrid solution and optimum number of modules.