Advanced development and application of transcritical CO2 refrigeration and heat pump technology—A review

Song, Yulong; Cui, Ce; Yin, Xiang; Cao, Feng

doi:10.1016/j.egyr.2022.05.233

Cited by 69 publications

(4 citation statements)

References 219 publications

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“…The make-up cycle unit of the jet enthalpy technology exhibits remarkable performance, sustaining more than 78% of the nominal heating capacity at an ambient temperature of 25 • C. Notably, this heating capacity surpasses that of conventional inverter units by a notable margin, with an increment of 17% [97]. The transcritical CO 2 cycle-based high-temperature heat pump technology has the potential to directly heat cold water with a temperature as low as 10 • C to over 90 • C, while effectively utilizing the temperature slip properties of CO 2 in its supercritical state to ensure robust operation even in harsh environmental conditions, as low as −25 • C. The CO 2 heat pump compressor exhibits up-frequency operation in low-temperature conditions, allowing for efficient heating output, meeting the heating requirements of colder regions, with an average COP of 2.236 [98,99]. A cascade cycle has been suggested to overcome the disadvantages of single-stage ASHP [100].…”

Section: Coupling Of Power To Buildingmentioning

confidence: 99%

Enhancing Energy Transition through Sector Coupling: A Review of Technologies and Models

et al. 2023

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In order to effectively combat the effects of global warming, all sectors must actively reduce greenhouse gas emissions in a sustainable and substantial manner. Sector coupling has emerged as a critical technology that can integrate energy systems and address the temporal imbalances created by intermittent renewable energy sources. Despite its potential, current sector coupling capabilities remain underutilized, and energy modeling approaches face challenges in understanding the intricacies of sector coupling and in selecting appropriate modeling tools. This paper presents a comprehensive review of sector coupling technologies and their role in the energy transition, with a specific focus on the integration of electricity, heat/cooling, and transportation, as well as the importance of hydrogen in sector coupling. Additionally, we conducted an analysis of 27 sector coupling models based on renewable energy sources, with the goal of aiding deciders in identifying the most appropriate model for their specific modeling needs. Finally, the paper highlights the importance of sector coupling in achieving climate protection goals, while emphasizing the need for technological openness and market-driven conditions to ensure economically efficient implementation.

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Section: Coupling Of Power To Buildingmentioning

confidence: 99%

Enhancing Energy Transition through Sector Coupling: A Review of Technologies and Models

et al. 2023

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“…Significant research has been completed concerning the development and optimisation of transcritical CO 2 heat pumps with several helpful literature reviews published [ [14] , [15] , [16] , [17]] ]. However, the focus is often on refrigeration or water heating and only recently has there been significant research into using the heat pumps for space heating.…”

Section: Introductionmentioning

confidence: 99%

Application of transcritical CO2 heat pumps to boiler replacement in low impact refurbishment projects

Lambert,

Dehouche

2024

Heliyon

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“…It is well known that CO 2 heat pumps exhibit an optimal gas cooler pressure due to the distinct working mode in the trans-critical region [22,23]. Because of this, several studies have been implemented on developing empirical optimal pressure correlations or algorithms for maximizing the coefficient of performance (COP) or other performance metrics [24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

Development of a surrogate model of a trans-critical CO₂ heat pump for use in operations optimization using an artificial neural network

Sazon,

Zhang,

Nikpey

2023

IOP Conf. Ser.: Mater. Sci. Eng.

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Conventional physics-based models can demand substantial computational resources when employed for operational optimization. To allow faster system simulations that can be employed for operational optimization, a surrogate model of the CO2 heat pump has been developed using an artificial neural network (ANN). The ANN model takes in six (6) inputs: evaporator water-side mass flow, its temperature, gas cooler water-side mass flow, its temperature, set-point output temperature, and high-side heat pump pressure. The model’s outputs comprise the electrical energy needed to run the heat pump, the heat from the gas coolers, the temperature of the heat pump-heated fluid, and the outlet temperature of the heat pump’s evaporator. Data used for training, validating, and testing the ANN model were generated by running a calibrated Modelica model of the CO2 heat pump for various combinations of input parameters obtained from Latin hypercube sampling. The ANN model developed includes an input layer with 6 inputs, 2 hidden dense layers, each with 30 neurons, and an output layer for 4 outputs (6-30-30-3). The ReLU activation function was implemented on each hidden layer and no regularizations were imposed. The Adam optimizer was used with a learning rate of 0.001 specified. Early stopping (patience = 2000) was implemented to ensure that the training data was not overfitted. A maximum of 30000 epochs was specified. The resulting Mean Square Error (MSE) obtained for the training, validation, and testing data sets were 1.38x10−5, 2.05x10−5, and 3.65x10−5, respectively. When tested against one-week operational runs generated by Modelica, the Root Mean Square Errors (RMSEs) for coefficient of performance (COP)s for spring, summer, autumn, and winter operations obtained were 0.232, 0.346, 0.089 and 0.076, respectively. The resulting surrogate ANN model can be integrated into the system model as a functional mock-up unit within Modelica to facilitate faster simulations for operational optimization.

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Advanced development and application of transcritical CO2 refrigeration and heat pump technology—A review

Cited by 69 publications

References 219 publications

Enhancing Energy Transition through Sector Coupling: A Review of Technologies and Models

Enhancing Energy Transition through Sector Coupling: A Review of Technologies and Models

Application of transcritical CO2 heat pumps to boiler replacement in low impact refurbishment projects

Development of a surrogate model of a trans-critical CO₂ heat pump for use in operations optimization using an artificial neural network

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Advanced development and application of transcritical CO2 refrigeration and heat pump technology—A review

Cited by 69 publications

References 219 publications

Enhancing Energy Transition through Sector Coupling: A Review of Technologies and Models

Enhancing Energy Transition through Sector Coupling: A Review of Technologies and Models

Application of transcritical CO2 heat pumps to boiler replacement in low impact refurbishment projects

Development of a surrogate model of a trans-critical CO2 heat pump for use in operations optimization using an artificial neural network

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Development of a surrogate model of a trans-critical CO₂ heat pump for use in operations optimization using an artificial neural network