Institute Of Energy Technology Research Articles

Dynamic modelling and optimal operation of the photovoltaic/thermal

This paper aims to introduce a dynamic model for a photovoltaic/thermal system, highlighting an approach and synthesis of existing dynamic models to depict the full photovoltaic/thermal system. The model was validated using data from an experimental setup at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor, under different weather conditions. The model's accuracy was assessed through normalized Root Mean Square Error, normalized Mean Bias Error, Correlation Coefficient, and the coefficient of determination error metrics, focusing on the temperature and electrical output power of the photovoltaic/thermal modules, as well as the temperature of the thermal energy storage tank. Furthermore, the paper also focuses on the optimal operation of the photovoltaic/thermal system under different mass flow rates of the working medium.

HI decomposition over the HI-100 test apparatus at a hydrogen production rate over 100 L/h

Studies on the iodine-sulfur (IS) thermochemical cycle for hydrogen production has been carried out since about 2005 by the Institute of Nuclear and New Energy Technology, Tsinghua University, China. The HI decomposition occupies the important position of hydrogen generation in the IS cycle. In this paper, the HI-100 test apparatus with a H2 production rate of 100 L/h was constructed and the HI decomposition was tested. First, the process and components for HI decomposition were designed. Then, the key components, including the feed tank, evaporator, gas heater, adiabatic reactor, condenser, and gas-liquid separator were made of industrial materials. After building this apparatus, the sealing test, heating water test, and HI decomposition have been conducted. The stable hydrogen production operation of more than 100 L/h had been achieved for 5 h, the maximum hydrogen production reached approximately 130 L/h, and the hydroiodic acid decomposition rate maintained about 22 %. The test results provide the design and experimental guidance for further amplification of HI decomposition for hydrogen production by the IS cycle.

Evaluation of Bio-Oils in Terms of Fuel Properties

In response to the global climate challenge and the increasing demand for energy, exploring renewable energy alternatives has become crucial. Bio-oils derived from biomass pyrolysis are emerging as potential replacements for fossil fuel-based liquid fuels. This paper shares findings from the Institute of Energy and Fuel Processing Technology on the quality of crude biomass pyrolysis bio-oil samples. These findings highlight their potential as motor liquid fuels. The article details the results of tests on the physicochemical properties of four distinct bio-oil samples. Additionally, it presents preliminary test results on the hydrodeoxygenation of bio-oils in a batch reactor. The production of homogeneous, stable mixtures using other fuel additives, such as diesel oil, rapeseed methyl ester (RME), and butanol, is also discussed.

High-Fidelity Neutron Transport Solution of High Temperature Gas-Cooled Reactor by Three-Dimensional Linear Source Method of Characteristics

Recently, a three-dimensional method of characteristics (MOC) code called Advanced Reactor CHaracteristics tracER (ARCHER) has been developed by the Institute of Nuclear and New Energy Technology, Tsinghua University, to solve the neutron transport problem in high-temperature gas-cooled reactors (HTRs) with explicit pebble-bed geometry. Although the spatial domain decomposition using the message passing interface (MPI) and the ray parallel using OpenMP have been implemented in the previous version of ARCHER, in order to simulate practical HTR problems it is still necessary to reduce the great computational burden through efficient algorithms. Therefore, the linear source approximation (LSA) scheme, which allows coarser transport calculation grids while maintaining high accuracy, has been added in the latest version of ARCHER to relieve memory pressure together with the MPI-based spatial domain decomposition. Moreover, on-the-fly calculation of the relative position coordinates of the ray segment center can further reduce the memory for storing segment information under LSA. In addition, time-consuming MOC transport sweeps can be reduced greatly with coarse-mesh finite difference (CMFD) acceleration. Numerical results show that both LSA and CMFD acceleration contribute to simulate the practical HTR-10 problem successfully.

Designing publicly funded organisations for accelerated low carbon innovation: A case study of the ETI, UK and ARPA-E, US

The role of publicly funded organisations in implementing accelerated low carbon innovation policy is receiving increasing attention. Due to different national contexts and priorities however, policy makers face high levels of complexity in understanding what organisational approaches might best suit their aims. This paper develops a set of ten principles for accelerated innovation organisation design, which seek to provide policy makers with a tool to better understand the interplay of different design features on innovation outputs. The principles are applied to a comparative case study of the Energy Technologies Institute (ETI), United Kingdom (UK), and the Advanced Research Projects Agency– Energy (ARPA-E), United States (US). Results demonstrate that the design of the ETI, which embedded incumbent industry actors and engaged a narrower set of staff competencies, caused it to prioritise un transformative innovation, contrary to its initial mission. Conversely, the operational approach of ARPA-E has created an entrepreneurial, flexible approach to pursuing transformative innovation. The organisation however lacks long term stability in a changing political environment. Conclusions explore the implications of these results for policy makers seeking to design organisations that are effective in accelerating low carbon innovation.

High-Pressure PEMWE Stack and System Characterization

As the urgency to decarbonize the industry and transport sector intensifies, renewable energy-based hydrogen production via advanced low temperature water electrolysis is attracting increased interest. Proton exchange membrane water electrolysers (PEMWE) offer several benefits over the more mature alkaline water electrolysis technology, including its load-following capability and the ability to operate at higher pressures. The latter is important because significant benefits can be harvested by adopting systems operating at pressure-levels compatible with the end use applications and thereby render the mechanical compressor redundant. At IFE we have developed a methodology which encompasses detailed energy- and techno-economic calculations of high-pressure systems, and a comparison between high-pressure electrolysis and state-of-the-art electrolysis at 30 bar in combination with a compressor has been carried out. Here, direct pressurization to 80 and 200 bar (relevant for, e.g., methanol and ammonia production) was found to be economically viable.To realize high-pressure H2 generation systems, many challenges related to system operability, efficiency and safety needs to be addressed. As part of the national infrastructure “The Norwegian Fuel Cell and Hydrogen Centre”, Institute for Energy Technology (IFE) has installed a flexible PEM water electrolyzer system platform for testing of small-scale prototype electrolyzers up to 33 kW and 200 bar differential pressure. The test rig is integrated with a sophisticated power conditioning system which consists of three custom-built DC/DC-converters (for PEMWE, PEMFC, and Li-ion battery systems), all coupled to the same DC-bus. This configuration makes it possible to test different hybrid electric topologies and to emulate different loads (e.g., grid load profiles, wind generation). This one-of-a-kind high-pressure PEMWE test facility at IFE is well suited to study performances of next-generation PEMWE stacks and systems, and to tailor and test control strategies that safeguards the system and maximizes efficiency and durabilityThe test rig has been commissioned with a prototype high-pressure stack with a production capacity of 2 Nm3/h (Nel Hydrogen), and the identified economically viable pressure range of 80-200 bar has been the main target for an experimental test campaign. The experimental results are presented from stack testing including polarization curves and EIS data as a function of temperature, pressure and current density. The results are discussed in relation to the techno-economic model, in order to identify pathways towards more efficient hydrogen production. Figure 1

Document-Based Nuclear Archaeology

Deeper reductions in the nuclear arsenals will require better understanding of historic fissile material management and production. The concept of “nuclear archaeology” has been considered since the 1990s to provide the tools and methods to develop independent production estimates, primarily based on nuclear forensic techniques. Here, we propose to add a framework for reconstructing the history of a nuclear program that complements traditional nuclear archaeology techniques by examining the role of operating records to support such an effort. As a test case, we use the JEEP II reactor, a 2 MW civilian research reactor at Norway’s Institute for Energy Technology (IFE), in operation for more than fifty years, however, recently shut down permanently. We have collected, analyzed, and started to preserve the reactor’s operating records, which exist on both analog and digital media, and to simulate parts of its history using OpenMC/ONIX neutronics calculations. A particular focus of this project has been on digital data curation and preservation to confirm and maintain the integrity, authenticity, and provenance of these records. In developing guidelines for best practices that conform to existing standards for long-term digital preservation and curation, we hope this project can help lay the basis for future nuclear archaeology efforts to support nuclear arms control and disarmament.

Experimental Validation of a Dynamic Photovoltaic/Thermal Collector Model in Combination with a Thermal Energy Storage Tank

The primary objective of this paper is to present a dynamic photovoltaic/thermal collector model in combination with a thermal energy storage tank. The added value of the proposed model is the use and integration of existing dynamic models for describing the entire photovoltaic/thermal system. The presented model was validated using measurements on the experimental system located at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor. The validation was carried out based on three different weather conditions—sunny, cloudy, and overcast. The validation results were evaluated using the normalized root mean square error and mean absolute percentage error for the temperature and output power of the photovoltaic/thermal collector and the temperature of the thermal energy storage tank. The model results concurred with the measurements, as the average mean absolute percentage error values for the temperature and output power of the photovoltaic/thermal collector and thermal energy storage tank temperature were 5.82%, 1.51%, and 7.58% respectively.

Experimental Validation of a Thermo-Electric Model of the Photovoltaic Module under Outdoor Conditions

An operating temperature of the photovoltaic (PV) module greatly affects performance and its lifetime. Therefore, it is essential to evaluate operating temperature of the photovoltaic module in different weather conditions and how it affects its performance. The primary objective of this paper is to present a dynamic thermo-electric model for determining the temperature and output power of the photovoltaic module. The presented model is validated with field measurement at the Institute of Energy Technology, Faculty of Energy Technology, University of Maribor, Slovenia. The presented model was compared with other models in different weather conditions, such as clear, cloudy and overcast. The evaluation was performed for the operating temperature and output power of the photovoltaic module using Root-Mean-Square-Error (RMSE) and Mean-Absolute-Error (MAE). The average RMSE and MAE values are 1.75 °C and 1.14 °C for the thermal part and 20.34 W and 10.97 W for the electrical part.

Designing low carbon innovation organisations: the Energy Technologies Institute experience

If clean energy innovation is to be accelerated at the pace required, new approaches to designing public innovation organisations need to be developed. Despite the importance of these organisations in driving sustainability transitions, their role has not yet been explored in the literature. This paper addresses this gap by refining ten principles for publicly funded innovation organisation design and applying them to a detailed case study of the Energy Technologies Institute (ETI), UK. Results demonstrate that the ETI's design reflected broader political and industrial relationships at the time of its formation, embedding six large, incumbent energy firms. This effected its ability to pursue the riskier aspects of its mission, resulting in the pursuit of more incremental technologies and outputs. Generalisable aspects of effective innovation organisation design and opportunities to further develop the principles are also identified.

Моделювання радіаційної обстановки під час «раннього» демонтажу будівельних конструкцій об’єкта «Укриття»

A model of the “early” dismantling of the building structures of the Shelter object is developed in the ChNPP VRdose Planner program. The ChNPP VRdose Planner software product was developed at the Institute for Energy Technology (IFE), Norway. ChNPP VRdose Planner is a tool for real-time computer simulation of the radiological environment and actions sequence planning. The simulation is performed in a directly existing environment, while optimizing radiation protection, and makes it possible to prepare reports on work plans with dose estimates. Based on experimental data, mathematical modeling of gamma fields was carried out and spatial distributions of the power of gamma-radiation dose over the roof of the central hall of the “Shelter” object ChNPP. The distributions were analyzed to clarify the location of the most intense sources of gamma radiation, the characteristics and locations of the sources of ionizing radiation were determined, a visual display of the change in the radiation field above the roof of the Shelter object is shown. The eastern wall of the central hall is an accumulation of fragments of the reactor core in the vertical plane, located from an altitude mark of 38.0 m to an altitude of 64.0 m — about 26 m high, about 23 m wide and 3 m thick. It has been established that the dismantling of the roll-off from the pipes should be started from the western side of the Shelter, since this provides a lower level of ambient equivalent dose rate. After dismantling the “light” roof and rolling up from pipes, the ambient equivalent dose rate at the 67.5 m mark increases from 1.1 to 2.8 times. The use of the ChNPP VRdose Planner program for planning and performing installation activities, as well as the activities for the maintenance, repair and replacement of the equipment in the radiation-hazardous conditions will allow: make justified decisions about the feasibility of a particular activity; choose the best technical solutions to achieve set goals; calculate or optimize the structure of radiation protection of the personnel. The use of a computer model will allow selecting and optimizing design solutions for the unstable structures deconstruction, verify them for the compliance with the established characteristics and requirements, and create an interactive software package for the personnel training.

Моделювання та візуалізація радіаційного стану на майданчику зберігання контейнерів ЦСВЯП за допомогою програмного комплексу ChNPP VRDose Planner

The results of three-dimensional modeling of working conditions of personnel in radiation-hazardous conditions of the Centralized Spent Nuclear Fuel Storage Facility (CSNFSF) of WWER type reactors of domestic NPPs, are presented using the software complex ChNPP VRDose Planner. Today, the software package ChNPP VRDose Planner, developed by the Institute of Energy Technology (Norway), is an effective tool for estimating the does load on personnel. It allows interpreting radiological information based on three-dimensional models of radiationhazardous objects where human activities are planned. The VRDose software complex allows creating virtual models of each worker and reproducing detailed technological process of performance of works with participation of the person. This creates a visual representation of the behavior of staff at all stages of work. The software complex is created for planning and implementation of works in difficult radiation conditions, allows carring out optimization of radiological protection and choosing the safest scenarios of performance of operations. Using this software package: 1) the predicted values of the dose rate on the surface of the container model and the model of the storage site were obtained; 2) the dose for the dosimeter was simulated and evaluated during the operation no. 32 “Control of gamma dose rate and neutron radiation of the loaded storage container HI-STORM at the storage site” for the time of operation on arrival and departure with the arrival and departure from the venue; 3) the contribution of the main emitting nuclides to the dose rate when measured on each side of the container is determined; 4) the possibility of its use to control the radiation impact on the environment and its minimization on the person during the construction and commissioning of the CSNFSF was assessed. By verifying the results obtained during the work on scientific and technical support of construction and commissioning of CSNFSF with the data obtained using the software package ChNPP VRDose Planner, it can be argued that they are sufficiently correlated. Given the above, the software package ChNPP VRDose Planner can be recommended for use during the work on scientific and technical support of the operation of CSNFSF and control of radiation exposure to the environment and its minimization for personnel for other design work to be performed, as part of work on the transformation of the Shelter object into an ecologically safe system, as well as in other projects of construction, operation and decommissioning of facilities using radiation and nuclear technologies.

Numerical investigation of coalescence filtration: Multiphase flow through fibrous structures

Coalescence filtration is a mechanical filtration process, which is used for the removal of liquid droplets from a gas stream. A numerical model is proposed using an Euler-Euler multi-phase formulation to model the macro-scale filtration process. The model is implemented for a 2D case using the commercial CFD software ANSYS© CFX. The capture of the dispersed phase is modelled using the penetration approach for single fiber capture efficiency which is extrapolated to multiple fibers, resulting in an exponentially-decaying interpolation scheme. To model the flow of gas through the dry filter, an empirical pressure-drop correlation is developed based on fiber-scale flow simulations for varied flow parameters. For the fiber-scale simulations, three-dimensional fibers are generated with random position, thickness and orientation using algorithms developed in house, ensuring that all fibers remain in the filter bed and that the fibers do not intersect. The correlation is extended to a wet filter by adapting the correlation parameters, with the assumption that the oil completely wets the fibers and results in a homogeneous increase in net packing density. The local velocity of the fiber-wetting oil is estimated analytically using the local oil saturation and gas velocity using a thin-film approach, taking into account the effect of the mean fiber orientation (determined using three-dimensional micro-CT scans) on the absorbed oil residence time in the filter bed. An analytical model is used to approximate the thickness of the oil film formed at the back of the filter surface and the pressure drop caused by the gas flow through it.Both steady-state and transient simulations are run and validated against measurement data provided by the Institute for Energy and Environmental Technology (IUTA), Germany. The steady-state pressure drop and oil-saturation predictions from the simulations follow the same trend as the experimental data albeit showing a stronger influence on air flow velocity. The transient simulations show the expected three-stage process with an initial gradual increase of the pressure drop, followed by a drastic increase, and finally, an approach to an equilibrium state.

Monte Carlo Simulation and Experimental Validation for Radiation Protection with Multiple Complex Source Terms and Deep Penetration for a Radioactive Liquid Waste Cementation Facility

A new radioactive liquid waste cementation facility was under commissioning recently in the Institute of Nuclear and New Energy Technology of Tsinghua University, which is designed to simultaneously process multiple intermediate-level radioactive waste drums. Therefore, the multiple volume sources and the scattering effect becomes a key issue in its radiation protection. For this purpose, the Monte Carlo program FLUKA code and experimental measurement were both adopted. In the FLUKA simulation, five different scenarios were considered, i.e., one drum, two drums, four drums, six drums, and eight drums. For the multiple volume sources, the source subroutine code of FLUKA was rewritten to realize the sampling. The complex shielding also leads to a deep penetration problem; hence, the optimization algorithm and variance reduction techniques were adopted. During the measurement, two scenarios, outdoor and indoor, were carried out separately representing the dose field when only one drum is considered and when the scattering effect is considered. A comparison between the experiments and calculations shows very good agreement. From both of the Monte Carlo simulation and the experimental measurement, it can be drawn that, in the horizontal direction, with the increase of the drum number, the dose rate increases very little, while in the vertical direction, the increase of the dose rate is very obvious with the increase of the drum number. The complicated source term sampling methods, the optimization algorithm and variance reduction techniques, and the experimental verification can provide valuable references for the similar scattering problem in radiation protection and shielding design.

Economic power control for offshore wind farms with loop connection cables

Abstract The Canadian developer and owner of green power facilities Northland Power Inc. owns two offshore wind farms (OWFs) in the German Bight, Deutsche Bucht and Nordsee One, operated by the subsidiary Northland Power Europe GmbH. The company supports and conducts research in the field of power flow optimization in wind farm networks. The work at hand represents the results of this effort to maximize the efficiency of the assets. The project was accomplished within a cooperation between the Nordsee One GmbH and the Institute of Electrical Power and Energy Technology at the Hamburg University of Technology. From an external point of view, an OWF represents an “en bloc” power plant connected to the onshore transmission grid via power export cables. Nevertheless, such a power plant comprises a complex, large-scale internal medium voltage network. In case of failure or cable outage, the network topology of an OWF may be modified and unintended overloading of inter-array cables (IACs) is possible. In order to address this issue, a new algorithm and software tool for economic power control in OWFs are introduced in the following which can be employed in wind farms with integrated loop connection cables (LCCs). This configuration particularly entails the risk of overloading cable segments depending on the present wind speed. The new algorithm provides the operator with adapted active power setpoints for each wind turbine generator (WTG) in a given network topology. The aim is to maximize OWF power generation and minimize internal power losses while secure network operation is guaranteed. Using load flow analysis based on WTG power output measurements, the load on each cable section is monitored and the cables can be utilized to their individual full capacity while overload is avoided. The practicability of the approach is demonstrated by means of simulation results.

Solar Photovoltaic Tracking Systems for Electricity Generation: A Review

This paper presents a thorough review of state-of-the-art research and literature in the field of photovoltaic tracking systems for the production of electrical energy. A review of the literature is performed mainly for the field of solar photovoltaic tracking systems, which gives this paper the necessary foundation. Solar systems can be roughly divided into three fields: the generation of thermal energy (solar collectors), the generation of electrical energy (photovoltaic systems), and the generation of electrical energy/thermal energy (hybrid systems). The development of photovoltaic systems began in the mid-19th century, followed shortly by research in the field of tracking systems. With the development of tracking systems, different types of tracking systems, drives, designs, and tracking strategies were also defined. This paper presents a comprehensive overview of photovoltaic tracking systems, as well as the latest studies that have been done in recent years. The review will be supplemented with a factual presentation of the tracking systems used at the Institute of Energy Technology of the University of Maribor.

Two-phase flow simulations at [formula omitted] inclination in an eccentric annulus

Co-current two-phase simulations of gas-liquid flow with mixture velocities from 1.2 to 4.2 m/s were run in a partially eccentric annulus and compared with entirely eccentric and concentric experimental data collected at the Institute for Energy Technology in Norway. The gas-phase was sulphur hexafluoride (SF6) for all cases, while the liquid-phase was Exxsol D60 for the horizontal cases and a mixture of Exxsol D60 and Marcol 82 for the inclined case. The outer diameter of the annulus was 0.1 m for all cases, while the inner diameter was 0.05 m in the horizontal configuration and 0.04 m for the inclined configuration. The purpose of this paper is to explore the effect of the holdup fraction, mixture velocity, and interior pipe’s position on the pressure gradient and flow regime, in effect a study of the pressure gradient and holdup fraction transients. The comparisons between simulations and experiments indicate that moving the pipe from an entirely eccentric to the partially eccentric configuration has a drastic impact on the pressure gradient. In all 4 cases where the inner pipe was changed from a completely eccentric geometry in the experiments to a less eccentric configuration in the simulations, we notice an increase of 48–303% of the mean pressure gradient. Comparatively, the 4 cases where the pipe was moved from a concentric experimental configuration to a more eccentric configuration in the simulations result in less drastic pressure gradient changes. Two cases were within 22% of the experimental results for mean, maximum, and minimum pressure gradient, while the last two cases exceeded the minimum and mean pressure gradients by 25–250%, respectively. The flow regime is rarely significantly affected by a change in eccentricity; 2 out of the 8 horizontal cases indicate either a transition from wavy flow to slug flow or significantly larger waves. The most prominent and frequent discrepancies identified were altered slug and wave frequencies. The last case, a 4o inclined, partially eccentric simulation was compared to an entirely eccentric experiment and results in a 0.2 Hz increase in wave frequency, up from the experimental 0.56 Hz and a 49% increase in the mean pressure gradient.

Experimental and numerical study of coarse particle conveying in the small absorber sphere system: Overview and some recent CFD-DEM simulations

Pneumatic conveying of absorber spheres in the pebble-bed high-temperature gas-cooled reactor is a special application of pneumatic conveying technique in the nuclear engineering. It may be regarded as an intermittent circulation of absorber spheres between the side reflector boring and the storage bin in the reactor. The whole process consists of several sub-processes, e.g., the granular discharge from the sphere storage bin into the boring, granular discharge from the side reflector boring into the feeder, particle entrainment in the feeder, sphere conveying in the transport pipe, and gas-solid separation in the storage bin. We give a brief summary of the experimental and discrete element simulation work done recently at the Institute of Nuclear and New Energy Technology of Tsinghua University, mainly from the viewpoint of gas-solid flow and granular flow. CFD-DEM coupling simulation is recently conducted to investigate the coarse particle conveying in the small absorber sphere system. We present some CFD-DEM simulation results of coarse particle conveying in ambient air and high-pressure helium gas. Based on the needs of engineering practice and scientific research, some research requirements are suggested. Further work is still needed, to make a comprehensive understanding of the conveying process, and to optimize the design and operation of the conveying system.

Burn-up determination and accident testing of HTR-PM fuel elements irradiated in the HFR Petten

The current paper reports the results of gamma spectroscopic burn-up determination and KüFA safety testing at JRC Karlsruhe on spherical high-temperature reactor fuel elements, which were fabricated by the Institute of Nuclear and New Energy Technology of the Tsinghua University, Beijing. The fuel elements were irradiated in the High Flux Reactor, Petten, in the frame of the HFR-EU1 and HTR-PM campaigns and transported to JRC Karlsruhe for post-irradiation examination and accident testing in the KüFA device in the frame of a bilateral safety research study. Burn-up determination was performed on seven fuel elements based on the quantitative measurement of their Cs-137 inventories using an established gamma spectroscopy set-up in the JRC hot cell facilities. Accident testing was conducted on three HTR-PM fuel elements in several phases at simulated accident temperatures between 1620 °C and 1770 °C for 150 h to simulate hypothetical depressurization and loss-of-forced circulation accidents. The release of Kr-85 was measured during the tests in a cold trap and solid fission product release was determined by gamma spectroscopic analyses of exchangeable cold plates in a low background environment. After successful completion of the KüFA tests the fuel elements are currently undergoing further post-irradiation examinations including profile disintegration as well as ceramography and scanning electron microscopy of individual coated particles.

Dimensional analysis and scaling in two-phase gas–liquid stratified pipe flow–Methodology evaluation

Multiphase flow models are validated by comparison with a relatively good supply of high-quality laboratory data, and a relatively sparse supply of field data, which tends to have poorer quality. One of the principal challenges for multiphase flow models, in terms of uncertainty, is the difference in scale and some of the fluid properties between field and laboratory conditions. Therefore, the models may become unreliable when they are applied to conditions that are very different from those in the laboratory.IFE (Institute for Energy Technology) has recently developed and demonstrated scale-up rules for the most basic multiphase pipe flows. The objective of the work presented in this paper was to select appropriate data from our existing database and design new, scaled laboratory experiments, well-suited to demonstrate (or test) the scaling rules by comparing the results. The data include fluid properties, pipe configurations and flow rates. Besides the observed flow pattern, liquid holdup and pressure gradient are the two main parameters for comparison.IFE's CO2 Flow Loop with a test section inner diameter (ID) of 44 mm, operates for two-phase flows over a large range of pressures and temperatures on the equilibrium line of pure CO2. In order to verify scale-up principles, series of experiments were conducted according to the scaling rules to simulate similar conditions. The experiments were performed with gas–liquid two-phase CO2 for fully-developed, steady-state flow, in a horizontal or near-horizontal pipe. The flow regimes include stratified and annular flows. The experimental results showed that measurements of liquid holdup, and pressure gradient in the CO2 Flow Loop are in excellent agreement with appropriately scaled data from the larger-scale facilities. The results also confirm that the gas-to-liquid density ratio plays an important role. The experiments provide valuable data sets for verifying scaling laws, which are lacking in the literature.