Minimum Heat Flux Research Articles

Effects of wall material, working fluid, and barriers on performance of a nano flat-plate heat pipe: Molecular dynamics simulation

The use of microscale heat generating or heat transfer equipment with higher capacity and smaller dimensions requires more accurate management and better disposal of their produced heat. This makes the necessity of designing and manufacturing superconductors completely clear. In the meantime, the nano-grooved flat plate heat pipes (FPHP) have gained the industry’s attention. Due to the provision of the conditions for manufacturing devices on a micro scale, it is possible to integrate this type of heat pipe with other microscale devices. In the meantime, understanding their behavior on small scales requires more studies. In this paper, the effect of using barriers to improve the thermal performance of a nano FPHP (1050×220×95Å) is evaluated. Simulations are performed on a molecular scale through molecular dynamics (MD) simulations using LAMMPS® software. Platinum (Pt), copper (Cu), and aluminum (Al) are used for HP’s body. In addition, argon (Ar), water (H2O), and ethanol (EtOH) are used as working fluids. The results show that increasing the number of barriers leads to improved thermal performance. Different cases include different teeth called barriers augmented inside HP are simulated. The combination of Cu-EtOH showed the best thermal performance (about 18% better than other cases). Cubical barriers have more heat flux improvement than conical ones (from 3.5% up to about 10.7%). Among the three fluids used, EtOH leads to a better heat flux (about 6% for Pt and up to 15% for Cu). Using 24 barriers, a very favorable result of 1992 W/cm2 heat flux is achieved. In this case, the minimum heat flux is obtained by using Pt and Ar and is 1609 W/cm2. Using Ar and the cub shape barriers, the highest mass transfer rates for Pt, Cu, and Al are about 35.2%, 38.9%, and 38%, respectively.

Steady and transient analysis on thermal hydraulic characteristic of helical coiled once-through steam generator of liquid metal fast reactor

A transient model for thermal–hydraulic characteristics of helical coiled once-through steam generator (HCOTSG) of liquid metal fast reactor was established based on global discrete grid method. The model meshed the liquid metal circuit and water-steam circuit. Meanwhile, unsteady heat conduction equations were built to accurately simulate coupled heat transfer between two sides. Four-equation drift-flux method was adopt for water-steam flow. Taking lead–bismuth fast reactor as example, thermal–hydraulic characteristics of HCOTSG were first calculated under steady conditions. It was found that heat flux distribution along steam generator is extremely uneven, and the difference between maximum and minimum wall heat flux reaches hundreds of times. Then, the transient response was simulated when inlet conditions of primary side were perturbed by step changes, and it was found that maximum wall heat flux increases from 1175.5 kW/m2 to 1365 kW/m2, increasing by nearly 16 %, when inlet lead–bismuth temperature step increases from 450°C to 480 °C.

Development of new universal correlations for minimum heat flux point for saturated pool boiling of cryogens

This study addresses the critical need for a reliable database for the minimum heat flux (MHF) point in saturated pool boiling of cryogens. Relying on a comprehensive review of the relatively sparse published literature, a key objective of the study is to amass a MHF database, which is then used to investigate influences of various parameters on MHF, assess the accuracy of published correlations, and develop new correlations specifically tailored to cryogenic fluids. By applying stringent point-by-point evaluation criteria, 165 data points for MHF point temperature (Tmin) and 158 data points for MHF point heat flux (q”min) are aggregated, comprising this study's “Consolidated Database” for MHF. This database includes data for liquid helium (LHe), liquid argon (LAr), liquid hydrogen (LH2), and liquid nitrogen (LN2) and boiling from clean as well as treated (coated or oxidized) surfaces. A total of 9 correlations for Tmin and 10 for q”min are evaluated for accuracy against the new Consolidated Database. Leveraging insights from prior correlation results and trends from the new Consolidated Database, new universal correlations are formulated for both Tmin and q”min. The new correlation for Tmin features Mean Absolute Errors (MAEs) of 9.05 % for clean surfaces and 7.7 % for treated surfaces. Similarly, the new q”min correlation shows MAEs of 21.50 % for clean surfaces and 25.22 % for treated surfaces. While the new correlations represent a significant advancement in the development of predictive tools for cryogens, this study points to a need for more comprehensive experimental investigation of heat transfer aspects of cryogens, which will undoubtedly further improve the robustness and accuracy of the new correlations.

The Relationship between Vertical Kinematic Eddy Heat Flux, Air Temperature and Turbulent Kinetic Energy in Atmospheric Boundary Layer: Baghdad City

Studying the heat flux in the boundary layer and understanding its relationship to the various atmospheric variables reflects positively on understanding the nature of turbulence in this layer and thus understanding the nature of the spread and movement of pollutants and the transmission and distribution of energy in this layer, also, the vertical heat flux is considered a significant influence on the movement of buoyancy and stability in the boundary layer and its effect on the horizontal wind movement, and therefore it is considered one of the important studies indirectly involved in the estimates of wind energy production, pollutant diffusion, and turbulence. This study involved the calculation of the Eddy Heat Flux and turbulent kinetic energy across Baghdad city. Our investigation revealed a correlation between the Eddy Heat Flux, temperature, and Turbulent Kinetic Energy (TKE). The observations have been made for wind speed with three components (u, v, w) and temperature by using a fast-response anemometer. As for the atmospheric pressure data, it was obtained from the automatic weather station located in the department of Atmospheric Sciences at Mustansiriyah University. The range of observations extended through the duration of thirty days for 24 hours from 1st July 2016 to 30th July 2016 every second. The maximum Eddy Heat Flux value was 0.092 J/(m2.s) at 10:00 on 23th July 2016, while the minimum Eddy Heat Flux value was -0.013 J/(m2.s) at 21:00 hour on 25th July 2016, the negative sign refer to a change in the direction of heat transfer,. It was also found that there is a positive relationship between the eddy heat flux and temperatures with a correlation coefficient of 0.93, as well as between the eddy heat flux and the turbulent kinetic energy with a correlation coefficient of 0.8.

Design and analysis of KA-130, the marine-based SMR for icebreakers

Designed for icebreakers, the KA-130 integral SMR provides a carbon-free solution for navigating the North Pole Route with nuclear propulsion. As an integral reactor, all primary components are integrated into the reactor pressure vessel, eliminating large-break loss-of-coolant accidents and enhancing reactor safety. The study evaluates its load following capability and demonstrates efficient load changes within two minutes. The safety analysis during small break loss-of-coolant accidents (SBLOCA) incorporates ship movements into the minimum critical heat flux ratio (MCHFR) calculations and includes a sensitivity analysis to identify significant scenarios. The most limiting case was the guillotine break at the safety injection line with low initial pressure, high core exit temperature and bottom-peaked core. The analysis shows that core flooding is maintained, and decay heat removal is successfully performed. Acceptance criteria, aligned with regulatory and KA-130 specific standards, ensure safety during and after SBLOCA, meeting MCHFR and collapsed water level conditions above the core.

The Ancient Lithospheric Parameters of Impact Basins on the Far Side of the Moon Based on the Mantle and Mare Basalt Load Model

AbstractResearch on the lithospheric elastic thickness (Te) of lunar mascon basins can provide a deeper understanding of heterogeneous thermal activity. In this study, we focused on four basins (Moscoviense, Freundlich‐Sharonov, Hertzsprung, and Apollo) located on the far side of the Moon. These basins exhibit a significant variation in admittance and correlation spectra, making it challenging to develop precise fitted models. Based on the global lunar crustal thickness model and mare basalt thickness, we developed a mantle and mare basalt load model to estimate the Te. This small Te (10.1 km) suggests a double impact process or extreme thermal activity caused by volcanism during the formation of the Moscoviense. For the typical highland basins, that is, Freundlich‐Sharonov and Hertzsprung, the Te (∼20 km) corresponds to a minimum heat flux of 34 mW m−2. Considering the additional energy introduced by the impact, this heat flux can be considered as the upper limit for the heat flux of the highland itself during the formation of a mascon basin. For the Apollo basin within the South Pole‐Aitken (SPA) terrane, the Te is 30.7 km. The crust beneath the SPA region is thinned, allowing a greater contribution of stiffer mantle material to the lithosphere, perhaps explaining the higher effective Te. Furthermore, the disparity between the highland and SPA terranes can give rise to their distinct basin formation processes. Impact basins formed within the SPA terrane may have experienced a faster cooling process compared to those formed on the highland terrane following the impact event, leading to a higher Te.

Experimental investigation of the external load effect on thermoelectric generator discharge time in a low power energy harvesting system

Thermoelectric generator systems are often evaluated and studied in open circuit and close circuit modes. In the open circuit case, minimum heat flux passes across the thermoelectric module and the module does not have any thermal losses. Moreover, in the close circuit system, the external consumer is connected to the module and higher heat is pumped from its hot side to cold side. Hence, investigating the effect of external load resistance as the consumer connected to the module on its response is a significant issue in thermoelectric systems. In this study, to evaluate the effect of various consumers (4, 8, 10, 15, 20 and 30 Ω) over the module on discharge time, output voltage and temperature on both sides of the module, thermoelectric systems lacking and containing phase change material as the useful means for energy storage and thermal management of thermoelectric system were designed and exposed to constant heat loads. Results of this study show that the power consumption of the internal resistance of the module (connected to the consumer) led to an increase in the temperature of both sides of the module compared to open circuit systems. Therefore, the thermal balance and temperature distribution over the module changes and more affected. The maximum output power and discharge time were obtained at the external resistance of 4 Ω (close to the average internal resistance of the module) in the studied systems. The phase change material prevented excessive temperature on the hot side during the charging process and provided proper thermal management to enhance voltage generation and discharge time. The thermoelectric generator is an effective technology in starting consumers with low resistance, such as light bulbs and remote controls.

Flow and Heat-Transfer Characteristics of Droplet Impingement on Hydrophilic Wires.

It is a common phenomenon that droplets collide with wires in industrial production, and their flow and heat-transfer behavior significantly impact the production efficiency. This article presents an experimental and numerical study on the impact of pure water droplets on hydrophilic stainless-steel wires. The dynamic behavior and solid-liquid heat-transfer law of droplet impacting the wire are emphatically analyzed. The impact position of the droplets has a significant effect on their morphology. Under the condition of low Weber number (We), eccentric impacts tend to cause droplets to separate from the wire. Additionally, both We and wire/droplet size ratio have noticeable effects on the droplet morphology. The smaller the We, the larger the wire/droplet size ratio, and the easier it is for droplets to be captured by wires. Conversely, as We increases and the wire-to-droplet size ratio decreases, some droplets become detached from the wire, primarily exhibiting a single-film falling mode. Furthermore, the impact morphology of droplets is influenced by the Ohnesorge number (Oh). The higher the Oh, the more inclined the droplet to develop a double-film falling mode. There is obvious field synergy in the process of droplet impacting on wire. The maximum heat flux is located at the three-phase contact line, while the minimum heat flux is observed at the bubble interface. The impact position of droplets influences the temperature distribution, although its impact on the magnitude of temperature variation is minimal.

Quantifying hinge torque in self-folding, shape memory polymer origami under varying thermal loads

Self-folding origami actuated by thermally responsive shape memory polymers (SMPs) presents a promising mechanism for the deployment of space structures. Pre-strained SMP sheets shrink when heated. The SMP sheets are patterned with black ink hinges that heat locally via a surface heat flux when exposed to infrared (IR) light. The localized heating induces gradients in shrinking, or shape recovery, which in turn produces folding. However, the thermal and mechanical loads applied to the structure during deployment pose unique challenges to the application of SMP as actuators. Herein, we investigate the effects of thermal loads (variable IR flux and convection) and folding resistance (mass moment of inertia) on self-folding behavior of polystyrene (PS) SMP sheets. We analyze digital video recordings to determine the transient bending angle (the angle traversed by the folding face of the SMP sheet) and hinge torque. It is observed that higher heat fluxes and reduced convection lead to higher maximum bending angles, lower fold start times, and higher hinge torques. We found that the measured hinge torque increases with increasing folding resistance. In addition, we highlight the significance of convective heat transfer by demonstrating self-folding under vacuum at IR flux intensities as low as 2,622 W/m2 at a wavelength of 980 nm and identify a minimum surface heat flux required to induce self-folding in the presence of convection. Comparisons to dynamic mechanical analysis (DMA) and a thermal finite element analysis (FEA) offer insight to the initiation of folding under varying thermal loads. These results provide a necessary understanding of the effects of varying thermal loads on the behavior of self-folding origami for deployable space structures.

Experimental Study on Boiling Vaporization of Liquid Hydrogen in Nonspreading Pool

Research on the boiling vaporization process of liquid hydrogen spilled on solid ground is very important for the safety risk assessment of liquid hydrogen. Since the main source of the heat flux in the vaporization process comes from the ground, the heat flux from the ground into the liquid pool should be studied in-depth. In this paper, the boiling vaporization process of liquid hydrogen on the surface of concrete is studied. The analysis of the boiling process of a liquid pool is conducted by utilizing the boiling curve and historical temperature data collected in close proximity to the surface of the concrete. It was found that the boiling regime of a liquid hydrogen pool on the concrete surface presents non-uniformity, and the film boiling of liquid hydrogen on the concrete surface ended earlier than the results calculated by boiling regime correlations. When the measured temperature in the experiment indicates a transition from film boiling to the transition boiling, the temperature difference between the thermocouple temperature measured at a depth of 2 mm and the boiling point of liquid hydrogen is 130 K higher than the predicted superheat of the minimum heat flux (MHF). In the later stage of the experiment, the average relative error between the experimental value of the vaporization rate and the predicted value of the model is 7.48%. This research advances the understanding of heat transfer between concrete ground and a liquid hydrogen pool. In addition, the experimental data obtained in this study contributes to improving the source term model for safety analysis of liquid hydrogen spills.

Simulation study of a box type solar cooker for different locations

Solar cooker which relies on solar energy can be a viable alternative for the reduction of pollution during the combustion of biomass during the cooking process. The emission from biomass contains hydrocarbons as its major source. This simulation study of box type solar cooker performed using ANSYS Fluent version R1 2022 helps in optimizing the design of solar cooker to predict solar heat flux values for different locations such as Chennai, Vellore, Karur and Rameswaram for a particular day and particular time intervals such as 9 am, 12 pm, 2 pm, 5 pm. The proposed work further highlights the region where the solar cooker can be efficiently used by utilizing non-conventional energy sources for cooking process. In the simulation process, Discrete Transfer Radiation Model (DTRM) was used for tracking the solar radiation and solar calculator to predict the direct and diffuse solar irradiation for a particular day, by considering the latitude, longitude and Greenwich Mean Time (GMT) for specified locations. The specified geographical regions are plotted in a spatial map with solar radiation data obtained from Indian Meteorological Department (IMD) through ArcGIS geospatial techniques. The maximum solar heat flux values obtained at 12 pm, in the simulation results are 718 W/m2, 698 W/m2, 726 W/m2 and 720 W/m2, it is identified that among the four regions karur recorded the highest solar heat flux value of 726 W/m2. The minimum solar heat flux values at 5 pm are 215 W/m2, 202 W/m2, 265 W/m2 and 230 W/m2. Vellore was observed to have the minimum solar heat flux value of 202 W/m2. Solar radiation data obtained from the solar calculator and IMD radiation data were in good agreement with each other with a maximum error percentage of 2.36% because of the variation in the sunshine factor.

Twist-Induced Near-Field Radiative Heat Switch in Hyperbolic Antiferromagnets

We study the twisted control of the near-field radiative heat transfer between two hyperbolic antiferromagnetic insulators under external magnetic fields. We show that the near-field heat flux can be affected by both the twist angle $\theta$ and the magnitude of the applied magnetic field with different broken symmetries. Irrespective of twist angle, the external magnetic field causes the radiative heat flux to change nonmonotonically, and the minimum heat flux can be found with the magnetic fields of about 1.5 T. Such nonmonotonic behavior is due to the fact that the magnetic field can radically change the nature of the magnon polaritons with time reversal symmetry breaking. The field not only affects the topological structure of surface magnon polaritons, but also induces the volume magnon polaritons that progressively dominate the heat transfer as the field increases. We further propose a twist-induced thermal switch device with inversion symmetry breaking, which can severely regulate radiative heat flux through different magnetic fields. Our findings account for a characteristic modulation of radiative heat transfer with implications for applications in dynamic thermal management.

Chilldown of cryogenic feed lines- An insight into the influence of feed line orientation and mass flux

Chilldown of cryogenic feed lines is the most indispensable part of any process that handles cryogenic fluids. Prediction of chilldown time ‘apriori’, requires a complete understanding of the influencing factors and the phenomenon involved. In the present study, the effect of feed line orientation and mass flux on chilldown performance is experimentally evaluated using liquid nitrogen. Experiments are carried out with a foam insulated stainless steel test section. Tests are performed for two different mass flux conditions with test section held in horizontal position as well as varying upward and downward inclinations. In tests with upward orientation, a significant jump in heat flux at top region is seen when the wall superheat reduces below a critical value and this is attributed to onset of liquid wetting at top region. In tests with downward inclination, a minor increase in the heat flux at top region is seen beyond 30° downward orientation attributable to the flow structure prevailing in the test section. It is noted that heat flux pattern at bottom region is not influenced much by test section orientation. Leidenfrost temperature, minimum wall heat flux, and critical heat flux values obtained from the present study are compared with the predictions made using correlations available in published literature. The findings of the present study would help to understand better the influence of feed line orientation and mass flux on wall heat flux pattern and thereby improve the prediction capability.

Теплопередавальні характеристики мініатюрних теплових труб для систем охолодження електронної техніки

Decrease in mass and dimensional characteristics of semiconductor devices with simultaneous increase in allocated power dissipation creates conditions of heat-loaded operation of the most critical elements of radio-electronic equipment. Such growth of heat flows requires effective small-size systems for maintaining safe temperature conditions of electronic equipment and its reliable functioning. The use of miniature heat pipes (MHP) commensurate in size with the microchip crystals can significantly reduce their temperature level of operation. The paper presents the experimental results of investigation of thermal resistance and maximum heat fluxes of miniature heat pipes with diameters from 3 to 6 mm and lengths from 150 to 300 mm with metal-fiber capillary structure. The porosity of the capillary structure varied from 70% to 88%. Water and ethanol were used as coolants. The study was carried out at different orientations of MHPs in space: vertical by gravity forces, horizontal, and vertical against gravity forces (+90°, 0°, –90°). It is shown that the heat transfer characteristics of the MHPs are affected by both geometric and mode factors. It is determined that the minimum thermal resistance and maximum heat flux significantly depend on the diameter of the vapor channel, porosity of the capillary structure and thermal physical properties of the heat transfer medium. The data on the heat transfer intensity in the heating zone depending on the size of the vapor channel are given. It is shown that decreasing the diameter of the vapor space of MHPs worsens their heat transfer characteristics.

Assessment of comfort property of jute-cotton blend denim trousers after repetitive laundering

In this analysis jute cotton blend denims performance at enzyme wash to 35 times respective laundering, in friction and roughness properties where 5 times laundered sample showed smoother surface in both inner and outer surface. In bending properties, 5 times laundered sample was found second lowest Bending Average Rigidity (BAR) and Bending Work (BW). In compression, highest Compression Average Rigidity (CAR), Recovery Average Rigidity(RAR) and less energy requirement Compression work (CW) to compress in both inner and outer surface was found in 5 times laundered sample. In Sensorial Comfort Aspect (SCA), 5 times laundered sample was found smoother surface property, quite higher bending property and higher compression average rigidity. Therefore, 5 times laundered sample was good sensorial comfort among all the samples. In Maximum Thermal Flux (MTF), 20 times laundered sample gives most warm feeling at inner surface because it provides minimum heat flux which ensure warmness in skin-garment micro environment. For thermo physiological comfort aspect, only 20 times repetitive laundered sample found maximum thermo physiological comfort among all samples. Thus, Jute-Cotton blend denims performance at enzyme wash to 35 times repetitive laundering up to 20 times repetitive laundering sample reported good results and the protruding fibre of jute was visible excessively on the surface.

Modeling smoldering ignition by an irradiation spot

Irradiation spots, such as lasers, lightning strikes, and concentrated sunlight, are common ignition sources in building and wildland fires, where smoldering is generally first ignited and then transitions to flaming. In this work, a physics-based 2-D computational model that integrates heat-and-mass transfer and heterogeneous chemistry is built to investigate the smoldering ignition of typical solid fuels using irradiation spots. Simulation results predict that, given the size of the irradiation spot, the ignition time decreases as the radiant heat flux increases. However, as the diameter of the irradiation spot decreases, the modeled minimum heat flux of smoldering ignition increases significantly, agreeing well with experiments and theoretical analysis. When the irradiation spot is smaller than 20-50 mm, assumptions of constant ignition temperature and fuel-burning flux become invalid. The commonly-used physical dimensions of thermally thin/thick fuels are not applicable for smoldering spotting ignition due to the significant radial conductive heat loss in the lateral direction. Further analyses show that the minimum irradiation of smoldering ignition increases as the fuel thickness increases, but it is insensitive to the fuel moisture content. This is the first time that a sophisticated 2-D model has been used to predict the smoldering ignition using irradiation spots, which deepens the understanding of the ignition by a remote heating source and large irradiation.

Investigation of effect of a mechanical agitator on pool boiling heat transfer

In this study, effect of a mechanical agitator on heat transfer at pool boiling is investigated experimentally and numerically. An axial agitator without/with blades is used as the mechanical agitator, which is mounted on the lower surface of the heater. Pure water is used as the working fluid. The bubble departure diameter is determined using the image processing technique. Computations are performed via ANSYS FLUENT. Effects of the speed of the agitator, the number of blades of the agitator and the distance between the agitator and the heater on heat transfer and bubble departure diameter are investigated. It is obtained that the convective heat transfer coefficient is increased by increasing the number of agitator blades from three to seven about 47% at minimum heat flux (17 kW/m2) and maximum speed (187.5 rpm) considered. At the same time, the bubble departure diameter has been detected a decrease by about 6%. It is also shown that the maximum increase in heat transfer is observed at the distance of 20 mm. It is obtained that when the distance between the agitator and the heater surface is reduced from 40 mm to 20 mm, the convective heat transfer coefficient increases by 58%, and the diameter of the vapor bubble decreases by 20%.

Universal Correlations for Post-CHF Saturated and Superheated Flow Film Boiling Heat Transfer Coefficient, Minimum Heat Flux and Rewet Temperature for Cryogenic Fluids in Uniformly Heated Tubes

Despite the many experiments conducted throughout the globe during the past sixty years for a variety of cryogens to determine film boiling heat transfer coefficient (HTC) in a uniformly heated round tube, experimental data are either rarely published or published only for a few cryogens, with majority of the data remaining in archives of original authors, or in obscure technical reports of an organization or other inaccessible sources. In the present study, a very comprehensive data mining effort is undertaken to develop a consolidated database for Post Critical Heat Flux (CHF) flow boiling HTC for cryogens from world literature dating back to 1959. With 1730 local Dispersed Flow Film Boiling (DFFB) and 1310 local Inverted Annular Film boiling (IAFB) HTC data points for LHe, LH2, LN2, and LCH4, it represents the largest cryogen post-CHF HTC database assembled to date. Using this database, new universal cryogen correlations for DFFB and IAFB HTCs are constructed and verified in terms of both predictive accuracy and trend. Similar efforts are carried out to collect a relatively small Minimum Heat Flux (MHF) and local Re-wet Temperature (RW) database, and construct correlations for both.

Evaluation of the success of in-vessel corium retention using external reactor vessel cooling mechanism for a small PWR

Among the several study fields of severe accidents, In-Vessel Retention (IVR) via External Reactor Vessel Cooling (ERVC) referred to as IVR-ERVC is a critical subject being explored for various reactor designs. This study aims to investigate and assess the effectiveness of IVR of molten corium in a PWR utilizing the ERVC mechanism. A RELAP5/SCDAP model developed for the assessment of IVR-ERVC was applied to a small PWR after its successful validation. The boundary conditions applied to the model are evaluated through simulation of severe accidents of the small reactor (998 MWth). Thermal hydraulic studies of sensitive parameters have been carried out to determine the safety margin and effectiveness of the IVR-ERVC method under a variety of process conditions. The results indicate that a high mass flux is required to avoid boiling crises at low degrees of subcooling (around saturation conditions). A mass flux of 186.44 kg/m2-s or higher is required to provide a sufficient safety margin for inlet water with degree of subcooling of 8 K. The minimum Critical Heat Flux (CHF) is found to be 2.5 MW/m2 at a mass flux of 186.0 kg/m2-s for this case. Critical Heat Flux Ratio (CHFR) is found in the range of 6.0–17.0 with the cooling water flow rate of 20 kg/s (mass flux of 34.48 kg/m2-s) and 65 K subcooling, which provides a sufficient safety margin to avoid boiling crisis. It is concluded that the ERVC is an effective mechanism for the prevention of RPV rupture under active and passive conditions of the reference reactor.

Experimental and analytical natural circulation analysis of the Jordanian 5 MW research reactor using plate type fuel by RELAP5 MOD3.3

The 5-MWth Jordanian research reactor is an open-pool type research reactor using plate-type fuel. It is cooled by the upward natural flow at low power-operation. Natural circulation cooling is important in the safety analysis because it is the last scenario of all accidents. Therefore, studying natural circulation is important in determining the safety limits, such as the maximum allowed temperature and the minimum critical heat flux ratio of fuel. In this paper, the reactor operated at 50KW by the natural circulation to investigate its neutronics and thermal–hydraulic characteristics. Then, the results were benchmarked with RELAP5 MOD 3.3 by implementing models with and without considering the effect of heat loss through the Upper Guide Structure. As a result of this study, different models show minor differences in thermodynamic parameters and an additional safety margin. Eventually, benchmarking the results and the calculations of RELAP5 led to a reasonable agreement in both simulated models.