Ice Blockage Research Articles

Experimental study on pressure drop and ice blockage characteristics of ice slurry flow in big-diameter pipes

Ice slurry utilization in district cooling brings about attractive reduction in both the storage volume and transportation power of the cold thermal energy. However, the ice slurry flow characteristics, particularly in big-diameter pipes, remains unclear, hindering the application of ice slurry in large-scale district cooling systems. This paper prepared the ice slurry from pure water without any additives to experimentally study its flow characteristics in big-diameter pipes, including DN50, DN80, DN100 and DN190 pipes. The normalized pressure drops and friction factors have been obtained at various velocities and ice fractions. Generally, the pressure drop characteristics did not conform to the Blasius correlation which could predict the single-phase flow until the Reynolds number exceeded a certain threshold, known as the transition Reynolds number. The transition Reynolds numbers were in the range of 3.91 × 104-6.77 × 104 depending on the ice volume fractions ranging from 5% to 21% in the present study. Some visualization measures have been employed to help to observe the flow pattern and confirm the occurrence of ice blockage which was found nowhere but in the branches and expansion. The ice blockage occurred intermittently in the branches, whereas it was irreversible in the expansion. The critical velocity at which the ice blockage began to occur was quantitatively determined, which increased with increasing the ice volume fraction. This study provides a guide for evaluating the pump power and transportation safety of the ice slurry flow in big-diameter pipes.

Thermal characteristics of nanofluid ice slurry flowing through a spiral tube: A computational study

Nanofluid ice slurry (NICS) has recently attracted significant attention in the field of thermal engineering as an alternative refrigerant, offering a cost-effective, stable, and environmentally friendly cold storage solution. To maximize its potential, a thorough understanding of its heat transfer characteristics is crucial. Unfortunately, this information is not available for spiral tubes which are commonly used in thermal systems due to their superior heat transfer performance. This may hinder further development and implementation of this technology. Hence, the present investigation aims to analyze the flow characteristics and heat transfer mechanisms of a graphene oxide hybrid NICS within a spiral tube employing a computational fluid dynamics (CFD) methodology. More specifically, an interphase heat and mass transfer model, derived from the Euler–Euler model, is formulated to accurately represent the phase transition phenomena occurring within the nanofluid. The results indicate that the spiral tube structure enhances ice crystal accumulation inside the tube, leading to lower outlet temperatures and improved heat transfer without causing ice blockage. The NICS shows a 3% higher pressure drop compared to pure water ice slurry. Increased nanoparticle concentrations enhance thermal conductivity, benefiting heat transfer, but also raise viscosity, resulting in greater internal friction. A Nusselt correlation based on Prandtl and Dean numbers is formulated to aid future studies and the design of NICS systems. When the Reynolds number increases from 3600 to 6600, the Nusselt number rises by approximately 21% for pure water ice slurry and 22% for nanofluid ice slurry.

Research on semantic segmentation algorithm of high latitude urban river ice based on deep transfer learning

ABSTRACT Automated observation methods for monitoring river ice in high-latitude urban areas are crucial for resource utilization, risk assessment, and navigation. However, current research lacks actual-scale river ice classification, such as low-altitude surveys. This study established a dataset of river ice in the Songhua River near Harbin, Northeast China, using UAV aerial photography and applied the RININet semantic segmentation algorithm for precise classification of different ice types in low-altitude aerial remote sensing images. To address environmental challenges, a feature extraction method integrating channel and spatial attention mechanisms was adopted, along with an improved pyramid pool structure to enhance feature recognition. Additionally, a two-stage transfer learning method established an ice recognition database, overcoming issues like small data volume and high annotation costs. Comparative evaluation metrics demonstrated the high accuracy of the semantic segmentation framework. Furthermore, a method for estimating ice blockage risk was proposed, applicable to various urban river ice management tasks, with practical significance.

Experimental research on the reflection and response characteristics of pressure pulse waves for different gas pipeline blockage materials

AbstractNatural gas pipelines are exposed to complex production and transportation environments, leading to blockages of varying compositions and forms due to various factors. This paper proposes a pressure pulsing wave‐based pipe blockage detection method, and a series of pipeline blockage detection experiments of different materials are carried out, including hydrate blockage, ice blockage, paraffin blockage, and water blockage. Through the blockage detection calculation theory and the reflection and transmission characteristics during pressure wave emission, the blockage position, length, and section blockage rate under different blockage materials are obtained, and the influence of different blockage materials on the reflection and transmission signal characteristics of the pressure pulse wave is analyzed. The results show that the solid blocking material does not noticeably impact the reflectivity and reflective properties of pressure waves, and different cross‐sectional shapes have a noticeable impact on the reflectivity of the pressure wave. The reflected wave waveform of the liquid blockage material is visible but irregular. The average error of blockage location is 0.78%.

Numerical investigation on high-fidelity flow field of an ice-class propeller in ice blockage and cavitation flow

Ice-class propellers are prone to generating severe cavitation in ice blockage environments, deteriorating hydrodynamic performance. In this paper, the IDDES method based on hybrid RANS/LES is first applied to research the hydrodynamics, excitation forces, and cavitation of an ice-class propeller in ice blockage and cavitation flow. And the internal influence mechanisms of ice-propeller distance and advance coefficient on the hydrodynamics, excitation forces, and cavitation are analyzed though high-fidelity flow field. The results indicate that the IDDES method performs well, the numerical and experimental errors are less than 3.0%, and the details of induced vortex cavitation are presented. An increase in the advance coefficient leads to a decrease in the mean thrust and torque, which is due to a reduction in the angle of attack. The ice blockage increases the excitation force of the blade behind the ice owing to an increase in pressure on the pressure surface. Meanwhile, ice blockage enhances flow separation, forming a large number of separation vortexes, which become conjoined vortexes under the influence of the propeller. The conjoined vortexes are sucked towards the propeller, forming induced vortex cavitation on the suction surface, and the pressure surface occurs pressure fluctuation. It is also found that the decrease in ice-propeller distance causes a delay in the excitation force. This paper provides a theoretical basis for the hydrodynamic and structural design of ice-class propellers, and offers a reference for the evolution of the flow fields.

Sustained production of gas hydrate through hybrid depressurization scheme with enhanced energy efficiency and mitigated ice blockage

Several trial productions have been conducted on marine natural gas hydrate reservoirs, demonstrating its enormous potential as an alternative energy source. Nonetheless, sustained and efficient production still remains challenging, with crucial issues on low gas production efficiency and blockages. The large amount of hydrate decomposition and resulting heat absorption can lead to prolonged subzero conditions close to the well; this can readily induce ice formation and blockage. This study aims to investigate the issue of ice blockages caused by insufficient energy supply during the recovery process. A systematic analysis of the energy consumption and ice blockage quantification at each stage of the traditional multi-stage direct depressurization and constant speed depressurization methods is conducted. A hybrid optimized scheme is proposed, which enhances energy utilization efficiency by appropriately utilizing reservoir sensible heat during the initial stage of production. Additionally, a multi-stage constant speed depressurization method is introduced in the later stages to mitigate production fluctuations and reduce blockage duration. Results showed a 69.5 % increase in energy efficiency and an average 67.1 % decline in gas blockage duration with comparable gas productivity. The proposed method could be a viable solution to mitigate challenges of icing blockages and fluctuating production during trial tests of marine hydrate reservoirs, achieving improved energy efficiency and sustainable production.

Effect of dispersant on the performances of an ice slurry-wet precooling system

This study addresses the problem of prolonged precooling time and excessive weight loss of fruits and vegetables during postharvest processes. Ice slurry precooling system shows potential but faces challenges like low undercooling and ice blockage. Dispersants are introduced to optimize heat and moisture transfer as well as the flow characteristics of the ice slurry. This research investigates the effects of four dispersants on the performance of an ice slurry-based wet precooling system through experiments. Key parameters analyzed include temperature and humidity in the chamber, cooling rate, and weight loss rate of the tested load. Results show that the addition of dispersants effectively reduces the freezing temperature, enhancing the cooling rate in the system. Among the four dispersants tested, sodium diacetate yields the lowest freezing temperature of −6.4 °C and the highest cooling rate of 0.3 °C min−1. Furthermore, dispersants influence moisture transfer between ice slurry and circulating air, impacting the humidity within the precooling chamber. Notably, the addition of sodium diacetate results in the lowest weight loss rate of 2.74 %. This research shows the potential of using dispersants in ice slurry-based wet precooling systems to enhance the postharvest preservation of fruits and vegetables.

Pore-scale numerical study: Brine water crystallization with ice crystal particle motion using the LBM-PFM-IBM

In this study, the ice formation behaviour in micro pipelines accompanied by free crystal movement was investigated using the using the coupled method of lattice Boltzmann method - phase field method - immersed boundary method (LBM-PFM-IBM) at the pore-scale. Firstly, we proposed a novel coupling method that significantly improved the accuracy of the PFM method [1] in simulating the growth rate of ice crystal tips at the pore scale. The calculation error, when compared to experimental results, was only 3.1%. Furthermore, we conducted numerical studies to examine the influence of particle velocity, particle size, and pipe width on ice blockage (IB) in pipelines where free crystal motion occurs using the proposed method. The results revealed that the mechanism of ice blockage at the micro scale differs significantly from that at the macro level. Increasing the velocity and size of free crystals was found to effectively suppress ice blockage, with the size of the crystals having a more substantial impact. On the other hand, the impact of pipeline width on ice blockage was not consistent. Changing the pipe width did not prove to be an effective means of preventing ice blockage from occurring.

Ice accumulation at a water intake: a case study on the Mille-Iles River, Québec

The blockage of water intakes by ice is recurrent in northern rivers during winter. Previous field studies have monitored field conditions leading to ice blockage and provided a review of mitigations methods. However, to improve the efficacy of these measures, the mechanisms that create the blockage need to be locally measured. For this purpose, a field campaign was implemented to monitor a water intake on the Mille-Iles River at Terrebonne, Quebec, during the winter of 2020–2021. Results from this study showed that ice accumulation on the trash rack had an average growth rate of 1.35 cm/h and reached a maximum thickness of 24 cm. The release rate of these trash rack accumulation events was on average 1.8 cm/h, which is 30% faster than the deposition rate. A minimum cumulative degree minutes of supercooling of 4.5 °C.min was required for the start of a trash-rack ice-accumulation event.

Study on the Dynamic Generation of Subcooled Water Using a Compact Heat Exchanger

The dynamic generation of ice slurry from subcooled water is one of the most promising ways to make ice; this process is utilized widely in ice storage air-conditioning systems. However, the random occurrence of ice blockage during the generation of subcooled water using conventional heat exchangers prevents the increase in subcooling, thereby reducing the efficiency of the release of the subcooled water and converting it into ice slurry. A more efficient approach to reducing the fluid passage time is to employ a compact heat exchanger with a highly efficient heat transfer performance, a heat transfer length of only 21.5 mm, and a hydraulic diameter of 0.32 mm. A compact heat exchanger was used to build a dynamic generation setup for subcooled water, and 40 wt% of non-freezing liquid and tap water was used as the working fluid for heat exchange to generate subcooled water. The results show that the compact heat exchanger can achieve a greater subcooling degree (3.8 K) and longer duration (108 min). This study further explored the potential for dynamic ice making from deep, subcooled water and improved the overall structure of the compact heat exchanger used. The experimental setup is recommended based on the analysis of the results.

Study on internal dynamic response during cold start of proton exchange membrane fuel cell with parallel and serpentine flow fields

A deeper understanding of the internal dynamics and transient phenomena during cold start of proton exchange membrane fuel cell (PEMFC) is essential to inspire better strategies. In this study, segmented fuel cell technology is applied to capture the internal current and temperature evolution during cold start of PEMFC. It is found that the effect of flow field on cold start performance is less important than that under normal temperature. The single-channeled serpentine (SS) flow field exhibits the fastest response rate and better cold start performance owing to its high pressure drop and excellent drainage ability. The flow field does not affect the overall evolution trend, but the response rate increases with the pressure drop. During successful cold start, the maximum current density first appears in the downstream of the cathode, then it moves upwards to the middle and inlet region. However, during failed cold start, the current density gradually decreases while moving upstream due to ice blockage. Besides, severe performance degradation occurs after failed cold start. The degradation of the SS flow field is significantly greater than the others, indicating that a rapid response and superior cold start performance may increase the chance of degradation once the cold start fails.

Experimental Study of Dynamic Icing Process on a Pitot Probe Model

An experimental study was conducted to characterize the dynamic ice accretion process over the surface of a typical aeronautic Pitot probe model under different icing conditions. The experimental study was conducted in the Icing Research Tunnel available at Iowa State University. While a high-speed imaging system was used to record the dynamic ice accretion process, a three-dimensional (3D) scanning system was also used to measure the 3D shapes of the ice layers accreted on the test model. While opaque and grainy ice structures were found to accrete mainly along the wedge-shaped lip of the front port and over the front surface of the probe holder under a dry rime icing condition, much more complicated ice structures with transparent and glazy appearance were observed to cover almost entire surface of the Pitot probe under a wet glaze icing condition. While a flower-like ice structure was found to grow rapidly along the front port lip, multiple irregular-shaped ice structures accreted over the probe holder under a mixed icing condition. The characteristics of the icing process under different icing conditions were compared in terms of 3D shapes of the ice structures, the profiles of the accreted ice layers, the ice blockage to the front port, and the total ice mass on the Pitot probe model. The acquired ice accretion images were correlated with the 3D ice shape measurements to elucidate the underlying icing physics.

Study on Purging Strategy of Polymer Electrolyte Membrane Fuel Cell under Different Operation Conditions

The commercial proton exchange membrane fuel cell (PEMFC) system needs to be equipped with the capacity to survive a harsh environment, including sub-freezing temperatures. The cold start of PEMFC brings about great technical challenges, mainly due to the ice blockage in the components, which seriously hinders the multi physical transmission process. A multiscale, two-dimensional model was established to explore the gas purging in PEMFC under different electrochemical reaction intensities. The results indicate that the optimal case is obtained by B3-1 with a power density of 0.796 W cm−2, and the power density increases first and then decreases, followed by stoichiometric flow ratio (ξ) changes. It is worth noting that the water mole fraction in the PEM is closely related to the water concentration gradient. However, the differences in the initial water distribution in porous media have little bearing on the condensed water in the gas channel, and the liquid water in the gas diffusion layer (GDL) is preferably carried away ahead of other porous parts. The results also show that the increase in the purge speed and temperature can remove the excess water on GDL and the catalytic layer in a short time. For a nitrogen-based purge, the operating condition in case B3-1 is shown as the best strategy based on the output performance and economic analysis during the shutdown and purge process.

Throttle and expansion characteristics of supercritical carbon dioxide during its venting

Supercritical CO2 has important applications in the fields of power cycle generation systems and carbon capture, utilization and storage (CCUS). The venting equipment represents a fundamental pressure-relief method for the purpose of depressurizing sections of those systems for inspection, maintenance or repair. The extremely low temperatures, dry ice blockage and overpressurization will appear in the system due to the throttling and expansion effect during venting. Meanwhile, the released CO2 may cause the exposure for the high density gaseous CO2, solid CO2 particles and cryogenics to the people in the venting area. The study of flow characteristics during CO2 venting is absolutely essential for assessing the hazard probability of dry ice formation and the blockage of relief valves during emergency or routine operational venting. In this paper, the theoretical analysis and experimental tests were conducted to study the throttle and expansion characteristics through the elbow, valve and orifice during straight vertical venting of supercritical CO2 with a 258 m long, 233 mm inner diameter pipeline system. The pressures and temperatures inside the main pipe and vent pipe, and the temperatures near field region were recorded during venting. After the valve was opened, the pressure in the vent pipe rose rapidly, and the rising range decreased with the decrease of the distance from the orifice. The temperature drops of CO2 were obvious after supercritical CO2 passed through the bend, the valve and the orifice. The supercritical CO2 in the main pipe changed into gas-liquid two-phase, and the liquid CO2 were produced in the vent pipe due to the throttling expansion effect. The CO2 temperature near the orifice were in quasi steady state after reaching the lowest value due to the continuous vaporization of liquid-phase CO2 and sublimation of dry ice particles, accompanied by the air entrainment process.

Experimental investigation of producing ice slurry with water using opposed-nozzle impinging jet method

In order to improve the efficiency of producing ice slurry, an experimental device of opposed-nozzle impinging jet was established. Deionized water of 2.5–10.5 °C was jet impinged with chilled air in an ice-making tank. The spray and performance of impinging and non-impinging jet was evaluated. The results show the temperature around the water nozzle is higher, which is benefit for preventing ice blockage. The impinging jet makes the water droplets smaller, more evenly distributed and longer residence time, which strengthens the turbulence flow and heat transfer, as well as reduces supercooling degree of water, while increasing the production of ice particles. The ice packing factor (IPF) decreases with the rise of the water initial temperature, but the corresponding reduction rate is smaller at the higher initial temperature. Meanwhile, the maximum IPF and the utilization rate of cooling capacity of impinging jet are about 4 times than that of the traditional non-impinging jet as the initial water temperature is in the range of 2.5–10.5 °C. The refrigeration coefficient of the ice-making system increases with the initial water temperature. The impinging flow can greatly improve the refrigeration coefficient of the ice-making system. The average refrigeration coefficient of impinging flow system is about 1.6 times that of non-impinging flow system in the range of 2.5–10.5 °C of the initial water temperature. Moreover, the impinging flow improves the refrigeration coefficient of the system more significantly under the condition of lower initial water temperatures.

Performance characteristics of direct contact refrigeration system based on phase change materials and different refrigerants

• Direct contact refrigeration system is built to improve system efficiency. • The problem of nozzle ice blockage is solved with phase change material. • COP of the system is 6.23 by using 35 wt% TBAB. In conventional ice storage refrigeration systems, the evaporator copper tube is immersed in a cold storage tank. Therefore, the thickness of the ice layer increases, the thermal conductivity of the evaporator decreases, resulting in a decrease in the system efficiency. To improve the efficiency of the refrigeration system, a new type of direct contact refrigeration system is designed and developed in this study. The direct contact between the refrigerant and water causes ice blockage in the nozzles and pipes. This is a common problem in direct contact refrigeration systems, and therefore, it is necessary to solve this problem. Four types of working media (R22, R134a, R410A, and HR223) are used to solve the problem of ice blockage in nozzles, and the impact on the system performance is discussed. The results showed that the working medium possesses a large latent heat of phase change, resulting in high system efficiency, however, and ice blockage still exists in the nozzles; the maximum efficiency of the system is 1.68. Water is replaced by phase change material (PCM), and the material is used for heat exchange with the refrigerant. The PCM is tetrabutylammonium bromide hydrate (TBAB), and the performance of TBAB with five mass fraction (25 wt%, 30 wt%, 35 wt%, 40 wt%, and 45 wt%) in the system is analysed. The results indicated that the refrigeration system with TBAB can solve the problem of ice blockage in nozzles. In addition, based on the experimental results, the coefficient of performance (COP) of the refrigeration system with TBAB concentration of 25 wt%, 30 wt%, 35 wt%, 40 wt%, and 45 wt% is 3.11, 4.55, 6.23, 4.83, and 4.46, respectively. A series of experiments demonstrate that TBAB of 35 wt% exhibited the best performance in the direct contact refrigeration system. This paper presents a novel and innovative approach to solve the problems of ice blockage in direct contact refrigeration systems to improve system efficiency.

Experimental and Numerical Study on Ice Blockage Performance of Propeller in Cavitation Flow

Cavitation greatly affects the ice blockage performance of propellers in polar areas, while the combined effect of cavitation and ice blockage on propellers has rarely been considered. In this work, the propeller model test in the cavitation tunnel and the viscous flow CFD numerical simulation based on RANS were conducted. In the cavitation tunnel test, the ice blockage model was simulated by a water-insoluble rectangular solid block, and the ice blockage was measured by the distance between the solid block and the propeller. The thrust and torque in tests and simulations were discussed under the uniform flow and ice blockage scenarios, as well as the variation of cavitation excitation force, pressure distribution of blades, cavitation characteristics and vortex intensity with advance coefficient when σn = 1.5, L/D = 0.15 in an ice blockage environment. The research shows that the numerical simulation results based on overlapping grids are in good agreement with the model test results, and the mean hydrodynamic errors are within 5%. In the uniform flow test, when the advance coefficient is small, the thrust and torque of the propeller will experience a sharp drop due to the influence of heavy cavitation. In the ice blockage test, the thrust and torque increase with the decrease of ice-propeller spacing, and the ice blockage becomes more serious as the cavitation grows. The propeller oscillates violently due to the cavitation excitation force, and the oscillation frequency increases with the increase of the advance coefficient. The cavitation is generated in the low-pressure area of the suction surface, and the cavitation shape captured in the present numerical simulation is consistent with the experimental phenomenon. Since the cavitation reduces the contact area between the water and the blade, the vortex strength will be reduced for the attachment of cavitation, and the vortex strength increases with the increase of the advance coefficient. This study will explore more hydrodynamic regularities with ice-class propellers in an ice blockage environment when cavitation occurrs, and provide technical support for the design of propellers of polar ships.

Exploration of Cause Analysis and Treatment of Ice Blockage in Gas Transmission Pipeline

Exploration of Cause Analysis and Treatment of Ice Blockage in Gas Transmission Pipeline

Numerical investigation on ice slurry flow in horizontal elbow pipes

Ice slurry has been put into use as secondary refrigerant in many industrial fields due to its promising characteristics. But the complex flow properties of ice slurry flow have brought significant difficulties to transport processes. In this paper, a CFD-PBM coupled model has been employed to investigate the flow characteristics of the ice slurry flow in horizontal various elbow pipes. The ice kinetics processes (growth, aggregation, and breakage) are all taken into consideration. The results show that different elbow angles affect the pressure, velocity, ice size and uniformity of ice slurry when flowing across the elbow. Longer length and higher bending angle of elbow make boundary layer separation and secondary flow more obvious. For the elbow angle less than 90°, the redistribution of pressure and velocity enhance the aggregation process at pipe section center at elbow outlet sections, which results in the growth of ice particles. The inlet velocity, ice packing fraction (IPF) and elbow angle both influence the uniformity of ice slurry. Inlet velocity has positive correlation, while IPF and elbow angle have reverse effect. In order to improve the efficiency of ice slurry transport process and avoid the ice blockage, higher velocity, lower IPF and suitable elbow angle (less than 90°) are suggested.

A novel anti‐freezing methane propellant subcooling approach and its performance analysis

AbstractUsing subcooled propellant could improve the overall performance of spacecraft. In cryogenic propellant subcooling process, liquid nitrogen is the most common cold source. For methane propellant, ice blockage may occur in the propellant subcooling operation since the saturation temperature of liquid nitrogen is lower than the freezing temperature of liquid methane. In this paper, a novel anti‐freezing subcooling approach for methane propellant is proposed. By mixing light alkane such as ethane or propane into methane, a methane mixture propellant with lower freezing temperature could be prepared. To guide the propellant preparation, the working principle of the subcooling scheme is introduced, and the thermodynamic performance of the mixed propellant is analyzed. The results show that for the methane–ethane system, the lowest freezing temperature is 72.9 K when the methane mole fraction is about 0.71. Icing‐free subcooling can be achieved in a liquid nitrogen heat exchanger subcooled approach when the methane fraction is controlled within 0.54 to 0.80. For the methane–propane system, the minimum freezing temperature of 72.0 K occurs at the methane fraction of 0.68, and the non‐icing range is about 0.42–0.79. For the methane–ethane–propane ternary system, the lowest solidification temperature even reaches 63.1 K. Moreover, apparent propellant densification could be yielded by the proposed subcooling scheme. In general, the present subcooling scheme can effectively avoid the freezing risk in the methane subcooling process and also prepare a densified methane propellant, and the new scheme is beneficial for fully exploiting the potential performance of the subcooled methane propellant.