Cold Regions Research Articles

Energy, exergy, economic and environmental studies on a nonflammable eco-friendly mixture for efficient heating in cold regions

As a compelling alternative to fossil fuel combustion, air-source heat pumps face challenges in inefficiency, flammability, and pollution when operated at low ambient temperatures. To address the demand for safe, eco-friendly and efficient heating during wintertime, this work is devoted to exploring a novel refrigerant for air-source heat pumps. The zeotropic mixture has the potential to meet all the above demands at appropriate operating parameters, although specific feasible mixtures are still under investigation. In this work, a novel mixture of carbon dioxide and trans-1,1,1,4,4,4-hexafluoro-2-butene is proposed, with the heating performance being parametrically optimized based on a genetic algorithm. Energy analysis indicates a coefficient of performance improvement of up to 15.7 %, and thus an improvement in heating seasonal performance factor of more than 13.5 % for different cities, compared with traditional configurations. Exergy analysis shows that the low irreversibility of throttling is the main contributing factor to the improvement in energy efficiency. Meanwhile, economic and environmental analyses reveal a payback period of less than 7.5 years and an annual cost reduction of up to 14.5 %, as well as a carbon dioxide emission reduction of over 15.7 %. The sensitivity of operating parameters is analyzed, and other advantages of this concept are discussed as well. The results indicate a safe, efficient, environmentally friendly, and cost-effective air-source heat pump. This study contributes to: 1) providing an energy-efficient and environmentally friendly alternative refrigerant for heat pumps; and 2) promoting the sustainable development of low-carbon energy transformation technology.

A self-adaption robust superhydrophobic cement mortar for resistance of cold environment

Superhydrophobic coatings have wide range of engineering applications due to its excellent wettability. However, the durability of superhydrophobic coatings is still challenging under complex environments, especially in cold regions. In this study, we prepared a new self-adaption superhydrophobic cement mortar (SSCM) by wettability modified aggregates with polydimethylsiloxane adhesive and silica nanoparticles decorated by 1H,1H,2H,2H-perfluorodecyltriethoxysilane. Subsequently, a series of multi-scale characteristics of the SSCM sample were systematically investigated, including the micro morphology, the chemical compositions, the self-adaption robustness, the anti−/de-icing properties, and the freeze-thaw (F-T) resistance. The results indicate that surface and inside of the SSCM samples exhibit a self-adaption superhydrophobicity with the 150.0° contact angle due to the low surface energy micro/nano structure of wettability modified aggregates. Meanwhile, the SSCM sample shows excellent anti−/de-icing abilities due to the stable rough micro/nano structure under negative-temperature ambient, which can delay the droplet freezing time by 4.3 times than that of the contrast sample. Additionally, the newly exposed section of SSCM sample can still have the self-adaption superhydrophobicity and endow significant F-T resistance even if the surface of SSCM was damaged. Meanwhile, the SSCM sample can improve the F-T resistance by 45 % compared to the contrast sample. This work provides a new strategy to solve the durability limitation of superhydrophobic coating in engineering practice.

Aufeis thickness and volume estimations from stereo satellite imagery and terrestrial photographs: Evidence from Central Ladakh, India

Aufeis – a phenomenon associated with permafrost and the cold arid region of Ladakh – serves as a critical water resource for local communities. In several tributaries of the Indus River, aufeis accumulation is enhanced in ice reservoirs (commonly known as “artificial glaciers”) to store winter baseflow for crop irrigation during the water-scarce period in spring. This study investigates aufeis thickness and volume across four study sites in the Trans-Himalaya of Central Ladakh: the ice reservoirs of Phuktse and Igoo and the catchments of Gya and Sasoma, where natural aufeis fields occur. Aufeis thickness and volume estimates were derived via differencing of digital elevation models calculated from very high-resolution stereo Pléiades imagery and terrestrial photographs. The study revealed ice thickness up to a maximum of 3 m and could further demonstrate the amplification effect of the walls of the ice reservoirs on aufeis accumulation in both, differenced elevation from Pléiades and terrestrial photographs. Aufeis volumes across the four study sites range from 34,106 ± 13,440 m3 in Phuktse up to 105,790 ± 28,511 m3 in Sasoma, indicating substantial amounts that need to be considered in future hydrological studies in the region. While the approach with terrestrial photographs is especially suitable for local studies, the results from very high-resolution stereo satellite data are promising for aufeis studies on large spatial scales. It represents an important contribution for the understanding of spatial aufeis patterns in the Trans-Himalaya and affected regions worldwide.

Dynamics of indoor volatile organic compounds and seasonal ventilation strategies for residential buildings in Northeast China

This study utilized a questionnaire survey to collect data from 265 residents in Changchun, encompassing building characteristics, ventilation frequency and overall satisfaction with the indoor environment. Statistical analysis revealed significant disparities in ventilation frequency and satisfaction with indoor temperature. The survey results indicate that the primary mode of indoor air exchange amongst Changchun residents is window ventilation, accounting for 93%. Field tracking was conducted to measure indoor air concentrations of volatile organic compounds (VOCs) in residential buildings during winter and summer seasons. The study revealed a significant increase in the average indoor/outdoor (I/O) ratio of the targeted 25 VOC concentrations in winter, rising from 10.8 to 17.7. The findings underscore indoor sources as predominant contributors to the measured VOCs. Temperature, humidity and room functions are the main factors affecting VOC concentration. Higher temperatures and increased relative humidity both contributed to elevated indoor VOC levels. This study recommended the opening of more windows during high temperature and high humidity in summer, to maintain good indoor air quality and effectively age the emission of VOCs from furniture. This study contributes to the enhancement of the database on indoor air quality and effective ventilation strategies in cold regions for safeguarding public health.

A Remote Sensing Approach to Characterize Cold Region Watershed Storage and its Influence on Streamflow Generation

A Remote Sensing Approach to Characterize Cold Region Watershed Storage and its Influence on Streamflow Generation

Refined Simulation Study of Hydrodynamic Properties and Flow Field Characteristics around Tandem Bridge Piers under Ice-Cover Conditions

Ice cover is a common phenomenon in rivers in cold regions during the winter freeze-up period, leading to the formation of unsteady bypass structures around underwater piers. To reveal the variation law of the flow field around a pier under ice, a numerical calculation method is proposed to obtain the spatial and temporal characteristics of the fluid flow environment around the pier. The verification of flow conditions and convergence showed that the numerical model constructed in this study is reliable and can meet research requirements. The simulation results showed that the ice-cover condition considerably impacted the extent of a scour hole, and in the horizontal plane Z of −0.02 m, the lateral influence of the scour hole was approximately 2.6 times the diameter of the pier, which was approximately 42% wider than that of a scour hole under open-flow conditions; in the area on the side of the pier, there was a peak in longitudinal section y/D of −0.6, and the relative turbulence intensity was 0.4 and 0.51 under open-flow and ice-cover conditions, respectively, indicating that ice cover made the peak more significant in the area.

Nitrogen and magnesium codoped biochar activates periodate to remediate bensulfuron methyl-contaminated water at low temperature: Performance, mechanisms, and phytotoxicity

Bensulfuron methyl (BSM), a typical sulfonylurea herbicide, has been widely used worldwide for weed suppression and crop protection. Nevertheless, the long-term and prolonged usage led to residues in environment, resulting in the reduction of crop yields and even threatening food security. In this study, the nitrogen/magnesium codoped biochar (NMg-BC) was prepared via two-step pyrolysis method to activate periodate (PI) for BSM degradation. The results demonstrated BSM degradation rate was 87.9 % within 10 min by NMg-BC/PI system at 15 ℃. The system exhibited the favorable tolerance to environmental changes (pH, temperature, anions, and humic acids), presenting high removal efficiency of BSM. Radicals (IO3•) and non-radicals (1O2 and electron transfer) pathways contributed to the degradation of BSM, while the latter performed a crucial role in BSM degradation. Theoretical calculations further confirmed doped of N and Mg changed the electron configuration and electrostatic potential (ESP) distribution of biochar, which was beneficial to provide more active sites for PI activation. Hydroponic experiments showed that NMg-BC/PI system could effectively degrade BSM, and its residue had no significant effect on the length and weight of soybean. The study provides a promising approach for the pollutant remediation in cold regions.

Design and fabrication of high-performance ultrafiltration membranes for low-temperature conditions

The influence of cold weather conditions on ultrafiltration (UF) membrane performance is noteworthy. Investigating alterations in UF membrane fouling behavior under low-temperature conditions and developing strategies to enhance their performance holds significant importance for advancing membrane separation technology in cold regions. We initiate an exploration into how low-temperature conditions impact the permeation and separation capabilities of unmodified PES UF membranes, concurrently scrutinizing the associated influencing mechanisms. Employing molecular design, we strategically incorporate hydrophilic carboxyl-functionalized groups into the molecular structure of poly (aryl ether sulfone) materials. This method facilitates the development of a series of PAES-modified UF membranes (LTM-x%), exhibiting exceptional performance in low-temperature conditions, grounded in the principles of the hydration layer theory. In a low-temperature condition (5±1 °C), the BSA solution flux and SA solution flux of the LTM-80 membrane surpass the pristine PES membrane flux by 187.38 % and 171.82 %, respectively. Notably, compared to the solution flux at room temperature (22±1 °C), the LTM-80 membrane shows only a slight decrease in the 5±1 °C temperature (flux decline rates of 18.52 % for BSA solution and 15.12 % for SA solution), in contrast to the pronounced decline observed in the pristine PES membrane (49.24 % for BSA and 47.67 % for SA). This investigation unveils an effective and viable strategy for designing and developing high-performance UF membranes suitable for cold regions.

3D Modeling Simulation and Innovative Design of a Saw Cutting Mechanism for a Movable Buckling Machine

In this research, a sawing mechanism of a mobile buckling machine was innovatively designed for the forest resources and environmental characteristics of the northeast region of China. The northeast region of China is rich in forest resources, but the climate is cold, which puts high demands on the performance and adaptability of mechanical equipment. In this study, the three-dimensional modeling of the saw-cutting mechanism was completed by Pro/Engineer 5.0 modeling software, and an in-depth dynamics simulation analysis was carried out using dynamics simulation software. The study aims to assess the applicability of this saw-cutting mechanism in the northeast region of China, analyze its design characteristics, and explore possible directions for performance optimization. Through this study, we expect to provide valuable references for future technological innovations, as well as to promote the practical application and development of mobile buckling machines in cold regions. This research not only has regional characteristics, but also reflects the innovative idea of combining mechanical equipment design with environmental adaptability.

Experimental Study on the Combined Heat Storage and Supply of Air/Water-Source Heat Pumps

As the application of renewable energy becomes increasingly extensive, heat pump technology with renewable energy as the heat source is achieving good results. Air-source heat pumps and water-source heat pumps can be widely used in cold areas. In this work, an integrated combined storage and supply system of an air-source heat pump and a water-source heat pump was studied, and the heating characteristics of the system at the beginning, middle, and end of the heating period were examined. It was found that, when the outdoor temperature of the system was very low, the efficiency of the combined storage and supply system reached the highest value of 2.57 when the source-side water tank was kept at 30 °C, and the performance of the combined storage and supply system was better than that of the air-source heat pump and the water-source heat pump in cold regions. Meanwhile, the independent storage of the air-source heat pump and the combined storage and supply system can be used for heating at the beginning and end of the heating period.

A Quasi-Steady Model for Estimating the Rate of Frost Heave When Subjected to Overburden Pressure

The soil beneath buildings constructed in cold regions is affected by frost heave, causing the walls to crack and even the buildings to incline and collapse. Therefore, predicting the frost heave when subjected to overburden pressure is crucial for engineering buildings in cold areas. Utilizing the conservation equation of mass, Darcy’s equation, and the assumption that the pore water pressure at the top of a frozen fringe, denoted as uw, during the quasi-steady state can be approximately estimated using the Clapeyron equation, a quasi-steady frost heave rate model considering the overburden pressure was proposed. This study considered the difference in pore water pressure within the frozen fringe, which causes water to move from the unfrozen zone to the ice lens, where it subsequently accumulates and freezes into ice. The pore water pressure at the bottom of the frozen fringe, denoted as uu, can be estimated using the soil water characteristic curve (SWCC). The thickness of the frozen fringe was determined using the freezing temperature, segregation temperature, and temperature gradient. The segregation temperature was determined using the two-point method. Additionally, the model suggested that, when uw = uu, the movement of water stopped, leading to the end of frost heave. To validate the proposed model, three existing frost-heaving experiments were analyzed. The findings demonstrated that the estimated rates of frost heave of the samples closely matched the experimental data. Additionally, external pressure delayed water migration. This study can offer theoretical support for building engineering in cold regions.

Ecological Stoichiometry Characteristic of Phytoplankton in Mountain Stream

This research investigated the phytoplankton ecological stoichiometry characteristics and the balance of the relationship between elements in a mountain river in a cold region. The samples of phytoplankton of four seasons were collected in May 2020, August 2020, November 2020, and February 2021 from the Taizicheng River in Chongli, Zhangjiakou City, China. We determined the contents of carbon (C), nitrogen (N), phosphorus (P), sulfur (S), hydrogen (H), and iron (Fe), and analyzed their ecological stoichiometric characteristics and correlation. Our results showed that the contents of C, N, P, S, H, and Fe in phytoplankton were 82.14 ± 32.12 g/kg, 9.22 ± 3.5 g/kg, 1.46 ± 0.55 g/kg, 1.96 ± 0.86 g/kg, 2.36 ± 1.36 g/kg, and 12.64 ± 10.57 g/kg, respectively. Generally, the contents of C, N, and P were relatively stable, while the contents of S, H, and Fe fluctuated greatly, and the coefficient of variation of Fe content was as high as 83.62%. The elemental molar composition of phytoplankton in the Taizicheng River is C156.00N15.41S1.54H51.17Fe5.10P, which showed a significant difference compared with the classical Redfield ratio C106N16P. The high proportion of element C indicated that phytoplankton in the Taizicheng River have a high demand for C and a strong ability to consolidate C. The ratio of N:P was consistent with previous research results. The N:P ratio of phytoplankton in the Taizicheng River was 15.41, suggesting that the growth of phytoplankton in the Taizicheng River was restricted by both N and P. The contents of C, N, and P were positively correlated, while there was no significant correlation among S, H, and Fe. C:P was significantly positively correlated with C:N and N:P, while there were no strong correlations between C:N and C:P, as well as H:S, Fe:S, and H:Fe, indicating that the coupling correlation between phytoplankton elements was different and C, N, and P were highly correlated as important phytoplankton nutrient elements. This study contributes to our understanding of the phytoplankton ecological stoichiometry characteristics and the limiting factors of nutrients in a mountain river and provides a scientific basis for further ecological conservation and management efforts.

Impact of Spatial Layout Design on Energy Consumption of Ice Rinks in Cold Regions

The differentiated physical environment requirements within the internal space of ice rinks in cold regions result in a complex heat exchange process, which becomes the primary cause of high energy consumption. Therefore, analyzing the impact mechanisms of spatial layout parameters on the energy consumption of ice rinks is crucial during the early design stages. This study employed the Delphi method to identify the key parameters affecting the total energy consumption of ice rinks. It conducted single-factor experiments using building performance simulations to quantify the relationship between each layout parameter and the energy consumption. Based on the single-factor experiment results, orthogonal experiments were conducted to develop an energy-efficient spatial layout combination. The study indicates that the height-to-width ratio and the mixed area width are the most significant parameters. By adjusting the values of these parameters, the total energy consumption can be reduced by approximately 18% to 31%. The spatial layout strategy for ice rinks in cold regions proposed in this study will help architects make more effective decisions during the early design stages.

Investigation on rock damage associated with ice-filling borehole blasting

Rock excavation and ore extraction in cold regions (e.g., alpine and high-altitude regions) are often conducted using the drill and blasting method. Ice may be presented in boreholes drilled in cold regions due to the potential freezing of water (e.g., water in rock fractures and pores) flowing into boreholes from the surrounding ground. The performance of rock blasting is inevitably affected by the presence of ice and no study has examined the effect of ice in boreholes on rock blasting performance. The present study investigates rock damage induced by the ice-filling borehole blasting. The damage modes and mechanisms of rock mass under the ice-filling borehole blasting are analyzed. The differences of rock damage induced by the sole ice-filling borehole blasting and the ice-water and ice-air mixed filling borehole blasting are identified. The effects of ice volumes in boreholes on blast-induced rock damage are examined. It is found that blast-induced rock damage is greatly reduced as water in boreholes turns into ice. In addition, the blasting with the ice volume greater than 6.7 % filled at the bottom of borehole can induce less rock damage compared to full-coupled charge blasting. To improve the performance of rock blasting with ice-filling boreholes, the effects of two methods, i.e., changing ignition locations and using different types of explosives on rock damage induced by the ice-filling borehole blasting are investigated. An empirical formula of rock damage volume incorporating ice volume, explosive properties, and rock properties is finally proposed as the reference for the design of ice-filling borehole blasting in cold regions.

Shore ice control on coastal geomorphic evolution in cold regions

Shore ice is a common feature on cold climate coasts, which are abundant in mid- and high-latitude regions, however it is understudied. Previous research has reported both beach protection and erosion as potential impacts from shore ice presence. Altered ice dynamics resulting from a changing climate are likely to intensify these impacts. To address this discrepancy and improve future coastal change predictions we conducted the first combined field, laboratory and modeling study of shore-ice processes and impacts. Beach and nearshore morphology mapping, experiments with a novel cryogenic wave tank, and 3D coastal evolution modeling revealed that shore ice protected the beach from storms, but scoured the nearshore at the ice edge and transported sediment offshore, likely past the depth of closure. This resulted in enhanced beach erosion during the ice-free and non-storm season, countering the protective benefit from the ice. This study indicates that shore ice plays an important and likely evolving role in geomorphic evolution along cold climate coasts.

Heating performance of PCM radiant floor coupled with horizontal ground source heat pump for single-family house in cold zones

As the energy demand for space heating increases, the necessity for innovative and energy-efficient heating technologies has become more urgent. This study proposes and evaluates a heating system that integrates a phase change material radiant floor with a horizontal ground source heat pump (PCM floor-HGSHP, Case 1), intending to maintain indoor comfort temperatures and enhance energy efficiency through the utilization of renewable energy sources. Despite the considerable potential of PCM floors, their combination with HGSHP requires further research to fully unlock their benefits. The study involved simulating the PCM floor using a validated TRNSYS component and developing an advanced rule-based control strategy with time-of-use tariffs as a key input to optimize system operation. To elucidate and quantify the advantages of the PCM floor-HGSHP system and verify its applicability in cold regions of China, a single-family house was used as a case study building, four representative cities were selected, and two comparative simulation cases were defined, along with three key performance indicators. The results indicate that, compared with the radiant floor heating system with HGSHP (RFHS-HGSHP, Case 2), the incorporation of PCM in the floor of Case 1 improves the indoor temperature stability by 8.6 %, enhances the load flexibility by 18.1 %, and reduces the total operating costs by 13.8 %. Furthermore, relative to the PCM floor with air-to-water heat pump system (PCM floor-AWHP, Case 3), the proposed system which substitutes the AWHP with the HGSHP, extends the duration of indoor comfort temperatures by 9.6 % and decreases the system electricity consumption by 33.7 %. The proposed system demonstrates excellent thermal and energy performance across all selected cities, proving to be both technically feasible and significantly beneficial for maintaining indoor comfort temperatures and reducing operational costs. This study offers valuable insights and technical support for designing and optimizing residential heating systems in cold regions, thereby promoting the development and application of renewable energy sources.

Pavement damage characteristics in the permafrost regions based on UAV images and airborne LiDAR data

The rapid degradation of “Xing'an-Baikal permafrost” in Northeast China has led to various road engineering problems. Efficient inspection and control of pavement quality are critical for maintaining the structural integrity of roads and driving safety in cold regions. Taking the Jagdaqi-Walagan section (JWS) of the Jagdaqi-Mo'he Highway as the object, based on field investigation, unmanned aerial vehicle images and airborne LiDAR data, combined with geographical information system, this study analyzed the pavement damage characteristics in mid- to high-latitude permafrost regions, including quantification of damage ratio, extraction of pavement cracks, and evaluation of pavement roughness and driving quality. The results showed that the average pavement damage ratio was 8.80 %, significantly higher in isolated permafrost regions. A higher damage rate in the Jagdaqi-Mo'he direction than the opposite, with a more concentrated cracking distribution. The worst pavement roughness and most severe pavement bumping at repetitive repair locations. This study provides an effective method for investigating pavement damages and analyzing their mechanisms, and explores the application potential of visible light images combined with LiDAR data in frozen soil engineering. The results provide a scientific basis for assessing current highway conditions, enabling scientific maintenance, and evaluating the risk of engineering damages.

Frost resistance of recycled aggregate concrete subjected to coupling sustained compressive load and freeze-thaw cycles

Recycled aggregate concrete (RAC) structures situated in cold regions are required to withstand the combined effects of mechanical load and environmental factors throughout their operational lifespan. The influence of sustained load introduces complexity to the degradation mechanism of RAC. This research examines the frost resistance of RAC across varying levels of recycled coarse aggregate (RCA) replacement (0, 50 %, 100 %) and sustained compressive loading (0, 0.3 fc, 0.5 fc). The frost resistance was quantified by the indices of macroscopic morphology change, mass loss, relative dynamic modulus of elasticity, and mechanical properties. Results show that 0.3 fc can effectively improve the frost resistance of RAC, a trend that becomes more pronounced with increasing replacement rates of RCA. Excessive stress (0.5 fc) was found to be unfavorable to the frost resistance of RAC and increase the compressive strength variability of RAC after freeze-thaw cycles. Analysis of meso/micro-structure characteristics using optical and scanning electron microscopes, along with the mercury intrusion porosimetry, reveals that optimal compressive loading (0.3 fc) enhances mortar integrity, reduces porosity, and improves compactness, thereby bolstering RAC’s frost resistance.

Performance analysis of an R290 vapor-injection heat pump system for electric vehicles in cold regions

Performance analysis of an R290 vapor-injection heat pump system for electric vehicles in cold regions

Advancing Food Security in the Cryolithozone and Exploring Organic and Mineral Fertilizer Strategies for Enhanced Crop Yields

The Cryolithozone, characterized by its frozen soil and harsh climatic conditions, presents unique challenges to agricultural productivity and food security. As global temperatures rise, the thawing of permafrost in the Cryolithozone offers opportunities for agricultural expansion but also raises concerns about soil degradation and nutrient loss. In this article, we explore innovative approaches to enhance crop yields and food security in the Cryolithozone, focusing on the integration of organic and mineral fertilizer strategies. We discuss the potential benefits and challenges of utilizing organic fertilizers, such as compost and manure, to improve soil fertility and mitigate nutrient deficiencies. Additionally, we examine the role of mineral fertilizers in supplying essential nutrients to crops in nutrient-deficient Cryolithozone soils. By synthesizing current research and best practices, we propose holistic fertilizer management strategies tailored to the unique environmental conditions of the Cryolithozone. These strategies aim to optimize nutrient utilization efficiency, minimize environmental impacts, and promote sustainable agricultural development in cold regions.