Heating Cables Research Articles

Research and Application of Online Electromagnetic Heating System with Internal Penetration in Oil Pipeline at Well Site

Abstract In response to the current situation of heating crude oil in the oil pipeline of Changqing Oilfield, most of the well sites have no associated gas, gas heating furnaces have been discontinued, and coal-fired heating furnaces pollute the environment. A study was conducted on the online through type heating system for the oil pipeline in the well site, with a focus on the composition and function of the digital heating system for the through type oil pipeline in the well site. The through type online heating system for the oil pipeline in the well site is mainly composed of a variable frequency electromagnetic controller The online controller and internal heating cable are composed of three parts. The oil pipeline generates heat by itself, while preventing the crystallization of paraffin and scale in the oil pipeline under the action of alternating electromagnetic fields, which is not easy to form wax. In 2023, on-site application was carried out on two oil pipelines in the Tongzhai operation area of the Third Oil Production Plant in Changqing Oilfield, replacing the existing gas heating furnaces and coal-fired heating furnaces to heat and transport crude oil in the oil pipelines. It does not generate heat itself and has a long service life. Due to the high thermal efficiency of the heat source coming from the inside of the oil pipeline, the buried pipeline renovation can be installed without breaking the soil. The flexible internal cable reduces the difficulty of construction and is safe and environmentally friendly, At the same time, it can remotely monitor the temperature of crude oil in the oil pipeline and the wellhead backpressure online.

Magnetic field of electrical heating cable systems of the floors for residential premises

Problem. In order to effectively protect public health from the magnetic field of electric heating cable systems of the floors, it is necessary to reduce it to a safe level. However, this requires careful study of the magnetic field. The purpose of the work is to develop a mathematical model and a verified methodology for calculating the magnetic field of electric heating cable systems of the floors in residential premises, and assessment of compliance of the magnetic field with the normative level. Method. A methodology for calculating the magnetic field of electric heating cable systems of the floors in residential premises has been developed. Scientific novelty. Based on Bio-Savar’s law and the principle of superposition, an analytical model of the magnetic field of electric heating cable systems of the floors and its calculation method was created. The magnetic field of the coaxial heating cable is determined, taking into account the value of its maximum eccentricity. The experimentally substantiated correctness of the obtained theoretical statements, which is confirmed by their coincidence with the results of the experiment with a spread of less than 7 %. Practical significance. A verified methodology for calculating the magnetic field of electric heating cable systems of the floors was proposed and an assessment of compliance of their magnetic flux density with the normative level of 0.5 μT was performed. It is recommended to lay modern two-wire heating cables at a depth of at least 75–100 mm from the floor. With a smaller laying depth, it is recommended to use coaxial heating cables, which have an order of magnitude smaller magnetic field. References 51, tables 1, figures 11.

Experimental study on snow melting and deicing of carbon fiber heating roads considering thermal insulation conditions

The electrothermal method for snow melting and deicing in road engineering provides efficient deicing. To improve the ice melting efficiency of carbon fiber heating cables, employing extruded polystyrene foam board (XPS)、polyethylene foam cotton (PEF) as insulation materials under the carbon fiber heating wire could reduce heat transfer to the lower layers of the road structure. Road model tests were conducted under various conditions to analyze how different heat insulation conditions、environmental temperatures affect road snow melting and ice melting. The results indicate that the placement of the heat insulation layer significantly affects the temperature fluctuation range between its upper and lower layers.The ice melting rate increases by 25∼50 % compared to pavement structures with no heat insulation layer. When heat insulation material is incorporated into the road structure layer, under preheated conditions, snow with a thickness of 0.2 cm on the surface of the plate heat insulation model can completely melt within 2.5 h, reducing the effective ice-melting time by 40∼51.7 %. A comparison of the thermal performance of the two insulation materials under various conditions reveals that the XPS plate is more suitable as an insulation layer compared to other materials.

Assessing water position through distributed temperature sensing using Rayleigh-based optical frequency-domain reflectometry: a laboratory feasibility study

This study demonstrates the ability of the Rayleigh-based phase-noise compensated optical frequency-domain reflectometry (PNC-OFDR) sensing method to monitor the distributed temperature field with an ultra-short data acquisition period of 2 ms, a spatial resolution of 2 cm, and a temperature resolution of 0.1 °C. A heating cable (H-cable) was embedded within a cylindrical concrete mortar specimen and subjected to various heating powers. A sensing optical cable (T-cable) was placed adjacent to the heating cable to monitor the temperature distribution continuously. Two water-holding boxes were installed along the specimen at two positions to retain water. The results of the study indicated that the PNC-OFDR technique demonstrated a high sensitivity to even small temperature changes, enabling it to accurately pinpoint the locations of water at two distinct points. The research determined the minimal heating power required for successfully locating the water positions. The magnitude of the heating power exerted a significant impact on the temperature change. Three distinct phases of temperature increment were observed for a given heating period: rapid, fast, and gentle increase. The insights gained from this study have the potential to be applied in natural fields, allowing for the detection of groundwater and seepage phenomena in vulnerable slopes.

Model Optimization of Ice Melting of Bridge Pylon Crossbeams with Built-In Carbon Fiber Electric Heating

This paper aims to improve the deicing performance and energy utilization of bridge pylon crossbeams with built-in carbon fiber electric heating (BPB–CFEH). Therefore, a three-dimensional thermal transfer model of BPB–CFEH with one arrangement is established. Two ice-melting regions and two ice-melting stages were set up according to the characteristics of the icing of the crossbeam. The effects of wind speed and ambient temperature on the paving power required to reach the complete melting of the icicles within 8 h were analyzed. The effects of the laying spacing and rated voltage of the carbon fiber heating cable on the melting ice sheet and the thermal exchange of the two regions of the icicle after heating for 8 h were compared. Additionally, its effect on energy utilization of the process from the ice sheet melting stage to the ice column melting stage was analyzed. Ice-melting experiments verified the applicability and reasonableness of the simulated ice-melting calculation formula. The results show that under ambient temperature of −10 °C and wind speed of 4.5–13.5 m/s, the proposed paving power is 817.5–2248.12 W/m2. Increasing the rated voltage and shortening the spacing increases the thermal exchange capacity of the two melting regions. The shortening of the spacing improves the energy utilization rate of the melting stage of the ice sheet to the melting stage of the icicle processes. The difference between the melting time obtained from the formula proposed by numerical simulation and the melting time obtained from indoor tests is about 10 min. This study provides a design basis for the electrothermal ice melting of bridge pylon crossbeams.

Деструктивные явления при некачественном прогреве монолитных железобетонных конструкций

The growth of the number of the building floors inevitably leads to an increase in the construction period and, consequently, to the need for monolithic reinforced concrete structures in winter. Electric heating by means of heating cables is the most widespread method of concrete curing in winter conditions in the Central region of Russia. The risk of defects in monolithic reinforced concrete structures increases under certain conditions. This risk is related to various types of technological process faults. The main types of monolithic structures defects have been repeatedly described. But there are practically no papers describing the types and causes of defects associated with failures during electric heating of concrete. The author has developed a block diagram of the main defects, and the main reasons for their occurrence have been identified. The paper summarizes the experience gained during two winter periods at the construction sites of Moscow city belonging to unique buildings and structures. Operational and quality inspection of the construction was performed. The author identified groups of defect causes: cable installation and installation errors; heating regime errors. The author identified specific types of defects for each group, and also gave recommendations on their avoidance in the future. The paper provides a ‘check list’ of parameters that must be checked during electric heating with heating cables. The checklist shows the control points that minimize the risk of defects.

Experimental Study on a Photovoltaic Direct-Drive and Municipal Electricity-Coupled Electric Heating System for a Low-Energy Building in Changchun, China

This paper takes a low-energy building in Changchun, China, as an object to test and study the characteristics of two heating modes, AC/DC (Alternative current/Direct current) switching and AC/DC synthesis, from the perspectives of temperature change, irradiation intensity, power generation, electricity consumption, etc. Firstly, the experimental research was conducted under two heating cable modes by establishing mathematical models and a test rig, and it was found that the photoelectric conversion efficiency on sunny, cloudy, and overcast days was 18%, 14.5%, and 12%, respectively. A simulation model was established by TRNSYS to run an ultra-low-energy building throughout the year. It was found that the highest and lowest monthly power generation occurred in February and July, respectively. The annual power generation of the system was 6614 kWh, and the heating season power generation was 3293.42 kWh. In the current research, the DC electricity consumption was slightly higher than the AC electricity consumption. Under conditions of similar radiation intensity and power generation, the indoor temperature of the AC/DC synthesis cable heating mode were 1.38% higher than the AC/DC switching heating able mode, and the electricity consumption were 10.9% and 4.76% higher, respectively, than those of the AC switching heating cable mode. This is of great significance for clean-energy heating, energy savings, and emissions reduction in northern China.

Thermal circuit model of DC submarine cable considering the influence of seawater property variations

The IEC 60287 standard, when calculating the steady-state current-carrying of DC submarine cables, does not take into account the influence of seawater property variations on changing the heat transfer efficiency of seawater, thereby affecting the current-carrying capacity of the cable. resulting in deviations in the calculated ampacity results. This paper considers the influence of seawater heat transfer characteristics on cable heat dissipation efficiency based on heat transfer theory, and Proposes an improved thermal circuit model for submarine DC cables that takes into account variations in seawater properties. Taking the example of a 160 kV submarine XLPE cable, the current-carrying capacity results of the improved model have an error of no more than 1.9 % compared to finite element simulation results. Under identical environmental conditions, the maximum deviation between the improved model and the IEC thermal circuit model is 123A, confirming the necessity of considering variations in seawater properties in the improved thermal circuit model. The seawater property variations studied in this paper include changes in seawater temperature, salinity, and pressure. If the impact of seawater property variations on submarine cable current-carrying capacity is not considered, the obtained current-carrying capacity results are higher, with a maximum error of 5.5 %. Among these variations, temperature has the most significant impact, with an error reaching 3.3 %, while salinity and pressure have relatively smaller impacts, with errors of 1.1 % each.

Modeling of the removal of combustion products in the pipe of a low-rise building as a control object

The features of the formation and methods of preventing condensation in the chimney of an apartment low-rise building with an individual decentralized heat supply system are considered. A mathematical model of the technological process of removing flue gases from gas boilers in an apartment building through a collective chimney pipe as a multidimensional control object with distributed parameters, which is understood as a set of thermophysical processes occurring during the removal of combustion products. Numerical simulation of a collective chimney pipe is performed on the example of a three-storey apartment building with gas boilers installed in each apartment as a control object. A method of step-by-step experiments is proposed. At the first stage, the dependences of the distribution of the temperature field inside the chimney during non-stationary operation of boilers and changing ambient temperature are obtained. The phenomenon of condensate occurrence has been confirmed experimentally, and the most characteristic areas subject to its occurrence have been identified. During the second stage of research, it was found that it is most effective and economically feasible to prevent the formation of condensate by using a heating cable in the attic and chimney head sections. It is shown that the change of control actions has an effect on the temperature of adjacent sections of the chimney. The revealed non-stationarity is taken into account by inter-channel connections through the object in the block diagram. It is proved that, in relation to solving the problem of removing combustion products from the chimney, an object with distributed parameters can be represented by a model with concentrated parameters, for which the structure is synthesized and proper operators and operators of inter-channel connections are found in the form of transfer functions with variable parameters. The resulting model is problem-oriented to create a two-dimensional automatic temperature control system on the inner surface of the chimney in order to prevent the formation of condensate in the pipe.

Performance analysis of thermally and non-conductive cement mortar prepared from waste iron scraps and magnetite sand

ABSTRACT The existing thermal conductive pavement exploits heating cables as the heat source commonly. However, the poor thermal conductivity of the upper layer in the pavement structure results in a low energy utilisation efficiency. In order to ensure energy transfer efficiency and reduce energy consumption, this paper investigates the application of waste iron scraps and magnetite sand in cement-based materials. The mechanical properties, electrical conductivity and thermal conductivity of cement mortar were tested by ISO method, two-electrode method and plate steady-state method, and the drying shrinkage condition of the specimens was studied by drying shrinkage test. The results showed that there was a critical value of mechanical property enhancement of mortar by waste iron scraps and magnetite sand, while the electrical and thermal conductivity were positively correlated with their admixtures. The study obtained the optimal ratio of waste iron scraps and magnetite sand in the system that would exhibit excellent thermal and mechanical properties while having low electrical conductivity. It can be concluded that this study provides suggestions for solving the problems of low exploitation rate of solid waste and low heat transfer efficiency of thermal conductive pavement.

Preparation of Self-limiting Heating Cables with Excellent Processability, Mechanical Properties and PTC Effect via Thermal and Electrical Treatments

Preparation of Self-limiting Heating Cables with Excellent Processability, Mechanical Properties and PTC Effect via Thermal and Electrical Treatments

Evaluating an enhanced thermal response test (ETRT) with high groundwater flow

Enhanced thermal response tests (ETRT) enable the evaluation of depth-specific effective thermal conductivities. Groundwater flow can significantly influence the interpretation of ETRT results. Hence, this study aims to critically evaluate an ETRT with high groundwater flow (> 0.2 m d−1). Different approaches in determining the specific heat load of an ETRT are compared. The results show that assuming constant electrical resistance of the heating cable with time can account for an inaccuracy of 12% in the determination of effective thermal conductivities. Adjusting the specific heat loads along the borehole heat exchanger (BHE) depth, the specific heat loads vary within 3%. Applying the infinite line source model (ILS) and Péclet number analysis, a depth–average hydraulic conductivity is estimated to be 3.1 × 10–3 m s−1, thereby, confirming the results of a pumping test of a previous study. For high Darcy velocities (> 0.6 m d−1), the uncertainty is higher due to experimental limitations in ensuring a sufficient temperature increase for the evaluation (ΔT > 0.6 K). In these depths, the convergence criterion of Δλeff/λeff < 0.05/20 h for the ILS sequential forward evaluation cannot be achieved. Thus, it can be concluded that time-averaging of the heat load by monitoring voltage and current during ETRT is essential. Therefore, the specific heat load adjustment along the heating cable is recommended. To improve the estimation of depth-specific effective conductivities with high groundwater flow and to reduce the sensitivity towards temperature fluctuations (ΔT ~ 0.1 K), measures for applying higher specific heat loads during the ETRT are essential, such as actions against overheating of the cable outside the BHE.

Analysis of heat transfer and prediction of preheating time of snow-melting on a highway T-beam bridge deck

Electrical heating is an innovative method of preventing icing of bridge decks during winter. Turning on the heating system before snowfall to prevent the icing of the bridge deck is more advantageous than melting already-formed ice. This article analyzes the heat-transfer performance of a bridge deck with heating cables during preheating before snowfall and predicts the preheating time of the bridge deck. Firstly, the temperature rise law and the state of the bridge deck with heating cables were studied through field experiments. Subsequently, a numerical model was developed. The effects of four factors on the heat-transfer performance of the bridge deck were analyzed. Finally, a bridge deck preheating-time model was established based on a multilayer perceptron regressor. This study enriches the application of neural networks and numerical simulations in preventing ice formation using the electrical heating method and is important for optimizing the heating system scheme and saving energy.

ОБЕСПЕЧЕНИЕ КАЧЕСТВА ПРОЕКТИРОВАНИЯ РЕЗИСТИВНОГО НАГРЕВАТЕЛЬНОГО КАБЕЛЯ НА ОСНОВЕ РАЗРАБОТКИ МЕТОДИКИ МАТЕМАТИЧЕСКОГО РАСЧЕТА

The article is devoted to developing a mathematical model for calculating the electrical and design parameters of a resistive heating cable. The aim of the work is to consider the main stages of designing a heating cable and to develop a methodology for calculating its main parameters and design, which will ensure the quality and performance characteristics of the future product that meets all modern technical, technological and economic requirements. The main stages of the heating cable design process are described and recommendations are given on selecting materials, calculating the electrical and design parameters, namely: rated power, electrical resistance, diameters and mass of conductors, insulation, shield and shell. Based on the electrically conductive shield design the paper examines in detail methods for calculating the weight and size parameters of shields in the form of a copper grounding conductor with foil, as well as in the form of a screening braid made of copper wires. The proposed methodology for calculating a resistive heating cable allows considering the design process in more detail. It is at this stage that the future product quality is determined, while ensuring the required characteristics and parameters, as well as reliability and consistency of the performance throughout the product entire life cycle.

Influence and comprehensive evaluation of porous metal foam filled fins on the performance of power cable surface waste heat recovery thermoelectric power generation device

Cables are essential components in power systems. Certain amount of heat is generated during the energy transfer process. Effective recovery and utilization of waste heat generated by cables is a helpful proposition. In this study, a cable waste heat recovery thermoelectric generation device (CTEG) is proposed. By installing cooling fins and thermoelectric generation devices on the cable surface, the waste heat on the cable surface is converted into electric energy. To improve the power generation efficiency of the device, a method of filling porous metal foam material in the fin teeth gap is used. The results demonstrate that filling the fin teeth gap with porous metal foam material with high porosity and low pore density (PPI) can significantly increase heat transfer efficiency and benefit the output power of the thermoelectric generation device. The flow field in the pipeline of thermoelectric generation device is also analyzed in this study. A comprehensive evaluation method is proposed to consider the power generation efficiency and heat transfer efficiency of the thermoelectric generation device. It is shown that filling porous metal foam material with high porosity and low pore density can maximize the power generation efficiency of the thermoelectric generation device, and at the same time, the pipe pressure drop loss can be compensated by the improvement of heat transfer. This research is significant because it provides useful information for enhancing the energy conversion efficiency of thermoelectric generation devices that recover waste heat from cable surfaces and generate electrical power.

Determination of Harness Production Time and Defective Product Formation Risk Factors with Artificial Neural Network

The aim of this research is to estimate the projected production times of the cable harnesses produced for the tender in a company operating in the aviation and defense industry in our country by artificial neural network. For this, artificial neural network model has been formed for the number of work order, the number of cable harness module, the number of cable harness pin, the number of cable harness label, the number of cable harness back shell, the number of cable harness heat shrink tube, and the number of cable harness terminal variables which may have an effect on the projected production times of cable harnesses for the tender. Multiple linear regression analysis method is used to compare the predictive power of this model and the most appropriate method for estimating the projected production time of cable harnesses for the tender is provided. The aim of the research is to determine the effect of cable harness connector type, cable harness label type and personnel competence level risk factors on the formation of faulty cable harnesses determined during the quality control and electrical testing steps in the production process using logistic regression analysis.

Comparative studies and optimizations of air distribution of underground building ventilation systems based on response surface methodology: A case study

As underground enclosed buildings, utility tunnels have limited ventilation conditions. An efficient ventilation system is necessary for improving the indoor thermal environment and air quality in utility tunnels. In this paper, exhaust fan ventilation (EFV), relay fan ventilation (RFV), and innovative wall-attached ventilation (WAV) schemes are compared using a series of evaluation indicators (i.e., energy efficiency coefficient, nonuniform coefficient, temperature not guaranteed rate, and age of air). The results show that the WAV scheme offers a higher ventilation efficiency, while decreasing the age of air and providing a uniform air distribution. Thus, the WAV scheme is recommended for utility tunnel ventilation systems. Additionally, the WAV scheme is further optimized and analysed based on response surface methodology (RSM). The influence of different factors (i.e., the slot outlet height (h), slot outlet width (b), air-supply velocity (u0), and cable heat source intensity (q)) on the evaluation indicators is studied, and the optimal design scheme (h = 1.40 m, b = 0.12 m, u0 = 3.00 m/s, q = 74.5 W/m2) is obtained and verified. The age of air in the optimal design scheme is 486.50 s. This paper can provide a reference for the ventilation design of urban underground buildings.

Climate change–induced stress disrupts ectomycorrhizal interaction networks at the boreal–temperate ecotone

The interaction networks formed by ectomycorrhizal fungi (EMF) and their tree hosts, which are important to both forest recruitment and ecosystem carbon and nutrient retention, may be particularly susceptible to climate change at the boreal-temperate forest ecotone where environmental conditions are changing rapidly. Here, we quantified the compositional and functional trait responses of EMF communities and their interaction networks with two boreal (Pinus banksiana and Betula papyrifera) and two temperate (Pinus strobus and Quercus macrocarpa) hosts to a factorial combination of experimentally elevated temperatures and reduced rainfall in a long-term open-air field experiment. The study was conducted at the B4WarmED (Boreal Forest Warming at an Ecotone in Danger) experiment in Minnesota, USA, where infrared lamps and buried heating cables elevate temperatures (ambient, +3.1 °C) and rain-out shelters reduce growing season precipitation (ambient, ~30% reduction). EMF communities were characterized and interaction networks inferred from metabarcoding of fungal-colonized root tips. Warming and rainfall reduction significantly altered EMF community composition, leading to an increase in the relative abundance of EMF with contact-short distance exploration types. These compositional changes, which likely limited the capacity for mycelial connections between trees, corresponded with shifts from highly redundant EMF interaction networks under ambient conditions to less redundant (more specialized) networks. Further, the observed changes in EMF communities and interaction networks were correlated with changes in soil moisture and host photosynthesis. Collectively, these results indicate that the projected changes in climate will likely lead to significant shifts in the traits, structure, and integrity of EMF communities as well as their interaction networks in forest ecosystems at the boreal-temperate ecotone.

Effects of Installing Different Types of Cooling Fins on the Cold Side of a Thermoelectric Power Generation Device on the Thermal Efficiency and Exergy Efficiency of Power Cable Surface Waste Heat Recovery.

This study investigates the thermal efficiency and exergy efficiency of a thermoelectric power generation device for recovering power cable surface waste heat. Numerical simulations are conducted to analyze the impact of different types of cooling fins on the system's performance. The results demonstrate that the installation of cooling fins improves heat transfer efficiency and enhances the thermoelectric power generation device's output power. Among the various fin designs, the system equipped with cooling fins with 17 teeth exhibits the highest performance. These findings highlight the importance of fin design in optimizing the system's thermal efficiency and exergy efficiency. This study provides valuable insights for the development and improvement of thermoelectric power generation systems for power cable surface waste heat recovery applications.

Development of a New Model for the Formation of Wax Deposits through the Passage of Crude Oil within the Well

Wax deposits related to flow assurance are a costly problem in oil production in many fields around the world. Modeling of this process is the main tool for creating and optimizing methods to deal with this problem. This paper considers a new empirical model for the formation of these deposits, based on the results of an array of laboratory studies, theoretical data and technological calculations are presented. The created technique takes into account the conditions of oil flow, data from laboratory studies, and the water cut of the product. The experience of the industrial operation of the technique showed a high convergence of the calculated and actual deposit profiles. Based on a comparison of the calculated and actual deposit profiles, it was concluded that the standard deviation of maximum wax thickness is 6.0%, and the depth with the greatest wax thickness is 3.5%, which is a fairly high result. The use of this technique makes it possible to optimize the depth of mechanical cleaning of the well, the installation of heating cables, as well as the parameters of hot flushing, which increases their efficiency and reduces the cost of combating the formation of wax deposition.