Installation Height Research Articles

Hydrodynamic and bearing behaviors of two typical deepwater dynamically installed anchors: torpedo anchor and fish anchor

Dynamically installed anchors, such as torpedo and fish anchors, are innovative and cost-effective anchorage foundations. In this study, the advantages and disadvantages of these two types of dynamically installed anchors are discussed by comparing the hydrodynamic and bearing characteristics of torpedo and fish anchors commonly used in practical engineering. First, based on OpenFOAM, 3D numerical models were established to investigate the directional stability and simulate the underwater free-fall process of anchors using static and dynamic model analysis methods. Using the validated model, the hydrodynamic performances (i.e., inclination angle, installation offset distance, penetration velocity, and drag coefficient) of torpedo and fish anchors were explored and compared. Based on these findings, the installation height of each anchor was recommended. Finally, the bearing performances of the torpedo and fish anchors were investigated using ABAQUS, and the selection principles of these two types of dynamically installed anchors were presented based on their hydrodynamic and bearing behaviors.

Improving the Uniform Distribution of Water Flux Density in Sprinkler Spray by Adopting Various Installation Methods

In a sprinkler system, the nonuniform water flux distribution resulting from the sprinkler head design, specifically due to the deflector and frame, impedes the primary extinguishing surface cooling effect of the sprinkler. In this study, the effects of the distance between heads, supplying flow rate, head installation direction, and head installation height on the uniformity of the water flux density distribution were investigated. Simulations were conducted using the water flux distribution reproduction method proposed in a previous study. As the distance between heads decreased, water was supplied to the bottom of the head, resulting in the improved uniformity of the water flux distribution. When the flow rate was corrected with the changes in the distance between the heads to maintain the average water flux density supplied to the floor, a uniform water flux distribution was observed even when the distance between heads was relatively large. In the case of head installation direction, the most uniform distribution was observed when the sprinkler heads were installed alternately at angles corresponding to 0° and 135°. As the installation height of the sprinkler heads increased, the difference between the maximum and minimum local water flux densities decreased, leading to a more uniform water flux density distribution.

Experimental studies of a remote device for biometric identification of the pre-mastitis state of the udder of dairy cows

Analysis of development of dairy cattle breeding in the Republic of Belarus is presented. The problems of reducing milk productivity and the period of economic use of dairy cows as a result of mastitis disease are noted. The importance of timely detection of sick animals, as well as treatment of the inflammatory process of the udder in the early stages is noted. The results of theoretical and experimental studies of a mock-up sample of a biometric identification device for the pre-mastitis state of udder of dairy cows are presented. In the course of experimental studies, a significant influence of ambient temperature on the thermal imaging picture was revealed, based on which the values of the radiation coefficient for cows were determined. The final adjustment of the previously established temperature ranges was made when determining one or another form of mastitis, namely, within 32.0−36.3 ℃ – the range of normal temperatures, 36.4−37.7 ℃ – “Subclinical mastitis”, 37.8−39.0 ℃ – “Clinical mastitis”. The most significant factors and optimization parameter have been determined. The percentage of the useful area of the studied object is selected as the optimization parameter. Based on the processing of experimental data, a mathematical model is obtained, described by a regression equation in the form of a polynomial of the second degree. The rational parameters of the device for biometric identification of the pre-mastitis state of the udder of dairy cows were obtained, namely: the angle of inclination of the thermal imaging module αо – 2,7o, the focal length to the object l – 794 mm, installation height of the thermal imaging module h – 495 mm. Also, based on the conducted research, priority areas and opportunities for development of the domestic agro-industrial complex through creation of integrated systems for monitoring the physiological state of animals within the framework of development of digital automated technologies of a “smart” farm have been identified.

Bowstring-type inerter negative stiffness damper for vibration control of slender towers

The difficulty of practical installation restrains the application of tuned damping devices in the high-performance vibration control of slender towers. In order to address this issue, a novel Bowstring-type Inerter Negative Stiffness Damper (BINSD) is proposed. The BINSD is composed of an inerter-negative-stiffness-dashpot system connected between the tower and a mass block (or a massless node) located on a vertical prestressed cable like a bowstring. In order to determine the multiple optimal parameters of the proposed BINSD, analytical parametric optimizations are investigated for the following three aspects. Firstly, the optimal tuning frequency and damping ratios are obtained via an analytical approach considering H∞ and H2 norms. Secondly, the optimal negative stiffness is determined by balancing the static and dynamic performances, particularly for practical excitations with mixed static and dynamic components (such as wind). Thirdly, the optimal installation height is analytically derived to fulfil a least negative stiffness criterion, which leads to an economic realization in practice. Finally, the effectiveness of the presented BINSD and corresponding optimal design approaches is numerically validated by the wind- and seismic- induced vibration control cases of a wind turbine tower. The proposed optimal design approaches lead to a high-performance, economic, and feasible design of BINSD.

Mechanical characteristics analysis of high dimensional vibration isolation systems based on high-static-low-dynamic stiffness technology

Large floating raft vibration isolation systems (FRVISs) based on high-static-low-dynamic stiffness (HSLDS) technology offer excellent low frequency vibration isolation performance with broad application prospects. However, the design process for these complex high-dimensional coupled nonlinear systems remains poorly developed, particularly when applied for ocean-going vessels that experience rolling and pitching motions. The present work addresses this issue by establishing a six-degree-of-freedom HSLDS vibration isolation model for FRVISs composed of eight isolators, and the model is applied to fully analyze the swing stability and multidimensional vibration isolation performance of these systems. The influence of nonlinearity on the mechanical properties of the vibration isolators is analyzed more clearly by assuming that each vibration isolator realizes nonlinear HSLDS characteristics in the z direction and linear characteristics in the x and y directions. The results demonstrate that the swing displacement responses of the system are greatly reduced under weak nonlinearity, which reflects the high static stiffness and high static stability characteristics of an HSLDS system. The multidimensional vibration isolation performance of the system is evaluated according to the impacts of nonlinearity, the installation height Hz of the isolators, and the relative position Dr of the two middle isolators. The results of analysis demonstrate that applying a value of Hz = 0 produces the best vibration isolation performance overall under strong nonlinearity by avoiding unnecessary secondary peaks in the force transmission rate under harmonic mechanical excitation and ensuring a maximum high-frequency vibration isolation effect. However, applying a weak nonlinearity is better than a strong nonlinearity if Hz is not zero. In contrast, Dr has little effect on the vibration isolation effect of the raft in the x, y, and z directions. Therefore, an equidistant installation with Dr = 0.5 would be considered ideal from the standpoint of installation stability.

Synergistic impact of horizontal fin installation height and nanoparticle volume fraction to enhance charging performance of phase change materials (PCMs)

This study numerically analyses the synergistic influence of nanoparticle and orthogonal fin on heat transfer performance of phase change materials using enthalpy-porosity method. The natural convection heat transfer and heat conduction during the melting process are coordinated by varying nanoparticle volume fraction and installation height of fin. Results illustrate that the optimal installation height of horizontal fin and nanoparticle volume fraction is 8.9 mm and 1.0 vol%, respectively. The corresponding total melting time is 1024 s and average energy charging rate is 484.5 W. Compared with the optimum conditions without nanoparticle (φ = 0.0 vol% and d = 7.0 mm), total charging time is reduced by 29.8% and average charging rate is increased by 51.1%. The equivalent Nusselt number demonstrates that the addition of high volume fraction nanoparticle decreases the convective heat transfer intensity. The low volume fraction nanoparticle enhances PCM thermal conductivity and has an insignificant effect on natural convective heat transfer. The Prandtl number demonstrates that when the volume fraction is 1.0 vol%, the effect of increasing thermal conductivity on strengthening heat conduction is greater than the negative effect of decreasing natural convection heat transfer caused by viscosity. Effective design guidelines to improve thermal charging performance of PCM-based LHTES devices are finally provided.

Design of heliostat field based on ray tracing

In the tower solar thermal power generation system, the optical efficiency of mirror field is the primary factor that determines the power generation efficiency of the whole system. Given the size and installation height of heliostat, in order to meet the requirements of rated Power 60MW, the parameters of heliostat field are designed and the model of tower solar thermal power generation system is established. Considering the cosine loss, shadow occlusion loss and truncation efficiency, and knowing that these three points are closely related to the position of the Sun, a method of ray tracing is proposed to calculate the sunshine accurately, the optimum parameters of helioscope field were determined by simulation. The simulation results show that the average thermal power output per unit mirror area can be increased by reducing the shadow occlusion between the heliostats.

Numerical investigation of the thermal efficiency of a multi-nozzle air curtain doorway under different wind conditions

Loading gate openings cause thermal inefficiency due to the substitution of indoor–outdoor air in cold seasons, and as a consequence, escalating energy consumption of warehouse buildings or unloading docks. Research findings have demonstrated that air infiltration/exfiltration through open doors results in the loss of a quarter of annual heating loads in buildings. Air curtains have shown a bright and promising future to compensate for the infiltration rate through the door opening, however, the most prior investigations were allocated to the jet planar air curtains and as yet there is a gap in the literature for other modified air curtain devices, including multi-nozzle air curtains (MNAC) with higher induction and resistance against the strong frontal winds, especially for gates higher than 4.27 m of installation height. Hence, in this work, designed MNAC with various configurations (i.e. large nozzles, small nozzles and holes) and installed on a warehouse loading gate was first characterized using the validated numerical turbulence model, SST (k−ω), to solve governing equations. The validate model is then used to evaluate the MNAC thermal efficiency, using the sensible energy gained by the inside zone, under various outside temperatures (−5, −10, −20, and −30∘C), and two wind conditions (i.e. with and without a front wind as recommended by ASHRAE (2010)). While the air curtains demonstrated limitations in fully controlling the infiltration rate during extremely cold and windy conditions, the results indicate that the MNAC systems have obtained thermal efficiency values higher up to 10% when compared to conventional planar air jets.

Optimization of Optical Efficiency Modeling and Heliostat Field Layout of Tower Solar Thermal Power Station

The aim of this paper is to study and optimize the layout of heliostat mirror fields in solar photovoltaic power plants to improve energy efficiency. By analyzing the key factors of optical efficiency, the optical efficiency model is constructed. The optical efficiency of a single heliostat mirror is calculated using five efficiency factors, namely, shadow shading efficiency, cosine efficiency, atmospheric transmittance, collector truncation efficiency, and mirror reflectivity. The DELSOL layout is used as the initial mirror field, and the mirror field design is optimized by the particle swarm algorithm. The optimal design parameters of the heliostat mirror field including the position of the absorption tower, the size of the heliostat, and the installation height were calculated by adjusting the positions of the heliostat and the absorption tower many times. The results show that the annual average optical efficiency of the heliostat field is 0.6127, and the annual average thermal power output is 37.4508 MW. Through optimization, the annual average optical efficiency of the heliostat field is increased to 0.75, and the annual average thermal power output reaches 64.98 MW. In addition, the results show that the heliostat field has a seasonal characteristic. The optical efficiency and the annual average thermal power output change monthly.

Anti-galloping analysis of iced quad bundle conductor based on compound damping cables

Based on the strain displacement relationship of spatial curved beam theory, a nonlinear dynamic equation for a hybrid model of iced bundle conductor galloping analysis with three translational degrees of freedom and one rotational degree of freedom was established. The element independence is numerically studied, and the impact of modal truncation on the galloping response is analyzed to verify the accuracy of the model. In addition, the compound damping cable is applied to transmission lines for the first time to prevent galloping, and a corresponding nonlinear vibration control finite element equation for the iced quad bundle conductor with a compound damping cable structure under wind load is developed. The study also examines the influence of various parameters on galloping amplitude. The results show that the hybrid model accurately predicts the galloping response of transmission lines. The compound damping cable can effectively suppress the galloping of the quad bundle conductor, and the vibration reduction effect reaches more than 85%. Increasing the installation height of the compound damping cable improves its damping effect. At the same installation height, when the horizontal installation position is close to the mid-span of the conductor, the damping effect first increases and then decreases, suggesting an optimal installation position exists. Moreover, properly increasing the stiffness of the primary cable and reducing the stiffness of the return spring can improve the vibration reduction effect of the compound damping cable. Additionally, if the damping coefficient and the mass of the primary cable are properly increased, the vibration reduction effect of the compound damping cable will be better.

CFD simulation and water model experiments with overflow-type supergravity reactor set up for continuously removing inclusions from aluminum melt

In this work, an overflow-type supergravity reactor has been tested for removal of inclusions from aluminum melt. A combination of numerical and physical simulations was employed to investigate the continuous separation process of recycled aluminum melt and inclusions, with a focus on evaluating the effects of reactor structures, process parameters, and inclusion characteristics on the inclusion separation efficiency. The results of numerical simulation indicate that the inclusion separation efficiency is positively related to overflow pipe length (L), overflow pipe installation height (H), gravity coefficient (G), inclusion density (ρ) and inclusion diameter (d), and negatively related to overflow pipe diameter (Φ) and melt inflow rate (Q). The overflow-type supergravity reactor exhibited excellent performance in separating inclusions from recycled aluminum melt. Under the conditions of L = 40 mm, H = 108 mm, Φ = 10 mm, G = 500, and Q = 0.5 kg/s, the separation efficiency of 18 μm Al2O3 inclusions reached nearly 100 %. The high consistency between the results of numerical and physical simulations provided full verification of the reliability and accuracy of the numerical simulation.

Review on Lightweight Mobile Flood Wall Barrier: Way Forward for Malaysia

Flooding is a persisting challenge in Malaysia. Combating flood risk has become a main priority for sustainable development in this country. The application of sophisticated engineering in hard structure approaches and flood control systems are often incongruous to the public. Therefore, there is a need to integrate the soft engineering approaches and the best practises of flood management to mitigate flood risk. There is also a need to integrate the concept of sustainable development into its planning policies towards flood hazard reduction. Mobile flood protection measures are useful as an alternative solution in flood protection and mitigation purposes. Mobile protective systems can be used for temporarily increasing the height of permanent flood protection structures during extreme events and can be utilised as emergency measure against flooding in unprotected low-lying areas. As the available mobile systems differ in the type of material, method of installation and available protection height, a description of their features, and potential application were examined including their respective opportunities and drawbacks. This article presents a review on different types of lightweight mobile flood wall barrier (MFWB) that were implemented to cope with floods in Malaysia with examples of application in other countries such as United Kingdom, Slovakia, and Netherlands. The MFWB products are reviewed and compared to each other according to the types, characteristics, mechanisms, drawbacks and how these measures are integrated into spatial planning. Based on the findings, several suggestions are given on how to improve the flood risk management in flood-prone areas and way forward for Malaysia.

Experimental study on wear failure of spindle hook teeth of cotton picker

Introduction: The wear failure of spindle will lead to a decrease in cotton harvesting rate of the cotton picker during field operation and serious wastage.Method: Three types of spindle samples at different installation positions and working areas were obtained through field experiments to explore the wear failure law of spindle hook teeth of cotton picker during field operation. Hardness of hook tooth coating and substrate of spindles were tested, surface and cross-section microstructure of the spindle hook teeth were characterized, and wear area and width of the spindle hook teeth were extracted.Results: Results showed that the hardness of the hook tooth coating is evidently higher than that of the substrate; the average coating hardness of the No. 3 spindle hook teeth reaches the maximum at 1033.6 HV0.1; defects, such as microcracks and micropores, exist in the coating of the three types of spindle hook teeth; and the thickness of the coating is between 70 and 130 μm. The wear area of spindle hook tooth changes exponentially and the wear width changes linearly with the increase of field operation area at the same installation position. The wear area and width of the spindle hook teeth gradually increase with the decrease of the installation height and the wear change of the hook teeth is negatively correlated with the installation height in the same field operation area.Discussion: The wear failure of spindle hook tooth is mainly caused by abrasive, fatigue, and oxidation wear. The results of this study can provide a reference for improving the wear resistance of spindle hook teeth.

Factors influencing precise control of room temperature for floor heating systems in severely cold regions of China

Precise control of room temperature for floor heating systems is a key step toward intelligent heating, which is of great significance in achieving thermal comfort and energy savings. Generally, the room temperature is controlled by thermostats that are placed on a wall, far away from the occupied zone. This may cause large temperature control deviation and cannot satisfy thermal comfort of the occupants. Based on the theory of the building thermal design, this study investigated the factors influencing the heating room temperature and temperature control deviation by combining a field experiment with a numerical simulation, providing a thermostat installation location strategy. The results show that air infiltration and solar radiation are the two main factors affecting the indoor temperature field. For conventional heating systems widely used in severely cold regions of China, it is not recommended to install thermostats near the occupants, but rather on the walls. The installation location should comprehensively consider room size, air infiltration, and solar radiation. To avoid the influence of outdoor factors and internal heat sources, 1.5 m can be used as the optimal installation height. These findings provide reference for the precise control of room temperature for floor heating systems.

Research on optimization model based on heliostat field

Tower solar power system (SPT) is a new type of clean energy technology with low carbon and environmental protection. In this context, it is very meaningful to explore how to arrange an efficient heliostat field and set the heliostat parameters, because the improvement here can improve the average optical efficiency of the heliostat field and collect thermal energy. In this paper, under the constraint of circular layout area, the solar energy transmission model of heliostat and the comprehensive optical efficiency model of heliostat field are established by coordinate system transformation method, Monte Carlo algorithm and HFLCAL calculation model. Then, considering the optimal layout scheme of the heliostat field, the EB layout is used to establish the basic layout of the heliostat field, and the heliostat with high comprehensive optical efficiency and meeting the actual use requirements is selected by the step-by-step traversal algorithm. Subsequently, the heliostat height, heliostat width, installation height and heliostat installation height difference between adjacent areas are introduced into the optimization model as particles, and then the PSO-GA hybrid optimization algorithm is used to approximate the optimal design of the SPT system. The goal of optimizing the comprehensive optical efficiency of the heliostat field and the output thermal power per unit area of the SPT system is achieved.

Research on Optimization Design Based on Heliostat Field

This study aims to deeply explore the mathematical modeling and performance optimization of solar heliostat fields, in order to improve their energy output efficiency. The solar heliostat field is an innovative solar heating system that focuses solar radiation on the absorption tower through a reflector, thereby generating high-temperature heat energy. This article mainly discusses the performance analysis and parameter optimization of the heliostat field to achieve optimal performance while meeting the rated power requirements. A simulated solar model was established using a three-dimensional Cartesian coordinate system, taking into account the effects of solar altitude angle and direct normal irradiance (DNI). The model in this paper comprehensively considers the effects of shadow occlusion loss, cosine efficiency, atmospheric transmittance, collector truncation efficiency, and mirror reflectance on the mirror field. The specific values of each parameter were calculated using model algorithms such as the HFLCAL model, To provide a basis for accurate performance analysis and solve the problem of parameter optimization, this article defines an objective function aimed at improving the energy utilization efficiency of the heliostat field by adjusting the parameters of the reflector, in order to achieve optimal performance. The above parameters are determined by establishing a genetic algorithm to define constants and initial parameters, and initializing the overall layout of the heliostat field to calculate the optical efficiency of the heliostat. In each iteration, the optimal heliostat field layout can be recorded. The final optimal solution includes parameters such as the position coordinates of the absorption tower, heliostat size, installation height, number of heliostats, and heliostat position.

Assessment of the validity of using a radiant panel in the low-height floor heating

This paper examines the viability of using a radiant panel in lightweight low-height floor heating. In this structure, a dry screed with high thermal resistance is replaced by a low-resistance adhesive layer with reinforcement mesh. The absence of the radiant panel results in a reduction in heat output of 5%–17% for floor finishes with a thermal resistance of 0.001 m2K/W, 50%–54% for 0.05 m2K/W and 60%–62% for 0.1 m2K/W. A structure with a panel is characterised by a lower surface temperature amplitude (maximum 2.4 K) compared to a structure without it (8.8 K), which improves the comfort of floor users. The annual heating cost in a building equipped with the analysed structures was determined. The absence of the panel resulted in a cost increase of 13%, 37% and 79% for floor finish resistances of 0.001, 0.05 and 0.1 m2K/W, respectively. The SPBT for the purchase of radiant panels is 40 years for a floor resistance of 0.001 m2K/W, demonstrating the unprofitability of this solution. For resistances of 0.05 and 0.1 m2K/W, SPBT was 14 and 6 years, respectively. The choice of floor heating system should take into account the required heat output, thermal comfort and economic aspects. Practical application This paper assesses the validity of using radiant panels in a low-height floor heating structure, where the dry screed layer is replaced by an adhesive layer with reinforcement mesh. This structure is gaining popularity due to its quick installation and low height but has the disadvantage of the high panel cost. The paper evaluates the effect of panels on heat output and identifies the conditions under which their use is economically justified. Recipients of results are designers and contractors of heating systems. The recommendations can be the basis for selecting the optimum design solution for a lightweight floor heating system.

A lever-type piezoelectric wave energy harvester based on magnetic coupling and inertial vibration

Wave energy is not easily harvested due to its low-frequency movement. This paper proposed a lever-type piezoelectric wave energy harvester (LPWEH) based on magnetic coupling and inertial vibration. Through four sets of L-shaped lever structures, the LPWEH can fully use the kinetic energy created by wave motion. Using magnetic coupling and inertial vibration excitation methods can realize improved output performance. Meanwhile, using these two non-contact excitation methods can reduce the wear of the piezoelectric sheets. The effects of the installation height of the oscillating lever, the included angle of the oscillating lever, and the magnet mass at the end of piezoelectric sheets on the prototype's output voltage are studied. With the best testing conditions, the LPWEH can achieve an output voltage of 36.93 V and an output power of 16.72 mW at a resistance of 6 kΩ. In tests of wave environment, the LPWEH can light up 34 LEDs. These findings demonstrate that the LPWEH has a promising application for converting wave energy into electric energy, which may be used to supply electricity to some low-energy electronic devices.

Installation performance of torpedo anchor at different installation heights under the action of currents: The example of T98 torpedo anchor

The deep-sea torpedo anchor is an innovative and cost-effective anchorage foundation. However, marine environmental loads such as currents have a significant impact on the free-fall installation of torpedo anchors in water, often leading to the failure of installation due to excessive inclination or large deviations from the installation location. Therefore, taking the T98 torpedo anchor commonly used in practical engineering as an example, this paper systematically investigates its installation characteristics under the action of currents. First, based on OpenFOAM®, a 3D numerical model is established to simulate the underwater falling process of torpedo anchors via dynamic model analysis method. Using the validated model, the influence of currents on the installation performance of torpedo anchors is then explored. Based on the findings, the installation conditions of T98 anchors at different installation heights are recommended. Finally, a semi-empirical method for estimating the anchor inclination and deviation of torpedo anchors under current action is proposed, which may facilitate the assessment of installation inclination and determine the installation release point of torpedo anchors.

Investigation of the Mixing Time Distribution and Connected Flow Fields in Two-Stage Stirred Vessels

In this study, laser-induced fluorescence is used to investigate the homogenization in stirred vessels equipped with single- and two-stage stirrers. The acquired local mixing times across the reactor cross-section are plotted as mixing time distribution (MTD) and then compared with the previously measured flow fields of the identical systems. With the help of a novel evaluation method, the mixing times are characterized with a normal distribution fit. With mean value and standard deviation as determined parameters, the mixing results of different installation heights and stirrer combinations are quantitatively evaluated and lead to clear recommendations for installations that enable efficient mixing.