Pump Pipe Research Articles

ANALYSIS OF THE PROPERTIES OF COATINGS USED TO PROTECT THE PUMP AND COMPRESSOR PIPE

In this article considers basic properties of protective coatings applied to the inner wall of tubing in order to extend pump and compressor pipe (PCP) service life PCP and minimize operational risks. The main complicating factors, such as scale deposits, corrosion aggressiveness, mechanical impurities, etc., arising during PCP operation are specified, groups of test media and test parameters for grading different types of coatings according to their resistance to complicating factors are singled out. Influence of various aggressive media on PCP, such as distilled water, petroleum product simulator, etc., coatings is described, and test media and test parameters for protective coatings are reviewed. The basic methods for determining the physical and mechanical characteristics, such as determining adhesion, thickness and dielectric continuity, of coatings are given, and brief informative and descriptive references for each of them are given. Recommendations are given for testing protective coatings on the inner surface of PCP for compliance with technical requirements, which ultimately allows selecting materials most resistant to aggressive field environments. The relevance of studying the influence of aggressive media on the protective coatings of the inner wall of tubing is due to the need to increase the level of reliability and durability of technical systems in operating conditions. The work is of interest to specialists in the field of materials science, technical expertise and tubing design, as well as researchers involved in the development of new materials and methods for surface protection in operating conditions. The results obtained will optimize the choice of protective coatings for specific operating conditions, which helps to increase the service life of tubing and reduce maintenance costs. This is of direct importance for reducing the risks of accidents and the environmental consequences of oil and gas production processes. In addition, the development of innovative materials and methods for protecting the surfaces of the inner wall of the tubing contributes to improving the efficiency of the operation of oil and gas wells, as well as helps to reduce equipment downtime.

Thermoelectric performance analysis of the novel direct-expansion photovoltaic thermal heat pump/power heat pipe compound cycle system in summer

Photovoltaic thermal heat pump technology has outstanding cogeneration ability by utilizing renewable energy to be accepted as a decarbonization pathway in the residential sector. However, existing photovoltaic thermal heat pumps consume higher energy under better external heat source conditions. To address this problem, a novel direct-expansion photovoltaic thermal heat pump/power heat pipe compound cycle system for heating and power generation as well as refrigeration, whose core equipment was a photovoltaic thermal module with straggled honeycomb fluid channel pattern on the serpentine arrangement, was proposed, manufactured, and studied with the method of experiment. The thermoelectric performance was compared between the heat pump and power heat pipe cycle modes, investigated under typical weather conditions, and discussed in contrast to the literature. The results showed that the average photoelectric conversion efficiency and coefficient of photothermal performance of the PVT modules, as well as COP of the novel system were 10.6%, 51.0%, and 6.19, respectively, at the average ambient temperature of 27.0 °C, average solar radiation intensity of 581 W/m2 and water temperature of 18.3–55.6 °C. And daily average COPs of the novel system under sunny, cloudy, and overcast conditions were 15.12, 7.40, and 3.17, respectively. The conclusion drawn from the experimental results is that the COP of the novel system was 10.0%–60.0% higher than that in the literature under similar outdoor conditions. The payback period of the additional cost of the novel system compared with the existing direct-expansion photovoltaic thermal heat pump was within 2.5 years. The novel system represents a practical response to the need to achieve total decarbonization of the residential sector.

Wall-embedded micro heat pump for radiant heating in buildings: Evaluation of energy and thermal comfort performance

This paper presents a novel radiant heating system with a wall-embedded micro heat pump (WEMHP) for residential buildings. The interior surface temperature of the exterior wall-section empowered by the micro heat pump is independently controlled, enabling distributed thermal comfort delivery. The micro heat pump consists of a miniature compressor along with an aluminum roll-bond condenser and evaporator. In contrast to conventional hydronic radiant systems and heat pumps with separate indoor and outdoor units (i.e., split systems), the WEMHP is a “packaged” system that would not require on-site installation and charging of a secondary water loop and circulation pump or refrigerant piping. This could ultimately lead to reduced installation and maintenance costs. In this study, a detailed system model is presented and integrated with a single-zone building model to assess the energy performance of the WEMHP in heating mode. For a designed living room scenario with an external wall WEMHP-to-wall ratio (HPWR) of 0.6 and window-to-wall ratio (WWR) of 0.2, the simulation results show that up to 23 % energy savings compared with a baseline air-to-air heat pump are possible. The results also indicate the HPWR needs to be higher than 0.4 to achieve performance comparable to the baseline. Additionally, experiments were conducted in a laboratory environment in which surface temperatures were controlled to emulate different scenarios for integration of WEMHP technology and to evaluate thermal comfort conditions. The experimental results show that the median operative temperature differences in the indoor environment were within 0.5 °C for various locations while the largest radiant asymmetry was 2.2 °C for the designed room configuration. Moreover, simulations were conducted to evaluate thermal comfort conditions in applications having a smaller HPWR of 0.4 with various values of WWR. Overall, the combined simulation and experimental study shows that the WEMHP has potential to reduce energy use while maintaining thermal comfort at acceptable levels where the HPWR is higher than 0.4.

Study on the Characteristics of Circumferential and Longitudinal Flow of Vault Concrete during Tunnel Lining Pouring Processes.

With a large number of railroad and highway tunnels opening for operation, the diseases caused by hidden lining defects are increasing. The study of flow characteristics of freshly mixed concrete during tunnel lining casting is the key to revealing the formation mechanism of hidden defects. This paper revealed the location of blank lining formation by investigating the circumferential and longitudinal flow characteristics of concrete in the vault during tunnel pouring to provide suggestions for improving the quality of tunnel lining pouring for the various projects. This paper adopted the method of indoor testing, selected the suitable working conditions and flow parameters, validated the accuracy of the test with a numerical simulation, and simulated the secondary lining pouring process of the tunnel arch from the circumferential direction and longitudinal direction. This revealed the flow characteristics of the freshly mixed concrete in the process of pouring the arch lining. The flow of concrete in the arch lining was basically characterized by two major features which were similar to the flow in the pumping pipe and the layered flow. It also revealed the relationship between the concrete flow rate, flow distance, and the location of the formation of the blank lining risk zone with the slump of the concrete, the pumping pressure, and the radius of the tunnel.

ОБОСНОВАНИЕ ЭНЕРГОСБЕРЕГАЮЩЕЙ ФУНКЦИОНАЛЬНОЙ СХЕМЫ АККУМУЛЯЦИОННОЙ УСТАНОВКИ ДЛЯ НАГРЕВА ВОДЫ НА ФЕРМАХ КРС

Analysis of electric energy consumption on cattle farms has shown that hot water supply is one of the energy-intensive technological processes on such farms. In order to save energy resources when heating water, a functional scheme of an accumulator installation has been developed that allows heating water for watering cows and providing technological needs. The standard water temperature for drinking is 12-15 degrees Celsius, for technological needs - 55-65 degrees Celsius. (Research purpose) The research purpose is substantiating and developing a functional scheme of an energy-saving installation for heating water using solar radiation for technological needs and thermal energy of ventilation air removed from the premises for watering cows on cattle farms. (Materials and methods) Applied patent search on the websites of Rospatent and Yandex.Patents. The analysis of analytical calculation dependencies was performed to determine the main technical characteristics of water heating installations for animal watering and technological purposes. (Results and discussion) A functional scheme of the hot water supply installation was proposed, including a water heater for technological needs using solar radiation energy and a water heater for animal watering using a thermoelectric heat pump and the heat of the ventilation air removed from the farm premises. (Conclusions) Developed a functional scheme of an accumulative water heating unit for watering cows and technological needs on cattle farms. It has been shown that the proposed scheme allows using the heat of the air removed from the premises and the renewable heat of solar radiation as alternative sources to traditional methods of heating water. The possibility of using low-potential thermal energy of the removed ventilation air for hot water supply of the animal watering system using a thermoelectric heat pump and heat pipes, as well as a solar collector for heating water for the technological needs of the farm, was investigated.

Comprehensive Evaluation of Adaptability Zoning for Shallow Geothermal Energy Development and Utilization: Case of Nantong City, East Coast of China

The development of green energy sources, such as shallow geothermal energy, is one of the most important measures to reduce the environmental pollution caused by the use of traditional energy sources. At present, coastal cities in the east of the Yangtze River Delta, China, have favorable conditions for the development of shallow geothermal energy because of their abundant geothermal resources. However, the development and utilization of shallow geothermal energy are still in their infancy, and adaptability zoning is yet to be fully carried out. The study area is Nantong City, which is in the eastern coast of the Yangtze River Delta. A comprehensive analysis of the conditions of shallow geothermal energy is carried out based on the analysis of the regional geological, hydrogeological, and environmental geological conditions. The adaptability zoning index system of the groundwater source heat pump and buried pipe ground source heat pump system is then constructed, and the weight of evaluation factors is determined according to analytic hierarchy process. Finally, the adaptability zoning of shallow geothermal energy development and utilization mode is obtained by using the spatial analysis function of geographic information. The results showed that the areas with good suitability and better suitability account for 98.24% of the study area and those with good economy and better economy account for 99.67% of the study area. This method can provide reference suggestions for the orderly development and sustainable utilization of shallow geothermal energy in coastal cities in plain areas.

Application on Welding Technology of Thick Pump Pipes

Application on Welding Technology of Thick Pump Pipes

An Ejector and Flashbox-Integrated Approach to Flue Gas Waste Heat Recovery: A Novel Systematic Study

In this study, a comprehensive examination was conducted to explore the technology involved in the recovery of waste heat from flue gas emitted by a 1000 MW unit. Traditional methods are constrained in their ability to harness waste heat from flue gas solely for the purpose of generating medium-temperature water. The system being examined not only recovers waste heat but also utilizes it to generate steam, thereby greatly improving resource efficiency. The process entails utilizing the flue gas to heat water to a certain temperature, followed by subjecting it to flash evaporation. This process leads to the generation of low-pressure waste heat steam. Within the steam ejector, the waste heat steam combines with high-pressure motive steam extracted from the source, resulting in the formation of medium-pressure steam. Within the steam ejector, the waste heat steam blends with high-pressure motive steam drawn from the source, forming medium-pressure steam that eventually feeds into the A8 steam extraction pipe (low-pressure turbine pumping pipe). The present study examines the fluctuation patterns in motive steam flow, suction coefficient, waste heat steam volume, and outlet temperature of the flue water heat exchanger when different motive steam sources are used. Additionally, the research calculates the reduction in CO2 emissions, the coal consumption for power supply, and the cost savings in fuel for the retrofitted system. The findings indicate that maximizing energy utilization can be achieved by operating the retrofitted unit at the lowest feasible waste heat steam pressure. The implementation of the new system has resulted in a substantial decrease in coal consumption for power supply. When employing main steam as the extraction steam source, the consumption of coal for power generation decreases in proportion to the decrease in waste heat steam pressure while maintaining a constant unit load. When the waste heat steam pressure reaches 0.0312 MPa, the recorded coal consumption for power generation varies between 289.43 g/kWh at 100% turbine heat acceptance (THA) and 326.94 g/kWh at 30%THA. When comparing this performance with the initial thermal power plant (TPP) unit, it demonstrates reductions of 2.26 g/kWh and 1.52 g/kWh, respectively. After implementing modifications to this 1000 MW unit, it is projected that the annual CO2 emissions can be effectively reduced by 6333.97 tons, resulting in significant cost savings of approximately USD 0.23 million in fuel expenses. This system exhibits considerable potential in terms of emission reduction and provides valuable insights for thermal power plants aiming to decrease unit energy consumption.

Long-Term Durability of Cement-Treated Soil Used in Offshore Airport Island Construction

In port and harbour areas, soft soils such as dredged soil can be solidified by mixing them with cement and other solidifiers in a pumping pipe. This method is known as pneumatic flow mixing. In this method, the soil and solidifiers are stirred and mixed using the turbulence effect of the plug flow generated in the pipe. The authors investigate the long-term durability of the treated soil on the artificial island where this method was first fully introduced. This paper summarises the results of five investigations on the island immediately after construction and 4, 10, 15, and 20 years after construction. No reduction in the unconfined compressive strength or needle penetration gradient was observed in the treated soil. Some degradation was observed at the top and bottom exposed surfaces of the treated soil, similar to that of soil subjected to other treatments. In addition to needle penetration and chemical tests, elemental mapping using an electron beam microanalysis was performed to determine the degree of degradation. The depth of degradation 20 years after construction was 18–25 mm. Although the amount of cement added in the pneumatic flow mixing method was relatively small, this value was within the range of degradation depths over time investigated in previous studies and did not represent a significant degradation.

Experimental investigation of an air source heat pump with multigroup heat pipe radiators

As a clean and sustainable electrified heating technology, air source heat pump (ASHP) has been widely used in household in China. However, some problems occurred with the commonly used water loop system, such as low efficiency, complicated structure, more likely to be frozen and burst as well as high electric energy consumption, etc. In this paper, a new air source heat pump with multigroup heat pipe radiators (ASHPMP) was presented. In ASHPMP system, the condenser and heat pipe were coupled together to form a new type of heat radiation terminal, which was named as heat pipe radiators, multiple terminals driven by the compressor provided heat for several rooms. An experimental apparatus of the ASHPMP system was developed and the experiment was carried out in residential buildings also, and R410A was used in the heat pump and R134a was used in heat pipes. The influence of temperature, pressure of heat pump and heat pipe on the heating performance of ASHPMP under frosting/defrosting condition was analysed. The results showed that the new system can operate stably under outdoor temperatures of −12.7 °C to 6.5 °C. As the indoor temperature was set at 20 °C, the heating coefficient of performance (heating COP) could reach up to 3.15 with outdoor temperature −12.7 °C, and it was 6.73 with outdoor temperature 6.5 °C.

Обоснование списочного парка насосов и трубопроводных ставов рудничной водоотливной установки

The complex of drainage system of an underground mining enterprise ensures the safety and continuity of mining operations. Deterioration of the level of reliability of the functioning of the mine drainage system can lead to the following serious consequences. The main link of the mine drainage system is a drainage system equipped with pumping units based on the centrifugal pumps. One of the main criteria for the safe operation of a mine drainage system is its equipment with a sufficient number of pumping units. An assessment of the efficiency of the classical methodology for calculating the listed park of pumping units is given, including consideration of the amendment made to it regarding the given water inflow regime. The main drainage installation of the Udachny underground mine, equipped with sectional pumps, was chosen as the object of research. It is established that the list park of pumping units calculated according to the known methods does not allow to ensure a high level of reliability of the operation of the drainage plant. The same picture is typical for the park of discharge pipe sections of the drainage plant. When calculating the list park of pumping units of a drainage system, it is more expedient to consider not the passport performance of the pump, but its average value between major repairs. The number of pumps under repair depends on the average duration of repair work and the average time between failures of the pump. A method is proposed for calculating the optimal number of pumping units and pipe sections of a drainage system from the point of view of ensuring its reliable level of functioning. The results of the performed research will be useful to the specialists responsible for the design of drainage systems for underground mines and coal mines in the Russian Federation.

Numerical study on residual rate of fluidized solidified slurry in pumping for scour repair around monopile

A new scour countermeasure for monopile foundation using solidified slurry have been proposed recently. The fluidized solidified slurry is pumped to the seabed area around pile for scour protection or into the developed scour holes for scour repair as the fluidized material solidifies gradually. During this complex process with pumping and solidification, the flow and diffusion of solidified slurry can result in the material loss and deterioration. However, there is still not a comprehensive and reasonable analysis on the state of retention of the fluidized solidified slurry in this process. Thus, the effect of scour protection can't be evaluated effectively. The current work focuses on the residual rate of fluidized solidified slurry during the pumping operation, which is the ratio between volume of the solidified slurry remaining in the scour pit and that pumped into. A series of multiphase flow (the ambient seawater and the solidified slurry) numerical simulations using a computational fluid dynamics (CFD) approach were conducted to investigate the effects of pumping location, current velocity, pumping velocity and material property of solidified slurry on the residual rate of fluidized solidified slurry. It was found that the pumping location near and at the downstream of the monopile with a lower pumping pipe nozzle is optimal for a higher residual rate of fluidized solidified slurry. Solidified slurry with smaller slump flow value pumped at a lower current velocity and higher pumping velocity contributes to a higher residual rate. Based on a comprehensive parametric study, an empirical formula is established to calculate the final residual rate of the solidified slurry for theoretical reference and practical application. This work provides an important insight in understanding the residual rate of solidified slurry in application to scour protection of monopile.

RESEARCH OF MODERN TECHNOLOGIES FOR THE RESTORATION OF STRUCTURAL ELEMENTS OF MINING PUMPS: ADVANTAGES AND DISADVANTAGES, PROMISING TECHNOLOGIES

The scientific article is devoted to the study of modern technologies for restoring the internal surfaces of critical parts of the structural elements of oil and gas pumps. By the method of critical analysis of defects, it was found that paraffin deposits and mechanical impurities are in the list of the main complicating factors leading to abrasive wear of the working surface of the parts being contacted. Asphalt-resin-paraffin deposits together with mechanical impurities are distributed unevenly, for example, along the diameter of the cylinder of the injection column, narrowing the passage section of the rod in different stroke length intervals. This phenomenon causes the rod to deviate from the design axis of the trajectory of movement and forms sections of the cylinder working under shock loads with maximum wear. Therefore, it is necessary to restore the degraded surface in places where maximum dynamic loads are applied. The patent search method and the evaluation of the claims allowed us to establish that the generally accepted methods of restoring internal surfaces are reduced to nitriding and chrome plating. Due to known technological shortcomings, these methods are limited in application, and it is impossible to restore the phase structure by these methods. To solve the technological problem of restoring the structure and modifying the inner surface of a small cylinder diameter, it is proposed to apply a coating with a ceramic protective layer based on nickel alloys of the carbide class, which has high hardness and inert properties. To restore the surface of worn parts in conditions of a limited coordinate space of long-dimensional elements of the RDP structure (pump and compressor pipes, a pair of cylinder-plunger and others), the authors propose a promising laser spraying.

Experimental and Numerical Research on Fluid Dynamic Interaction Effects of Reciprocating Pump–Pipeline System

AbstractThe performance of a reciprocating pump–pipeline system is often limited by the fluid dynamic interaction between pump, pipeline, and valves. In this paper, the fluid dynamic characteristics of a reciprocating pump–pipeline system are investigated via experiments and numerical analysis. A simple experimental platform consisting of a reciprocating pump, suction and discharge pipes, and flow control valve are offered and the experimental tests under multiworking conditions are carried out to explore the fluid dynamic interaction of the reciprocating pump–pipeline system. Combined with theoretical analysis and computational fluid dynamics (CFD) simulations, a dynamic model of the pump–pipeline system is presented with considering the fluid dynamic interaction effect of pump valves, plunger stroke, and flow control valve. All of the predicted results coincide well with the experimental data, and the inherent mechanism and the feature of the fluid dynamic interaction are revealed by experiments and numerical analysis. It is shown that the fluid dynamic characteristics of pipeline significantly influence the lag phenomenon and the motion behaviors of pump valves. The discharge flowrate rises nonlinearly with the increase of plunger stroke and the leakage rate is associated with the resistance of flow control valve. The pressure pulsation in discharge pipe is directly related to and markedly impacted by the control valve opening and the plunger stroke. However, the influence of the reservoir liquid-level on the system dynamic behavior is relatively slight. This work would give information for the optimum design and operation maintenance of reciprocating pump–pipeline system.

MODEL FOR CALCULATING THE STATIC CHARACTERISTICS OF HYDRAULIC SYSTEMS OF HYDRO TECHNICAL BUILDINGS

Hydraulic mechanisms that actuate flat gates, widely used in hydraulic structures, are studied as hydraulic actuators of the system. Their static mathematical models are developed using an integrated methodology with a hydraulic pump, inlet and suction pipes, and internal and external resistance factors. Unlike existing mathematical models, the model developed in this paper allows a detailed description of the characteristics of hydraulic drives due to the fact that pressure losses in the throttle, regulator, and power amplifier, as well as local resistances in hydraulic pipelines, are taken into account.

Determination of Separation Efficiency of Hydrocyclone Used Pre-Filter in Micro Irrigation at Different Inlet Velocities and Sand Diameters

Hydrocyclones are used as pre-filter to reduce suspended particles in irrigation water on the subsequent filters. The aim of the study was to determine separation efficiency (SE) of hydrocyclones, called H1, H2 and H3 according to inlet/outlet diameters, at water velocities of 1.0 (V10), 1.5 (V15) and 2.0 (V20) ms-1, and sands diameter of 0.5 (D05), 1.0 (D10), 1.5 (D15), 2.0 (D20) and 2.5 (D25) mm. Therefore, a hydrocyclone laboratory test system was constituted using a water tank, motor pump, inverter, flowmeter, valve, hydrocyclone, disk filter, and polythene pipe. Separation efficiencies were calculated by dividing amounts of sand collected in collection box by feeding amount of sand. The lowest average separation efficiency was determined as 37% at H1V10D05 treatment and the highest ones as 97% at both H2V20D10 and H3V20D20, and the other ones changed between two values. Average separation efficiencies resulted as 69%, 88% and 88% for H1, H2 and H3 hydrocyclones, and 71%, 84% and 90% for V10, V15 and V20 water velocities, and 78%, 82%, 82%, 83% and 84% for D05, D10, D15, D20 and D25 sand diameters, respectively. Besides these, average separation efficiency for three parameters was 82%. Since the inlet size of H2 is smaller than that of H3 and its SE was higher than that of H1 and equal to that of H3, the most suitable hydrocyclone was determined as H2 to be used in the micro irrigation. The highest average separation efficiency was 90% at a water velocity of 2.0 ms-1. According to separation efficiency of the hydrocyclone, the optimum water velocity in the inlet of the hydrocyclone was determined as 2.0 ms-1. The separation efficiency of hydrocyclone showed that the efficiencies increased with increasing water velocity from 0.5 ms-1 to 2.0 ms-1 and sand diameters from 0.5 to 2.5 mm. In separation efficiency for micro irrigation, water velocities and suspended materials play crucial roles as well as hydrocyclone mechanical properties.

Implementasi Alat Penjernih Air Tanah (Artesis) Menjadi Air Layak Pakai Pada Gedung Elektro Politeknik Negeri Bengkalis

Meeting the need for clean water has become a very common problem and has not been resolved in most parts of the Indonesian state in general, especially in coastal areas. Even though artesian well water is available, the condition of the water is generally slightly yellowish in color and has a high acid content. The same thing happened to the Electrical Building of the Bengkalis State Polytechnic, so that the toilet, ceramics and some equipment in the toilet quickly turned yellow and corroded due to the high acid content in the water and could create a dirty/dirty impression on the toilet. The method implemented is to create a water purification system using a media tube sourced from bore well water (artesian) which is yellow in color and has a high acid content, which can produce clear water and low acid levels so as to avoid yellowing in the toilet and equipment in the toilet. The stages carried out are installing water purification installations (installation of water jet pump machines, media tubes and piping systems), installing electrical installations for water purification systems, testing water purifiers, and making iron cages for media tubes. (artesian) which is yellow in color and has high acid content can become clear water and low acid content, so that it can overcome the problem of the need for clear water suitable for use at the Bengkalis State Polytechnic Electrical Building. Based on the results of the activity, which is made capable of producing water that is fit for consumption with no odor and the color is clearer than before, and this water purifier has been submitted to the Department of Electrical Engineering at the Bengkalis State Polytechnic through the Head of the Electrical Engineering Department on August 19, 2022Amri, H., & Syaiful, A. (2018). Implementasi Teknologi Pengolahan Air Tanah Artesis Menjadi Air Layak Minum Di Desa Buruk Bakul. Jurnal Pengabdian DIKEMAS, 2(1), 1-4.Yaqin, R. I., Ziliwu, B. W., Demeianto, B., Siahaan, J. P., Priharanto, Y. E., & Musa, I. (2020). Rancang Bangun Alat Penjernih Air Portable Untuk Persediaan Air Di Kota Dumai. Jurnal Teknologi, 12(2), 107-116Wan M. F.(2015).“Implementasi Teknologi Pengolahan Air Gambut Menjadi Air Layak Konsumsi Bagi Masyarakat Desa Sungai Alam, BengkalisIndra, S.,T., Mulyono,R.,A., Suprawihadi,R. (2019). Alat Pengolah Air Tanah Menjadi Air Bersih dengan Proses KombinasiAerasi-Filtrasi Upflow (Desain Rancang Bangun). Jurnal Kesehatan,10(1), 53-60.

Development of a reliability model for crack growth occurrence for a secondary hull component

Ship hull vibration is a major contributor to fatigue crack growth and main engine excitation is identified as an important vibration source. A general method to solve any vibration problem arising onboard a ship does not exist, which encourages the use of a reliability-based framework for assessing ship vibration and its consequences. A stochastic model of vibration response is developed for the probabilistic formulation of the failure probability of the occurrence of crack propagation of a secondary structural hull component. The secondary structural component considered is a pipe stack support. The pipe stack support connects a cargo pump pipe stack to the wall inside the cargo tank, and the support is welded directly onto this wall. First, a generic cargo hold model is analysed with engine speed and the relative distance between the engine and the structural component under consideration as stochastic variables. Then, submodels are used to investigate the local vibration of the support and the stress response is evaluated for a combination of different engine speeds and relative distances. A surface is fitted to the vibration response and used for probabilistic analysis by Monte Carlo (MC/DSPS) and FORM/SORM reliability methods. The limit state is formulated as the possibility of fatigue crack growth based on a threshold stress intensity factor. This threshold factor depends on the initial crack size and different initial sizes are investigated. The adequacy of the functional representation for the stochastic model, which is fitted to discrete data points, is also assessed. It is seen that a functional representation using a sum of sine terms give an adequate fit for describing the stress response induced by engine speed, while a polynomial representation was adequate for the relative distance variable. The failure probability estimated by Monte Carlo simulations and SORM indicates that the pipe stack support is not critical for the occurrence of fatigue crack growth. A main observation from the analysis is that the reliability-based design of secondary structural components, also looking at the interaction with the global structure, may help to improve the vibration-induced stresses in local hull details by application of proper design measures.

Analysis of the Sound Field Characteristics of a Muffler at Different Flow Conditions

To reduce the noise in a pump piping system and increase the usage time of equipment, a new type of porous muffler is proposed in this paper. A water guide cone is incorporated into the muffler structure, which may help to redirect the fluid media in the piping system. The porous structure is adapted from a muffler shell, water cone wall and round bottom plate. According to this structure, the muffler sample is made, and a pump pipeline system test bench is set up. The outlet noise of the pump pipeline system is measured after installing the muffler. At the same time, the muffler is numerically simulated by combining computational fluid mechanics and Lighthill acoustic theory. The characteristics of the flow field and external sound field under three different flow conditions of 200 m3/h, 400 m3/h and 600 m3/h are assessed. The numerical simulation results show the same dominant frequency and trend as the experimental results. The rationality of the numerical simulation is verified. Research shows that: the level of sound pressure at the muffler's outlet is lower than at the inlet, causing muffling, and the characteristics of a quadrupole sound source appear at the outlet. The proposed muffler has a certain effect in reducing noise in the pump pipeline system.

Active solar collector located on roof ridge assisted Chinese solar greenhouse for thermal environment enhancement

ABSTRACT Maximizing the use of solar energy to increase the indoor temperature of greenhouse is of great significance to the green and energy-saving intensive greenhouse production in China. In this study, an active solar heating system (ASHS) was developed and analyzed, consisting of five solar water heaters equipped with vacuum tube solar collectors, one heat storage tank and heating system including booster pump and heating pipes. During the day, the water was heated in the solar collectors and stored in tanks before being placed into circulation in the heating pipes to distribute the heat to the aerial and root zones of plants. To evaluate the performance of ASHS and the feasibility of practical application, climate and plant growth parameters were monitored in two Chinese Solar Greenhouses (CSGs) located in Yangling, China. Results revealed that under the operating condition with the flow rate of 5.4 L/min, the effective heat collection, average heat collection efficiency and energy-saving efficiency of ASHS were 1.9 MJ/(m2•h), 64% and 84%, respectively. The coefficient of performance (COP) was between 4.5 and 6.2, and the payback period was 12.0 years. Furthermore, the results revealed that the ASHS successfully provided 76% of its annual heating needs, heated the CSG for 4 months and maintained the nocturnal temperature above 8 ℃. The actual application effect proved that it increased average indoor air temperature by 2.2 ℃ and substrate temperature by 3.3 ℃ in heated greenhouse. The growth rate of tomato plant height in the heated greenhouse was 0.7427 cm/d, greater than that in the unheated greenhouse (0.6 cm/d). The novel system proposed in this study adopting particular location enables the rise of the ambient and the substrate temperatures with lower energy consumption, improvement of the environmental conditions in CSG, and a more suitable growing environment for plants in the cold season.