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The efficiency of the pump device is an important parameter to judge the overall dynamic performance of the pumping station. The commonly used method at home and abroad is to carry out model tests of the pump device. The performance parameters of the prototype pump and pump device are obtained by the similarity conversion formula. However, at present, there are not many device model tests for large vertical submersible pumps. Taking a large vertical submersible mixed-flow pumping station in China as an example, research predicted the performance of the pump device through a model test and a submersible pump prototype test. The results show that the model test of the large vertical submersible mixed-flow pump device has a maximum efficiency of approximately 77.8%, and the prototype test conversion device has a maximum efficiency of approximately 80.33%. The device model test and the pump factory prototype test results are compared. It is found that the performance parameters of the pump measured by the prototype test are in good agreement with the device model test under the design conditions, and there is a certain error when the deviation from the design conditions is significant. The device model test and the factory test of the pump are indispensable in the large-scale road of submersible pumps, and a large number of tests are needed to sum up the experience. [ABSTRACT FROM AUTHOR]

The efficiency of the pump device is an important parameter to judge the overall dynamic performance of the pumping station. The commonly used method at home and abroad is to carry out model tests of the pump device. The performance parameters of the prototype pump and pump device are obtained by the similarity conversion formula. However, at present, there are not many device model tests for large vertical submersible pumps. Taking a large vertical submersible mixed-flow pumping station in China as an example, research predicted the performance of the pump device through a model test and a submersible pump prototype test. The results show that the model test of the large vertical submersible mixed-flow pump device has a maximum efficiency of approximately 77.8%, and the prototype test conversion device has a maximum efficiency of approximately 80.33%. The device model test and the pump factory prototype test results are compared. It is found that the performance parameters of the pump measured by the prototype test are in good agreement with the device model test under the design conditions, and there is a certain error when the deviation from the design conditions is significant. The device model test and the factory test of the pump are indispensable in the large-scale road of submersible pumps, and a large number of tests are needed to sum up the experience.

This study focuses on the shaft power at the neutral angle of a controllable pitch propeller to analyze the change in the required power due to propeller fouling. It is named and defined as a power for keeping propeller's rotation (RP) because a propeller does not generate the net thrust to push the hull but dissipates the power to keep its constant speed. Statistical analysis was conducted using a decade of the observed data from a research vessel. This study assumed that the change in RP can be considered as an indicator showing the state of propeller fouling. In addition, the state of fouling on the hull can be estimated indirectly based on RP because the data correlated the shaft power under several operating conditions with RP on the same voyage. The fouling state was classified into three conditions based on RP. The comparison of shaft power at the same ship speed between the clean condition and the serious fouled condition showed that the shaft power was increased by 35% on average due to fouling. When the ship navigates under 10 knots, propeller fouling has a larger impact on the increase in shaft power than hull fouling. [ABSTRACT FROM AUTHOR]

In response to the global call for action to reduce CO2 emissions, operational measures such as speed, route optimization, and hull cleaning play a significant role in the maritime industry. These measures can be implemented immediately without significant investment in both newbuilding ships and existing ships. To make accurate decisions regarding operational measures, reliable and precise models of environmental conditions and effects of hull fouling are required. In this study, a data-driven approach using linear regression was applied to predict shaft power, fuel consumption, and speed after intensive data preparation and feature engineering. First, a shaft power prediction model was developed by combining three independent submodels: the RPM-power model, hull fouling model, and environmental effect model. Subsequently, fuel consumption and speed prediction models were developed based on the shaft power prediction model. Model validation was performed on a 174K LNG carrier, and the results showed good accuracy even in long-term ship operations of more than two years. The mean absolute percentage errors (MAPEs) of the prediction models were 1.60%, 1.70%, and 2.68% for the shaft power, fuel consumption, and speed, respectively. The validated models were applied to two LNG carriers, and satisfactory results were obtained. This study contributes to greenhouse gas (GHS) reduction by providing interpretable, flexible, and accurate models that can help make correct decisions regarding optimal operational measures.

The aim of the study is to determine the optimal structural parameters for a plastic centrifugal pump inducer within the framework of an orthogonal experimental method. For this purpose, a numerical study of the related flow field is performed using CFX. The shaft power and the head of the pump are taken as the evaluation indicators. Accordingly, the examined variables are the thickness (S), the blade cascade degree (t), the blade rim angle (β1), the blade hub angle (β2) and the hub length (L). The impact of each structural parameter on each evaluation index is examined and special attention is paid to the following combinations: S2 mm, t 2, β1 235°, β2 360° and L 140 mm (corresponding to a maximum head of 98.15 m); S 5 mm, t 1.6, β1 252°, β2 350° and L 140 mm (corresponding to a minimum shaft power of 63.06 KW). Moreover, using least squares and fish swarm algorithms, the pump shaft power and head are further optimized, yielding the following optimal combination: S 5 mm, t 1.9, β1 252°, β2 360° and L 145 mm (corresponding to the maximum head of 91.90 m, and a minimum shaft power of 64.83 KW). [ABSTRACT FROM AUTHOR]

A wave rotor optimizes the use of energy resources by enhancing thermodynamic cycles, and further optimization of wave rotor geometry is emerging as an attractive research area. Among the geometric features, the stagger angle of channels lacks sufficient study in spite of its important effects. To address this question, this work developed and applied the velocity triangle models to modify the basic geometry of wave rotors for different stagger angles, and investigated the flow fields with two-dimensional numerical methods. Results showed that: (1) different stagger angles worked out similar unsteady pressure wave systems and kept nearly constant compression and expansion ratios of the wave rotor; (2) increased stagger angle made the inlet and outlet flows turn toward the axial direction, which was beneficial to compact and light-weighted integration of the wave rotor to a gas turbine; (3) increased stagger angle made the wave rotor consume more shaft power, but even the maximum shaft power was small. This work revealed a critical mechanism how the velocity variation across an unsteady pressure wave produced rim work in a staggered channel, and made a recommendation to comprehensive optimization of wave rotor geometry for better integration in a gas turbine and acceptable shaft power consumption. [ABSTRACT FROM AUTHOR]

The investigation of dynamic characteristics is very important and the excellent dynamic characteristics mean the low friction losses and a high mechanical efficiency. This paper presents a mathematical model to analyze the dynamic characteristics of swing compressor with no valves. The movement and mechanical characteristics of three main components have been analyzed in detail. A method based on the gas force has been applied to calculate the indicated power, which is compared with the indicated power calculated through the integrated area of P-V diagram. The calculation errors between these two methods are within 2%. Additionally, the frictional loss, shaft power and mechanical efficiency have been calculated at different discharge pressures and different shaft speeds. An experiment has been carried out and the required shaft power has been measured to verify the theoretical results. The errors between calculation results and experimental results of shaft power are within 4%, which proves that this dynamic mathematical model is accurate. Besides, the simulation results show that four important factors affecting the total frictional loss are the frictional loss in eccentric bearing, the frictional loss between swing rod and bushes, the frictional loss between rotor and cylinder and the frictional loss in thrust bearing.

Optimization of vacuum cleaner fan components is a low-cost and time-saving solution to satisfy the increasing requirement for compact energy-efficient cleaners. In this study, surrogate-based optimization technique is used and for the first time it is focused on maximization of Airwatt parameter, which describes the fan suction power, as an objective function (Case II). Besides, the shaft power is minimized (Case I) as another optimization target in order to reduce the power consumption of the vacuum cleaner. 11 geometrical variables of 3 fan components including impeller, diffuser and return channel are selected as the optimization design variables. 80 training points are distributed in the sample space using Advanced Latin Hypercube Sampling (ALHS) technique and the outputs of sample points are calculated by means of CFD simulations. Kriging and RSA surrogate models have been fitted to the outputs of the sample space. Through coupling of constructed Kriging models and Multi-Island Genetic Algorithm (MIGA), the optimal design for each of the optimization cases is presented and evaluated using numerical simulations. A 20.22% reduction in shaft power in Case I and an improvement of 27.73% in Airwatt in Case II have been achieved as the overall results of this study. Despite achieving goals in both optimization cases, a slight decrease in Airwatt in Case I (−6.20%) and a slight increase in shaft power in Case II (+4.82%) are observed relative to primary fan. Furthermore, the Analysis of Variance (ANOVA) determines the importance level of design variables and their 2-way interactions on the objective functions. It was concluded that geometrical parameters related to all of the fan components must be considered simultaneously to conduct a comprehensive optimization. The reasons of enhancement in optimal cases compared with the reference design have been further investigated by analysis of the fan internal flow field. Post-processing of the CFD results demonstrates that the applied geometrical modifications cause a more uniform flow through the flow passages of the optimal fan components. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Moving liquids by industrial and domestic hydraulic circuits annually requires tens of billions of kilowatts of electricity per hour. Today there is not any universal indicator that would characterize generalized conversion efficiency of electrical energy into hydraulic and efficiency of using of hydraulic energy. This greatly complicates the optimization of the hydraulic circuit parameters on energy criterion in its design or testing calculation. Aim: The aim is to assess the losses in the discharge equipment of hydraulic circuits, as well as in pipeline through the introduction of common indicator of the effectiveness of transporting liquid. Materials and Methods: We show that specifications for energy efficiency of hydraulic circuit it is not enough the pumping efficiency of the installation, or calculate the efficiency of individual elements of the hydraulic circuits. To achieve the goal asked to enter the energetic coefficient of energy perfected circuit, which is the ratio of output flow power from the hydraulic circuit to the flow power on the pump shaft. Results: The proposed coefficient takes into account the loss of pressure in the pump and in the pipeline and provides an objective assessment of the energy efficiency of the circuit; in addition, it allows you to compare the energy perfection of hydraulic systems with different parameters and different pumps. The proposed coefficient should be used in the design of hydraulic circuits and during the checking calculation.

The article discusses one of the possible methods for assessing of energy efficiency in a complex hydraulic network. It is shown that to characterize the energy excellence of a complex hydraulic network, only the efficiency of the pumping unit cannot be used, since it does not take into account all possible hydraulic losses and the mutual influence of the elements of the “pump pipeline” system. For this purpose, it is proposed to use the coefficient of energy perfection of the network, which is the ratio of the power of the fluid flow at the outlet of the hydraulic network to the power on the pump shaft. This indicator takes into account losses both in the elements of the pumping unit and in the pipeline system and, therefore, gives an objective and comprehensive assessment of the energy efficiency of this system as a whole. By using the power balance of the system elements, a formula for calculating this indicator for an extensive hydraulic network consisting of sequential and parallel sections is derived. The analysis of the obtained formula, which showed that the advantage of the proposed formula is to take into account the hidden mutual dependence between the quantities that determine the coefficient of energy perfection. In particular, the formula takes into account the influence of the resistance of a complex hydraulic network on the operating parameters of the pump (pressure and flow) and its efficiency. It is shown that in some cases, the increase in the hydraulic resistance of the network, and hence the power loss in the system, is compensated by the increase in pressure developed by the pump and its efficiency. Thus, it is proved that the negative impact in the pipeline system can thus affect the performance of the pumping unit, that the coefficient of energy perfection of the network will not only not decrease, but also increase. The formula allows you to compare the energy excellence of complex hydraulic networks with various parameters and different pumping units and allows you to optimize the system with total energy consumption. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The static force exerted on a hawser at zero ship speed by a vessel, otherwise known as the bollard pull, is one of the key performance indicators of Tugs, Anchor Handling Tugs (AHTs) and Anchor Handling Tug Supply Vessels (AHTSVs).The value of bollard pull is considered critical as it defines the functionality and performance of the vessel. When a company decides on chartering a vessel, a definite prerequisite considered is the value of the bollard pull. The value may be obtained via three ways: calculations, model-testing, and full-scale trials. The latter is often used officially to certify the vessel's bollard pull rating, with the presence of the vessel's owners, surveyors, and any other third parties. The tests and trials follow a set of guidelines provided by classification societies but do not have a standardized set of rules. Therefore, disagreements often arise over the results of such tests and trials. Tests are often carried without any load cells measuring the shaft power to ascertain the brake horsepower (BHP). Simply, engine rpm/ rating is used to fix the 100%maximum continuous rating (MCR)which often in the range of 105--108%MCR. Some of the parties involved in certifying the correct bollard pull tests (BPTs) do not even understand what is all about the bollard pull. Everybody is looking for a higher figure for the bollard pull on the certificate when the reality is different. The author examines and discusses the broad spectrum of factors that affects the "true" value of the bollard pull and explains why such a standardized set of mandatory BPT and the trial code is deemed necessary. The author also presents some of the interesting BPTs data to show the differences in various ways of conducting BPTs. [ABSTRACT FROM AUTHOR]

In the early 1940s the first practically usable helicopters rose into the sky. Their importance was quickly recognised both by the military and civilian decision makers. A good summary of their most important advantage is the next quotation: "If you are in trouble anywhere in the world, an airplane can fly over and drop flowers, but a helicopter can land and save your life." (Igor Sikorsky, 1947) Just after their appearance it immediately became an urgent problem to replace the relatively low-power and heavy piston engines, for which the much lighter and more powerful turboshaft engines offered a good alternative. Significant improvement of helicopter engines, which has embodied mainly in power to weight ratio, thermal cycle efficiency, specific fuel consumption, together with reliability and maintainability, of course, has influenced the technical-tactical parameters of helicopters. In this paper I introduce the evolution of helicopter turboshaft engines, the most important manufacturers and engine types. Through statistical analysis I display what kind of performance parameters the helicopter turboshaft engines had in the past and have in the present days. [ABSTRACT FROM AUTHOR]

A scroll expander was designed, fabricated, and tested as a power converting device in a waste heat recovery system fitted to the cooling system of internal combustion engine. An algebraic spiral was adopted as the base curve for the scroll wrap profile for the compact scroll design. A reduction of approximately 13.2% was accomplished in the scroll diameter, compared to conventional involute scroll. Additionally, numerical analysis on the expander performance showed that the performance of the designed algebraic scroll expander was about the same as that of a conventional scroll expander. The fabricated prototype was tested in a R134a Rankine cycle with a heat source of 20 kW. For the operating conditions of 20–26 bar and 90–93℃ at the expander inlet and 8–9 bar at the outlet, the expander produced a shaft power of 0.6–0.7 kW at an operating speed range of 1500–2000 r/min. This corresponded to an expander efficiency of 40–45%. The volumetric efficiency also increased as the expander speed increased, reaching to 80% at 2000 r/min. Furthermore, compared to the numerical simulation results, the mechanical efficiency from the test data was found to be considerably low as much as 30%. [ABSTRACT FROM AUTHOR]

Tug today represents irreplaceable part of port infrastructurein all the world harbours and it is almost unthinkable torun a business of some port in international relations withoutusing them. All the world ports intend to get equipped withbetter equipment in order to be more competitive for cargo handling.Modernization of port includes harbour tugs as well.Their purchase depends on the financial power of the investorin infrastructure, whether the state or a private company whichis the common owner of the tugs fleet in the port with which itmost often has a "Concession contract" for undertaking thementioned activities besides the rest of the known contractedways of cooperation.

A ship’s energy efficiency performance is generally estimated by conducting special sea trials of few hours under very controlled environmental conditions of calm sea, standard draft and optimum trim. This indicator is then used as the benchmark for future reference of the ship’s Energy Efficiency Performance (EEP). In practice, however, for greater part of operating life the ship operates in conditions which are far removed from original sea trial conditions and therefore comparing energy performance with benchmark performance indicator is not truly valid. In such situations a higher fuel consumption reading from the ship fuel meter may not be a true indicator of poor machinery performance or dirty underwater hull. Most likely, the reasons for higher fuel consumption may lie in factors other than the condition of hull and machinery, such as head wind, current, low load operations or incorrect trim [1]. Thus a better and more accurate approach to determine energy efficiency of the ship attributable only to main machinery and underwater hull condition will be to filter out the influence of all spurious and non-standard operating conditions from the ship’s fuel consumption [2]. The author in this paper identifies parameters of a suitable filter to be used on the daily report data of a typical LNG tanker of 33000 kW shaft power to remove effects of spurious and non-standard ship operations on its fuel consumption. The filtered daily report data has been then used to estimate actual fuel efficiency of the ship and compared with the sea trials benchmark performance. Results obtained using data filter show closer agreement with the benchmark EEP than obtained from the monthly mini trials . The data filtering method proposed in this paper has the advantage of using the actual operational data of the ship and thus saving cost of conducting special sea trials to estimate ship EEP. The agreement between estimated results and special sea trials EEP is expected to improve further with use of better and more accurate filtering techniques.

The design, construction and test of an Organic Rankine Cycle (ORC) with R123 as the working fluid were performed. A scroll expander was integrated in the system. The conductive oil with its temperature of 150 °C was used to simulate the low-grade heat source. An AC dynamometer unit measured the expander shaft torque, rotating speed and shaft power. The experiments were conducted in two operating modes: the constant mass flow rate and the constant shaft torque. Under the constant mass flow rate operating mode, the stepped increase of the shaft torque increased the expansion ratios of the expander and decreased the vapor superheats at the expander inlet. Thus, the shaft power and thermal efficiency were increased. Alternatively, the constant shaft torque operating mode involved two different regions, interfaced at the pumping frequency of 9 Hz. By the increase of the mass flow rates, the vapor superheats at the expander inlet was decreased and the shaft power was increased, but the ORC thermal efficiencies were slightly decreased. Both operating modes yielded the saturation shaft powers that were the maximum values one could use. It was found that the measured shaft powers and ORC thermal efficiencies were lower than the enthalpy determined values based on the fluid pressures and temperatures at the expander inlet and outlet. The maximum measured shaft power and thermal efficiency were 2.63 kW and 5.31 %, compared with the enthalpy determined values of 3.87 kW and 9.46 %, respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] First paper dealing with numerical dynamic simulation of thermal-lag Stirling engine. [•] Observation on different operating modes, such as rotating, swinging, swinging-to-rotate, and swinging-to-decay modes. [•] Study of influential factors affecting the operating modes. [•] Optimal geometrical or operating parameters of the baseline case for maximum engine power are found. [ABSTRACT FROM AUTHOR]

The influence of various levels of mathematical modelling on gas turbine performance is systematically analysed. It is shown that internal combustion with real gas effects gives rise to an optimum turbine entry temperature which does not arise in a perfect gas analysis and has not been described previously in the literature. At any pressure ratio, the maximum possible efficiency with real gas effects is significantly lower (15-20 per cent) than the maximum possible value predicted by a perfect gas analysis. An explicit equation has been derived for determining the optimum pressure ratio as a function of turbine entry temperature and component efficiencies. It is shown that the optimum design depends very strongly on turbine and compressor efficiencies. It is demonstrated that the optimum relation between pressure ratio and turbine entry temperature depends strongly on whether the optimization is carried out at fixed pressure ratios or at fixed temperatures. All previous references seem to have considered only the latter method. [ABSTRACT FROM AUTHOR]

Improving operational performance and reducing fuel consumption is increasingly important for shipping companies. Ship performance degrades over time due to hull and propeller fouling; therefore assessing when fouling effects are significant enough to warrant cleaning is critical. Advancements in onboard data logging systems, combined with machine learning techniques, unlock the potential to predict fouling effects accurately and determine when to clean. This study evaluates five models for shaft power prediction: Multiple Linear Regression, Decision Tree (AdaBoost), K – Nearest Neighbours, Artificial Neural Network and Random Forest. The importance of pre-processing is highlighted, contributing to the creation of a model with lower errors than previous studies. The significance of environmental parameters was explored, with the novel integration of wave statistics to the operational dataset, and simulated power-speed curves created from predictions to identify performance deterioration due to fouling. The Random Forest model was most effective in predicting shaft power, with an error of 1.17%. The addition of 'Days Since Clean' and 'Significant Wave Height' increased prediction accuracy by 0.07% and 0.12% respectively. Simulated power-speed curves revealed a 5.2% increase in shaft power due to fouling. This study provides operators with a method to determine when to conduct hull and propeller cleaning. • Random Forests and Tree-based models show potential in propulsion power prediction. • Models are improved with the addition of environmental and operational metrics. • Model error below 5% gives required accuracy for identification of fouling changes. • Approach enables determination of when to undertake hull and/or propeller cleaning. [ABSTRACT FROM AUTHOR]