Energy Efficiency Factor Research Articles

Electrohydrodynamic Swirl-Flow Generators for Application in Thermal Management

The arrangement of electrodes in an electrohydrodynamic (EHD) gas pump inside a square channel is experimentally examined for its effective use in thermal management. Particularly, the study looks into modifying the characteristics of flow produced by an EHD gas pump through the arrangement of its electrodes. The aim is to produce swirl flow, which can effectively increase the flow mixing inside the channel and leads to the desired outcome. To this end, a two-stage gas pump powered by direct-current voltages ranging from 24 to 26 kV with electrodes flush mounted on two neighboring walls is devised. In addition to the volume flow rate produced, the performance of the pump is evaluated using an energy efficiency factor, which is defined as the volume flow rate delivered by a unit power input. It is found that the EHD gas pump with offset electrodes can not only produce more volume flow rate but also has a larger value for energy efficiency, which may be more favorable for the application in thermal management. The present results reveal that the EHD gas pump has great potential for applications in thermal management and can be more energy efficient when operated with uneven applied voltages.

Therapeutic dose and long-term efficacy of high-intensity focused ultrasound ablation for different types of uterine fibroids based on signal intensity on T2-weighted MR images

Objective To investigate the therapeutic dose and long-term efficacy of high-intensity focused ultrasound (HIFU) ablation for different types of uterine fibroids based on signal intensity on T2-weighted MR images (T2WI). Materials and methods Four hundred and one patients with a solitary uterine fibroid treated with HIFU were classified into four groups consisting of extremely hypointense, hypointense, isointense and hyperintense fibroids. Each group was further classified into two subtypes: homogeneous and heterogeneous, based on signal homogeneity of fibroids. The therapeutic dose and long-term follow-up results were compared. Results There were significant differences in treatment time, sonication time, treatment intensity, total treatment dosage, treatment efficiency, energy-efficiency factor (EEF) and non-perfused volume (NPV) ratio among the four groups (p<.05). The average NPV ratio achieved in patients with extremely hypointense, hypointense, isointense and hyperintense fibroids was 75.2 ± 14.6%, 71.1 ± 15.6%, 68.2 ± 17.3% and 67.8 ± 16.6%, respectively; the re-intervention rates at 36 months after HIFU were 8.4%, 10.3%, 12.5% and 6.1%, respectively. Sonication time, treatment intensity and total energy for heterogeneous fibroids were greater than that for homogeneous fibroids in patients with extremely hypointense fibroids (p<.05). The treatment time for heterogeneous fibroids was significantly longer than that for homogeneous fibroids in patients with isointense fibroids (p<.05). Multivariate ordered logistic regression analysis showed that the ablation volume of fibroids and treatment time were related to NPV ratio (p<.05). Conclusion Every group of patients obtained satisfactory long-term results. Hyperintense fibroids are difficult to treat by HIFU. Heterogeneous fibroids are more difficult to treat with HIFU than homogeneity fibroids.

Lower Limb Exoskeleton - Energy Optimization of Bipedal Walking With Energy Recycling - Modeling and Simulation

Humans tend to use more energy to walk compared to other limb-based locomotion animals. This higher energy usage is due to “heel strikes” and “negative work” during human gait. Passive walkers elevate this phenomenon by utilizing elastic joints that absorb/reuse some of the negative work. The objective of this study is to absorb energy at one phase of the gait cycle, store it, and then release it at a later phase through the use of a lower limb exoskeleton. Knee geometry is one important factor in energy efficiency during gait. Animals with reversed knees compared to humans (backward knee), such as ostriches, exhibit improved energy efficiency. As part of this study, new energy optimization strategies were developed utilizing collision-based ground reaction forces and a discrete lagrangian. The minimal cost of transport (CoT) gait patterns were calculated with both forward-knee and backward-knee human-exoskeleton models. Simulation results show that wearing a backward-knee exoskeleton can reduce the CoT by 15% of while carrying external loads ranging from 20 to 60 kg. In addition, when the exoskeleton utilized energy recycling, the CoT was shown to be further reduced to 35%. These simulation results suggested that the optimal design for an exoskeleton aimed at utilizing energy recycling principles should incorporate backward-knee configurations much like those found in energy-efficient biped/quadruped animals.

Predicting main engine power and emissions for container, cargo, and tanker ships with artificial neural network analysis

The most significant aspect of international shipping is sea transportation, and the developments to be made in maritime transport will inspire and predict all other fields. Therefore, determining a ship’s main engine power has great importance in terms of both energy efficiency and environmental factors. The maritime transport and shipping industry has currently begun to understand the importance of artificial intelligence technology. This study uses an artificial neural network (ANN) model to predict the main engine power and pollutant emissions of container, cargo, and tanker ships over 14 parameters: maximum speed, average speed, breadth, year built, ship type, status, length overall (LOA), light displacement, summer displacement, fuel type, deadweight tonnage (DWT), gross tonnage, engine cylinder size, and engine stroke length. In order to provide accurate results, the ANN analysis was trained with data from 3,020 ships, which is quite high compared to the studies in the literature. Many ANN models have been developed and compared to achieve minimal errors and highest accuracy in the results. The regression values, which involve the training, validation, and test values for the different ship types, were obtained as 0.99773 for container ships, 0.98964 for cargo ships, and 0.97755 for tanker ships, with a value of 0.97189 for all ships. The ANN structure was tested using many variations for hidden neuron counts, with the ANN analysis made with 30 neurons obtaining the best results. The ANN analysis results were compared with real values, which showed that very accurate results had been obtained according to the mean squared error (MSE), regression, and mean absolute percentage error (MAPE) results. The MSE value had exceeded 20,000 in the two-input ANN model, but decreased to 0.03, 0.081, and 0.13 with the 14-input model for container, cargo, and tanker ships, respectively. In order to make accurate predictions with maximum precision in the ANN analyses, the study attempted to use different values for the numbers of hidden neurons and inputs and then presented the performance results. The developed model can be used in future studies to be done on fuel consumption and energy efficiency for ships in maritime transport.

Total-factor energy efficiency of ten major global energy-consuming countries

Improving energy efficiency is regarded as a key path to tackling global warming and achieving the Sustainable Development Goals (SDGs). In 2020, the energy consumption of the world's ten major energy-consuming countries accounted for 66.8% of the global total. This paper applied data envelopment analysis (DEA) to calculate these ten major energy-consuming countries' total-factor energy efficiency (TFEE) at national and sectoral levels from 2001-2020, and explored the influencing factors of total-factor energy efficiency with the Tobit regression model. The results showed significant difference in the ten countries' energy efficiency. The United States and Germany topped the list for total-factor energy efficiency, while China and India were at the bottom. Meanwhile, the energy efficiency of the industrial subsector has increased significantly over the past two decades, while that of the other subsectors has been relatively flat. The industrial structure upgrading, per capita GDP, energy consumption structure, and foreign direct investment had significant impacts on energy efficiency with national heterogeneity. Energy consumption structure and GDP per capita were determinative factors of energy efficiency.

Engineering Analysis of the Closed-Type Wind Turbine Diffuser

In this paper considered the engineering analysis of a diffuser with a closed-type wind power plant by converting the kinetic energy of the oncoming wind into electrical energy. The study of the wind turbine diffuser was carried out in order to increase the energy efficiency of converting wind energy into electrical energy. The closed-type wind turbine design is converted into a finite element model for aerodynamic calculations. The model of a closed-type wind turbine is investigated by changing the angle of attack of the diffuser, with various options for its parameters in order to find the most optimal conditions for increasing the energy efficiency factor of the energy carrier, which will ensure high energy efficiency of converting wind energy into electrical energy. Based on the study results was recommended the diffuser with the optimal angle of attack by constructing a closed-type wind turbine.

Efficiency of the Consumption of Energy in the Road Transport of Goods in the Context of the Energy Crisis

Transport costs are strongly influenced by fuel prices and fuel consumption in transport, i.e., energy efficiency. The aim of the article is to present the problem of energy efficiency in freight transport with the use of Heavy Duty Vehicles (HDV). The authors presented the factors of energy efficiency in road transport, energy efficiency of the road vehicles, the share of fuel costs in the total costs of transport companies and the relationship between the increase in fuel prices and the increase in transport rates. Research methods include, apart from literature analysis, interviews conducted in Polish transport companies in 2022 and the analysis of data collected by the authors on the transport services market over the last 20 years. The increase in rates over the last 20 years, until 2021, largely coincided with the increase in fuel prices, while in 2022, for the first time in this period, the increase in fuel prices was greater than the increase in rates. However, the prices for transport services increased with the increase in energy consumption costs, not with changes in fuel prices. The cost of energy consumption depends on the efficiency of its use, which is constantly increasing, although to a small extent. Research shows that the efficiency of fuel consumption in high-tonnage transport changes at a rate of 0.8–1% per year while the proportion of fuel costs in Polish transport companies transporting goods by road in the last 20 years oscillates between 29% and 46%. There was also an increase in the freight rates on this market, in most cases by over 30%. Despite this, however, the profitability of some companies deteriorated. A large increase in transport rates, compensating for the increase in fuel prices, applies mainly to transport companies whose strategy is to compete with the quality of services, and when high-value loads are transported, while a small increase in transport rates, which does not compensate for the increase in fuel prices, applies mainly to companies whose strategy is to compete on the price of transport services and when low-value cargo is being transported. The results of research on the market in Poland conducted by the authors of the article agrees with the results and opinions of other authors and researchers from other countries. The authors also agree with the view that the possibilities of increasing the efficiency of energy consumption in road transport by the carriers themselves are limited. The road transport market, especially in Poland, is highly competitive, which results in high efficiency of transport processes. However, this efficiency is largely affected by factors beyond the control of these companies (technological factors, infrastructure and energy sources). It seems that the involvement of the state is necessary. The research carried out by the authors of the article also confirmed the existing relationships between the weight of the transported cargo and energy consumption identified by other authors.

Experimental investigation of heat transfer performance of Al2O3 nanofluids in a compact plate heat exchanger

• Heat transfer of Al2O3 nanofluids in compact plate heat exchanger is investigated. • Stability of Al2O3 nanofluids is evaluated. • Thermophysical properties of Al2O3 nanofluids are characterized. • Energy performance and heat transfer enhancement are demonstrated. • Al2O3 nanofluids showed great promises for applications in thermal management systems. This study experimentally investigates the performance of a compact gasketed plate heat exchanger (PHE) employing Al 2 O 3 nanofluids prepared for several low concentrations of Al 2 O 3 (0.01, 0.05, 0.10, 0.15 and 0.20 vol.%) and base fluids of distilled water (DW) and its mixture with ethylene glycol (15% and 30% of EG) for several flow rates (0.03-0.093 l/s). The main thermophysical properties of those nanofluid samples were experimentally measured. The prepared nanofluids samples showed a Newtonian rheological behaviour and an increase in viscosity up to 7.5% for 0.2 vol.%. The enhancements in the thermal conductivity were significant and the values were 7.3 %, 8.4% and 9.1% for Al 2 O 3 nanofluids at 0.2 vol.% compared to the base fluids DW, 15% EG and 30% EG, respectively. A newly developed experimental setup is used to operate the nanofluids through the PHE under particular conditions for heating purposes (mainly high temperature), and their performance is evaluated in comparison with the conventional heat transfer fluids (the base fluids). Nusselt number, pressure drop, and energy efficiency factor were determined for the nanofluids and base fluids. The results indicated a heat transfer enhancement with the increase of the particles’ concentration reached the maximum value of 27% at 0.2 vol.% for DW based Al 2 O 3 nanofluid and was accompanied by an increase in pressure drop of 8%. The heat transfer enhancement became lower with the increase of the EG percentage such as 19.1% at 0.2 vol.% for 30% of EG based Al 2 O 3 nanofluid based. In addition, the energy efficiency factor increased by the addition of Al 2 O 3 nanoparticles to the base fluids and with the increase of flow rates up to the value of 1.3 at the highest particles concentrations. This work provides an important step concerning the performance of particular design of Al 2 O 3 nanofluids and operation conditions in compact PHEs on the road to the development of thermal management systems under the current industry’s trends for optimizing energy use and minimizing equipment.

Thermodynamics Analysis of the Distributed Parameter Model of Counterflow Heat Exchanger

In this paper we are interested in the thermodynamic analysis of a counterflow heat exchanger, when the dynamics are described by two hyperbolic partial differential equations (PDEs). First from the first and second law of thermodynamics we derive the different models of the heat exchanger. Next we perform an analysis of the equilibrium profiles from a certain condition on the system parameters that guarantees the existence and uniqueness of the solution of the PDEs model. In this analysis we show the importance of the thermal pinch as an energy efficiency factor. Finally we study the passivity and the asymptotic stability of the considered heat exchanger essentially basing ourselves on the entropy as a storage function, entropy production as a dissipation function, and the thermodynamic availability function as a Lyapunov function.

Evaluation of Current Farm Machinery Selection Practices of Wonji Shoa Sugar Factory

The Government of Ethiopia is trying to improve sugar industry sector by establishing new factories, expansion projects and rehabilitation of existing ones. The main input in this process is agricultural mechanization; however it has been resulted in a huge number of farm machinery of various types and sizes, without consideration of proper selection and matching between tractors and their attachments (implements). This approach had led to high cost of agricultural operation, resulted in an unbalanced distribution of machinery and the agricultural operations throughout the years. Wonji Shoa Sugar factory is one of the victims of the aforementioned problem. The present study was conducted to evaluate the current farm machinery selection practices of Wonji Shoa Sugar Factory. Three soil types namely; heavy clay, vertisol and sandy loam were selected with four field activities (subsoiling, ploughing, harrowing and furrowing). For subsoiling, ploughing and harrowing, 9410-R John Deer tractor with implements of 5 shank and 3.2 m wide mounted subsoiler, 2.8 m wide double gang offset disc plough, and 3.5 m wide semi mounted four gangs double offset were used respectively. For furrowing YTO-1804 tractor and a four bottom fully mounted 4.5 m wide rider was used. For each experiment, the draft force requirement of the implements, the drawbar power, fuel consumption, overall energy efficiency and power utilization ratio were determined at different tractor travel speeds. Subsoiling, ploughing and harrowing were activities were evaluated at the travel speed of w 3, 4, 5 and 6 km/hr. And a travel speed of 4, 5, 6 and 7 km/hr were used for furrowing operation. Linear regression tests were run to examine the interactions between the factors and determine their significant impact. The results of this study noted for furrowing operation as lowest draft force, drawbar power, fuel consumption and energy efficiency of 14 kN, 12.65kW, 13 lit/hr and 8.7 % respectively in sandy loam soil type. The maximum Draft force of 79.8 kW and drawbar power of 131 kW was noted for subsoiling operation in Heavy clay soil. Moreover the results of all operation in all soil type, as indicated by both overall energy efficiency and power utilization factor shows the mismatch between the tractor and implements, as the tractors were overpowered. That means a less amount of the available power from the tractor is being used to operate the implement. If the tractor had been matched with a bigger and compatible implement a better efficiency and higher productivity of the tractor implement combination could have been achieved.

中国能源效率影响因素分析——基于省级面板数据的实证分析

中国能源效率影响因素分析——基于省级面板数据的实证分析

Towards Sustainability: Analysis of Energy Efficiency Factors in Buildings of Smart Cities Using an Integrated Framework

Towards Sustainability: Analysis of Energy Efficiency Factors in Buildings of Smart Cities Using an Integrated Framework

How Do Industrial Ecology, Energy Efficiency, and Waste Recycling Technology (Circular Economy) Fit into China’s Plan to Protect the Environment? Up to Speed

The challenges of environmental protection are especially prevalent in South and Southeast Asian nations, which adversely affects their sustainable developmental goals. During the last two decades, increased industrialization and urbanization have caused massive air pollution, particularly in the most industrialized and densely populated countries. Due to China’s fast economic expansion and development, the demand for natural resources has increased, resulting in climate change, biodiversity loss, soil degradation, and environmental risks. China’s ecological footprint has been the subject of little investigation on the premises of a circular economy. This study used a literature review methodology on the critical key factors that hinder or facilitate the transition of a linear economy towards a circular economy. Further, based on the literature review, this study used industrial ecology, energy efficiency, and waste recycling technology factors to analyze the role of the circular economy on the country’s environmental sustainability agenda for the period of 1975–2020. The results show that in the short run, the link between ecological footprints and per capita income is monotonically decreasing; however, in the long run, the relationship is U-shaped. In both the short and long run, waste recycling technology and cleaner manufacturing significantly decrease ecological footprints. Renewable energy consumption increases ecological footprints in the short run but decreases them in the long run. The management of natural resources reduces ecological footprints to support the ‘resource blessing’ hypothesis. The Granger causality corroborated the unidirectional relationship between ecological footprints, oil rents, and urbanization and ecological footprints. In addition, economic growth Granger causes industrialization and waste recycling technology while green energy Granger causes economic growth, industrialization, and recycling technology. The two-way link between economic development and urbanization exists within a nation. The variance decomposition analysis (VDA) predicts that in the future, China’s natural resources, green energy demand, and technological spillover will limit its ecological footprint through material and technology efficiency.

Analysis of spatiotemporal difference and driving factors of green total factor energy efficiency in RCEP members: insights from SBM-GML and Tobit models.

It is vital to determine the changing spatiotemporal patterns and driving factors of green total factor energy efficiency (GTFEE) in order to design scientific policies to promote energy efficiency in the Regional Comprehensive Economic Partnership (RCEP) region. From 2010 to 2019, the super-efficient SBM model and the global Malmquist-Luenberger index provide an appropriate framework for measuring the spatiotemporal evolution of GTFEE and the dynamics of energy productivity in RCEP countries. With the coefficient of variation and the Thiel index, an extensive view of the spatiotemporal variance in GTFEE is offered, taking regional heterogeneity into account. Furthermore, the Tobit model is introduced to investigate the factors influencing the GTFEE of RCEP members, which may address the restricted values of the dependent variable when compared to the least squares regression model. Findings suggest that (1) The GTFEE of RCEP members tends to be low and unevenly distributed spatially and temporally, with much room for improvement. (2) The energy productivity index fluctuates strongly, and the improvement primarily comes from technological progress. (3) The Non-ASEAN region possesses higher GTFEE than the ASEAN region, albeit regional variations are diminishing. (4) In terms of the major factors influencing the regional GTFEE, the non-ASEAN region looks to be distinct from the ASEAN region. The findings shed light on the trends and influencing factors of GTFEE in RCEP and serve as a resource for international energy cooperation and sustainable development.

Spatial and temporal research on ecological total factor energy efficiency in China: Based on “Ecology-Economy-Geography” heterogeneity framework

Scientific measurement of energy efficiency is the cornerstone of improving energy efficiency and realizing energy transition. Considering that the production technology of each region is restrained by factors including economic development and natural resource endowment, this paper first uses the emergy theory to measure the ecological carrying capacity of each region, and then selects other representative data to construct the “Ecology-Economy-Geography” heterogeneous framework. From the perspective of energy input minimization, the spatial and temporal features of China's ecological total factor energy efficiency (ETFEE) from 2006 to 2019 have been discussed by employing the sequential directional SBM model and Luenberger productivity index. After robustness tests, we conclude that: (a) The grouping results under multidimensional variables are different from the traditional grouping of “East-Central-West”; (b) The meta-frontier Ecological Total Factor Energy Efficiency (METFEE) and group frontier Ecological Total Factor Energy Efficiency (GETFEE) vary in spatial distribution and temporal change; (c) Technological progress is the key to improving METFEE, but part of the improvement will be offset by diminishing returns of “catch-up effect”. Finally, policy recommendations to promote the ecological total factor energy efficiency in China are put forward.

Swarm Intelligence-Based Multi-Objective Optimization Applied to Industrial Cooling Towers for Energy Efficiency

Cooling towers constitute a fundamental part of refrigeration systems in power plants and large commercial buildings. Their main function is to treat the heat emitted by other equipment to cool down the temperature of the environment and/or processes. In the considered refrigeration system, cooling towers are coupled with compression chillers. The serious world-wide concerns with regard to environmental wear and water scarcity are now common knowledge. One way to mitigate their impact is to reach a state of maximum energy efficiency in industrial processes. For this purpose, this work proposes the application of multi-objective optimization algorithms to find out the optimal operational setpoints of the studied refrigeration system. Here, we exploit swarm intelligence strategies to offer the best trade-offs. This consists of finding solutions that maximize the cooling tower’s effectiveness and yet minimize the global power requirement of the system. Additionally, the solutions must also respect operational constraints for the safe operation of the equipment. In this investigation, we apply two algorithms, multi-objective particle swarm optimization and multi-objective TRIBES, using two different models. The achieved results are compared considering two different scenarios and two different models of the refrigeration system. This allows for the selection of the best algorithm and best equipment model for energy efficiency of the refrigeration system. For the studied configuration, we achieve an energy efficiency factor of 1.78, allowing power savings of 9.48% with tower effectiveness reduction of only 5.32%.

The underlying drivers of energy efficiency: a spatial econometric analysis.

It is theoretical and practical to investigate the causes and effects of energy efficiency. However, few empirical studies have been conducted to examine the potential underlying drivers of energy efficiency from a spatial perspective. In light of this, we combined the data envelopment analysis and spatial econometric analysis to explore the driving factors of energy efficiency. The results show that China's energy efficiency shows significant characteristics of regional disparity and spatial agglomeration; that is, high energy efficiency has presented a benefit agglomeration, while low energy efficiency has presented a disadvantage agglomeration. The empirical results indicate that technological progress, trade openness, and foreign direct investment have effectively improved energy efficiency, while energy structure and industrial structure adversely affect energy efficiency. Furthermore, technological progress, trade openness, energy structure, foreign direct investment, and industrial structure exert different influences on energy efficiency, but their potential underlying mechanisms vary essentially across regions. Thus, using a spatial econometric model allowing for spatial dependence in analyzing drivers of energy efficiency is urgent and necessary for promulgating energy policies.

Heat transfer intensification of turbulent forced convection by inserting discontinuous twisted tapes in a wavy tube; hydrothermal and thermodynamics analysis

The current study presents a numerical investigation on turbulent hydrothermal characteristics in a wavy passage equipped with discontinuous twisted tapes. The working fluid is water and passage walls are kept under constant wall temperature. The effect of Reynolds number (Re = 2500, 4500, 6500, 8500 and 10500), twist angle (TA = 90∘ and 180∘) and inclination angle (IA = 15∘ and 30∘) on velocity fields and streamlines, temperature contours, Nusselt number, friction factor, turbulent kinetic energy (TKE), thermal performance factor (TPF), energy efficiency factor (EEF) and entropy generation rate are evaluated. More uniform temperature and velocity fields can be found as both wavy passage and twisted tape are simultaneously applied. Both heat transfer rate and pumping power rise with increasing Reynolds number, twist and inclination angles. Results reveal that the twisted tape play more remarkable role on Nusselt number and friction factor at lower inclination angle. The best value of EEF is detected 24.6% occurring for passage with IA = 15∘ and TA = 180∘ at Re = 2500. Among all considered cases, those of empty wavy passage with IA = 30∘ at Re = 8500 and 10500 provides negative values of EEF, referring to inefficient cases from energy viewpoint. The contribution of wavy passage and twisted tape on heat transfer enhancement is individually assessed and it is found that the best value of twisted tape involvement on enhanced heat transfer is 79.6% taking place for configuration with IA = 15∘ and TA = 180∘ at Re = 4500. Finally, based on CFD results, passages are examined from thermodynamics viewpoint and it is shown that the second law efficiency growths with increasing twist and inclination angles.

A step towards green economic policy framework: role of renewable energy and climate risk for green economic recovery

According to the World Bank, energy efficiency is a critical facilitator of most Sustainable Development Goals. Its contribution to CO2 emission reduction is astounding. Environmentalists have recently emphasized the essential need to determine energy efficiency causes. This research broadens the debate's horizons by proposing additional possible energy efficiency factors using data from the Chinese economy. From 1990 to 2020, we examined the influence of investment in renewable energy resources, financial inclusion, industrial production, and trade openness on China's energy efficiency and climate risk. Additionally, this study is added to the literature by examining the causal relationships between variables while considering the temporal dimension. The findings indicate that industrial production, financial inclusion, public R&D on renewable energy, and trade openness contribute significantly to China's energy efficiency and climate risk. All other factors, except industrial production, are positively associated with energy efficiency. The path of causality is established from energy efficiency and climate risk to financial inclusion, industrial production, renewable energy, public research and development budgets, and trade openness. According to the findings, changes in energy performance have frequency-changing impacts on all variables. Policymakers believe that the financial system must be strengthened since this will significantly influence renewable energy.

General Strength, Energy Efficiency (EEDI), and Energy Wave Criterion (EWC) of Deadrise Hulls for Transitional Mode

Abstract In the modern world, environmental issues come to the fore. The document of MARPOL for reducing the emission of pollutants into the atmosphere relates to the energy efficiency coefficient EEDI. This coefficient is directly related to the power of the main engine and, accordingly, to the water resistance. The way to reduce the energy efficiency factor EEDI by increasing the relative length L V 3 {L \over {\root 3 \of V }} of the ship was proposed in this article. To determine the maximum value of the relative length, knowledge of the general strength of the vessel is required. The value of the relative section modulus of an equivalent girder for a small vessel of transitional mode is defined. The result of the graphic solution of two equations is the value of such a relative section modulus. This parameter is required to determine the limiting value of the relative length and to find solutions to reduce the coefficient EEDI. Comparative analysis of the obtained data with the data of the strength and weight of the H-girder with a length similar to the ship was conducted. The formula for determining the limiting value of the relative length was obtained from the equation of general strength. For a preliminary assessment of the future project of the ship, in terms of permissible design accelerations and the possibility of the ship moving against a sea wave of a certain height, a graph was built based on the application of the energy wave criterion EWC and the requirements of various classification societies.