scholarly journals Determining the causes, prevention and elimination of unstable modes of gas turbochargers of marine diesels

2021 ◽  
Vol 27 (1) ◽  
pp. 33-51
Author(s):  
Володимир Миколайович Калугін ◽  
Олександр Міхайлович Мунтян
Keyword(s):  
Waste Heat ◽  
Operating Experience ◽  
Optimal Solution ◽  
Operating Conditions ◽  
Heat Recovery Boiler ◽  
Effective Functioning ◽  
Contractual Arrangements ◽  
Safe Level ◽  
Air Supply ◽  
Trial Test

Annotation – With commissioning of the “Socofl Star” ship’s series, negative occurrences relative to surging of the Main Engine (ME) «Hanshin Diesel» 6LF46 turbochargers (TC) VTR 401-2. To elimination of a surging, it was necessary reduce loading of ME to the safe level. This action caused the ship’s speed to fall from 11 – 10 to 4 knots which resulted in worsening of the ship’s maneuverability characteristics and lead to the failure to provide the ship’s service speed stipulated in the contractual arrangements. Existence of this problem instigated the shipowner to charge us as experts with the mission of carrying out appropriate investigations and working out recommendations as to how to prevent and eliminate surging of TC. This task was solved on the m/v “Socofl Star”. Based on results the ME shop test and trial test of the vessel and also the saved-up data of work of ME in various conditions of swimming, the analysis of the causes of a surge of the TC was made. It is established that small values of safety factor of stability of the compressor of TC on a surging – KCT which are not allowing to ensure effective functioning of TC on the main modes of loading of ME are its reason. For increase in area of steady work of TC it is necessary to reduce the hydraulic resistance of components of the Air-Gas Path (AGP) of the ME which can be realized by changes in a design of units of air supply and gas exchange or reduction of productivity and extent of increase in pressure of air in the compressor of TC. Under operating conditions vessels an optimal solution an objective is removal of a part of blowing-off air after compressor of the TC. The air can be discharged into the flue gas header after the waste heat recovery boiler or directly into the atmosphere. This allowed the shipowner not to make constructive changes to the components of the AGP of ME and TC. The description of the operated unloading device controlled remotely on removal of air which ensures effective functioning of TC and ME that is confirmed by results of natural tests and the subsequent operating experience of vessels of the “Socofl Star” series is provided.

Close supercritical versus inverse Brayton cycles for power supply, using waste of a biogas-driven open Brayton cycle

2021 ◽  
pp. 1-25
Author(s):  
Mohammad Ebadollahi ◽  
Hadi Rostamzadeh ◽  
Omid Pourali ◽  
Hadi Ghaebi ◽  
Majid Amidpour
Keyword(s):  
Performance Enhancement ◽  
Waste Heat ◽  
Optimal Solution ◽  
Energy System ◽  
Operating Conditions ◽  
Brayton Cycle ◽  
Small Communities ◽  
Energy And Exergy ◽  
Sustainable Energy System ◽  
Environment Index

Abstract Power generation via a biogas-driven Brayton cycle (BC) can be regarded as the best scenario for electricity supply of decentralized complexes or small communities. However, the central problem associated with such technology is high temperature of its exhaust gases which can be recovered via appropriate waste heat elimination schemes. Although various studies have previously discussed optimal operating conditions of the enhanced biogas-driven BC in terms of thermodynamics and economic, no comprehensive investigation in terms of selecting the best bottoming cycle for the biogas-driven BC has been carried out up to yet. This spurs the current investigation to recommend the best bottoming cycle between a close supercritical BC (CSBC) and an inverse BC (IBC) for waste heat recovering of a biogas-driven BC around the optimum point. Another novelty of the present study is inclusion of the Environment Index (EI) along with energy, exergy, and economic metrics in the performed multi-objective optimization scheme, resulting in the design of a highly sustainable energy system. The results indicated that no single optimal solution exists in selecting the best bottoming cycle by accounting energy, exergy, exergoeconomic, and exergoenvironmental metrics, simultaneously. Hence, a trade-off should be deliberated in selecting the best case in the design process. Accordingly, the integrated BC/CSBC system is superior over the BC/IBC system in terms of thermodynamics (i.e., both energy and exergy metrics) around both base and optimal design points; however, is not commendable in terms of economic and exergoenvironmental viewpoints. Quantitatively speaking, selecting the BC/CSBC system can lead to thermal and exergetic performance enhancement of around 3.3%, while degrading economic and exergoenvironmental metrics around 7.2% and 8.3%, respectively.

scholarly journals Component-Oriented Modeling of a Micro-Scale Organic Rankine Cycle System for Waste Heat Recovery Applications

2021 ◽  
Vol 11 (5) ◽  
pp. 1984
Author(s):  
Ramin Moradi ◽  
Emanuele Habib ◽  
Enrico Bocci ◽  
Luca Cioccolanti
Keyword(s):  
Electric Power ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Pump Efficiency ◽  
Micro Scale

Organic Rankine cycle (ORC) systems are some of the most suitable technologies to produce electricity from low-temperature waste heat. In this study, a non-regenerative, micro-scale ORC system was tested in off-design conditions using R134a as the working fluid. The experimental data were then used to tune the semi-empirical models of the main components of the system. Eventually, the models were used in a component-oriented system solver to map the system electric performance at varying operating conditions. The analysis highlighted the non-negligible impact of the plunger pump on the system performance Indeed, the experimental results showed that the low pump efficiency in the investigated operating range can lead to negative net electric power in some working conditions. For most data points, the expander and the pump isentropic efficiencies are found in the approximate ranges of 35% to 55% and 17% to 34%, respectively. Furthermore, the maximum net electric power was about 200 W with a net electric efficiency of about 1.2%, thus also stressing the importance of a proper selection of the pump for waste heat recovery applications.

Optimization of a Sintering Waste Heat Power Unit

2014 ◽  
Vol 1008-1009 ◽  
pp. 897-900
Author(s):  
Xue Min Gong ◽  
Jiu Lin Yang ◽  
Chen Wang
Keyword(s):  
Power Generation ◽  
Power Unit ◽  
Waste Heat ◽  
Steam Pressure ◽  
Operating Conditions ◽  
Parameters Optimization ◽  
Heat Power ◽  
Optimal Value ◽  
Generation Capacity ◽  
Main Steam

An optimization was performed for a sintering waste heat power unit with all data obtained in the site and under the unit normal operating conditions. The physical and mathematical model for the process of cooling and generation is established, which makes the net power generation as an objective function of the cooling machine imported ventilation, the thickness of sinter and the main steam pressure. Optimizing for single parameter, we found that each parameter had an optimal value for the system. In order to further optimize the system's operating parameters, genetic algorithm was used to make the combinatorial optimization of the three parameters. Optimization results show that power generation capacity per ton is increased by13.10%, and net power generation is increased by 16.17%. The optimization is instructive to the operation of sintering waste heat power unit.

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

Numerical Analysis of Non-Radial Blading in a Low Speed and Low Pressure Turbine for Electric Turbocompounding Applications

2021 ◽  
Author(s):  
Eva Alvarez-Regueiro ◽  
Esperanza Barrera-Medrano ◽  
Ricardo Martinez-Botas ◽  
Srithar Rajoo
Keyword(s):  
Numerical Analysis ◽  
Numerical Simulations ◽  
Thermal Stresses ◽  
Waste Heat ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Blade Angle ◽  
Low Speed

Abstract This paper presents a CFD-based numerical analysis on the potential benefits of non-radial blading turbine for low speed-low pressure applications. Electric turbocompounding is a waste heat recovery technology consisting of a turbine coupled to a generator that transforms the energy left over in the engine exhaust gases, which is typically found at low pressure, into electricity. Turbines designed to operate at low specific speed are ideal for these applications since the peak efficiency occurs at lower pressure ratios than conventional high speed turbines. The baseline design consisted of a vaneless radial fibre turbine, operating at 1.2 pressure ratio and 28,000rpm. Experimental low temperature tests were carried out with the baseline radial blading turbine at nominal, lower and higher pressure ratio operating conditions to validate numerical simulations. The baseline turbine incidence angle effect was studied and positive inlet blade angle impact was assessed in the current paper. Four different turbine rotor designs of 20, 30, 40 and 50° of positive inlet blade angle are presented, with the aim to reduce the losses associated to positive incidence, specially at midspan. The volute domain was included in all CFD calculations to take into account the volute-rotor interactions. The results obtained from numerical simulations of the modified designs were compared with those from the baseline turbine rotor at design and off-design conditions. Total-to-static efficiency improved in all the non-radial blading designs at all operating points considered, by maximum of 1.5% at design conditions and 5% at off-design conditions, particularly at low pressure ratio. As non-radial fibre blading may be susceptible to high centrifugal and thermal stresses, a structural analysis was performed to assess the feasibility of each design. Most of non-radial blading designs showed acceptable levels of stress and deformation.

scholarly journals Thin Gas Film Isothermal Condensation in Aerodynamic Bearings

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Eliott Guenat ◽  
Jürg Schiffmann
Keyword(s):  
High Speed ◽  
Waste Heat ◽  
Load Capacity ◽  
Saturation Pressure ◽  
Operating Conditions ◽  
Fluid Film ◽  
Small Scale ◽  
Vapor Compression ◽  
Density Profiles ◽  
Film Pressure

Abstract High-speed small-scale turbomachinery for waste heat recovery and vapor compression cycles is typically supported on gas-lubricated bearings operating close to the saturation conditions of the lubricant. Under particular conditions, the gas film might locally reach the saturation pressure with potentially hazardous effects on the performance of the gas bearing. The present work introduces a model based on the Reynolds equation and the development of cavitation modeling in liquid-lubricated bearings for condensing gas bearings. The effect of condensation on load capacity and pressure and density profiles is investigated for two one-dimensional bearing geometries (parabolic and Rayleigh step) and varying operating conditions. The results suggest that the load capacity is generally negatively affected if condensation occurs. An experimental setup consisting of a Rayleigh-step gas journal bearing with pressure taps to measure the local fluid film pressure is presented and operated in R245fa in near-saturated conditions. The comparison between the evolution of the fluid film pressure under perfect gas and near saturation conditions clearly suggests the occurrence of condensation in the fluid film. These results are corroborated by the very good agreement with the model prediction.

Novel Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources, Part II: Experimental Investigation

2003 ◽  
Vol 125 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Gunnar Tamm ◽  
D. Yogi Goswami
Keyword(s):  
Low Temperature ◽  
System Analysis ◽  
Waste Heat ◽  
Thermal Power ◽  
Experimental System ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Working Fluid ◽  
Water Mixture ◽  
Theoretical Simulation

A combined thermal power and cooling cycle proposed by Goswami is under intensive investigation, both theoretically and experimentally. The proposed cycle combines the Rankine and absorption refrigeration cycles, producing refrigeration while power is the primary goal. A binary ammonia-water mixture is used as the working fluid. This cycle can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low temperature sources such as geothermal and solar energy. An experimental system was constructed to demonstrate the feasibility of the cycle and to compare the experimental results with the theoretical simulation. Results showed that the vapor generation and absorption condensation processes work experimentally, exhibiting expected trends, but with deviations from ideal and equilibrium modeling. The potential for combined turbine work and refrigeration output was evidenced in operating the system. Analysis of losses showed where improvements could be made, in preparation for further testing over a broader range of operating conditions.

Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study

2015 ◽  
Author(s):  
Fredrik Ahlgren ◽  
Maria E. Mondejar ◽  
Magnus Genrup ◽  
Marcus Thern
Keyword(s):  
Power Output ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Maritime Transportation ◽  
Working Fluid ◽  
Net Power Output

Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.

scholarly journals Evaluation and analysis of exergoeconomic performance for the calcination process of green petroleum coke in vertical shaft kiln

2021 ◽  
pp. 294-294
Author(s):  
Peng Li ◽  
Baokuan Li ◽  
Zhongqiu Liu ◽  
Wenjie Rong
Keyword(s):  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Shaft Furnace ◽  
Exergy Efficiency ◽  
Heat Recovery Boiler ◽  
Vertical Shaft ◽  
Exergy Destruction ◽  
Calcination Process ◽  
Recovery Boiler

The main objective of this paper is to establish a mathematical framework to analyze the complex thermal economic performance of the calcination process. To find the factors affecting exergy efficiency loss, different exergy destruction is investigated in detail. Furthermore, the exergy flow cost model for exergy cost saving has also been developed. The results show that the vertical shaft furnace is a self-sufficiency equipment without additional fuel required, but the overall exergy destruction accounts for 54.11% of the total exergy input. In addition, the energy efficiency of the waste heat recovery boiler and thermal deaerator are 83.52% and 96.40%, whereas the exergy efficiency of the two equipment are 65.98% and 94.27%. Furthermore, the import exergy flow cost of vertical shaft furnace, waste heat recovery boiler and thermal deaerator are 366.5197 RMB/MJ, 0.1426 RMB/MJ and 0.0020RMB/MJ, respectively. Based on the result, several suggestions were proposed to improve the exergoeconomic performance. Assessing the performance of suggested improvements, the total exergy destruction of vertical shaft furnace is reduced to 134.34 GJ/h and the exergy efficiency of waste heat recovery boiler is raised up to 66.02%. Moreover, the import exergy flow cost of the three different equipment is reduced to 0.0329 RMB/MJ, 0.1304 RMB/MJ and 0.0002 RMB/MJ, respectively.

scholarly journals A Latent Heat Storage System for Low-Temperature Applications: From Materials Selection to Prototype Performances

2021 ◽  
Vol 11 (21) ◽  
pp. 10350
Author(s):  
Didier Haillot ◽  
Yasmine Lalau ◽  
Erwin Franquet ◽  
Sacha Rigal ◽  
Frederic Jay ◽  
...  
Keyword(s):  
Low Temperature ◽  
Latent Heat ◽  
Heat Storage ◽  
Waste Heat ◽  
Material Selection ◽  
Energy Transition ◽  
Industrial Sector ◽  
Operating Conditions ◽  
Acid Mixture ◽  
Latent Heat Storage

The industrial sector is increasingly obliged to reduce its energy consumption and greenhouse gases emissions to contribute to the world organizations’ targets in energy transition. An energy efficiency solution lies in the development of thermal energy storage systems, which are notably lacking in the low-temperature range (50–85 °C), for applications such as district heating or low-temperature waste heat recovery. This work aims to bring a latent heat storage solution from material selection to prototype evaluation. The first part of this paper is dedicated to the characterization and aging of a phase change material selected from a screening of the literature (fatty acid mixture mainly composed by stearic and palmitic acid). Then, this material is encapsulated and tested in a prototype whose performances are evaluated under various operating conditions. Finally, a numerical model validated by the experimental results is used to explore the influence of a wider range of operating conditions, dimensioning choices, and material conductivity improvements.

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