Engine Waste Heat Recovery System Research Articles

State of charge estimation based on active disturbance rejection control for power batteries in engine waste heat recovery system

The Coulomb counting (CC) method is the most widely accepted state of charge (SOC) estimation method in the industry. However, the cumulative error generated during operation is a huge challenge for the engineering application. A feedback regulation framework is designed to address this situation; however, the basic problem of this framework is that the error regulation occurs only after the error is generated. As a result, its initiative to suppress system disturbance is insufficient. To overcome this problem, an active disturbance rejection control–based-feedback-estimator is proposed in this paper. The regulation is designed based on the terminal voltage error between actual measurement and theoretical value. And active disturbance rejection control is employed to improve the estimation accuracy and adaptability. The power batteries’ SOC estimation in engine waste heat recovery system is studied in this paper. Compared with the traditional CC method and a proportional–integral (PI) feedback estimation method, the proposed active disturbance rejection control-feedback-estimator exhibits better estimation performance and adaptability to system disturbances and uncertainties. There are only three parameters [Formula: see text], [Formula: see text], and [Formula: see text] to tune, and estimation performance can be maintained without having to retune parameters when boundary conditions change, proving the effectiveness of the proposed active disturbance rejection control-feedback-estimator.

Fundamental Study on Flash Spray Characteristics in Steam Engine for Waste Heat Recovery System

In recent years, global warming and the depletion of fossil fuels have become more serious, and the efficient use of available energy sources has become an issue. In addition, in the domestic energy supply process, the majority of primary energy is not effectively utilized and is discarded as waste heat (unused heat). Therefore, to realize a sustainable society, it is essential to develop technologies to effectively utilize these waste heats and implement them in society. Therefore, waste heat recovery systems are attracting attention. In this study, a flash steam engine waste heat recovery system using flash steam and heat transfer from the wall surface was proposed as a new waste heat recovery system. This report describes the results of visualization and heat flux measurements of flash spraying of a low-temperature boiling working fluid and discussion of the results as a first step in the development of a flash steam engine for waste heat recovery from a low-temperature heat source.

Thermal and acoustic performance of silencing heat exchanger for engine waste heat recovery

The integrated design of gas heat exchanger and after-treatment unit can reduce the size and weight of the engine waste heat recovery system, releasing the back pressure of exhaust gas and enhancing net benefit of the waste heat recovery system. In this study, we propose a silencing heat exchanger that integrates an exhaust heat exchanger with an impedance composite muffler in the post-treatment system, using metal foam material instead of the sound absorbing material in the impedance composite muffler. By adapting ANSYS Fluent and LMS Virtual.Lab, thermal simulation and acoustic simulation of the silencing heat exchanger were realized, and comparative analysis of the modified structure and the basic structure was carried out. The modified silencing heat exchanger was then designed and fabricated, and the thermal and acoustic performance were tested. The results show that the modified silencing heat exchanger can achieve improved heat transfer and flow performance, and more uniform temperature distribution at the hot side, simultaneously resulting in an 8.4% reduction in exhaust pressure drop. Even more, the improvement of silence effect in the middle and high frequency band is fairly obvious, and the overall transmission loss is 44.4% higher than that of the basic structure.

Diesel engine waste heat recovery system comprehensive optimization based on system and heat exchanger simulation

Abstract To further improve the thermal efficiency of diesel engines, a waste heat recovery system model utilizing organic Rankine cycle (ORC) is constructed and verified through system bench test and heat exchanger bench test. To recover waste heat from diesel engine exhaust, ethanol, cyclopentane, cyclohexane, R1233zd (E), and R245fa were selected for comparison. The quality of heat source, the quality of evaporator, the system output, and the system complicity were taken as variables for comparison. Analysis shows that for ORC systems without recuperator, ethanol system has the best system output of the five in a wide operation temper range, with the highest exergy efficiency of 24.1%, yet the exergy efficiency increase after the application of recuperator, 9.0%, is limited. For low temperature exhaust, cyclopentane system has the best performance with or without recuperator, and the cyclopentane system with recuperator has the best performance in terms of exergy efficiency, 27.6%, though complex heat exchangers are also required for high power output. The system output of the R1233zd system is better than the R245fa system, yet the advantage of low evaporate temperature can be better utilized for low quality waste heat recovery.

Extended state observer assisted Coulomb counting method for battery state of charge estimation

The state of charge (SOC) estimation method for power batteries in engine waste heat recovery system is studied in this article. The nonmodel-based Coulomb counting (CC) method is among the most popular techniques. However, challenges imposed by inaccurate estimation of initial SOC, current measurement error as well as uncertain system dynamics caused by temperature, and thermal effects will produce an accumulated error. To overcome this error and improve the CC method's disturbance rejection capability, a linear second-order extended state observer (ESO) is designed to address this problem. A comparative simulation study is carried out to study the estimation performance of the proposed ESO-assisted CC method and the conventional CC method. Study results of the proposed approach exhibit better estimation performance and adaptability for inaccurate estimation of initial SOC, current measurement error, and uncertain system dynamics. There is only one parameter ωo to tune. The adaptability of estimation performance can be maintained without parameters resetting, which proves the effectiveness and disturbance rejection capability of the proposed ESO-assisted CC method for SOC estimation.

Assessment and optimization of exhaust gas heat exchanger with porous baffles and porous fins

The shell and tube heat exchanger with segmental baffles is widely applied in industry owing to its low cost and easy maintenance. However, when adopted it as the exhaust heat exchanger in engine waste heat recovery system, the large pressure drops on shell side and low thermal efficiency greatly affect the efficiency of the whole system. To overcome the aforementioned shortcomings, a structure of shell and tube heat exchanger with porous baffles and porous fins is put forward and numerically analyzed in this study. Comparisons on the pressure drop, heat transfer and comprehensive performance are firstly conducted between the proposed heat exchanger and other five heat exchangers with different structures. The results show that adding porous baffles and porous fins can increase heat transfer by 92.14%, decrease pressure drop by 64.70%, and reduce weight by 11.35% under the mass flow rate is 0.1280 kg/s, hence the proposed heat exchanger owns the best overall performance among six heat exchangers. Subsequently, the effects of key design parameters (fins number per meter, inner tube pitch and porosity) on the performance of the proposed heat exchanger are analyzed and optimized by artificial neural network and genetic algorithm to achieve the best for comprehensive performance. The results are as follows: when the above three parameters are 94 m−1, 58.6 mm and 0.702 respectively, the performance achieved the best.

Real-time realization of Dynamic Programming using machine learning methods for IC engine waste heat recovery system power optimization

This study aims to present a method for real-time realization of Dynamic Programming algorithm for power optimization in an organic Rankine Cycle waste heat recovery system. Different from existing studies, for the first time machine learning algorithms are utilized to extract the rules from offline Dynamic Programming results for optimal power generation. In addition, for the first time a single state Proper Orthogonal Decomposition and Galerkin Projection based reduced order model is combined with Dynamic Programming for its high accuracy and low computation cost. For a transient driving cycle, Dynamic Programming algorithm is utilized to generate the optimal working fluid pump speed. A total of eleven state-of-art machine learning algorithms are screened to predict this pump speed. Random Forest algorithm is then selected for its best pump speed prediction accuracy. A rule-based method is added to the Random Forest model to improve energy recovery. As one of the main discoveries in this study, in the rule extraction process, the Random Forest model reveals that the time delayed exhaust gas mass flow rate and exhaust temperature improve the rule extraction accuracy. This observation points out the difference between steady state and transient optimization and that the steady state optimization results do not necessarily hold true in transient conditions. Another key observation is that Random Forest – rule-based method retrieves 97.2% of the energy recovered by offline Dynamic Programming in a validation driving cycle. In addition, the inclusion of rule-based method significantly increases the Random Forest model’s energy recovery from 66.5% to 97.2%. This high accuracy means that the machine learning models can be used to extract Dynamic Programming rules for real-time application.

Analysis and optimization of organic Rankine cycle for IC engine waste heat recovery system

Abstract In this view, organic fluids can help to extract heat from low temperature reservoir and to produce vapour. Organic fluids were used in Rankine cycle to see the power output of the plant using Cycle tempo software which is used for simulating the Rankine cycle and necessary parameter inputs with Isobutane, R11, R12, R123 and R245fa working fluids. The minimum net electric power is obtained from R12 with the value of 5.46 kW and 8.21 kW of maximum power is obtained from organic Rankine cycle using Isobutane as working fluid.

An active observer-based predictive energy management strategy for engine waste heat recovery system

In this paper, energy management of waste heat recovery system has been attacked based on a three-step problem formulation approach. The problem has been formulated into a bilevel programme, where the upper level is designed to optimise the usage of recovered energy and the lower level is arranged to maximise the recovered energy. However, detailed models for real-time decision making cannot be easily obtained. In order to ensure the energy management performance, an active observer named extended state observer is adopted to compensate for static models via online information of the real energy network. The final decision making of the energy management is conducted based on the reconstructed model, which is simpler and more accurate. An energy network constructed by - - - - - is employed as the research object. Simulation study conducted by GT-SUITE software is used to verify the sub-goals of the problem configuration, including model self-reconstruction capability and fuel-saving potential. For two given testing cycles, simulation results indicate fairly good self-reconstruction capability can be ensured, while considerable fuel-saving capability can be reached comparing with a baseline strategy, indicating the effectiveness of the proposed approach.

An active observer-based predictive energy management strategy for engine waste heat recovery system

In this paper, energy management of waste heat recovery system has been attacked based on a three-step problem formulation approach. The problem has been formulated into a bilevel programme, where the upper level is designed to optimise the usage of recovered energy and the lower level is arranged to maximise the recovered energy. However, detailed models for real-time decision making cannot be easily obtained. In order to ensure the energy management performance, an active observer named extended state observer is adopted to compensate for static models via online information of the real energy network. The final decision making of the energy management is conducted based on the reconstructed model, which is simpler and more accurate. An energy network constructed by <engine>-<power turbine>-<organic Rankine cycle system>-<electric cooling system>-<battery>-<integrated starter and generator> is employed as the research object. Simulation study conducted by GT-SUITE software is used to verify the sub-goals of the problem configuration, including model self-reconstruction capability and fuel-saving potential. For two given testing cycles, simulation results indicate fairly good self-reconstruction capability can be ensured, while considerable fuel-saving capability can be reached comparing with a baseline strategy, indicating the effectiveness of the proposed approach.

디젤엔진에 적용하기 위한 엔진폐열 회수 시스템에 관한 기초 연구

디젤엔진에 적용하기 위한 엔진폐열 회수 시스템에 관한 기초 연구

Analysis of a 1 kW organic Rankine cycle using a scroll expander for engine coolant and exhaust heat recovery

The development of engine waste heat recovery technologies attracts ever increasing interests due to the rising strict policy requirements and environmental concerns. This paper presented the study of engine coolant and exhaust heat recovery using organic Rankine cycle (ORC). Eight working fluids were selected to evaluate and compare the performance of the integrated waste heat recovery system. Rather than the conventional engine ORC system mainly focusing on the utilization of exhaust energy, this work proposed to fully use the engine coolant energy by changing the designed parameters of the ORC system. The case study selected a small engine as the heat source to drive the ORC system using a scroll expander for power production. The evaluation results suggest that under the engine rated condition, the solution to fully recover the engine coolant energy can achieve a higher power generation performance than that of the conventional engine ORC system. The results suggest that adding a recuperator to the ORC system can potentially improve the system performance when the working fluids are dry and the overall dumped heat demand of the system can be reduced by 12% under optimal conditions. When the ORC evaporating and condensing temperature are respectively set at 85°C and 30°C, the integrated engine waste heat recovery system can improve the overall system efficiency by 9.3% with R600, R600a or n-Pentane as the working fluid.

Experimental investigation on heat transfer characteristics of plat heat exchanger applied in organic Rankine cycle (ORC)

Diesel engine waste heat recovery system based on the organic Rankine cycle (ORC) has been widely studied and developed by more and more researchers in the world. The brazing plate type heat exchangers (PHE) are widely used in the ORC system, especial in the diesel engine waste heat recovery ORC. This paper describes experimentally study the single phase and boiling heat transfer characteristics of three types of working fluid on PHE’s surfaces. These working fluids are water, 50% coolant and R245fa. The single phase convective heat transfer dimensionless empirical equation for the three types working fluid on three different chevron angle plate surfaces is provided, which has the mean absolute error 9.7% in the range Re=250–7000 and Pr=2.0–12.0. And the evaporation heat transfer empirical equation for the Organic fluid R245fa is given with the mean absolute error 9.97%, which can predict the 95% of the test data with the error less than ±20%.

Active regulation of battery charge-sustaining in ECMS: Application in energy management for engine waste heat recovery system

Equivalent consumption minimization strategy (ECMS) is a widely used energy management method in the battery equipped bio-sources energy system, in which an equivalence factor is adopted to weigh the two kinds of energy, usually fuel and electricity. The regulation of the equivalence factor will affect not only the fuel consumption but also the battery's state of charge (SOC) sustainability, which results great influence upon the energy management of the system. In this paper, a new perspective of treating the relationship between the equivalence factor and instantaneous fuel consumption as well as instantaneous electricity consumption as a first-order dynamic system is proposed, thus the relationship between the equivalence factor and SOC is deduced as a second-order dynamic system. Based on the perspective, a linear second-order Active Disturbance Rejection Control (ADRC) is employed to regulate the equivalence factor, which can estimate and compensate, in real-time, disturbances in the system from input-output information only. An engine waste heat recovery energy network constructed by - - - - - is selected as the research object, simulation verifications upon 11 different driving cycles based on the simulation platform established by GT-SUITE software are conducted to test the fuel-saving capability and SOC self-sustainability by the proposed approach with a same set of tuning parameters. Simulation results indicate that both the fuel-saving capability and the SOC self-sustainability can be ensured by the active control of equivalent factor with a same set of tuning parameters upon all the 11 driving cycles, demonstrating a great adaptability of the control parameters.

A Commander–Tracker–Executor based energy management framework for an engine waste heat recovery system

Energy management for an internal combustion engine waste heat recovery system presents a complex problem. There are the coupling issues of energy recovery and energy utilization. In addition, there are the problems arising from the large thermal inertia of the energy network. A Commander–Tracker–Executor energy manager framework is proposed as the management solution. Under this approach the Commander is designed to optimally split the engine’s exhaust energy among the different energy devices of the energy network at the lowest fuel cost. A disturbance estimation-based receding horizon controller is designed as a Tracker to follow the Commander’s commands in real time. The Commander’s decisions are made in real time based on each energy device’s efficiency model, the torque demand given by the driver, and the corresponding heat rejection requirement of the whole system. The Tracker works as a trajectory follower to transform the Commander’s decisions into the actuators’ control objectives. The Executor ensures that the energy management goals are achieved in line with the actuators’ control objectives. An energy network constructed of &lt;Engine&gt;- &lt;Power Turbine&gt;- &lt;Organic Rankine Cycle System&gt;- &lt;Electric Cooling system&gt;- &lt;Battery&gt;- &lt;Integrated starter and Generator&gt; has been taken as an example for the simulation study. The simulation results indicate that: the manager exhibited fairly good fuel-saving potentiality along a whole driving cycle; the proposed Commander showed effective exhaust energy splitting performance; and the Tracker scheme demonstrated good tracking capability and robustness.

Glycerol steam reforming in a bench scale continuous flow heat recovery reactor

In the present study glycerol was successfully gasified using a diesel engine waste heat recovery system obtaining hydrogen and methane rich gaseous products. The reforming reactor was equipped with a vaporization pre-chamber to ensure uniform reactants distribution and a fixed reaction bed, being mounted in countercurrent flow configuration with the engine combustion gases stream. Accordingly, the reactions were conducted at gradually increased temperature conditions; starting at around 300 °C in the top section of the reaction bed and finishing in a controlled outlet bed temperature of 600–800 °C. When compared to homogeneous temperature reactors, the configuration used here produced a syngas of higher methane and ethylene contents. With regards to the reactor performance, syngas lower heat values of more than 22 MJ/kg were achieved with glycerol feed concentrations within 50–70% and outlet bed temperatures above 700 °C, corresponding to cold gas efficiencies of around 85%. The present results indicate that glycerin can be utilized as a syngas feedstock for steam reforming processes based on waste heat recovery.

Exergetic Cost Analysis of Marine Diesel Engine Waste Heat Recovery System Based on Matrix Model Thermo-Economics

Diesel engine is the main power of the marine vessel, its thermal efficiency is the highest in all thermodynamic engines, but still more than 50% of the energy is not being used, so making full use of the waste heat of the main diesel engine scientifically and effectively, not only reduce the fuel consumption and the shipping cost, but also reduce the value of the ship EEDI effectively. To be able to design and transform the green ship, thermodynamic analyzing of the ship power plant and master the energy utilization of each part is necessary. Raising the efficiency of an energy system is within the domain of thermodynamics. Raising the efficiency cost-effectively (thermo-economics) is a multi-disciplinary problem in which thermodynamics interfaces other disciplines of knowledge which in this particular case are design, manufacture and economics. In this paper, it introduces the analysis method of thermo-economics briefly, the thermal economic analysis of the marine diesel engine waste heat recovery system is taken based on matrix model thermo-economics, and the unit exergetic cost is calculated. Some thermal equipments of the system are showed with the result of the performance evaluation. The results shows that thermo-economics is a promising tool for the analysis of complex energy systems. This method also provides a great prospect for energy system optimizations.

Study on Marine Diesel Engine Waste Heat Recovery System with Multi-Stage Flash

As international oil price rise rapidly, the proportion of the fuel cost share of the transport cost has become increasingly high. At the same time, in order to reduce CO2 emission, the meeting of MPEC formulated and adopted the resolution on EEDI, so saving energy and reducing emission has become a marine industry benchmark. In this paper, through the study on marine diesel engine waste heat recovery system with multi-stage flash, establishing the universal model of multi-stage flash unit, and optimizing the parameters of the low-temperature waste heat recovery system with multi-stage flash. This paper constructs the power equation in matrix model, and each matrix of the model has a simple rule to be filled in, which make it versatile, and suitable for computerization, through estimating the power generation and CO2 emission reduction of the system on main diesel engine different loads, analyzing the waste heat recovery system with economic method finally.

Design of Marine Diesel Engine Waste Heat Recovery System with Organic Rankine Cycle

Being an energy-saving project with great development potential, Organic Rankine Cycle (ORC) is becoming one of the research hotspots in recent years. However, there is little research about the waste heat recovery with Organic Rankine Cycle on ships as yet. In this paper, the marine diesel engine waste heat recovery system with Organic Rankine Cycle was designed and analyzed. Isopentane was used as working fluid in the Organic Rankine Cycle. The conditions for the system to recover marine diesel engine waste heat were given, and its schematic diagram was provided. Finally, the ORC turbine which is the most important components of the system was designed. The numerical simulations of the ORC turbine were carried out by using the CFD program. The operation performance and flow field were analyzed.