Diesel Engine Waste Heat Recovery Research Articles

Performance Prediction and Optimization of an Organic Rankine Cycle Using Back Propagation Neural Network for Diesel Engine Waste Heat Recovery

This paper presents a methodology to predict and optimize performance of an organic Rankine cycle (ORC) using a back propagation neural network (BPNN) for diesel engine waste heat recovery. A test bench of an ORC with a diesel engine is established to collect experimental data. The collected data are used to train and test a BPNN model for performance prediction and optimization. After evaluating different hidden layers, a BPNN model of the ORC system is determined with the consideration of mean squared error (MSE) and correlation coefficient. The effects of key operating parameters on the power output of the ORC system and exhaust temperature at the outlet of the evaporator are evaluated using the proposed model and further discussed. Finally, a multi-objective optimization of the ORC system is conducted for maximizing power output and minimizing exhaust temperature at the outlet of the evaporator based on the proposed BPNN model. The results show that the proposed BPNN model has a high prediction accuracy and the maximum relative error of the power output is less than 5%. It also shows that when the operations are optimized based on the proposed model, the power output of the ORC system can be higher than the experimental results.

Thermo-economic analysis and optimization of combined PERC - ORC - LNG power system for diesel engine waste heat recovery

In order to recover diesel engine exhaust gas waste heat, a new configuration consisting of screw expander based Partial Evaporation Rankine Cycle (PERC) combined with Organic Rankine Cycle (ORC) and Liquefied Natural Gas (LNG) power system is proposed and its performance is investigated from thermo-economic viewpoint. In studied system, a heat exchanger preparing domestic hot water is considered to recover the residual waste heat after PERC evaporator and thermo-economic performance of the system is investigated for 6 various organic fluids in ORC. Also, parametric analysis is performed to assess the effects of PERC evaporation temperature, PERC expander inlet steam quality and ORC condensation temperature on system performance. Finally, multi objective optimization is used to find the favorable performance point of system. LNG and PERC systems have a proper operation respectively from energy and exergoeconomic viewpoints. Also, ORC condenser has the highest total cost rate. System optimization results show that using isopentane fluid leads to the highest net power output and total cost rate respectively equal to 178.6 kW and 19.3 $/h and using toluene fluid leads to the lowest net power output and total cost rate that are respectively equal to 154.7 kw and 17.36 $/h.

Artificial neural network (ANN) based prediction and optimization of an organic Rankine cycle (ORC) for diesel engine waste heat recovery

This paper presents performance prediction and optimization of an organic Rankine cycle (ORC) for diesel engine waste heat recovery based on artificial neural network (ANN). An ANN based prediction model of the ORC system is established with consideration of mean squared error and correlation coefficient. A test bench of combined diesel engine and ORC waste heat recovery system is developed, and the experimental data used to train and test the proposed ANN model are collected. A genetic algorithm (GA) is also considered in this study to increase prediction accuracy, and the ANN model is evaluated with different learning rates, train functions and parameter settings. A prediction accuracy comparison of the ANN model with and without using GA is presented. The effects of seven key operating parameters on the power output of the ORC system are investigated. Finally, a performance prediction and parametric optimization for the ORC system are conducted based on the proposed ANN model. The results show that prediction error of the ANN model with using the GA is lower than that without using GA. Therefore, it is recommended to optimize the weights of the ANN model with GA for a high prediction accuracy. The proposed ANN model shows a strong learning ability and good generalization performance. Compared to the experimental data, the maximum relative error is less than 5%. The experimental results after optimizing the operating parameters are very close to ANN’s predictions, indicating one or more operating parameters can be adjusted to obtain a higher power output during the experiment process.

Utilizing the scavenge air cooling in improving the performance of marine diesel engine waste heat recovery systems

Abstract This paper aims at improving power generation efficiency of marine diesel engine waste heat recovery systems. It presents a novel technique of integrating the heat rejected in the scavenge air cooling process and the exhaust gas in operating a single and dual pressure steam power generation cycles. Moreover, a thermodynamic analysis of proposed systems was performed to identify the optimum operating parameters for achieving an overall efficiency improvement. The analysis considered the exergy destruction in each component and the energy/exergy efficiencies. A performance analysis was conducted to assess applicability and power output at off design conditions. An evaluation of achieved improvements by suggested designs was presented from both an economical and environmental standpoint. In conclusion, results show that, the recommended cycle increased overall efficiency improvement from 2.8% for the conventional system to 5.1%, with an additional power output of 1210 kW, representing 9.7% of the engine's power. Also, exergy efficiency increased significantly by 6.6% when using the presented system. Furthermore, the waste heat recovery system attained a reduction in fuel consumption of 1538 Ton/year, reducing carbon dioxide emission by 4790 Ton/year.

A thermodynamic feasibility study of an Organic Rankine Cycle (ORC) for heavy-duty diesel engine waste heat recovery in off-highway applications

This work assesses the possibility of fitting an organic Rankine cycle (ORC) system in a commercial agricultural tractor, recovering waste heat from a 300-kW brake power heavy-duty diesel engine. Two different cycle architectures are considered: a single evaporator layout to recover tail-pipe exhaust heat, and a parallel evaporator configuration to recover both exhaust and exhaust gas recirculation (EGR) heat. A second lower-temperature cooling circuit is also considered as possible different heat sink for the ORC system. Ten different working fluids have been assessed, and the optimum system configuration, in terms of fuel consumption, has been obtained applying an optimization algorithm to a process simulation model. A preliminary study has been carried out to evaluate the impact of the ORC system on the engine–vehicle-cooling system. A maximum fuel consumption reduction of 10.6% has been obtained using methanol and recovering heat from tail-pipe and EGR. However, considering also components and heat rejection performance, water steam, toluene and ethanol allow to obtain the best compromises between thermodynamic performance and engine–vehicle-cooling circuit impact.

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%.

Thermoeconomic multi-objective optimization of an organic Rankine cycle for exhaust waste heat recovery of a diesel engine

In this paper, the ORC (Organic Rankine cycle) technology is adopted to recover the exhaust waste heat of diesel engine. The thermodynamic, economic and optimization models of the ORC system are established, respectively. Firstly, the effects of four key parameters, including evaporation pressure, superheat degree, condensation temperature and exhaust temperature at the outlet of the evaporator on the thermodynamic performances and economic indicators of the ORC system are investigated. Subsequently, based on the established optimization model, GA (genetic algorithm) is employed to solve the Pareto solution of the thermodynamic performances and economic indicators for maximizing net power output and minimizing total investment cost under diesel engine various operating conditions using R600, R600a, R601a, R245fa, R1234yf and R1234ze as working fluids. The most suitable working fluid used in the ORC system for diesel engine waste heat recovery is screened out, and then the corresponding optimal parameter regions are analyzed. The results show that thermodynamic performance of the ORC system is improved at the expense of economic performance. Among these working fluids, R245fa is considered as the most suitable working fluid for the ORC waste heat application of the diesel engine with comprehensive consideration of thermoeconomic performances, environmental impacts and safety levels. Under the various operating conditions of the diesel engine, the optimal evaporation pressure is in the range of 1.1 MPa–2.1 MPa. In addition, the optimal superheat degree and the exhaust temperature at the outlet of the evaporator are mainly influenced by the operating conditions of the diesel engine. The optimal condensation temperature keeps a nearly constant value of 298.15 K.

Parametric optimization and performance analysis of ORC (organic Rankine cycle) for diesel engine waste heat recovery with a fin-and-tube evaporator

This paper presents the parametric optimization and performance analysis of ORC (organic Rankine cycle) system using GA (genetic algorithm) for recovering exhaust waste heat of a diesel engine. First, the effects of three key parameters, including evaporation pressure, superheat degree and condensation temperature on the system performances are conducted with POPA (net power output per unit heat transfer area) and EDR (exergy destruction rate) as objective functions. The optimal evaporation pressure, superheat degree and condensation temperature corresponding to the maximum POPA and the minimum EDR are provided under engine various operating conditions. Subsequently, as a key component of the ORC system, the performance of a fin-and-tube evaporator used in this ORC system is evaluated. The results show that the optimal evaporation pressures are mainly influenced by the engine operating conditions, whereas the superheat degree and the condensation temperature present a slight variation over the whole operating range. Furthermore, the PPTD (pinch point temperature difference) in the evaporator may occur at different positions with the variation of engine operating conditions. At engine maximum rated power point, the ORC system can achieve maximum POPA of 0.74 kW/m2, and the ratio of maximum effective heat transfer area to actual area of the evaporator is 69.19%.

Experimental Investigation of a Cascaded Latent Heat Storage System for Diesel Engine Waste Heat Recovery

Thermal storage plays a vital role in improving the overall efficiency of a waste heat recovery system. A phase change storage system exhibits high energy storage density and isothermal behavior during the charging and discharging processes. In the present work, the cascading arrangement of the phase change storage system is studied to analyze the improvement in the efficiency of the storage system during the charging process, and to compared it with a single storage tank system. The performance parameters, such as the amount of heat recovered, the heat lost, charging rate, charging efficiency, and the percentage of energy saved, are investigated in detail.

Thermo-economic optimization of an organic Rankine cycle system for large marine diesel engine waste heat recovery

The thermo-economic optimization of an ORC (organic Rankine cycle) used to recover waste heat from large marine diesel engines are conducted numerically. The variations of net power output, thermal efficiency, and total cost of equipments of the ORC system with various turbine inlet and outlet pressures are investigated. The net power output index is first proposed to evaluate the performance for this waste heat recovery system. To consider the environmental protection, working fluids which are zero ozone depletion potential and low global warming potential are selected in the simulation of the ORC system. For the widely-used working fluid, R245fa, an improvement of 6% in thermal efficiency is obtained for the proposed system compared with the ORC system recovering heat from marine diesel engine. The results show that, among these working fluids, R1234yf performs the best in the optimal thermo-economic performance evaluation, followed by R1234ze, R152a, and R600a; R245fa performs the least favorably. In addition, the maximal thermo-economic performance of the presented ORC system with R1234yf is higher than that with R245fa by 9%. Finally, the calculated corresponding optimal thermal efficiency of the ORC system and turbine inlet and outlet pressures of working fluids are obtained and compared.

Study on Recovery System for Marine Diesel Engine Waste Heat

Firstly, this paper briefly introduces the Utilization status on marine diesel engine waste heat recovery. Combined with the characteristics of waste heat caused by marine diesel engine and technology of organism Rankine cycle, the paper designs a new waste heat recovery system for marine diesel engine based on organism Rankine cycle, And through researching the changes of temperature between marine diesel engine waste heat and the system working medium, pure organism R123, R245fa or R134a are selected as system's cycle fluid because of environmentally friendly and cycle performance more appropriate. The system application of economy on the ship are analyzed in the theoretical calculation.

Parametric study of power turbine for diesel engine waste heat recovery

Turbocompounding is a promising technology to recover waste heat from the exhaust and reduce fuel consumption for internal combustion engine. The design of a power turbine plays a key role in turbocompound engine performance.This paper presents a set of parametric studies of power turbine performed on a turbocompound diesel engine by means of turbine through-flow model developed by the authors. This simulation model was verified and validated using engine performance test data and achieved reasonable accuracy. The paper first analyzed the influence of three key geometrical parameters (blade height, blade radius and nozzle exit blade angle) on turbine expansion ratio and engine fuel consumptions. After that, the impacts of the geometrical parameters on power distribution, air mass flow rate and exhaust temperature were analyzed. Results showed that these parameters had significant effects on engine BSFC and power. At high engine speeds, there existed an optimum value of geometry parameter to obtain the lowest BSFC. At low engine speeds, the engine BSFC kept increasing or decreasing continuously as the geometry parameters changed. Research also found that the engine BSFC was most sensitive to the nozzle exit blade angle, which should be considered carefully during the design process. This paper provides a useful method for matching and designing of a power turbine for turbocompound engine.

Thermo-economic environmental optimization of Organic Rankine Cycle for diesel waste heat recovery

An Organic Rankine Cycle for diesel engine waste heat recovery is modeled and optimized. The design parameters are nominal capacity of diesel engine, diesel operating partial load, evaporator pressure, condenser pressure and refrigerant mass flow rate. In addition four refrigerants including R123, R134a, R245fa and R22 are selected and studied as working fluids. Then, the fast and elitist NSGA-II (Non-dominated Sorting Genetic Algorithm) is applied to maximize the thermal efficiency and minimize the total annual cost (sum of investment cost, fuel cost and environmental cost) simultaneously. The results of the optimal design are a set of multiple optimum solutions, called Pareto optimal solutions. The optimization results show that the best working fluid is R123 in both of economical and thermo dynamical view point for a specified value of output power. R245fa, R134a and R22 are placed in the next ranking, respectively. The optimum result of R123 shows the 0.01%, 4.39%, and 4.49% improvement for the total annual cost in comparison with R245fa, R22, and R134a, respectively. The above values for efficiency are obtained 1.01%, 12.79% and 10.57%, respectively. Furthermore R123 needs the highest investment cost while the environmental and fuel costs are the lowest.

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.

A study on the thermodynamic analysis of a cascaded latent heat storage system over the single storage tank system for diesel engine waste heat recovery

This article presents the comparison of performance of a cascaded Latent Heat Storage (LHS) system over the Single Storage Tank (SST) system for heat recovery from a diesel engine. The energy and exergy saved and efficiencies during the charging process are evaluated and reported using actual system data. The discharge process is analysed with a case study and it is concluded that it is possible to improve both the energy and exergy efficiencies appreciably using the cascaded LHS system. The exergy analysis, combined with the environmental perspective, is the useful solution methodology for many of the energy and environmental problems.

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.

Second law analysis of a diesel engine waste heat recovery with a combined sensible and latent heat storage system

The exhaust gas from an internal combustion engine carries away about 30% of the heat of combustion. The energy available in the exit stream of many energy conversion devices goes as waste. The major technical constraint that prevents successful implementation of waste heat recovery is due to intermittent and time mismatched demand for and availability of energy. The present work deals with the use of exergy as an efficient tool to measure the quantity and quality of energy extracted from a diesel engine and stored in a combined sensible and latent heat storage system. This analysis is utilized to identify the sources of losses in useful energy within the components of the system considered, and provides a more realistic and meaningful assessment than the conventional energy analysis. The energy and exergy balance for the overall system is quantified and illustrated using energy and exergy flow diagrams. In order to study the discharge process in a thermal storage system, an illustrative example with two different cases is considered and analyzed, to quantify the destruction of exergy associated with the discharging process. The need for promoting exergy analysis through policy decision in the context of energy and environment crisis is also emphasized.

Diesel engine waste heat recovery for drying of clay minerals

This paper presents a typical application of diesel engine waste heat recovery for drying the clay mineral; bentonite. The industrial use of bentonite and the problems associated with high moisture contents are summarized. The drying rate of bentonite was experimentally investigated for different material sizes, weight per unit area and drying air temperature. The experimental results were correlated and used for the design and the analysis of the developed drying system. In addition, the effect of bentonite production rate on the amount of moisture removal and crying heat requirements are presented. The developed waste heat recovery system is simple, economical and produces no negative effect on the engine performance.