Diesel Engine Waste Heat Recovery Research Articles

Experimental investigation of axial finned tube evaporator thermal distillation system using for diesel engine waste heat recovery process

The study aims to improve the waste thermal energy retrieval from flue gas of an internal combustion engine (ICE). The recovered waste heat energy was used for distillation by using a thermal distillation system. The performance of the thermal distillation unit was investigated by varying the evaporator (boiler) type and engine load (25, 50, 75 %). Four different types of boilers were used including one smooth copper tube and other three were two, three and four axial finned copper tube evaporators. The impact of boiler type and engine load on the net retrieved energy and exergy, net energy and exergy efficiency, and distillate yield rate of thermal distillation unit was also examined. The results showed that the net extracted heat energy and exergy for axial finned tube evaporator was approximately 26.823 – 45.513 % and 7.614 – 25.203 W higher than that of smooth tubes evaporator at 25 and 75 % engine load, respectively. The distillation yield was found to be ~ 2.35 liter/ hour in the case of four axial finned tube boiler at 75 % engine load.

Design and performance optimization of diesel engine waste heat recovery methanol reforming hydrogen generation system

Abstract A shell-and-tube Methanol Steam Reformer (MSR) system was designed for diesel engines. The effects of structural and operational parameters of the spiral baffles in the methanol reformer on heat transfer and hydrogen production performance were investigated. Additionally, a multi-objective optimization using response surface methodology was conducted to study the interactive effects of spacing and thickness, as well as liquid hourly space velocity and steam–methanol ratio, on the methanol conversion rate, hydrogen concentration and hydrogen production. The results indicated that reducing the baffle spacing and increasing the baffle thickness further improved heat transfer efficiency. Optimal conditions were achieved at a spacing of 30 mm and a thickness of 2 mm, resulting in a methanol conversion rate of 64.2 %. Increasing the steam–methanol ratio from 0.5 to 2 increased the methanol conversion rate from 50.6 % to 79.7 %, with a subsequent decrease in hydrogen concentration. Increasing the liquid hourly space velocity from 635 h−1 to 1905 h−1 significantly reduced the methanol conversion rate from 94.5 % to 64.2 %, but the hydrogen production increased from 0.111 mol/s to 0.228 mol/s. Optimization results indicate that the liquid hourly space velocity and steam–methanol ratio have a greater influence on the hydrogen production efficiency of the methanol reformer.

Power prediction and packed bed heat storage control for marine diesel engine waste heat recovery

The generation capability of the waste heat recovery system cannot be fully utilized by relying solely on the exhaust gas, as the mass flow rate and temperature of exhaust fluctuate in real time. The volatility of ship engine conditions and the instability of power demand can pose a challenge to real-time power allocation. Developing integrated prediction and control methods for power allocation becomes necessary. An integrated system is devised to fully utilize waste energy from marine diesel engines by combining a regenerative organic Rankine cycle with a controllable packed bed. The trends of thermodynamic properties and dynamic charging and discharging processes of the system are analyzed. To provide a plausible management strategy for allocating power in real time, a bidirectional long-short-term memory network power prediction method based on improved complete ensemble empirical mode decomposition with adaptive noise and improved marine predator algorithm is proposed. It is found that 315.6 kW of power can be obtained from the system, and its payback period is 6.84 years. In addition, by using the proposed model, the system can reduce diesel engine power generation. The findings suggest the proposed solution is a viable and meaningful strategy.

Diesel engine waste heat recovery turbine design: geometric and materials effects on ORC turbines

The significance of this work is the demonstration that an ORC (Organic Rankine Cycle) system can be successfully implemented on heavy-duty vehicles and contribute to fuel consumption (and emissions) reduction. Additionally, this paper focuses on providing due consideration to the materials aspects of the most critical component of the ORC system, namely, the turbine—expander. The expander of an ORC system optimized off an experimental prototype coupled to a 7 L diesel engine and optimized from the point of view of the rotor geometry, materials and clearances to be applicable to the specific experimental setup. The optimum clearance between the rotor blades and shroud, in terms of performance and economical aspects, was calculated at 0.4 mm. Based on the initial geometry of the ORC turbine, for this particular application and optimising for performance, refrigerant R134a was found to be the best choice. Then the rotor geometry was optimized using ANSYS simulation. The maximum performance obtained by the expander to achieve 72.95% total to static isentropic efficiency. It was calculated on GT-Power that the optimized ORC system, implemented on a heavy-duty vehicle, can reduce fuel consumption by up to 17%.

Evaluation of Three Working Fluid on an Organic Rankine Cycle of a Waste Heat Recovery Electric Generator

The aim of this study is to evaluating an Organic Rankine Cycle (ORC) system from diesel engine waste heat recovery by selecting three different working fluids with different pressure and temperature condition. The working fluid include N-Pentane, R-245fa, and R-134a are conditioned on variations in pressure and evaporation temperature with a difference of 0.5 bar and 5 °C to achieve the best thermal efficiency. The proposed evaluation involved two phases, first is analysis of the working fluid with various condition is carried out using REFPROP software and then results of that analysis will be used as the basis of input in calculating the overall heat balance using the Cycle Tempo software. This study found that a diesel engine with a capacity of 1000 kVA wastes energy of 1177 kW which is released through exhaust pipe and engine radiator can produce a turbine power of 144,47 kW. The highest thermal efficiency of 13.48% was obtained by using the working fluid R-245fa at the evaporator pressure and temperature of 23.5 bar and 154 ⁰C, respectively.

Design and modeling of a multigeneration system driven by waste heat of a marine diesel engine

In this study, a novel marine diesel engine waste heat recovery layout is designed and thermodynamically analyzed for hydrogen production, electricity generation, water desalination, space heating, and cooling purposes. The integrated system proposed in this study utilizes waste heat from a marine diesel engine to charge an organic Rankine and an absorption refrigeration cycle. The condenser of the Organic Rankine Cycle (ORC) provides the heat for the single stage flash distillation unit (FDU) process, which uses seawater as the feedwater. A portion of the produced freshwater is used to supply the Polymer Electrolyte Membrane (PEM) electrolyzer array. This study aims to store the excess desalinated water in ballast tanks after an Ultraviolet (UV) treatment. Therefore it is expected to preclude the damage of ballast water discharge on marine fauna. The integrated system's thermodynamic analysis is performed using the Engineering Equation Solver software package. All system components are subjected to performance assessments based on their energy and exergy efficiencies. Additionally, the capacities for power generation, freshwater production, hydrogen production, and cooling are determined. A parametric study is conducted to evaluate the impacts of operating conditions on the overall system. The system's overall energy and exergy efficiencies are calculated as 25% and 13%, respectively, where the hydrogen production, power generation, and freshwater production capacities are 306.8 kg/day, 659 kW, and 0.536 kg/s, respectively. Coefficient of Performance (COP) of the absorption refrigeration cycle is calculated as 0.41.

Application of two-phase pulsating flow in organic Rankine cycle system for diesel engine waste heat recovery

Organic Rankine cycle is a promising technology to recover the waste heat of an internal combustion engine. Improving evaporator performance plays a vital role in achieving high heat to power conversion efficiency of this system. The circulating flow of working fluid in the system is realized by a pump, which is beneficial to heat transfer enhancement of the evaporator with pulsating flow. In this study, a two-dimensional axisymmetric model of evaporator tube is built. Two-phase flow characteristics of R245fa under continuous and pulsating flows are analyzed. Furthermore, particle swarm optimization (PSO) is employed to optimize the parameters of pulsating flow when diesel engine (DE) is operating under the motorway road condition. Results show that the heat transfer performance of R245fa can be improved effectively by the pulsating flow with a high angular frequency. Critical angular frequency, which enhances the heat transfer, exists. It also has a weak influence to flow performance. Compared with those in continuous flow under the motorway road condition of DE, the average convective heat flux and the volume fraction of R245fa vapor at the outlet optimized by PSO can be increased by 158.11% and 87.24%, respectively, whereas the pressure drop can be decreased by 1.47%.

Investigation of supercritical CO2 cycles potential for marine Diesel engine waste heat recovery applications

In the present work, an investigation is carried out for the assessment of the energy efficiency improvement, which can be achieved with the employment of a supercritical CO2 power cycle operating in conjunction with a marine Diesel engine. The focus is directed towards the appropriate design of the CO2 cycle, which recovers heat from three distinct waste heat sources exhibiting different temperature levels (exhaust gas, compressed scavenge air and jacket cooling water), and contributes to the propulsion load in order for the total fuel consumption to be minimized. Engineering optimization problems, based on the superstructure optimization concept, are formulated and solved, in order for the optimal configuration of the CO2 cycle and the thermodynamic states of the working fluid to be specified. For this purpose, several possible alternatives regarding the CO2 cycle are examined, and a CO2 cycle configuration resulting to improved performance of the overall system is proposed as an outcome of the optimization algorithms application. The implications of size limitations of several of the heat exchangers included in the CO2 cycle and their effects on the performance of the overall system are also assessed. The results indicate that, in comparison with a standalone operating marine Diesel engine, an efficiency enhancement in a range approximately between 6.6% and 7.25% is attainable with the best performing CO2 cycle configuration, according to the heat exchangers size limitations that may be imposed in a practical implementation of the proposed solution. Although applied for the case of a marine Diesel engine, the findings and results of the present study can also be relevant to other applications as well, in which a heavy duty turbocharged Diesel engine is used.

Design and thermodynamic analysis of a combined system including steam Rankine cycle, organic Rankine cycle, and power turbine for marine low-speed diesel engine waste heat recovery

In the current global decarbonization energy background of carbon peak emissions and carbon neutralization, more and more attention has been paid to the research of improving the energy efficiency of marine power plants. The thermal cycle device is used to recover the waste heat of marine diesel engines and reduce carbon emissions. Therefore, a set of high-efficiency waste heat recovery systems including power turbine (PT), steam Rankine cycle (RC), an organic Rankine cycle (ORC) is designed and tested. The test results showed that the designed system ran stably. Then, according to the test results, the system was further calculated. The calculation results showed that it is possible to generate power up to 1,079.1 KW at 100% load utilizing this system. Besides, the maximum thermal efficiency and exergy efficiency of the RC-ORC unit occurred at 90% load, which were 28.48% and 65.72% respectively. Furthermore, the techno-economic evaluation was carried out. The results show that the payback period and the depreciation payback period of this system are 5.2 years and 6.9 years, respectively. Finally, the system was improved, the coupling degree of RC-ORC was reduced, and the reliability and stability of the system were improved on the premise that little power generation ratio increased at high load and slight decreased at low load.

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.

Numerical analysis and optimization design of fin-and-tube evaporator in organic Rankine cycle system for diesel engine waste heat recovery

Organic Rankine cycle (ORC) can efficiently recover exhaust heat of internal combustion engines (ICEs). Evaporator is an important component that determines how much waste heat can be recovered. Enhancing heat transfer performance and reducing flow resistance of the exhaust in the evaporator can improve not only heat-to-work conversion efficiency of the ORC system but also reduce the influence of the evaporator on the operation of the ICE. Experimental results of the combined diesel engine–organic Rankine cycle (DE–ORC) system showed that the simulation model of a fin-and-tube evaporator is established via computational fluid dynamic method. The heat transfer performance and flow state of exhaust are investigated by improving the structure of the fin-and-tube evaporator under typical working conditions of the diesel engine. In addition, genetic algorithm is used to optimize the evaporator to obtain the nonuniform structure of the evaporator. Results showed that the performance of the evaporator can be improved using a star-shaped fin and appropriately selected parameters of elliptical tube. The nonuniform structural evaporator can further enhance the heat transfer performance and reduce the influence of the ORC system on the operation of the diesel engine. The optimization results demonstrated that the area goodness factor (η) increases by 173.76% while the field synergy module average angle (θφm) and friction factor f reduces by 6.17° and 56.67%, respectively.

Design and optimization of hydrogen production by solid oxide electrolyzer with marine engine waste heat recovery and ORC cycle

Hydrogen is considered as a promising alternative to future energy systems. Water or steam electrolysis at elevated temperature consumes less electricity due to the highly efficient utilization of thermal energy. In this paper, a solid oxide electrolyzer cell (SOEC) is integrated with a marine diesel engine to use both electricity and waste heat for hydrogen production. An Organic Rankine Cycle (ORC) is applied to produce electricity from SOEC production streams. A comprehensive thermodynamic analysis model of SOEC, ORC and marine diesel engine waste heat recovery is conducted. The results indicated that the system could produce hydrogen at a rate of 0.431 kg/s and power output of 32386.45 kW with a power reduction of 60%. An efficiency of 104.41%, 12.12% and 53.56% could be achieved for the electrolyzer cell, ORC and integration system, respectively. The waste heat available efficiency could reach only 44.13% under the design conditions. To study the impact of some key parameters on the system performance, sensitivity analysis of current density, H2O inlet flow rate and total SOEC area were performed. It was found that an optimal current density and H2O flow rate can be obtained. Moreover, higher total cell area benefits the integration system thermodynamically.

Prediction and optimization of power output of single screw expander in organic Rankine cycle (ORC) for diesel engine waste heat recovery

The output characteristics of single screw expander has a direct and crucial influence on the performance of organic Rankine cycle (ORC) system. In this paper, a machine learning prediction model driven by experimental data is developed and applied to predict the power output of single screw expander. After screening different structural parameters of the model, genetic algorithm (GA) is used to optimize the initial weights and thresholds of the model, so as to further improve the generalization ability of the model. In addition, the generalization ability of the model is compared with that of the model not optimized by GA. Furthermore, the influence of operating parameters on the power output of single screw expander is analyzed by fitting algorithm in three-dimensional space. The optimization boundary value needed for prediction and optimization is determined by fitting algorithm in four-dimensional space. Finally, a prediction and optimization model is created by coupling the machine learning prediction model with GA, and the maximum power output and corresponding operating parameters of the single screw expander under full operating conditions are predicted and optimized. The results show that with the application of machine learning and GA, the maximum power output of single screw expander can be predicted and optimized precisely under full operating conditions. So as to directly guide the selection of relevant parameters in the process of theoretical analysis and experimental research.

Performance analysis of supercritical ORC utilizing marine diesel engine waste heat recovery

Marine diesel engine is widely used in merchant ships as a propulsion system. The wasted heat of the diesel engines is one of the main drawbacks in this system. The aim of this paper is to recover this wasted heat to be used in designing combined heat and power plant. A bulk carrier WADI SAFAGA has been investigated as a case study. Power and electricity from Supercritical Organic Rankine Cycle will be produced as wasted heat recovery of the main engine. Maximum power, thermal efficiency and specific fuel consumption have been investigated according to the change of the evaporating pressure of organic fluid from 50 bar to 75 bar with increment of 5 bar. Heat exchangers must be redesigned due to the replacement of cooling water by refrigerant (R34a and R245fa). Also, parametric and economic studies will be taken into account. A comparison between diesel generator and SORC generator will be studied from economic and weight dimensions together with the specific power of generator point of view. The results showed that using SORC with R134a at working pressure of 50 bar have a satisfied performance with respect to the saving in specific fuel consumption, lubrication oil and cooling water. In addition, replacing three diesel generators by one SORC generator would decrease the weight by 12 tons, and would also decrease fuel consumption by 2.1 ton/day, shrinking the heat exchangers size, specific fuel consumption was decreased by 61 g/kW-h. Finally, the wasted heat of the main engine will decrease by 18%.

Auxiliary power through marine waste heat recovery using a CO2-organic cascading cycle

An appreciable part of primary energy input to a marine diesel engine is rejected as waste heat. Thus, through marine diesel engine waste heat recovery significant amount of secondary energy can be produced to satisfy the auxiliary power requirement of the marine ship. In present study, a CO2-organic fluid cascading cycle is considered for the utilization of the waste heat released by the marine diesel engine. R290, R600 and R1233zd (E) are considered as the working fluids of the bottoming cycle for their lower global warming potentials. The analysis revealed that power output of the cascading cycle is comparable to that of the baseline transcritical CO2 power cycle. However, for similar power output, operating pressure in the flue gas-CO2 heat recovery unit of the transcritical CO2 power cycle is significantly higher compared to that of the cascading cycle. Thus, possible leakage due to very high operating pressure of a conventional CO2 power cycle can be addressed by using the cascading system. Bare module costs per unit power output of cascading cycles are also significantly smaller. It is also apparent from the study that the marine diesel engine waste heat recovery through the CO2-organic cascading cycle would lead to 8–9.5% annual fuel saving. Reduced fuel consumption will also result in lesser CO2 emission from the marine ship.

Energy and exergy analysis of combined ORC – ERC system for biodiesel-fed diesel engine waste heat recovery

A combined cooling, heating, and power generation system is proposed for the recovery of exhaust waste heat of the diesel engine. The engine rejected heat recovery system consisted of a domestic water heater (DWH), an organic Rankine cycle (ORC) and an Ejector Refrigeration Cycle (ERC) for heating aims, power generation, and cooling aims, respectively. The Diesel engine is fed by different fuels and biofuels to drive the bottoming cycles. The Transesterification method has been used for biodiesel extraction from different oil-basis materials. The produced biodiesel supplied to the Diesel engine in different engine speeds and loads to evaluate the system performance from viewpoints of the energy and exergy. The highest generated power for the total system is obtained in the case of sunflower biodiesel blend and B10 sample as the fuel. The maximum overall system energy efficiency obtained when the canola B30 blend is applied in 100% load and 2400rpm. Based on the obtained results, the exergy efficiency considerably increases in the case of biodiesel, and diesel blends as the fuel compared to the pure diesel. Exergy efficiency was optimized for the proposed combined heating, cooling and power generation system at 100% load, 1700 rpm and B10 blend obtained from canola oil.

Carbon Dioxide as Working Fluids in Transcritical Rankine Cycle for Diesel Engine Multiple Waste Heat Recovery in Comparison to Hydrocarbons

In consideration of the high-temperature characteristic of engine’s waste heat and stricter environmental regulations, natural substance, including CO2 and hydrocarbons, have been treated as promising working fluid for diesel engine waste heat recovery due to its environment friendly and excellent physical and chemical properties. This paper presented a comprehensive performance analysis on transcritical Rankine cycles for diesel engine multiple waste heat recovery using hydrocarbons and CO2 as working fluid. The optimal turbine inlet pressures corresponding to maximum net power output, maximum exergy efficiency and minimum electricity production cost (EPC) were obtained. The effect of working fluid on these optimal pressures has been discussed. For fluids with low critical temperature, the optimal pressure corresponding to maximum net power output is lower than the one for maximum exergy efficiency, while the opposite results can be found for fluid with high critical temperature. Then, the effect of various working fluid properties in transcritical cycle performance is discussed. Comparison results show that CO2 obtains only more power output than Ethane, Propane and Propene, but CO2 is capable of absorbing more energy from engine coolant and regeneration heat with comparable total heat transfer areas and has an advantage in turbine size, particularly for hydrocarbons with high critical temperature.

Comparative analysis and multi-objective optimization of organic Rankine cycle (ORC) using pure working fluids and their zeotropic mixtures for diesel engine waste heat recovery

In this paper, the thermodynamic and thermoeconomic performance of an ORC system with pure working fluids and their zeotropic mixtures each having different critical temperatures are compared. Two high critical temperature (toluene and decane) and two low critical temperature (R245fa and R123) working fluids as well as their zeotropic mixtures are considered. The effects of four parameters including evaporation temperature, condensation temperature, superheat degree and mass fraction of the zeotropic mixtures on the thermodynamic and thermoeconomic performances of the ORC system are investigated. The multi-objective optimization based on genetic algorithm is conducted to reveal the optimal performances of the ORC system. The results show that high critical temperature working fluids and their zeotropic mixtures possess better thermodynamic and thermoeconomic performances, however, the zeotropic mixtures do not improve the thermodynamic and thermoeconomic performances obviously. Furthermore, the zeotropic mixtures at the mass fraction of 0.9 toluene/0.1 decane have the best thermoeconomic performance. The zeotropic mixtures can significantly reduce the heat transfer area of the heat exchangers under high evaporation temperature condition. In addition, the multi-objective optimization indicates that the optimal evaporation temperature approaches its upper bound while the optimal condensation temperature and superheat degree almost close to their lower bounds.

Dizel Motor Atık Isısı Geri Kazanımlı Organik Rankine Çevriminin Termodinamik Analizi

In this study, thermodynamic analysis of the organic Rankine cycle (ORC) using a diesel engine waste heat recovery was performed for different working fluids. R123, R245fa, R600a, R236ea and R134a are used as working fluid in the cycle. For temperature of the heat source in the exhaust of the diesel engine 80-180 o C was chosen. The required thermodynamic values and calculations for the analysis were calculated by the Engineering Equation Solver (EES) program. For these working fluids, the performance values of the cycle were studied under different operating conditions. The highest efficiency values were obtained for all operating conditions analyzed in the organic Rankine cycle using R123 working fluid as %23. In addition, the turbine power is determined as 7.2 kW for the same operating conditions.

How to approach optimal practical Organic Rankine cycle (OP-ORC) by configuration modification for diesel engine waste heat recovery

Abstract Conventional diesel engine has multiple waste heat sources, which make ORC configuration selection difficult. This paper proposed an ORC configuration modification and evaluation method. Pinch analysis technique was employed to integrate multiple waste heat sources into one composite curve. We presented an optimal practical ORC (OP-ORC) that matches the composite waste heat source and the cold source. ORC configuration modification was performed by improving the thermal matching between the ORC and the heat (cold) sources. Relative efficiency, which defined as the thermal efficiency ratio of the actual ORC to the OP-ORC, was used as criterion to evaluate various modified ORC configuration. An ORC modification case for multiple waste heat sources derived from a diesel engine was presented. With the thermal efficiency of 18.57% achieved by the OP-ORC, analysis results showed that the basic preheating ORC using Cyclopentane can only achieve a thermal efficiency of 9.28%. After cycle modification, a modified ORC could obtain a thermal efficiency of 14.23%, which is significantly close to the OP-ORC with a relative efficiency of 76.6%. This method would provide researchers with information to assess the benefit and the cost about each configuration modification and determine the direction of further improvement.