Gas Turbine Design and Matching Research of Waste Heat Recovery System for Marine Diesel Engine

With the emphasis on energy and environmental protection,energy-conservation and emission-reduction become vital issues for industrial development.Moreover,with the development of legislation on marine environment,the marine diesel engine has become focusing on energy saving and emission reduction for ships.For low-speed diesel engines under high load,waste heat from exhaust gas can be recovered by the compact and efficient gas turbine.In this paper,the matching design research between low speed diesel engine and gas turbine is carried out.To balance efficiency and compactness,the impeller was adjusted and generated by ANSYS BLADEGEN,based on 1D thermodynamic design.And the 1D calculation is similar to the ANSYS CFX simulation result:the total-static efficiency is 73.8%compared to 76.7%.Moreover,the flow separation happened at the impeller suction side and created vortex due to the high incidence angle.The off-design operating point simulation of the turbine shows though the pressure ratio increase will cause the efficiency to decline a little,the total shaft power rises.In sum,this paper worked out a power turbine suitable for a low-speed diesel engine according to the turbine character matching design and simulation,which provides foundation to the construction of a steady operation of waste heat recovery system for marine diesel engine.

Experiment Study on the Exhaust-Gas Heat Exchanger for Small and Medium-Sized Marine Diesel Engine

This paper aims to design a special exchanger to recover the exhaust gas heat of marine diesel engines used in small and medium-sized fishing vessels,which can then be used to heat water up to 55°C–85°C for membrane desalination devices to produce fresh water.A new exhaust-gas heat exchanger of fins and tube,with a reinforced heat transfer tube section,unequal spacing fins,a mixing zone between the fin groups and four routes tube bundle,was designed.Numerical simulations were also used to provide reference information for structural design.Experiments were carried out for exhaust gas waste heat recovery from a marine diesel engine in an engine test bench utilizing the heat exchanger.The experimental results show that the difference between heat absorption by water and heat reduction of exhaust gas is less than 6.5%.After the water flow rate was adjusted,the exhaust gas waste heat recovery efficiency was higher than 70%,and the exhaust-gas heat exchanger’s outlet water temperature was 55°C–85°C at different engine loads.This means that the heat recovery from the exhaust gas of a marine diesel engine meets the requirement to drive a membrane desalination device to produce fresh water for fishers working in small and medium-sized fishing vessels.

Analysis of Efficiency of the Ship Propulsion System with Thermochemical Recuperation of Waste Heat

One of the basic ways to reduce polluting emissions of ship power plants is application of innovative devices for on-board energy generation by means of secondary energy resources.The combined gas turbine and diesel engine plant with thermochemical recuperation of the heat of secondary energy resources has been considered.It is suggested to conduct the study with the help of mathematical modeling methods.The model takes into account basic physical correlations,material and thermal balances,phase equilibrium,and heat and mass transfer processes.The paper provides the results of mathematical modeling of the processes in a gas turbine and diesel engine power plant with thermochemical recuperation of the gas turbine exhaust gas heat by converting a hydrocarbon fuel.In such a plant,it is possible to reduce the specific fuel consumption of the diesel engine by 20%.The waste heat potential in a gas turbine can provide efficient hydrocarbon fuel conversion at the ratio of powers of the diesel and gas turbine engines being up to 6.When the diesel engine and gas turbine operate simultaneously with the use of the LNG vapor conversion products,the efficiency coefficient of the plant increases by 4%–5%.

Thermodynamic and Economic Studies of a Combined Cycle for Waste Heat Recovery of Marine Diesel Engine

In the present study,the thermodynamic and economic performance of a combined thermodynamic cycle formed by an ORC and a Kalina cycle,which can simultaneously recover waste heat of exhaust gas and cooling water of marine engine,has been analyzed.Two typical marine engines are selected to be the waste heat source.Six economic indicators are used to analyze the economic performance of this combined thermodynamic cycle system with different marine engine load and under practical comprehensive operating condition of marine engine.The results of the present study show that the combined thermodynamic cycle system with R123 as organic working fluid has the best performance.The system with cis-butene has the worst economic performance.Under practical comprehensive operating conditions of ships,R123 has the shortest Payback Periods,which are 8.51 years and 8.14 years for 8 S70 ME-C10.5 engine and 5G95 ME-C10.5 engine,respectively.Correspondingly,payback Periods of Cyclopentane are 11.95 years and 11.90 years.The above values are much shorter than 25 years which are the lifetime of a marine ship.Under practical comprehensive operating conditions of ships,the combined cycle system can provide output power which is at least equivalent to 25%of engine power.Considering that R123 will be phased out in near future,cyclopentane may be its good successor.Cyclopentane can be used safely by correct handling and installing according to manufacturer's instructions.

An approach for IC engine coolant energy recovery based on low-temperature organic Rankine cycle

To promote the fuel utilization efficiency of IC engine, an approach was proposed for IC engine coolant energy recovery based on low-temperature organic Rankine cycle(ORC). The ORC system uses IC engine coolant as heat source, and it is coupled to the IC engine cooling system. After various kinds of organic working media were compared, R124 was selected as the ORC working medium. According to IC engine operating conditions and coolant energy characteristics, the major parameters of ORC system were preliminary designed. Then, the effects of various parameters on cycle performance and recovery potential of coolant energy were analyzed via cycle process calculation. The results indicate that cycle efficiency is mainly influenced by the working pressure of ORC, while the maximum working pressure is limited by IC engine coolant temperature. At the same working pressure, cycle efficiency is hardly affected by both the mass flow rate and temperature of working medium. When the bottom cycle working pressure arrives at the maximum allowable value of 1.6 MPa, the fuel utilization efficiency of IC engine could be improved by 12.1%.All these demonstrate that this low-temperature ORC is a useful energy-saving technology for IC engine.

Waste heat recovery from heavy-duty diesel engine exhaust gases by medium temperature ORC system

A medium-temperature waste-heat recovery system based on the organic Rankine cycle (ORC) is designed to recover the exhaust energy from a heavy-duty diesel engine. Analysis of the 1st law of thermodynamics for an ORC system is performed. This analysis contains two parts. The first part is an analysis with undefined heat exchangers to gain an understanding of the ORC and find out suitable organic fluid parameters for a better ORC efficiency. The second part of the analysis uses combined engine test results and two designs of heat exchangers. By comparing the two designs, an improved system of heat exchangers is described. This analysis also quantifies the effect of engine parameters on ORC system. The study concludes that the supercritical Rankine cycle is a better approach towards waste heat recovery. The ORC system is found to perform better under part-load conditions if the medium-high power condition rather than rated working point of the engine is used as the design parameter. The ORC system achieves the highest waste-heat recovery efficiency of up to 10-15% for the optimised heat ex-changer design.

Overall optimization of Rankine cycle system for waste heat recovery of heavy-duty vehicle diesel engines considering the cooling power consumption

The Rankine cycle system for waste heat recovery of heavy-duty vehicle diesel engines has been regarded as a promising tech- nique to reduce fuel consumption. Its heat dissipation in the condensation process, however, should be take：l away in time, which is an energy-consuming process. A fan-assisted auxiliary water-cooling system is employed in this paper. Results at 1300 r/min and 50% load indicate that the cooling pump and cooling fan together consume 7.66% of the recovered power. What＇s worse for the heavy load, cooling accessories may deplete of all the recovered power of the Rankine cycle system. Af- terwards, effects of the condensing pressure and water feeding temperature are investigated, based on which a cooling power consumption model is established. Finally, an overall efficiency optimization is conducted to balance the electric power gener- ation and cooling power consumption, taking condensing pressure, pressure ratio and exhaust bypass valve as major variables. The research suggests that the priority is to increase condensing pressure and open exhaust bypass valve appropriately at high speed and heavy load to reduce the cooling power consumption, while at low speed and light load, a lower condensing pressure is favored and the exhaust bypass valve should be closed making the waste heat recovered as much as possible. Within the sub-critical region, a larger pressure ratio yields higher overall efficiency improvement at medium-low speed and load. But the effects taper off at high speed and heavy load. For a given vehicular heavy-duty diesel engine, the overall e：＇ficiency can be improved by 3.37% at 1300 r/min and 25% load using a Rankine cycle system to recover exhaust energy. The improvement becomes smaller as engine speed and load become higher.

Effects of working parameters on gasoline engine exergy balance

To improve the energy utilization efficiency of internal combustion （IC） engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure （BMEP） at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.

Study on pneumatic-fuel hybrid system based on waste heat recovery from cooling water of internal combustion engine

The paper proposes a novel pneumatic-fuel hybrid system,which combines a traditional internal combustion engine(ICE)and a pneumatic engine.One important merit of this concept is that the system can recover waste from cooling water of internal combustion engine to optimize the working process of pneumatic engine,and thus to improve the entire efficiency of the hybrid system.Meanwhile,energy-saving effect due to lower cooling fan power can be achieved on ICE by waste heat recovery of pneumatic engine.Based on thermodynamic analysis,an experimental system is designed and established for verification.The experimental results show that the performance of pneumatic engine is improved when the waste heat recovery concept of the hybrid system is applied.Then an application example on a 4-cylinder engine is analyzed and discussed using numerical simulation.The results show that the fan power of the ICE cooling system can be saved up to 50%by applying the hybrid system.Considering the appreciable improvements on the energy efficiency with only limited system modifications when the concept is applied to traditional ICE based power systems,the proposed hybrid concept has the potential to serve as an alternative technology aiming for energy saving and emission reduction.

Analysis of an electricity-cooling cogeneration system for waste heat recovery of gaseous fuel engines

Waste heat recovery(WHR)is one of the most useful ways to improve the efficiency of internal combustion engines,and an electricity-cooling cogeneration system(ECCS)based on Rankin-absorption refrigeration combined cycle for the WHR of gaseous fuel engines is proposed in the paper.This system can avoid wasting the heat in condenser so that the efficiency of the whole WHR system improves,but the condensing temperature of Rankin cycle(RC)must increase in order to use absorption refrigeration system,which leads to the decrease of RC output power.Therefore,the relationship between the profit of absorption refrigeration system and the loss of RC in this combined system is the mainly studied content in the paper.Because the energy quality of cooling and electricity are different,cooling power in absorption refrigeration is converted to corresponding electrical power consumed by electric cooling system,which is defined as equivalent electrical power.With this method,the effects of some important operation parameters on the performance of the ECCS are researched,and the equivalent efficiency,exergy efficiency and primary energy rate are compared in the paper.

Experimental investigation on diesel engine's waste heat capacity under mapping characteristics

Waste heat recovery for internal combustion engine(ICE)has been considered as an important strategy to improve efficiency and promote fuel economy,thus alleviating the problems of energy shortage and environmental pollution.This paper investigates the characteristics of various kinds of waste heat energy,namely,waste heat in exhaust,cooling water and charge air,over the engine’s whole operating region.Based on the energy balance experiments,the energy distribution of a conventional heavy-duty diesel engine is obtained under mapping characteristics.According to exergy analysis,the energy recovery potential for waste heat is studied as well.The experimental results indicate that exhaust energy increases with engine speed and load,while cooling water energy is more sensitive to load,especially at low and middle speed.Charge air energy,on the other hand,mainly counts on speed rather than load.Exhaust energy possesses the highest recovery potential in terms of both quantity and quality.Through waste heat recovery,a dramatic improvement in engine efficiency is achievable,actually,the maximum value can amount to 60%or even more.

Comprehensive evaluation of marine waste heat recovery technologies based on Hierarchy-Grey correlation analysis

In this study,comprehensive evaluation of the technologies on waste heat recovery technologies for maritime applications has been carried out.We have focused our research on exhaust gas turbine system(EGT),thermodynamic organic rankine cycle(RC),Kalina cycle(KC)and thermoelectric generators(TG),which are the most appropriate and most up-to-date techniques for recovering power from marine engines.Each technology has its own advantages and disadvantages,so the comprehensive evaluation of these technologies is essential to accurately determine which technology will be applied to which target.This belongs to the multi-criteria decision(MCDM)process.The combined assessment methodology,consisting of gray correlation and analysis hierarchy processes,has been applied to evaluate four waste heat recovery techniques in terms of technical,economic,social and environmental aspects.According to the comparison results,the exhaust gas turbine system has been evaluated as the most promising technology among the various WHR technologies that can be applied to marine engines.Sensitivity analysis suggests that if investment cost of TG falls to about the same level as the one of EGT,TG could be the best method among these technologies.Reduction of investment cost of TG technology could be realized by development of low cost thermoelectric material.We have analyzed the correlation between each cost through DOE analysis and investigate the effect of individual costs on the total cost.This work helps in identifying the most suitable heat recovery technologies for marine engine.

Comparison of Conventional and Advanced Exergy Analysis for Dual-Loop Organic Rankine Cycle used in Engine Waste Heat Recovery

At present,the dual-loop organic Rankine cycle(DORC)is regarded as an important solution to engine waste heat recovery(WHR).Compared with the conventional exergy analysis,the advanced exergy analysis can better describe the interactions between system components and the irreversibility caused by economic or technical limitations.In order to systematically study the thermodynamic performance of DORC,the conventional and advanced exergy analyses are compared using an inline 6-cylinder 4-stroke turbocharged diesel engine.Meanwhile,the sensitivity analysis is implemented to further investigate the influence of operating parameters on avoidable-endogenous exergy destruction.The analysis result of conventional exergy analysis demonstrates that the priorities for the components that should be improved are in order of the high-temperature evaporator,the low-temperature turbine,the first low-temperature evaporator and the high-temperature condenser.The advanced exergy analysis result suggests that the avoidable exergy destruction values are the highest in the low-temperature turbine,the high-temperature evaporator and the high-temperature turbine because they have considerable endogenous-avoidable exergy destruction.The sensitivity analysis indicates that reducing the evaporation pinch point and raising the turbine efficiency can decrease the avoidable exergy destruction.

车用小型化内燃机余热回收ORC系统试验

基于有机朗肯循环(ORC)原理,针对车用内燃机余热回收系统,搭建了集成化试验台架并开展了台架综合性能试验,探究了内燃机余热回收ORC系统小型化优势和上车应用的潜力.结果表明:设计搭建的试验台架主体尺寸为800 mm×750 mm×620 mm,质量为200 kg左右,具有一定的小型化优势;ORC系统整体运行具有较好的稳定性和可靠性,在发动机转速为1300 r/min、转矩为600 N·m工况下,工质质量流量为0.1716 kg/s,蒸发压力达到1.26 MPa,膨胀机运行转速调整为1456 r/min时,ORC系统的输出功率达到2.64 kW.

回收船舶柴油机余热的双回路有机朗肯循环系统性能分析

为了降低船舶二氧化碳排放,利用双回路有机朗肯循环(DORC)系统对船舶柴油机的排烟和缸套冷却水余热进行回收发电。通过夹点温差法构建热力学模型,高温回路用于回收排烟热量,低温回路用于回收缸套冷却水热量和高温回路冷凝热。分析9对工质组合时DORC系统的冷凝器热力学参数对系统性能的影响,结果表明:随着高温回路的冷凝温度和冷凝热负荷的增高,低温回路蒸发压力和净输出功呈现升高趋势,在高温回路冷凝热负荷为715.2 kW~1 241.2 kW时,系统总净输出功呈现先升高后降低的趋势。当高温回路采用环乙烷,低温回路采用一氯三氟丙烯(反式)为工质时,系统总净输出功可达到410.6 kW。

内燃机余热回收低压有机朗肯循环系统性能优化及试验

利用工质比热容与余热源之间的匹配关系,提出了缸套水与烟气余热分别由五氟丙烷(R245fa)工质两相区与过热区匹配吸收的单回路低蒸发压力有机朗肯循环(SLL-ORC),并与复杂度相当的预回热CO_(2)跨临界动力循环(PR-CTPC)进行对比.结果表明:在回收余热温度低、缸套水余热量大的内燃机余热时,SLL-ORC性能较好,其理论最大输出功率为16.13 kW,对应蒸发压力为910 kPa、过热度为80℃,且余热回收系统具有较高的热效率.基于此SLL-ORC构型搭建试验台架,试验验证了缸套水在R245fa工质两相区回收的可行性,在试验测试余热源和透平转速均未达到设计值时系统发电机产生的电能为9.41 kW,有效提升柴油机热效率绝对值可达2.98%.

耦合海水淡化的船舶柴油机排气净化装置设计

为综合高效实现船舶柴油机烟气废热回收海水淡化以提升尾气净化率,本文以KincaidB&W6L90GE型船舶柴油机为研究对象,提出一种耦合海水淡化的船舶柴油机废气高效净化技术,介绍了耦合海水淡化的船舶柴油机排气净化技术原理,理论设计计算耦合海水淡化的船舶柴油机废气净化系统的蒸发段和冷凝段,得到烟气余热回收制淡系统蒸发段和冷凝段的换热系数分别为42.29W/(m^(2)·℃)和1067.42W/(m^(2)·℃)、换热面积分别为517.31m^(2)和38.26m^(2),该系统整体尺寸为Φ6m,总高度为6.452m,并进一步得到船舶烟气净化系统整体尺寸为Φ4.0m,总高度为9.66m,完成了系统的整体尺寸设计计算和结构布置。

船舶主机余热梯级利用系统工质比较分析

本文以WARTSILA RT-flex96C型柴油机为研究对象,设计了船舶柴油机余热梯级利用系统——双级朗肯循环余热利用系统。选择四种工质组合方案针对所设计的系统进行热力计算,计算结果表明,以水和R113的组合方案热力性能最佳。计算了在高温循环的蒸发压力为0.79MPa、窄点温度为30℃、过热度为50℃,低温回路的蒸发压力为1.46MPa、窄点温度为15℃,冷凝温度均为30℃的情况下,系统的输出净功、热效率和㶲效率分别为3872.7kW、23.67%和61.71%。最后本文研究了高温回路蒸发温度、过热度以及窄点温度这三种参数对系统性能的影响。

舰船柴油主机动力装置的余热循环和利用系统设计

舰船柴油主机动力装置的余热循环和利用对提升舰船能源利用效率以及作战能力都具有重要意义。本文在确定余热循环和利用系统需求的基础上,对舰船柴油主机动力装置的余热循环和利用系统的整体结构进行了设计,系统包括余热回收锅炉系统、动力涡轮系统、有机工质发电系统、汽轮机发电系统、热交换系统以及能量管理系统,最后对柴油主机动力装置的余热循环和利用系统进行了模拟测试。测试结果表明:该系统可以有效利用柴油主机余热,基于ORC循环的系统热回收效率最大可达6.5%,柴油主机余热利用效率最大可达19%。

数据中心柴油发电机冬季保温余热回收系统应用实例研究

提出了将北方地区数据中心空调制冷系统余热回收后用于室外柴油发电机缸套水冬季保温,保障柴油发电机快速启动。以实际应用数据中心为案例,介绍了该余热回收系统的设计运行原理、技术路线、具体设计实施方案。对余热回收系统的经济性及节能效果进行了分析,结果表明,柴油发电机保温余热回收系统节能率高达72.1%,年节省运行费用22.67万元,静态投资回收期为3.8 a。该余热回收系统具有初投资低、实施方便、效果显著、收益快的优点,可在北方地区数据中心进行推广。