柴油机曲轴箱强制通风系统的试验研究与开发

在玉柴某型柴油机上,通过装闭式循环强制通风油气分离器与开式循环油气分离器进行对比试验,研究闭式循环强制通风系统对发动机性能的影响.结果表明:加装闲式循环曲轴箱强制通风系统可调节发动机的曲轴箱压力在合理范围内变化;分离效率的高低直接影响到通入增压器压气机进气中含油量的高低.同时解决了开式循环曲轴箱通风系统中柴油机的含油废...     

闭式循环柴油机系统的仿真研究

本文基于内燃机热力循环理论，编制了内燃机工作过程仿真程序，针对4102柴油机进行了开式循环和闭式循环的稳态模拟。通过计算结果与试验数据的比较，验证了计算的正确性。并比较了开式循环和闭式循环的各项参数，给出工质中不同含量的二氧化碳对闭式循环柴油机的影响规律。     

闭式循环柴油机使用不同工质的性能研究

闭式循环柴油机是具有废气再生系统,能够脱离大气工作的独立动力装置,进气成份与在空气中工作时不同,而且可以调节。本文通过试验与计算结果的分析,探讨进气工质(包括惰性气体等)对柴油机性能的影响及如何选择工质成份。提出了一套适用于计算不同工质成份对柴油机性能影响的计算方法,并已编成可供实用系统设计使用的程序。按此程序计算的结果与试验数据基本吻合。     

压气机进气温度对联合循环机组性能影响的探讨

通过热力学模型分析和热力系统平衡计算,研究了9F级燃气轮机压气机进气温度变化对燃气轮机及联合循环发电机输出功率及效率的影响,压气机进气温度变化不仅对燃气轮机联合循环机组满负荷时的性能有影响,在部分负荷运行时对机组的效率也有影响。通过对压气机进气温度进行调节,可以改善燃气轮机联合循环的运行性能。     

拟闭式循环柴油机着火过程的研究

简要分析了以“人造大气”工作的闭式循环柴油机所需解决的技术问题和理论问题。针对发动机工作过程的特点，着重就工质成分对拟闭式循环柴油机自然着火过程的影响进行了实验和研究。结果表明，添加氩气有助于缩短冷焰和热焰诱导期，而工质中ＣＯ２浓度的增加则会延长冷，热焰诱导期；在着火滞燃期随工质成分而变化的趋势上，理论计算与实验测量基本相吻合。     

高速柴油机动力及排放性能与运行参数之间的共性规律

为给新品发动机性能概念设计阶段的参数定义提供优化方向,基于先进发动机性能对标技术,对4台车用高速柴油机稳态工况下的运行参数、性能参数以及排放水平进行了全面的检测.通过对实测数据的二次开发与分析,提炼出影响柴油机动力性的进气参数K和影响柴油机源排放的缸内稀释参数L.结果表明:进气参数K与动力性指标的关系,以及缸内稀释参数L与源排放的关系在不同柴油机及同一柴油机不同工况之间有着良好的共性规律.应用分析结果,可针对新品柴油机开发需求,确定各工况下主要运行参数的取值范围.     

进气成分对柴油机低温燃烧影响的试验和数值模拟

通过改变进气成分（向进气管喷入CO2、N2和EGR）对柴油机燃烧和排放影响的对比,从试验和模拟两方面研究了进气成分对柴油机低温燃烧性能和排放特性的影响．试验结果表明,进气中CO2比例较大时,碳烟大幅降低的主要原因是CO2的热效应和化学效应,而CO2和N2的稀释效应对降低NO。排放的效果相当,氧体积分数降低是NOx排放降...     

增压多缸柴油机各缸进气不均匀性的研究

在某增压8缸柴油机性能试验和多个气缸压力测量的基础上,利用试验数据对该柴油机的一维性能仿真计算模型进行了标定和校核,计算和分析了不同试验工况下柴油机各缸进气流量的不均匀性。结果表明:在相同转速的情况下,各气缸进气量的大小对比关系不随负荷的变化而变化,随着负荷的增加,各缸的平均进气流量增加,各缸的进气不均匀度增加;不同转速时,各气缸进气量的大小对比关系有所变化,进气不均匀度也不相同。     

一种竖管降膜蒸发太阳能海水淡化装置的实验研究

设计了一种竖管降膜—横管冷凝的太阳能海水淡化装置。以电加热作为供热热源,在不同的运行参数下进行了实验研究,分析了影响装置性能的各种因素。分析表明:在供能相同的情况下,闭式循环的单位能耗产水率比开式循环提高了约1.0~1.5倍;提高循环热水进口温度有利于提高产水率和单位能耗产水率;海水流率有一个理想取值范围。     

燃煤气的闭式 STIG 循环的热力学分析

本文将煤气化技术用于闭式注蒸汽燃气轮机循环,对以煤气化产物为燃料的闭式注蒸汽循环进行了热力学分析,并与燃煤气的开式ＳＴＩＧ循环做了比较,同时分析了回收水量的影响因素。     

TBD620柴油机进气系统性能研究

对TBD620柴油机进气系统进行了理论和试验研究。缸头气道稳流试验数据表明该机在低负荷工况下,在进气量较小时,采用单独涡流气道进气和直流气道不完全封闭,可以获得较大的进气涡流,达到改善大功率柴油机低负荷性能的目的。     

Combustion characteristics of a closed cycle diesel engine with different intake gas contents

This paper is to carry out a numerical simulation of combustion characteristics for a closed cycle diesel engine (CCDE) with different intake gas contents under different engine speeds and equivalence ratios. The numerical simulation used Kiva3V-Release2 code as the main program by modifying some subroutines containing different intake gas contents of oxygen, argon, and nitrogen and their thermodynamic properties. The results show that the pressure will increase earlier if the percentage of argon is higher when we use argon to replace nitrogen, and the ignition delay will be shorter, too. The higher in-cylinder temperature results from a higher concentration of argon.     

柴油机主辅双进气道系统性能优化研究

对大功率柴油机采用主辅双进气道系统改善低负荷工况下的进气涡流进行理论分析和试验研究,并对进气控制挡板参数进行了优化。研究结果表明：在低负荷工况下,以螺旋气道进气为主,直流气道进气为辅,可以获得较强的进气涡流,达到改善低负荷性能的目的。     

可变涡流对高速柴油机性能影响的仿真研究

采用计算仿真的方法模拟某高速柴油机缸内的工作过程,分析柴油机缸内及进排气道内的流场、缸内燃烧过程以及有害排放物的生成。计算过程中采用部分或完全关闭一个进气道的方法改变缸内涡流状况,分析不同气道关闭方案下缸内涡流的强度,及其对柴油机动力性、经济性及排放性能的影响。计算结果表明,对柴油机完整工作循环进行三维数值模拟计算可获得缸内瞬态流场参数,当转速低于2400r·min-1时,完全关闭一个进气道可以在对动力性和经济性影响很小的情况下显著提高缸内涡流强度,减少碳烟的峰值生成量;部分关闭一个进气道,可以在对动力性、经济性几乎不影响的情况下减少NOx的生成量。     

Study on homogeneous charge compression ignition combustion in argon circulated closed cycle hydrogen engine

It is important to improve thermal efficiency and to reduce harmful exhaust gas emissions in internal combustion engines. A closed cycle engine system that uses a monatomic molecular gas as the working fluid can be expected to have high thermal efficiency due to the high specific heat ratio of the gas. Several studies have been reported on closed cycle engines with conventional spark ignition or compression ignition. This research newly proposes an argon circulated closed cycle homogeneous charge compression ignition (HCCI) engine system fueled with hydrogen. In this engine system, effects of in-cylinder gas initial temperature and residual water in recirculated gas on combustion characteristics were investigated. The results show that the system with argon circulation has the wider range of operable conditions and the higher thermal efficiency compared to the case with air as the working fluid.     

Ignition delay of dual fuel engine operating with methanol ignited by pilot diesel

An investigation on the ignition delay of a dual fuel engine operating with methanol ignited by pilot diesel was conducted on a TY1100 direct-injection diesel engine equipped with an electronic controlled methanol low-pressure injection system. The experimental results show that the polytropic index of compression process of the dual fuel engine decreases linearly while the ignition delay increases with the increase in methanol mass fraction. Compared with the conventional diesel engine, the ignition delay increment of the dual fuel engine is about 1.5° at a methanol mass fraction of 62%, an engine speed of 1600 r/min, and full engine load. With the elevation of the intake charge temperature from 20°C to 40°C and then to 60°C, the ignition delay of the dual fuel engine decreases and is more obvious at high temperature. Moreover, with the increase in engine speed, the ignition delay of the dual fuel engine by time scale (ms) decreases clearly under all engine operating conditions. However, the ignition delay of the dual fuel engine increases remarkably by advancing the delivery timing of pilot diesel, especially at light engine loads.     

SOFIM柴油机气波增压研究

将SOFIM涡轮增压中冷柴油机改造成气波增压中冷柴油机。匹配气波增压器的柴油机需重新设计进、排气管，根据气波增压的要求，采用进气均匀性更好、总管容积更大的进气管及中央出口渐扩式排气管，采用变频电机优化增压器转子与曲轴间的传动速比，使得在整个发动机工况内均能实现较高的增压比。试验结果表明，气波增压柴油机的动力性和排放性能在低转速下优于原机，在中高转速下比原机差，通过设计容量更大的进、排气管及进一步优化速比可改善气波增压柴油机在高工况下的性能。     

Availability analysis of a turbocharged diesel engine operating under transient load conditions

A computer analysis is developed for studying the energy and availability performance of a turbocharged diesel engine, operating under transient load conditions. The model incorporates many novel features for the simulation of transient operation, such as detailed analysis of mechanical friction, separate consideration for the processes of each cylinder during a cycle (“multi-cylinder” model) and mathematical modeling of the fuel pump. This model has been validated against experimental data taken from a turbocharged diesel engine, located at the authors’ laboratory and operated under transient conditions. The availability terms for the diesel engine and its subsystems are analyzed, i.e. cylinder for both the open and closed parts of the cycle, inlet and exhaust manifolds, turbocharger and aftercooler. The present analysis reveals, via multiple diagrams, how the availability properties of the diesel engine and its subsystems develop during the evolution of the engine cycles, assessing the importance of each property. In particular the irreversibilities term, which is absent from any analysis based solely on the first-law of thermodynamics, is given in detail as regards transient response as well as the rate and cumulative terms during a cycle, revealing the magnitude of contribution of all the subsystems to the total availability destruction.     

Low-load hydrogen-diesel dual-fuel engine operation – A combustion efficiency improvement approach

Hydrogen-diesel dual-fuel operation can provide significant benefits to the performance and carbon-based emissions formation of compression-ignition engines. The wide flammability range of hydrogen allows engine operation at extremely low equivalence ratios while its high diffusivity and flame speed promote wide range combustion inside the cylinder. Nonetheless, despite the excellent properties of hydrogen for internal combustion, unburned hydrogen emissions and poor combustion efficiency have been previously observed at low-load conditions of compression ignition engines.The focus of the present study is to assess the effects of different engine operation and diesel injection parameters on the combustion efficiency of a heavy-duty dual-fuel engine while observing their interactions with the brake thermal efficiency (BTE) and emissions formation of the engine. In an attempt to reduce the unburned hydrogen rates at the exhaust of the engine, exhaust gas recirculation (EGR) and different diesel injection strategies were implemented. Statistical methods were applied in this study to reduce the experimental time.The results show a strong connection between unburned hydrogen rates, combustion and brake thermal efficiencies with the EGR rate. Higher EGR rates increase the intake charge temperature and provide improved hydrogen combustion and fuel economy. Operation of the dual-fuel engine at low-load with high EGR rate and slightly advanced main diesel injection can deliver simultaneous benefits to most of the harmful emissions and the BTE of the engine. Despite the efforts to achieve optimal engine operation at low loads, the combustion efficiency for most of the tested cases was in the range of 90%. Thus, increased hydrogen rates should be avoided as the benefits of the dual-fuel operation are weak at low-load conditions.