LPG／汽油两用燃料汽车加装电控补气三元催化器系统的匹配研究

本文对在LPG／汽油两用燃料汽车上加装三元催化器和电控补气装置的优化匹配过程进行了详细的介绍，加装该系统可以有效地降低尾气排放污染，使两用燃料车辆达到新的排放法规的严格要求。     

汽油/液化石油气两用燃料通用小型发动机排放性能试验分析

我们以一型号为192F型汽油/液化石油气两用燃料通用小型发动机为研究对象,介绍了该发动机的燃料供给系统结构,并根据此类发动机排放测试标准GB 26133-2010进行汽油和液化石油气2种燃料的排放性能试验。通过对试验结果的分析,该发动机燃用液化石油气比燃用汽油CO排放量降低,NOx排放增加。     

生物质锅炉一氧化碳排放超标原因及控制措施

生物质锅炉在运行过程中如果控制不好,容易出现废气中一氧化碳浓度过高的问题,呈现出其排放浓度和颗粒物、二氧化硫、氮氧化物等其他污染物浓度成反比例关系的规律,其产生的原因在于锅炉在链条自动进料过程中,炉内燃料堆积得不到搅拌,燃料在缺氧状态下燃烧产生大量的一氧化碳.通过在锅炉前端加装预燃烧器,使燃料预燃烧后送至炉体内进行二次燃烧的控制措施,可以让燃料得到充分燃烧并且降低排放废气中的含氧量.经对加装预燃烧器的生物质锅炉进行废气检测,排放废气中含氧量可稳定保持在11％左右,各项气态污染物可稳定达标.     

汽油/液化石油气两用燃料摩托车的性能与排放研究

介绍了在国内率先开发成功的汽油/液化石油气（LPG）两用燃料摩托车的结构与性能，对该摩托车进行了转鼓试验，道路噪声试验和百公里燃料消耗率的测试。其结果表明：新开发的两用燃料摩托车在燃用LPG燃料时，其动力性能与原车相当，燃料经济性比燃用汽油时有所改善，其十五工况的排放，燃用汽油时接近欧Ⅱ限值，燃用LPG时优于欧Ⅱ限值，摩托车整车噪声达到2005年以后国家对摩托车的噪声限值。     

公交客车天然气／汽油两用燃料发动机供气技术研究

对汽油机改装为天然气,汽油两用燃料发动机的供气系统在动力性、经济性及排放性能方面进行了比较分析,传统的混合器式天然气发动机对空燃比难以实现高精度的控制,采用电控缸外进气阀处多点喷射系统可以明显改善发动机经济性和排放性能,得到较高的功率输出。     

汽油/压缩天然气两用燃料发动机颗粒物排放特性研究

在某款1.4 L自然吸气两用燃料发动机上进行台架试验,用DM S500快速颗粒分析仪在发动机转速为4000 r/min不同进气压力工况下,对汽油和压缩天然气(compressed natural gas,CNG)的颗粒物排放特性进行采样分析.试验结果表明,两种燃料的总体颗粒物数量(particle number,PN)...     

汽油—液化石油气（LPG）两用燃料发动机的研究

介绍了汽油－液化石油气（LPG）两用燃料发动机空燃比的调节和作者研制成功的无混合器式双蒸发器LPG供气系统,该供气系统取消了LPG发动机惯用的混合器,在原机双腔化油器的主、副腔喉管处钻孔,接入LPG主供气系和LPG加浓系,从而取消了混合器,解决了全负荷时动力性与部分负荷时燃料经济性、排放之间的矛盾,取得了良好的效果。用该系统改装的汽油－LPG两用燃料发动机,在燃用汽油时性能无任何变化,燃用LPG时取得了动力性、燃料经济性和排放指标俱佳的效果。     

通过快速压缩膨胀装置来研究火花点火液化石油气发动机以提高其性能

为了模拟研究桑塔纳 JV4 81Q汽油机改装成汽油 / L PG两用燃料发动机后的燃烧 ,在快速压缩膨胀装置上采取改变点火时刻、混合气浓度、压缩比以及燃烧室形状等措施研究 L PG燃烧特性 ,然后将研究得出的改进措施应用在该两用燃料发动机的改装上。台架试验结果表明 ,采取上述措施后 ,发动机的输出功率得到了提高 ,排放性能得到了改善。     

替代率对船用LNG/柴油双燃料发动机性能的影响

以淄柴Z6170船用柴油机为基础,通过加装额外的天然气供给系统将其改装成LNG/柴油双燃料发动机,在推进特性不同负荷点进行试验,研究替代率对发动机经济性能和排放性能的影响。试验结果表明,随着替代率的增加,燃料消耗率和HC排放有不同程度的增加,NOx和CO则在高低负荷表现出不同的规律。     

汽油/压缩天然气(CNG)两用燃料汽车研究

在神龙富康化油器汽车改为汽油/CNG两用燃料汽车后,整车重量增加55kg动力性下降19%,CO排放增大达25.6倍,HC下降28%.所以化油器式汽车在改用天然气后应对燃烧系统进行必要的调整,否则改用天然气的优越性不能充分的体现出来.而调整后再燃用汽油时就可能引起爆震或残余废气过高.因此应尽可能缩短汽油/CNG两用燃料汽车的过渡时间,加快CNG加气站的建设,将两用燃料汽车改为纯CNG汽车。     

Matching of a DC motor to a photovoltaic generator using a step-upconverter with a current-locked loop

A photovoltaic (PV) generator is a nonlinear device having insolation-dependent volt-ampere characteristics. Because of its relatively high cost, the system designer is interested in optimum matching of the motor and its mechanical load to the PV generator so that maximum power is obtained during the entire operating period. However, since the maximum-power point varies with solar insolation, it is difficult to achieve an optimum matching that is valid for all insolation levels. In this paper it is shown that for maximum power, the generator current must be directly proportional to insolation. This remarkable property is utilized to achieve insolation-independent optimum matching. A shunt DC motor driving a centrifugal water pump is supplied from a PV generator via a step-up converter whose duty ratio is controlled using a current-locked feedback loop     

Natural convection of a non-Newtonian fluid about a horizontal cylinder and a sphere in a porous medium

The problem of natural convection of a non-Newtonian fluid about a horizontal isothermal cylinder and an isothermal sphere in the porous medium is considered. The present study is based on the boundary layer approximation and only suitable for a high Rayleigh number. Similarity solutions are obtained by using the fourth order Runge-Kutta method. The effects of the wall temperature T_W and the new power-law index n on the characteristics of heat transfer are discussed.     

Studies on a two-staged micro-combustor for a micro-reformer integrated with a micro-evaporator

A new micro-combustor configuration for a micro fuel-cell reformer integrated with a micro-evaporator is studied experimentally and computationally. The micro-combustor as a heat source is designed for a 10–15 W micro-reformer using the steam reforming method. In order to satisfy the primary requirements for designing a micro-combustor integrated with a micro-evaporator, i.e., stable burning in a small confinement and maximum heat transfer through a wall, the present micro-combustor is a simply cylinder, which is easy to fabricate, but is two-staged (expanding downstream) to control ignition and stable burning. The aspect ratio and wall thickness of the micro-combustor substantially affect ignition and thermal characteristics. For optimized design conditions, a pre-mixed micro-flame is easily ignited in the expanded second-stage combustor, moves into the smaller first-stage combustor, and finally is stabilized therein. The measured and predicted temperature distributions across the micro-combustor walls indicate that heat generated in the micro-combustor is well transferred. Thus, the present micro-combustor configuration can be applied to practical micro-reformers integrated with a micro-evaporator for use with fuel cells.     

Coupling a two-temperature model and a one-temperature model at a fluid-porous interface

We study a convective heat transfer problem in a fluid-porous domain in the case of the local thermal non-equilibrium assumption (LTNE). The issue of this study is to determine appropriate boundary conditions to model heat transfer, while using models with a different number of equations: a two-temperature model in the homogeneous porous region versus a one-temperature model in the free region. To proceed, a two-step up-scaling approach is used, which has the particularity to provide closed jump relations depending on intrinsic characteristic of the interface. Thus, the use of jump or continuity conditions depend only on the interface location inside the fluid-porous transition region. The pertinence of the approach is illustrated on a 2D convective heat transfer problem considering a solid heat source in the porous medium.     

Using a fin with a parabolic concentrator

The consequences of using a fin collector in focusing solar collectors is examined and is found to have merits.     

Bioconvection in a squeezing flow of a micropolar fluid in a horizontal channel

The bioconvection flow of an incompressible micropolar fluid containing microorganisms between two infinite stretchable parallel plates is considered. A mathematical model, with a fully coupled nonlinear system of equations describing the total mass, momentum, thermal energy, mass diffusion, and microorganisms is presented. The governing equations are reduced to a set of nonlinear ordinary differential equations with the help of suitable transformations. The resulting nonlinear ordinary differential equations are linearized using successive linearization method, and the resulting system of linear equations is solved using the Chebyshev collocation method. The detailed analysis illustrating the influences of various physical parameters, such as the micropolar coupling number, squeezing parameter, the bioconvection Schmidt number, Prandtl numbers, Lewis number, and bioconvection Peclet number on the velocity, microrotation, temperature, concentration and motile microorganism distributions, skin friction coefficient, Nusselt number, Sherwood number, and density number of motile microorganism, is examined. The influence of the squeezing parameter is to increase the dimensionless velocities and temperature and to decrease the local Nusselt number and local Sherwood number. The density number of motile microorganism is decreasing with squeezing parameter, bioconvection Lewis number, bioconvection Peclet number, and bioconvection Schmidt number.     

Exploration of heat transfer effect in a magnetohydrodynamics flow of a micropolar fluid between a porous and a nonporous disk

An analysis is carried out for the flow characteristics of a conducting micropolar fluid. The fluid was passed in between two parallel disks of infinite radii. The novelty of the study is to consider one of the disks as porous and the other one as nonporous, and the external magnetic field is applied along the transverse direction of the flow. The flow phenomena for the polar fluid characterized by the magnetic effect in conjunction with the temperature equation reduce to a set of coupled nonlinear ordinary differential equations using the requisite transformations and nondimensionalization. An analytical approach such as the variation parameter method is employed to tackle the system efficiently. To emphasize the effect of various physical parameters contributing to the flow phenomena, that is, non-zero tangential slip, Reynolds number, Prandtl number, magnetic parameter, and material parameter on the flow profiles of axial and radial velocities, the microrotation and temperature profiles are presented graphically. To validate the simulated results, a comparison with established results is made, and it is concluded that both are in good correlation.     

Comparative analysis of a Sisko nanofluid over a stretching cylinder through a porous medium

The present article examines the Sisko nanofluid flow and heat transfer through a porous medium due to a stretching cylinder using Buongiorno's model for nanofluids. Suitable similarity transformations are used to transform the governing boundary layer equations of fluid flow into nonlinear ordinary differential equations. The finite difference method is used to solve coupled nonlinear differential equations with MATLAB software. The impact of different parameters viz., the Sisko material parameter, porosity parameter, curvature parameter, thermophoresis parameter, and Brownian diffusion parameter on the velocity and temperature distribution are presented graphically. Moreover, the effect of the involved parameters on the heat transfer rate is also studied and presented through table values. It is noticed from the numerical values that the porosity parameter reduces the velocity while enhancing the temperature. The curvature parameter enhances the velocity throughout the fluid regime and reduces the temperature near the surface while enhancing the temperature far away from the surface. The study reveals that the thermophoresis and Brownian diffusion parameters that characterize the nanofluid flow reduce the wall heat transfer rate, while the curvature parameter enhances it. This investigation of wall heating/cooling has essential applications in solar porous water absorber systems, chemical engineering, metallurgy, material processing, and so forth.