应用低温热循环技术实现节能降碳

介绍了低温热循环技术的应用原理,采用有机朗肯循环技术进行处理。分析认为,低温热循环ORC处理系统的运行,明确系统运行过程中低温余热回收利用的关键点,并且总结低温热循环技术应用的实际效果与今后发展方向;有机朗肯循环技术在低温热循环处理中运用具有十分显著的成效,可以实现低温余热的高效回收与利用,旨在通过低温热循环技术实现节能降碳的目标,满足行业发展对于节能减排的要求。

高Cr铁素体耐热钢高温热循环过程的组织演化规律

为探究高Cr铁素体耐热钢高温热循环过程的组织演化规律,通过采用光镜与透射电镜显微组织分析方法,对高Cr铁素体耐热钢单次和二次高温热循环加热后基体组织和沉淀相的演变规律展开研究,从而为第4类裂纹萌生微观机制的研究提供试验依据.结果表明:高温热循环加热后,奥氏体相分数都随着峰值温度的增高呈现先增加后降低的趋势,在峰值温度1,100,℃处达到最大;M_(23)C_6碳化物在峰值温度达1,100,℃后全部溶解,而MX碳化物在峰值温度达1,300,℃后才全部溶解,且MX的尺寸在不同热循环过程中基本保持不变;马氏体板条宽度随着峰值温度的升高而增加;沉淀相的溶解和δ-铁素体的形成对基体的硬度有明显影响.

低温热循环处理Fe基非晶粉末对爆炸喷涂涂层摩擦学性能的影响

目的提高爆炸喷涂Fe基非晶涂层的摩擦学性能。方法采用液氮-室温循环处理喷涂粉末,通过爆炸喷涂制备原始粉末和处理粉末对应涂层。利用X射线衍射仪(XRD)检测涂层非晶相,用维氏显微硬度计和球-盘式摩擦试验机分别测试涂层的显微硬度和摩擦学性能,用附带能谱仪的扫描电子显微镜(SEM)表征样品的组织形貌及特征区域的元素含量。结果粉末经低温热循环处理后,仍为非晶态组织,且未发生开裂和破碎现象。与原始粉末制备的涂层相比,低温热循环处理粉末制备的涂层孔隙率由1.0%降低至0.4%;未熔颗粒明显减少,粉末铺展更加充分;显微硬度略有降低(由845.4HV降至813.5HV),但测试误差明显减小,威布尔分布拟合直线斜率由7.1196升高至9.6414;摩擦系数由0.76降低至0.73,磨损更加稳定;磨损率相近,均在10−6次方数量级。结论Fe基非晶粉末经低温热循环处理后,其对应涂层的组织更为均匀致密,显微硬度分布更为均匀,摩擦磨损性能更为稳定,磨损机制由原始粉末制备涂层的疲劳剥层磨损,转变为以氧化磨损和塑性变形主导。

低温热循环水作为供暖热源的探讨

高效、合理利用不同品位余热,成为纯碱生产企业提高水资源利用效率、减少煤耗而达到节能、降耗、节水、减排的主要举措之一。介绍我公司通过对低温热循环水回水的综合分析,将热循环水用于集中供暖。希望为行业提供一些参考和借鉴。

高温热循环对Ti-22Al-25Nb合金板材性能的影响

通过设计700℃×1 h热循环疲劳试验,研究了700℃热循环对Ti-22Al-25 Nb合金板材室温性能和组织的影响规律。结果表明:700℃热循环后会在Ti-22Al-25 Nb合金板材表面形成氧化层,在氧化层与基体间形成脆性层,热循环次数越多,氧化层与脆性层越厚,室温强度与屈服强度越低;室温伸长率随着循环次数增多而降低,在热循环100次后降为2%,之后在热循环500次以内可保持在2%以上。

含Ag@Ni核壳结构粉体镍基复合涂层的多循环高温摩擦学性能

为了抑制Ag的扩散,采用化学镀方法制备Ag@Ni核壳结构粉体,并利用大气等离子喷涂技术制备NiCrAlY-Mo-Ag@Ni涂层,详细研究核壳结构设计对涂层在高温循环工况下的力学及摩擦学性能的影响。研究结果表明:Ag的核壳结构设计可以提高镍基涂层中Ag与NiCrAlY的界面结合强度,进而显著提高复合涂层的硬度。Ni覆层有效地抑制了Ag在高温摩擦过程中的扩散与耗散。800℃时NiCrAlY-Mo-Ag@Ni涂层的摩擦因数仅为0.25,磨损率仅为1×10^(-5)mm^(3)/(N·m),显著低于NiCrAlY-Mo-Ag涂层。同时,Ag的核壳结构设计使得涂层在高温多循环工况下始终保持良好的自润滑性和耐磨性。

低温热双循环发电机组检测实验台的研制

以低温热双循环发电机组检测实验台为研究对象,综合利用计算机技术、传感器技术和测试技术,配以自行开发的数据采集与监控软件,搭建出一套高精度、高自动化的基于RS-485总线的分布式数据采集与控制系统。研究结果表明:实验台能实现对各运行参数实时采集、显示、保存并可控制各个变频水泵的启停与频率,为新一代节能、环保、高效的发电机组提供检测实验平台。

干气密封在离心式高温热媒循环泵上的应用

干气密封是从气体动压轴承的基础上发展起来的一种新型非接触式密封,它最初应用于离心式压缩机轴封。介绍了干气密封的特点及工作原理,指出影响干气密封性能的主要因素,对干气密封技术运用于聚酯高温热媒循环泵进行了总结和归纳。

航空发动机热障涂层技术研究进展

随着高性能航空发动机的研制,热障涂层技术成为提高发动机性能的关键技术之一。对热障涂层材料体系和制备工艺进行了对比,认为电子束物理气相沉积技术在未来热障涂层的研制中具有较大潜力。并且针对1100℃条件下热循环试验中涂层失效进行了分析,表明TGO层在对涂层寿命具有很大的影响。

粘结层成分对单晶合金热障涂层寿命影响研究

采用电子束物理气相沉积工艺(EB-PVD)制备了针对第二代单晶高温合金的热障涂层,用SEM观察分析了不同成分粘结层的热障涂层热循环试验后的结构和晶体形貌,在N2条件下对比了不同成分粘结层材料与第二代单晶高温合金的热膨胀系数,分析了热循环试验后粘结层与热生长氧化(TGO)层成分、厚度及完整性情况。结果表明:NiCoCrAlYHf与第二代单晶高温合金热膨胀系数更为接近,匹配性更好;采用EB-PVD工艺制备的热障涂层在热循环试验过程中会产生大量垂直裂纹使涂层具有良好的应变容限;粘结层中Al元素含量的提高以及Hf等元素的加入,使得热循环试验后涂层TGO层的Al2O3纯度较高、生长缓慢无块状物生成,并且极大地改善了粘结层和合金基体的内氧化,涂层1 100℃循环氧化寿命达到1 200 h以上。

电阻箔复合材料规范(续一)

本方法利用金属箔微电阻测量原理,测定不同试验温度下电阻箔的直流电阻,用以确定电阻箔在试验温度下的直流电阻值与基准温度下直流电阻值的相对变化程度。

Theoretical study on the ideal open cycle of the liquid nitrogen engine

This article described the characteristics of the liquid nitrogen engine's ideal open cycle.Using two interconnecting strokes to achieve the power output can mitigate the trade-off between high efficiency and the potential mechanical complexity of multiple-cylinder engines. The total specific energy of the binary media (methane-nitrogen) cycle system could be much higher than the unitary medium (liquid nitrogen) cycle system. By theoretical analysis, the reasonably acceptable driving range proved the feasibility of the liquid nitrogen engine used for supplying power for a lightweight car.

Thermal reliabilities of Sn−0.5Ag−0.7Cu−0.1Al_(2)O_(3)/Cu solder joint

The effects of trace addition of Al_(2)O_(3) nanoparticles(NPs)on thermal reliabilities of Sn−0.5Ag−0.7Cu/Cu solder joints were investigated.Experimental results showed that trace addition of Al_(2)O_(3) NPs could increase the isotheraml aging(IA)and thermal cyclic(TC)lifetimes of Sn−0.5Ag−0.7Cu/Cu joint from 662 to 787 h,and from 1597 to 1824 cycles,respectively.Also,trace addition of Al_(2)O_(3) NPs could slow down the shear force reduction of solder joint during thermal services,which was attributed to the pinning effect of Al_(2)O_(3) NPs on hindering the growth of grains and interfacial intermetallic compounds(IMCs).Theoretically,the growth coefficients of interfacial IMCs in IA process were calculated to be decreased from 1.61×10^(−10 )to 0.79×10^(−10) cm^(2)/h in IA process,and from 0.92×10^(−10) to 0.53×10^(−10) cm^(2)/h in TC process.This indicated that trace addition of Al_(2)O_(3) NPs can improve both IA and TC reliabilities of Sn−0.5Ag−0.7Cu/Cu joint,and a little more obvious in IA reliability.

NUMERICAL STUDY ON THE FORMATION OF THE SOUTH CHINA SEA WARM CURRENT II. BAROCLINIC CASE

In this part, Levitus’ climatological temperature and salinity are incorporated in the numerical model developed in Part I. Diagnostic and prognostic experiment on the thermohaline circulation were conducted. The smooth Levitus’ data do not include any information on the South China Sea Warm Current (SCSWC), so it is not in the model produced diagnostic thermohaline circulation. Although the SCSWC does not appear in the wind driven circulation in the barotropic case, it appears in the prognostic wind driven circulation in the baroclinic case. This implies that the differing circulation patterns between barotropic case and baroclinic case are due to the stratification. The prognostic thermohaline circulation with wind stress and inflow/outflow transports at open boundaries are also discussed. Coupling of density and dynamic forces makes the circulation pattern more complicated. Even though the stratification is not always a direct cause of the formation of the SCSWC, it is at least an indirect cause.

Effects of process parameters on warpage of rapid heat cycle moulding plastic part

The effects of process parameters in rapid heat cycle moulding （RHCM） on parts warpage were investigated. A vehicle-used blue-tooth front shell （consisting of ABS material） was considered as a part example manufactured by RHCM method. The corresponding rapid heat response mould with an innovational conformal heating/cooling channel system and a dynamic mould temperature control system based on the Jll-W-160 type precise temperature controller was proposed. During heating/cooling process, the mould was able to be heated from room temperature to 160 ~C in 6 s and then cooled to 80 ~C in 22 s. The effects of processing conditions in RHCM on part warpage were investigated based on the single factor experimental method and Taguchi theory. Results reveal that the elevated mould temperature reduces unwanted freezing during the injection stage, thus improving mouldability and enhancing part quality, whereas the overheated of mould temperature will lead to defective product. The feasible mould temperature scope in RHCM should be no higher than 140 ~C, and the efficient mould temperature scope should be around the polymer heat distortion temperature. Melt temperature as well as injection pressure effects on warpage can be divided into two stages The lower stage gives a no explicit effect on warpage whereas the higher stage leads to a quasi-linear downtrend. But others affect the warpage as a V-type fluctuation, reaching to the minimum around the heat distortion temperature. Under the same mould temperature condition, the effects of process parameters on warpage decrease according to the following order, packing time, packing pressure, melt temperature, injection pressure and cooling time, respectively.

Feedforward Variable Structural Proportional-Integral-Derivative for Temperature Control of Polymerase Chain Reaction

To track the rapidly changing temperature profiles of thermal cycling of polymerase chain reaction （PCR） accurately, an innovative feedforward variable structural proportional-integral-derivative （FVSPID） controller was developed. Based on the step response test data of the heat block, a reduced first order model was estabfished at different operating points. Based on the reduced model, the FVSPID controller combined a feedforward path with the variable structural proportional-integral-derivative （PID） control. The modified feedforward action provided directly the optimal predictive power for the desired setpoint to speed up the dynamic response. To cooperate with the feedforward action, a variable structural PID was applied, where the P mode was used in the case of the largest errors to speed up response, whereas the PD mode was used in the case of larger errors to suppress overshoot, and finally the PID mode was applied for small error conditions to eliminate the steady state offset. Experimental results illustrated that compared to the conventional PID controller, the FVSPID controller can not only reduce the time taken to complete a standard PCR protocol, but also improve the accuracy of gene amplification.

Performance analysis of a zeotropic mixture(R290/CO_2) for trans-critical power cycle

Low critical temperature limits the application of CO_2 trans-critical power cycle.The binary mixture of R290/CO_2has higher critical temperature.Using mixture fluid may solve the problem that subcritical CO_2 is hardly condensed by conventional cooling water.In this article,theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of200℃.The results indicated that the problem that CO_2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO_2.Variation trend of outlet temperature of thermal oil in supercritical heater with heating pressure is determined by the composition of the mixture fluid.Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290.There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure.

Thermodynamic analysis of simplified dual-pressure ammonia-water absorption power cycle

A simplified dual-pressure ammonia-water absorption power cycle(DPAPC-a) using low grade energy resources is presented and analyzed.This cycle uses turbine exhaust heat to distill the basic solution for desorption.The structure of the cycle is simple which comprises evaporator,turbine,regenerator(desorber),absorber,pump and throttle valves for both diluted solution and vapor.And it is of high efficiency,because the working medium has large temperature difference in evaporation and small temperature difference in absorptive condensation,which can match the sensible exothermal heat resource and the cooling water simultaneously.Orthogonal calculation was made to investigate the influence of the working concentration,the basic concentration and the circulation multiple on the cycle performance,with 85-110 ℃ heat resource and 20-32 ℃ cooling water.An optimum scheme was given in the condition of 110 ℃ sensitive heat resource and 20 ℃ cooling water,with the working concentration of 0.6,basic concentration of 0.385,and circulation multiple of 5.The thermal efficiency and the power recovery efficiency are 8.06 % and 6.66%,respectively.The power recovery efficiency of the DPAPC-a is 28.8% higher than that of the steam Rankine cycle(SRC) and 12.7% higher than that of ORC(R134a) under the optimized situation.