模拟火灾环境下木材炭化速率的实验研究

研究了早期火灾条件条件下辐射源功率、样品与辐射源间距离及辐射时间等因素对积炭性材料炭化速率的影响。实验样品处于无焰燃烧状态，采用全过程录像跟踪拍摄，对录像进行处理后，得到实验样品的炭化层厚度的数据，对实验数据进行分析计算，得到的经验公式可用于描述材料炭化速率与实验因子的关系。结果表明，辐射源功率越大，样品与辐射源间距离越小，炭化速率越大。     

几种常用木材热解(燃烧)后的烟气析出规律试验研究

在火灾可燃物热解与着火实验台上，对白桦、红皮云杉、蒙古栎、山杨、樟子松五种木材进行了热解燃烧试验，测定了各种木材在20～60kW／m^2辐射热流下的主要烟气成分，得到了在不同辐射热流下，各种木材的烟气析出规律，分析了辐射热流和样品密度对烟气析出过程的影响，探讨了样品表面温度、失重速率和烟气析出的内在联系。     

燃烧室沉积物对火花点火发动机碳氢排放的影响

为了弄清燃烧室沉积物对发动机排气碳氢的影响，使用一台实验用单缸火花点火发动机来形成燃烧室沉积物。在燃烧室沉积物存在的条件下，开展了不同工况下碳氢排放的实验研究，分析了燃烧室沉积物对发动机动力性和燃油经济性的影响。实验结果表明：当发动机运行一段时间后，其燃烧室表面沉积物将达到一稳定平衡厚度，此时排气碳氢浓度随转速的升高、冷却水温的增加以及点火推迟而降低。在本实验各类工况下，沉积物的存在将使发动机排气碳氢浓度增加２０％～３０％。同时沉积物的存在将使发动机的功率和燃油经济性有所提高（功率增加１．１％～１．６％，燃油经济性提高２．７％～３．０％），此现象被认为主要是因沉积物的隔热作用，而不是压缩比的增加所致。     

火花点火发动机准维湍流卷吸燃烧模型的适用性研究（二）

本文利用作者提出的火花点火发动机准维湍流卷吸燃烧模型，对压缩比为１０和１２的火球形燃烧室以及压缩比为１０的碗形燃烧室变工况进行了计算，将计算得到的示功图、质量燃烧率等与实验值进行了对比对分析。结果表明，合理选取与燃烧室结构相对应的四个经验常数，准维湍流卷吸燃烧模型完全适用于火花点火发动机变工况及不同燃烧室结构工作过程的计算，能够正确反映火花点火发动机结构参数和运转参数对燃烧过程的影响。     

涡轮导叶对环形燃烧室点火的影响

在TurboCombo实验平台上实验研究了涡轮导叶对环形燃烧室点火过程的影响.采用高速相机观察记录火焰周向传播过程以及火焰与涡轮导叶的耦合作用.分析对比了不同当量比、热功率及主流速度条件下带涡轮导叶的环形燃烧室与独立环形燃烧室点火过程的异同与周向点火时间.实验结果表明,两种构型下的周向点火过程基本相似,但相同条件下带涡轮导叶的环形燃烧室相较于独立的环形燃烧室周向点火时间更短.考虑了湍流褶皱及燃后气体膨胀效应后,预估了周向火焰传播速度并与实验结果在较大雷诺数下吻合得较好.     

丙酮丁醇乙醇/汽油混合燃料对高速发动机性能影响的试验研究

以发动机4000 r/min、节气门开度35％ 为试验工况,对纯汽油及不同掺混体积分数丙酮丁醇乙醇(acetone-butanol-ethanol,ABE)与汽油混合物开展了不同点火提前角和喷油量的试验研究.分析了不同ABE混合比、点火提前角和过量空气系数对发动机性能的影响,并对每种燃料发动机最大功率工况的性能参数进行...     

吸收式热泵回收烟气冷凝热的实验研究

基于清华大学超低能耗示范楼热电冷联供平台,对利用吸收式热泵回收天然气烟气冷凝热进行了实验研究,分析了余热回收系统的开启、变工况和关机动态响应过程.实验表明,烟气余热回收系统的开启过程较长,应尽量使内燃机与热泵的容量匹配,缩短开机时间;内燃机发电功率对系统供热功率和供热温度影响较大,对冷凝热回收功率、冷冻水温度和制热COP影响较小;系统供热温度对热泵性能影响较大;应选择合适的关机模式,以保证系统安全、缩短关机时间.     

丙酮-丁醇-乙醇(ABE)/汽油混合燃料对高速发动机性能影响的试验研究

以发动机4000r/min、节气门开度35%为试验工况,对纯汽油及不同掺混体积分数丙酮-丁醇-乙醇(acetone-butanol-ethanol,ABE)与汽油混合物开展了不同点火提前角和喷油量的试验研究。分析了不同ABE混合比、点火提前角和过量空气系数对发动机性能的影响,并对每种燃料发动机最大功率工况的性能参数进行了比较。结果表明：点火提前角和过量空气系数相同时,混合燃料中ABE含量越高,燃油流量越大,发动机功率越大,有效热效率越高;燃油流量的总热量增大和热-功转换效率提高是促使发动机功率增大的主要原因;随ABE掺混比增加,NO比排放明显降低,CO比排放略有增加,碳氢化合物比排放先增后减。浓混合气工况增加ABE含量比在当量空燃比状态下增加ABE含量,发动机的有效热效率增大更明显,发动机的NO比排放降低更加明显。研究表明高速汽油机掺混ABE燃料具有较好的应用前景。     

基于缸内净压力的直喷发动机最佳点火正时

为探求汽油机在不同工况下最佳点火正时与各燃烧特征参数的对应关系,在一台低压空气辅助单缸直喷试验机上进行变工况实验,利用自主研发的燃烧分析,系统对各工况的燃烧状况进行分析,对比了不同工况下50%燃烧量对应的曲轴转角(CA50)、最高燃烧压力对应的曲轴转角(PCP)、净压力二次导数峰值对应曲轴转角(MANP)3种燃烧特征参数与最佳点火正时之间的对应关系,并着重分析了净压力二次导数曲线的变化规律.研究表明,MANP作为一种新的燃烧特征参数能够较好地表征缸内燃烧的状况,并且与最佳点火提前角有很好的对应关系;CA50和PCP皆能在一定范围内与最佳点火正时有良好的对应关系,但仍有不确定性,相对而言,以MANP作为最佳点火正时的评价标准具有更高的精度.     

高能（电子）点火系与供油系匹配试验研究

通过对两种点火系进行定功率质量调整对比，说明高能点火可燃用较少的汽油而发生同样的功率，因而排放与油耗率均得到改善，据此试验结果，对化油器进行匹配调整，取得提高发协机动力性（Ｐｅ ｍａｘ提高３．９％），改善经济性和降低排放（常用工况油耗率下降４．７％，ＣＯ和ＨＣ平均下降５０％以上）的效果，动态性能也有明显提高。试验还表明，高能点火正确匹配使用，它不但是机内净化的有效装置，也是改善发动机性能的重要途径     

手机电磁辐射的影响及防护

近年来,手机辐射严重危害人体健康。叙述了手机的种类以及各款手机在通话开始瞬间状态、通话持续状态、待机状态等状态下的辐射程度,指出,手机使用过程中电池辐射逐渐减小,待机状态下,电磁辐射保持最低值,提出了对手机电磁辐射的防护建议。     

Correlation of monthly-average daily global, diffuse and beam radiation with bright sunshine hours

Correlations between monthly-average daily radiation and bright sunshine hours for 11 Indian stations have been studied. It is found that the global radiation can be predicted to an accuracy of 0.5% by using the linear relation, G/G_ext = a + b (n/N). For diffuse radiation, three different correlations have been tried. For individual applications, any of the three correlations discussed in this paper can be used, but for collective applications, the correlation D/G_ext = a + b (n/N) gives better results. Beam radiation is found to be highly dependent upon the local conditions. To develop a single formula for 11 stations involves a large percentage of error. The Hay method [9] is comparable to the equation G/G_ext = a + b(n/N) for global radiation, but for diffuse radiation, the equation D/G_ext = a + b (n/N) is superior to the Hay method. The correlations for global and diffuse radiation are G/G_ext = 0.3156 + 0.4520(n/N) and D/G_ext = 0.3616 − 0.2123 (n/N), respectively.     

An application of the multilayer perceptron: Solar radiation maps in Spain

In this work an application of a methodology to obtain solar radiation maps is presented. This methodology is based on a neural network system [Lippmann, R.P., 1987. An introduction to computing with neural nets. IEEE ASSP Magazine, 4–22] called Multi-Layer Perceptron (MLP) [Haykin, S., 1994. Neural Networks. A Comprehensive Foundation. Macmillan Publishing Company; Hornik, K., Stinchcombe, M., White, H., 1989. Multilayer feedforward networks are universal approximators. Neural Networks, 2(5), 359–366]. To obtain a solar radiation map it is necessary to know the solar radiation of many points spread wide across the zone of the map where it is going to be drawn. For most of the locations all over the world the records of these data (solar radiation in whatever scale, daily or hourly values) are non-existent. Only very few locations have the privilege of having good meteorological stations where records of solar radiation have being registered. But even in those locations with historical records of solar data, the quality of these solar series is not as good as it should be for most purposes. In addition, to draw solar radiation maps the number of points on the maps (real sites) that it is necessary to work with makes this problem difficult to solve. Nevertheless, with the application of the methodology proposed in this paper, this problem has been solved and solar radiation maps have been obtained for a small region of Spain: Jaén province, a southern province of Spain between parallels 38°25′ N and 37°25′ N, and meridians 4°10′ W and 2°10′ W, and for a larger region: Andalucía, the most southern region of Spain situated between parallels 38°40′ N and 36°00′ N, and meridians 7°30′ W and 1°40′ W.     

Evaluation and comparison of hourly solar radiation models

In this paper, an attempt has been made to develop a new model to evaluate the hourly solar radiation for composite climate of New Delhi. The comparison of new model for hourly solar radiation has been carried out by using various model proposed by others. The root mean square error (RMSE) and mean bias error (MBE) have been used to compare the accuracy of new and others model. The results show that the ASHRAE and new proposed model estimate hourly solar radiation better for composite climate of New Delhi in comparison to other models. Hourly solar radiation estimated by constants obtained by new model (modified ASHRAE model) for composite climate of India is fairly comparable with measured data. The percentage mean bias error with new constants for New Delhi was found as low as 0.15 and 0% for hourly beam and diffuse radiation, respectively. There is a 1.9–8.5% RMSE between observed and predicted values of beam radiation using new constants for clear days. The statistical analysis has been used for the present study. Copyright © 2008 John Wiley & Sons, Ltd.     

Some comments on time variation in solar radiation over Baghdad, Iraq

In the present work an attempt was made to study and examine some aspects of radiation climatology which are important in solar energy utilization. The yearly cumulative global radiation for Baghdad is 216 MJ/m² per year, while the annual total of daily diffuse radiation at Baghdad is about 70.82 MJ/m². The mean monthly values of clearness index K_T present a maximum of 65.9% in August and a minimum value of 48.4% in January. The annual mean of daily global radiation and its spectral OG1, RG2 and RG8 at Baghdad is about, 18.03, 13.53, 10.86 and 9.36 MJ/m², respectively. Over the year, the highest UV radiation were received during June and July (243 Wh/m²) and the lowest in December (79 Wh/m²). Furthermore, UV radiation constituted on average 3.25% of global radiation.     

Re-examination of ASHRAE insolation models with reference to Indian locations

Recently, the Indian Meteorological Department has made available measured horizontal global and diffuse radiation data for cloudless days for many Indian locations. A study is undertaken to re-examine the normal incident and diffuse radiation models suggested by ASHRAE using data for seven locations. Both models were found to be valid, but the diffuse radiation model needs refinement. The computed values of A, B and C were found to be different from those of ASHRAE. Comparison of computed insolation using these values of A, B and C with measured data shows good agreement. Calculation performed with ASHRAE values shows disagreement with measured data by some amount for global and by significant amounts for diffuse radiation.     

计及反射辐射的分布式光伏阵列建模研究

针对分布式光伏阵列传统建模方法不能考虑阵列自身安装特点及周边复杂太阳辐射环境,从而导致模型不准确的缺陷,文章提出了一种计及反射辐射的光伏阵列建模方法。利用气象站采集数据,通过研究建筑物立面对光伏阵列产生的反射辐射,建立了反射辐射模型。同时,根据太阳位置、建筑物以及光伏阵列相对位置关系,分析建筑物对光伏电站的遮挡影响,建立了复杂环境下光伏阵列辐射模型。以光伏组件的输出数学模型为基础,结合光伏阵列的安装方式,通过叠加法得到光伏阵列输出模型,并通过实验验证了模型精度。     

福建省太阳总辐射和地面辐射平衡的分布

首先利用福州市的辐射观测资料，建立计算太阳总辐射的经验公式，并计算福建省各市、县的太阳总辐射的年、月平均辐照度。然后利用地区代表站的地面反射率，求得福建省各月、年地面所吸收的太阳辐射能的分布。再利用地面温度、气温、水汽压和总云量，计算得出福建省各地的地面有效辐射的月、年平均辐照度。最后得出福建省各月、年地面辐射平衡的分布。     

On the generation of hourly shortwave radiation data on tilted surfaces

In this paper we describe a method for computing hourly values of global radiation on inclined planes at any desired location. Fundamental to the computations are a 10 year series of global radiation and temperature measurements from 64 weather stations in Switzerland. As a first step, the monthly mean values are interpolated to any desired location. Hourly values are then generated stochastically on the basis of the interpolated monthly values. Using additional models, the hourly values of horizontal global radiation are transposed to inclined surfaces. This strategy involves a number of newly developed models, of which those for interpolation, and inclusion of skyline profile in calculating radiation on inclined surfaces, are the most important. The individual models are combined in a single comprehensive procedure. This was briefly validated, showing that coupling the independent models leads to satisfactory results, and confirming the validity of the chosen approach. Although the methods and models were checked for Switzerland, they are based on components that have been tested over a wide range of geography.     

晴天地面太阳紫外总辐射的观测结果和统计计算方法

利用１９９０年至１９９１年２４个月北京地区的太阳分光辐射观测资料和常规气象观测资料，分析了晴天条件下地面太阳紫外总辐射的变化规律，给出了用于计算晴天条件下到达地面的太阳紫外总辐射的两种公式，并计算了因臭氧总量减少引起地面太阳紫外总辐射增加的百分率。