高温气体辐射特性计算模型

高温气体辐射特性的准确计算在燃烧、红外探测等工程应用中有重要意义。对国内外气体辐射特性研究现状进行了介绍,分析了3类气体辐射特性计算方法的基本原理和主要特征,着重介绍了新发展起来的全光谱k分布(FSK)模型。列表归纳总结了各辐射特性计算模型的适用条件、计算精度及计算速度。计算了平行平板间水蒸气和二氧化碳混合气体层壁面热流,给出了各模型计算结果与逐线计算间的相对误差比较图。对不同情况下气体辐射特性计算方法的选择提出了建议,针对现有模型的缺陷对今后的研究方向作了展望。     

宽带k分布模型与其他气体辐射特性计算模型精度比较

气体辐射特性计算模型的选择对于辐射热传递的计算至关重要。对采用宽带k分布模型和其它气体辐射特性计算模型计算的于两无限大平板间非等温气体辐射传递的精度进行了比较结果显示:宽带k分布模型与逐线计算结果吻合较好,比总体模型的计算精度高得多。计算结果说明:对于非等温介质,关联k假设在较大的光谱区间内相对有效,且能通过将单一气体的k分布吸收系数相加获得水蒸气和二氧化碳混合气体的k分布吸收系数的,该处理方法简单易行,宽带k分布模型很适合气体辐射换热问题的求解。     

余热锅炉辐射受热面辐射系数的影响因素

论述了余热锅炉内辐射传热的影响因素,计算得到了烟气入口温度、三原子气体含量、含尘量、饱和蒸汽压力、有效辐射层厚度、积灰厚度等因素对辐射系数C′的影响关系,以此指导余热锅炉的设计。     

灰气体加权和模型的发展综述

气体辐射特性的准确计算对辐射换热过程的分析有重要影响。国内外学者对气体辐射特性模型中的灰气体加权和模型(WSGG)和与k分布法相关的模型进行了大量研究,本文对WSGG模型发展现状以及存在的问题进行了总结分析。针对WSGG模型具有效率高、精度低的特点,而k分布法精度高可以弥补其不足,认为可以将k分布法引入WSGG模型,建立一种快速准确且能与任意辐射传递方程求解方法兼容的气体辐射特性计算模型。     

气体污染物的红外辐射特性

基于 HITRAN Database给出的谱线参数 ,利用逐线计算方法计算了 SO2 ,CO,N2 O,NO,NO2等气体污染物的红外辐射特性 ,给出了总压为 1atm、温度为 2 96K、波数范围 4 0 0～ 80 0 0内气体污染物的吸收系数分布图。为便于比较 ,同时给出了水蒸汽和二氧化碳气体的吸收系数分布图。     

SO_2气体的辐射特性

基于ＨＩＴＲＡＮＤａｔａｂａｓｅ给出的谱线参数,提出了ＳＯ２气体光谱辐射特性的逐线积分计算方法。利用逐线计算方法计算了ＳＯ２气体的光谱辐射特性,给出了总压０１ＭＰａ、温度２００Ｋ～２０００Ｋ、压力行程０００００６～１ｍ·ＭＰａ参数范围内ＳＯ２气体的黑度计算图     

高温状态下温度场的计算

本文将湍流流场计算的ＳＩＭＰＬＥ算法与辐射传热的热流法计算结合在一起，联立求解了高温状态下炉内的流动及温度分布情况，得到了气体流动的速度场以及由传导，对流和辐射共同作用的温度分布情况。通过计算比较。从定量的角度验证了高温状态下的辐射传热的主导作用。     

地球变暖动态特性及滞后现象分析

工业生产过程中排放的温室气体会造成全球变暖现象,但全球变暖与工业排放在时间上具有一定的滞后效应.通过分析地球、大气、太阳三者热平衡体系的辐射换热,建立了地球及其大气的动态数学模型;利用此模型考察了造成地球温度变化的主要原因和变暖滞后的现象.结果表明:工业温室气体的过度排放会造成大气对地球辐射的吸收系数提高,导致地球温度升高;同时,太阳辐射能量增加,地球和大气对太阳辐射吸收增加,导致地球温度升高.结合近年来人为因素造成的地球温度升高现象进行了定量热分析,预测了温室气体CO2体积分数线性增加条件下的地球温度走势.     

用改进的离散坐标法计算炉内三维辐射传热

采用离散坐标法进行炉内三维辐射传热的计算,首先在正方体炉膛内验证了该法的精确性,计算结果与区域法进行比较,表明离散坐标法算法可靠,计算工作量小,适合于炉内辐射传热的计算。然后针对长方体炉膛计算了吸收－发射－散射介质的传热问题,表明传统的离散坐标法不适合计算具有复杂相函数曲线的辐射传热问题,因此采用改进的离散坐标法,并得到了合理的结果。最后,对于煤粉燃烧炉膛将辐射传热问题和炉内流动、燃烧过程耦合起来进行计算,表明离散坐标法是一种很有工程应用价值的炉内辐射传热计算方法。     

三维湍流回流气相和煤粉燃烧辐射传热离散坐标模型和热流模型比较

针对空腔内纯三维辐射传热和大速差射流燃烧室内三维湍流回流气体燃烧和煤粉燃烧,对其中辐射传热分别采用离散坐标模型和热流模型进行了分析与比较。模拟结果表明,两种模型所得到的温度分布在趋势上类似,而在定量上有差别。对纯辐射传热模拟,与区域法的精确数据对比表明,离散坐标模型的结果更合理。对燃烧的模拟结果是,离散坐标模型所得的气体温度要高于热流模型的相应值,亦即热流法低估了气体温度和壁面热流。二者所得到的速     

附加绝热反射盖板式温室型太阳能干燥器的研究

提出了附加绝热反射盖板式温室型太阳能干燥器的新结构，建立了太阳反射辐射计算模型，给出了干燥器性能测试结果。     

Three-dimensional CFD analysis for simulating the greenhouse effect in solar chimney power plants using a two-band radiation model

The greenhouse effect in the solar collector has a fundamental role to produce the upward buoyancy force in solar chimney power plant systems. This study underlines the importance of the greenhouse effect on the buoyancy-driven flow and heat transfer characteristics through the system. For this purpose, a three-dimensional unsteady model with the RNG k–ε turbulence closure was developed, using computational fluid dynamics techniques. In this model, to solve the radiative transfer equation the discrete ordinates (DO) radiation model was implemented, using a two-band radiation model. To simulate radiation effects from the sun's rays, the solar ray tracing algorithm was coupled to the calculation via a source term in the energy equation. Simulations were carried out for a system with the geometry parameters of the Manzanares power plant. The effects of the solar insolation and pressure drop across the turbine on the flow and heat transfer of the system were considered. Based on the numerical results, temperature profile of the ground surface, thermal collector efficiency and power output were calculated and the results were validated by comparing with experimental data of this prototype power plant. Furthermore, enthalpy rise through the collector and energy loss from the chimney outlet between 1-band and two-band radiation model were compared. The analysis showed that simulating the greenhouse effect has an important role to accurately predict the characteristics of the flow and heat transfer in solar chimney power plant systems.     

垂直面太阳散射辐射计算方法研究

建筑设计必须考虑太阳辐射在建筑立面上的热作用,但气象台站仅观测水平面辐射数据,垂直面上的太阳辐射资料稀缺。为提出一种依据水平面辐射观测数据来计算垂直面散射辐射的方法,该文研究并建立辐射观测站,并进行长期辐射观测,积累了一定量的辐射数据。通过对垂直面上散射辐射主要影响因素的分析,提出基于晴空指数Kt和直射辐射与垂直面法线方向夹角φ的垂直面散射辐射计算方法。利用观测数据确定公式中的计算系数,并将该文研究提出的计算方法与国内外的5种太阳散射辐射计算模型进行比较分析。结果表明:1)该文提出的计算方法所需计算参数仅依据国内常规辐射观测数据即可。2)该方法能够实现对不同朝向垂直面散射辐射的计算。3)与国内外常用计算模型相比,该方法在不同天空晴朗度、不同朝向上整体精度更高。研究认为该文方法与国内气象部门的辐射观测数据相匹配,所需计算参数少、精度高、简单易用,可为建筑能耗计算和热环境分析提供新的垂直面散射辐射计算方法。     

高空飞艇薄膜太阳电池内辐射量计算研究

修正了任一方向的平面内太阳辐射计算模型,使之适用于编程计算各种倾角和方位角平面上的太阳辐射。在曲面上进行网格划分,生成若干个小平面,推导出平面法向量与倾角和方位角之间的关系式,逐个计算每个小平面上太阳辐射量,叠加后近似代替整个曲面上的太阳辐射量。运用此方法计算了高空飞艇的薄膜太阳电池上辐射量,并与此薄膜太阳电池在水平投影面内辐射量计算结果进行比较。结果表明,用水平投影面内辐射量代替薄膜太阳电池内辐射量有很大的偏差。因此,在高空飞艇能源系统性能详细分析阶段需要使用曲面内太阳辐射量计算模型,为随后的光电转换与能源系统计算提供准确的太阳辐射数据。     

Solar radiation of a greenhouse as a tool to its irrigation control

Because of the particular conditions existing in a greenhouse interior, the evapotranspiration of the crops is a function of the total solar radiation reaching the level of the evaporating surfaces. It is therefore possible to propose a method for estimating the water needs of the greenhouse crops in relation to the cover material, the developing stage of the crops and the total solar radiation outside the greenhouse. This method can be a useful guide in avoiding gross errors in greenhouse irrigation. Finally, some calculations made for the latitudes of the Mediterranean countries facilitate the use of the above method.     

蒙特卡洛法模拟集热器入射面太阳辐射的算法研究

复杂几何形式的太阳集热器辐射分析一般采用射线跟踪法,模拟的太阳辐射仅考虑直射辐射的入射方向,不适用于精确的辐射分析。通过把集热器入射面作为太阳辐射的入射起始面,以蒙特卡洛法为基础模拟太阳辐射。通过考虑直射辐射、散射辐射、太阳辐射的光谱分布以及太阳辐射32/张角等影响因素,研究了模拟射线的辐射位置、辐射方向、波长分布及辐射能量的相关算法,并进行了数值计算验证。以上研究综合考虑了影响太阳辐射的因素,准确模拟了进入集热器入射面的太阳辐射,为太阳集热器精确的辐射分析提供了基础。     

Solar energy utilization by a greenhouse: General relations

Most of solar radiation incident on a greenhouse is absorbed by greenhouse components (i.e., the cover, humid air, plants and soil) and the remaining portion is lost to outside the greenhouse. It is essential to know the absorbed and lost energy terms for any thermal analysis of greenhouses. Existing greenhouse thermal models use the radiative properties of the greenhouse components to directly determine the absorbed energy terms. However, these models neglect the lost energy term and neglect the effects of the multiple reflections of solar radiation between the greenhouse components.The present study describes the general relations for estimating the amounts of solar energy absorbed by the greenhouse components and lost to outside the greenhouse. The relations take into consideration the interrelations as well as the multiple reflections of solar radiation between these components. Thus, the greenhouse system was treated as a solar collector having an absorber plate (i.e., the greenhouse soil) and a cover system consisting of three semi-transparent parallel layers (i.e., the greenhouse cover, the humid air, and the plants). Superposition theory and ray tracing technique were used for the analysis. The presented relations were applied to an experimental plastic-covered greenhouse with a floor area of 34 m². The greenhouse, located in Riyadh, Saudi Arabia, was planted with tomatoes with a leaf area index (LAI) of 3.0 and was cooled by a wet pad and fan system. Results of the presented relations were accurate and more realistic comparing to results of other relations reported in the literatures. Absorption of solar radiation by water vapor in the greenhouse was negligible. The presented relations can estimate the absorbed and lost energy terms for a greenhouse precisely with a max possible error of +1.8% on each term if the LAI was less than 1.5. The error is significantly decreased to less than +0.7% if the LAI in the greenhouse is increased to 5.     

Thermal modelling of asymmetric overlap roof greenhouse with experimental validation

Global solar radiation availability model and thermal model for newly designed asymmetric overlap roof shape (AORS) greenhouse are presented and experimentally validated. Instantaneous solar radiation flux is utilised in a dynamic thermal model to ascertain the hourly plant and inside air temperature. The AORS is also compared with the previously developed two best greenhouse shapes. An experimental validation of both the models is carried out for the measured instantaneous solar radiation, plant and inside air temperature for a typical day in summer at Ludhiana (31°N and 77°E), Punjab, India. During the experimentation, a tomato crop was grown inside the greenhouse. From the results, it can be inferred that an east–west orientation AORS greenhouse should be preferred due to a lesser solar radiation capture in summer months. The predicted plant and air temperatures are in good agreement with the measured data having a root mean square error of 4.69 and 3.7, respectively.     

用Lowtran7进行分光辐射的计算研究（Ⅰ）—不同波段分光总日射比较份额的计算研究

利用Lowtran7所能提供的计算参数，分别计算了小于400nm(紫外辐射），400－700nm(光合有效辐射）和大于700nm（红外辐射）3个波段的总日射占全波段总日射的比例，并研究了不同太阳高度角、不同气溶胶、不同海拔高度以及大气中不同水汽和气溶胶含量对上述比例的影响。以前实测中发现的光合有效辐射所占比例有随地理纬度减少而略有增长的趋势得到了合理的论证；而理论模式的计算结果与我们的实测季节过完全一致，则证明所用方法是合理和可行的。