Biodiesel Production Facilities from Vegetable Oils and Animal Fats

Abstract

Biodiesel is a renewable fuel that can be produced from vegetable oils, animal fats, and used cooking oil including triglycerides. Biodiesel, an alternative biodegradable diesel fuel, is derived from triglycerides by transesterification with methanol and ethanol. Concerns about the depletion of diesel fuel reserves and the pollution caused by continuously increasing energy demands make biodiesel an attractive alternative motor fuel for compression ignition engines. There are four different ways of modifying vegetable oils and fats to use them as diesel fuel, such as pyrolysis (thermal cracking), dilution with hydrocarbons (blending), emulsification and transesterification. The most commonly used process is transesterification of vegetable oils and animal fats. The transesterification reaction is affected by molar ratio of glycerides to alcohol, catalysts, reaction temperature, reaction time and free fatty acids and water content of oils or fats. In the transesterification, free fatty acids and water always produce negative effects, since the presence of free fatty acids and water causes soap formation, consumes catalyst and reduces catalyst effectiveness, all of which result in a low conversion. Biodiesel has over double the price of diesel. The high price of biodiesel is in large part due to the high price of the feedstock.     

New Options for Conversion of Vegetable Oils to Alternative Fuels

Biodiesel from transesterification of vegetable oils is an excellent alternative fuel. There is, however, a need to develop a direct process for conversion of vegetable oils into gasoline-competitive biodiesel and other petroleum products. Methyl esters of vegetable oils have several outstanding advantages among other new-renewable and clean engine fuel alternatives. The purpose of the transesterification process is to lower the viscosity of vegetable oil. Compared to No. 2 diesel fuel, all of the vegetable oils are much more viscous, whereas methyl esters of vegetable oils are slightly more viscous. The methyl esters are more volatile than those of the vegetable oils. Conversion of vegetable oils to useful fuels involves the pyrolysis and catalytic cracking of the oils into lower molecular products. Pyrolysis produces more biogasoline than biodiesel fuel. Soap pyrolysis products of vegetable oils can be used as alternative diesel engine fuel. The soaps obtained from the vegetable oils can be pyrolyzed into hydrocarbon-rich products. Zinc chloride catalyst contributed greatly to high amounts of hydrocarbons in the liquid product. The yield of ZnCl ₂ catalytic conversion of the soybean oil reached the maximum 79.9% at 660 K.     

Experimental Investigation of Heat Transfer Characteristics and Cooling Performance of Mini‐ and Microheat Exchangers

This paper presents an experimental investigation of forced convection heat transfer in two heat sinks for electronic system cooling and investigated the comparisons of the thermal behavior of the mini‐ and microchannel heat exchangers. The hydraulic dimension of one of the heat sinks is 2 mm while that of the other is . Deionized water was used as the working fluid for studies conducted in both the heat exchangers. The effect of heat flux and volumetric flow rate (in laminar flow regime) on temperature and heat transfer coefficient is studied. Irrespective of the average heat transfer coefficient and the total thermal resistance, advantages and limitations of each device are analyzed and discussed in the light of experimental results. Furthermore, the results obtained from the experiments were in good agreement with those obtained from the design theory analyses.     

Characteristics of transient heat transfer during quenching of a vertical hot surface with a falling liquid film

An experimental study has been conducted to elucidate characteristics of transient heat transfer during quenching of a vertical hot surface with a falling liquid film. The experiment was done at atmospheric pressure for the following conditions: an initial surface temperature from 200 to 400^°C, a subcooling of 20– 80 K, average velocity of 0.52– 1.24 m/s, and the block material is copper and carbon steel. The surface temperature and heat flux are estimated from the measured temperatures in the block during the quench by a two‐dimensional inverse solution. It follows that as the position of wetting advances downward, the position at which the heat flux becomes a maximum also advances downward. The time at which the position of maximum heat flux begins to move is one of the most important parameters and can be predicted by a proposed correlation. In addition, it is revealed that the maximum heat flux for copper depends on the length to which it occurs from the leading edge. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(6): 345– 360, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20167     

无沸腾喷雾冷却中流量和喷头高度对换热性能的影响

采用薄膜电阻加热器进行了喷头进口压力,喷头类型,喷头高度对换热系数影响的实验研究。研究了冷却介质的质量流量对换热性能的影响,并测量了同一喷头在不同喷头高度下的换热系数大小。实验发现当喷雾面积近似等于实验用薄膜加热器面积时冷却能力达到最大。根据以上实验结果可以最优化喷雾冷却性能。     

AGTB叶型前缘气膜冷却效果的数值模拟研究

以AGTB叶型为对象,对文献中获取换热系数的两种计算方法进行了对比研究,结果表明维持主流和射流温度一致的等温法不能很好地反映气膜冷却流动中的传热现象,而主流和射流有温差的非等温法使得传热现象和流动现象都得到了很好的反映,且更接近实际物理问题.而后以实际发动机中的AGTB叶型为研究对象,将开槽气膜冷却孔结构应用于该叶片,...     

q∝△(T-1)的不可逆吸收式制冷系统的优化

以内可逆吸收式制冷循环模型为基础,建立一个不可逆吸收式制冷循环的模型,该模型的热传导规律为q∝△（T^-1）,包括低温热源到制冷空间的热漏及工质内部耗散,工质与外部热源间的有限热传导率的不可逆性,并用于导出制冷系数与制冷率的关系及在优质状态下的传热面积的分配关系。确定了在q∝△（T^-1）规律不可逆吸式制冷系统的主要参数的实际优选范围。     

工业炉炉体及烟气冷却技术分析

从能量利用，耗水量，安全性与经济性等多个方面对工业炉炉体冷地方式进行了分析与比较，指出了汽化冷却比水冷却更加节能降耗。并对加热炉与电炉烟气产邓过程－余热回收利用的两种形式进行了综合评价，从不同的角度肯定了各自的优点。     

太阳能制冷与供暖系统的设计与比较

根据上海的气候条件，以上海地区某写字楼为对象，提出4种太阳能驱动的溴化锂吸收式与电动蒸汽压缩式热泵联合制冷与供暖系统。这4种系统分别由热管式真空管集热器或抛物面槽形聚光集热器，单效或双效溴化锂吸收式制冷机，以及风冷热泵或水源热泵构成。分析比较这4种系统的节能型和经济性的结果表明，采用抛物面槽形聚光集热器＋双效溴化锂吸收式制冷机＋风冷热泵组成的系统，同时具备较好的节能性与经济性，一次能源利用率可降低约50％。     

吸附式制冷单元管的设计与性能研究

基于吸附制冷的理念,设计并研究吸附式制冷的核心部件——制冷单元管。工质对选择13X型沸石分子筛-水,设计单元管外径30 mm,吸附端长600 mm,冷凝/蒸发端长360 mm,添加可膨胀石墨以强化性能。为得到单元管的实际性能,通过实验研究制冷单元管的循环周期、温度与压力变化,并改变实验条件研究环境对制冷单元管的影响。研究结果为系统设计及吸附式制冷单元管的进一步改进提供参考。     

定量分析凝汽器冷却水管结垢对机组经济性的影响

以热力学第一定律为基础,应用传热学原理,定量分析了凝汽器冷却水管结垢对凝汽器真空、机组功率以及机组热耗率的影响。研究成果对提高电厂机组运行的经济性有着重要的现实意义。     

Analysis of Heat Dissipation Performance between a Horizontal and Longitudinal Battery Pack Based on Forced Air Cooling

A battery pack is the main energy storage element, and directly affects the performance of an electric vehicle. Battery thermal management system research and its development for a modern electric vehicle is required. This paper selects the forced air cooling of battery pack as the research object, and uses simulation methods to research the heat dissipation performance with different structures of battery packs. The results indicate that according to the four types of transient state conditions, the rising temperature of both battery packs are significantly higher than the temperature difference, the maximum temperature rise and temperature difference of a horizontal battery pack are lower than a longitudinal battery pack. When an electric vehicle begins to decrease speed, the curves of temperature rising and temperature difference increase. This shows the internal heat is continuously rising, so even in a electric vehicle beginning to decrease speed, the fan must work. The reference basis for choosing battery pack type and an analysis of heat flow field characteristics, including fan run‐time control, are offered.     

微燃机冷热电联供系统性能的模拟研究

介绍了冷热电联供(CCHP)系统,以上海某示范性微燃机冷热电联供系统为研究对象,通过建立系统主要设备的数学模型,模拟分析了系统在不同环境温度下的性能和系统全年的运行工况。结果表明:微燃机冷热电联供系统的性能受环境温度的影响,系统过渡季节不运行时年平均能源综合利用率可达到70%以上。     

多参数影响下的气膜冷却特性及预测方法

气膜冷却是当代燃气轮机透平中重要的冷却手段,气膜冷却设计在透平设计中非常重要,而这就要求有快速、准确的气膜冷却预测方法。综述了国内外学者对不同孔型气膜冷却多参数影响机制的研究成果,比较了针对复杂气膜冷却系统的多种预测方法。发现经验公式法传统上应用广泛,但其精度受制于公式的适用范围;基于神经网络预测气膜冷却特性具有精度高、参数适用范围广的特点,采用CFD方法预测气膜冷却特性耗时较长,精度不高。结果表明神经网络法在工业应用上前景好,CFD法则需要对各向同性的湍流模型进行修正才能有效地开展气膜冷却机理研究。     

热处理钢板气雾冷却数学模型的开发与应用

针对某钢厂新建的热处理钢板气雾冷却装置,基于有限差分传热仿真计算,开发了相应的热处理钢板气雾冷却数学模型,其中详细考虑了钢板在冷却区内所经历的多种传热边界条件,包括水冲击传热、辊子接触传热、辐射传热和自然对流传热。通过现场的钢板表面温度测试工作表明,模型预测值与实际测试值之间的吻合情况良好,模型具有较高的仿真精度。应用该模型,按照一定的热处理工艺要求(主要指对出口温度和钢板表面/中心温降速率的控制),对气雾冷却区进行了冷却水表的理论设计(即各种厚度规格钢板所对应的冷却水流量),其设计结果已成功地应用于生产现场。     

风冷式冷渣器的测试及数值计算

对一种用于煤粉炉炉渣冷却的风冷式冷渣器进行了测试和数值计算。结果表明,此设备仅用空气冷却炉渣,有效利用了炉渣的余热,同时起到了节水的作用。在较低负荷下此设备冷却效果较好,高负荷下排渣温度较高,需要对设备进一步改进。数值计算与测试结构相符,说明数值计算对此类设备的设计和改进有一定指导意义。     

利用空气—土壤换热系统对温室降温除湿的分析

叙述了利用FLUENT6.3软件中的组分输运模型及多相流模型,对置于温室外的空气—土壤换热器（SHESS）进行三维动态模拟,采用典型时段的气象参数,分析换热器在输入环境空气时出口温度和含湿量随时间的变化趋势。指出,埋管深4m的换热器,最大可将输入空气的温度降低10.9℃,平均可降低9.2℃;最大减少含湿量8.14g/kg.干,平均可减少3.86g/kg.干,得出,空气—土壤换热器在北方地区夏季对温室具有明显的降温除湿效果的结论。     

空冷汽轮机低压排汽面积选择和变工况特性分析

根据我国西北某地区的典型环境温度对600MW直接空冷机组的低压末叶片进行优化,得到合理的低压排汽面积,同时根据末级叶片的设计特点对其变工况特性进行分析,从而对620mm末叶片的变工况性能有一定了解。分析结果表明,设计背压为15kPa.a时,末叶片采用620mm比较合适;采用专用强化叶型、控制反动度、控制攻角等方法的620mm末叶片可以有效保证空冷机组变工况安全高效运行。     

城市集中三联供系统的应用与研究现状

本文介绍了国内外城市集中三联供系统的应用概况,以及三联供系统的研究现状,并对今后的研究工作提出了建议。     

冷却水温变化对凝汽器传热性能影响的定量分析

采用数值计算方法对不同工作条件下凝汽器壳侧蒸汽的流动传热进行了模拟,通过与抽气器性能曲线的匹配,确定出凝汽器的工作点,进而定量分析了冷却水入口水温的变化对凝汽器背压的影响,计算结果表明,随着冷却水入口水温的升高,凝汽器背压的抬高幅度越来越明显。对两台不同机组凝汽器的计算表明,当冷却水温改变时两台不同机组的背压有着相似的变化规律。