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1.
海洋温差发电有机朗肯循环工质选择 总被引：3，自引：0，他引：3
为了筛选出适宜于海洋温差热力发电有机朗肯循环的工质.采用PR状态方程计算11种低沸点有机流体工质在闭式海洋温差有机朗肯循环中的热力性能.结果表明,随着工质临界温度升高,循环热效率总体呈上升趋势.正丁烷具有较高的循环热效率,其蒸发压力较低、凝汽压力比较适中,比较适合用作海洋温差发电有机朗肯循环的工质. 相似文献
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海洋温差能是一种环境友好型、可持续利用的清洁能源,但是较低的海洋温差能发电系统效率阻碍了海洋温差能发电的商业化应用。提出一种新式循环,采用氨水混合工质,以及贫氨溶液回热和中间抽汽回热方式,实现对贫氨溶液及乏汽的热量二次回收利用。基于能量守恒方程和热力学定律,通过对循环中各设备部分建模分析,构建了新循环的热力模型,并与海洋温差能发电常用循环——朗肯循环进行性能对比分析,结果表明,新循环的热效率与净输出功相比朗肯循环均有显著提高,循环热效率最高可达4.565%,相较朗肯循环提高了25.9%。15 kW等级海洋温差能发电系统中,新循环的净输出功为7.038 kW,高于朗肯循环中的5.343 kW。新循环模型的建立及由此得到的各部分性能分析结果,可为海洋温差能商业化开发提供基础数据理论支撑。 相似文献
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《海洋技术学报》2018,(6)
在简述海洋温差能发电项目进展的基础上,文中综述了闭式海洋温差能循环系统用工质对热力循环效率影响的现状,以及朗肯循环和非共沸工质的Kalina循环等循环的研究和进展。目前,海洋温差能热力循环的热效率仍需要进一步提高,这一方面的研究主要集中在选择合适的热力循环工质,提高热力循环的发电温差,以及在热力循环中采取回热、中间抽气、贫氨溶液再热回收、引射器引射乏气等措施上。循环热效率也从朗肯循环的3%提高到了上原循环、国海循环等热力循环的5%以上。但目前对海洋温差能闭式循环的研究仍然偏向于理论,运用试验手段的试验研究相对较少,同时仍存在扩充非共沸工质种类等需要研究解决的问题。 相似文献
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为了解决北极海域海洋观测与通讯导航节点浮标的供电问题,提出利用北极海域冰面上冷空气与冰下海水之间的温差能转换为电能,为冰基浮标供电。根据北极温差的时空分布特性与冰基浮标的应用场景,提出了一种基于有机朗肯循环的冰基浮标温差能发电系统,并对其进行了建模与仿真分析。根据5 种工质的热力循环性能计算结果,确定R124 工质作为系统的循环工质。仿真结果表明：温差能发电系统在北极冬季两个月的总发电量为745 kWh,相当于3.72 t 能量密度为200 Wh/kg 的锂电池。因此,北极海域温差能转换发电系统能输出相当可观的功率与电能,显著提升冰基浮标的供能水平,提高其观测能力,延长其持续工作时间,减少破冰船对其的维护频率,从而打造冰下观测网络的关键节点,支撑北极冰下移动观测网络的构建。 相似文献
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本文研究了使用引射器来提高海洋温差能热力循环效率,热力循环采用氨-水混合工质,通过对使用引射器与没使用引射器的热力循环进行数值模拟和对比分析,探究不同工质浓度、透平进口压力和温、冷海水温度对循环净输出功和热力循环效率的影响。研究结果表明,使用引射器后循环净输出功和热力循环效率都得到了提高。随着氨工质浓度的增加,循环净输出功不断增加,热力循环效率先增大后减小;随着透平进口压力的变化,循环净输出功和热力循环效率均先增大后减小;循环净输出功和热力循环效率随温海水温度的升高而升高,随冷海水温度的升高而减小。 相似文献
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受专利保护和技术封锁的制约,海洋温差能发电关键技术及设备国产化问题亟待解决。以建造大型温差能发电平台为背景,通过建立朗肯循环OTEC发电系统仿真模型,对比分析R717、R13a和R600工质发电系统性能参数,探索装机规模对热效率和单位换热面积发电量的影响,为大型OTEC发电系统建造提供理论依据和技术支持。结果表明:R717系统在蒸发器和冷凝器热负荷以及工质方面均优于R134a和R600系统。相同装机功率下,R717工质的循环和系统热效率均最大。增加装机规模有助于提升系统的热效率和单位换热面积发电量。R717系统热效率最大,单位换热面积发电量在合适的范围内,是海洋温差发电系统较为理想的循环工质。 相似文献
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针对海洋温差能可利用温差小,利用效率低的问题,本文提出了一种采用非共沸混合工质的新型海洋温差能回热循环,并基于热力学定律对提出的热力循环进行热力学分析。选取蒸发压力、工质的质量分数作为变量,对提出的热力循环进行热力学分析研究。研究结果表明:以工质质量分数为变量时,循环热效率和系统净输出随蒸发压力的增加先增大后减小,系统热效率在工质质量分数为0.91时取得最大值5.28%,净输出功在浓度为0.96时取得最大值3.83 kW。以蒸发压力为变量时,循环热效率和系统净输出随工质质量分数的增大先增大后减小,系统热效率在蒸发压力为0.595 MPa时取得最大值5.26%,净输出功在压力为0.58 MPa时取得最大值3.57 kW。在相同运行控制参数下与Uehara循环、Yoon循环进行对比,提出的循环系统热效率最佳。提出的热力循环系统分析结果可对提高海洋温差能利用效率提供理论依据和参考。 相似文献
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水下井口的疲劳完整性是海洋油气田长期安全开采的前提。工业界往往采用贴应变片直接测量水下井口应变来计算弯矩和疲劳损伤,但水下井口应变片粘贴困难且不能长时间连续工作。采用对水下井口监测方法,基于隔水管—防喷器组—水下井口的运动和力学特性,考虑防喷器组惯性力矩建立系统耦合动力学方程,最终形成基于监测数据的水下井口循环弯矩计算方法。以南海某深水水下井口为例,建立隔水管—防喷器组—水下井口系统有限元模型并进行动态分析,提取隔水管底部张力、转角、防喷器组加速度及转角等参数,代入所建立的系统耦合动力学模型,得到水下井口弯矩与有限元计算结果吻合良好。研究表明只需通过在线监测获得所需的输入数据,无需监测水下井口应变即可获取水下井口循环弯矩。建立的系统耦合动力学模型可为水下井口疲劳完整性评估提供理论依据。 相似文献
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《Marine Policy》2017
This paper considers the practical application of exhaust gas waste heat recovery from the main engines of merchant ships. A water-based Rankine Cycle is used as a baseline and this is compared with five organic Rankine cycle systems using benzene, heptane, hexamethyldisiloxane, toluene and R245fa. The thermodynamic model of the waste heat recovery system is described. This is then applied in a case study utilising an Aframax tanker. The case study allows the comparison of the different waste heat recovery systems in more realistic scenarios. The efficiency of the different systems is compared as well as their potential to reduce CO2 emissions, ship impact, and economic viability are also discussed. The paper closes with consideration of the safety and regulatory issues associated with the use of organic fluids in the marine environment. 相似文献
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环境中的黑碳及其全球生物地球化学循环 总被引：20，自引：0，他引：20
黑碳是生物物质或化石燃料燃烧产生的难熔物质的连续统一体,从焦化植物残体、木炭到烟炱,以及石墨态黑碳,组成了黑碳的3种主要类型。它们的理化性质变化很大,焦化植物残体和木炭主要在低温下形成;烟炱是高温气态物质浓缩形成;而石墨态黑碳可能是岩石成因的。黑碳的分解主要是光化学分解和微生物降解。黑碳在全球碳循环中占有重要的位置。每年燃烧可产生50～270Tg黑碳,其中约10％来源于化石燃料燃烧。细小的黑碳在大气中被搬运到远离燃烧地的土壤或海洋中沉积下来,在沉积物有机碳中占有很大的比例。从地质历史时期看,它对于大气圈中CO2、O2的含量演化有重要影响。本文将黑碳的分析测量方法归纳为5类：显微镜法、光学法、热氧化法、化学方法和分子标志物法。同时指出当今黑碳研究中需要一种标准参考物,黑碳的测量应进一步细化到分子水平,并加强不同类型黑碳的全球生物地球化学循环过程研究。 相似文献
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Norio Ogura 《Marine Chemistry》1977,5(4-6)
The presence and nature of high molecular weight organic matter in seawater was critically reviewed and its biogeochemical cycle was discussed.Organic matter that passes through a filter of 0.5–1 μm pore size is called dissolved and that which does not pass through such a filter is defined as particulate. The size of colloidal particles ranges from 0.001 to 1 μm, and therefore, they are included in the dissolved fraction having high molecular weight.High molecular weight organic matter greater than 100,000 molecular weight was found in the seawater of Tokyo Bay. The values ranged from 0.1 to 1.5 mgC/l, and accounted for 8–45% of the total dissolved organic matter.Decomposition experiments on dissolved organic matter showed that macromolecular organic matter is refractory to bacterial attack. However, macromolecular organic materials tend to aggregate or adsorb on small particles to a sufficient size for precipitation. Organic aggregates thus formed sink to the bottom of the sea and bioelements included in them are removed from water column. High molecular weight organic materials are, therefore, considered to play an important role in transportation and distribution of matter in seawater.In order to elucidate the chemical and biological properties of macromolecular organic matter, concentration and isolation of this material are important, using methods such as adsorption on organic adsorbents or ultrafiltration. 相似文献
14.
To predict the cycle and propulsive performance, and further instruct the integral engine design, an ideal power cycle model for a two-phase underwater ramjet is established. Four performance parameters are defined to evaluate overall performance of the two-phase underwater ramjet systems: transmission efficiency, propulsive efficiency, overall efficiency and specific impulse. Then, a scaled-down experimental ramjet engine was tested in a direct-connect ground testing system to validate the present model, and the predictions with present model compare favorably with experimental results. Subsequently, the influences of cruise velocity, air/water mass ratio and cruising depth on the theoretical performance of the two-phase underwater ramjet are discussed. The results indicate that one of the most outstanding advantages of two-phase underwater ramjet is its high propulsive efficiency with the order of 50–95%. As a result, the overall efficiency magnitude are as high as 30% at cruise speed of 100 m/s. Furthermore, regarding rules of specific impulse vs cruise velocity under a certain air/water mass ratio, the occurrence of peak specific impulse of order 400 s is observed. 相似文献
15.
H. Searl Dunn 《Ocean Engineering》1977,4(1):23-39
The optimum performance of a simple Rankine cycle ocean thermal energy conversion plant is investigated analytically. It is shown that the ratio of maximum net power output to heat exchanger surface area varies as H(Δt − t0)2 where H describes the overall heat transfer properties of the evaporator and condenser, Δt is the temperature difference between the warm and cold sea water supplies, and t0 is a parameter depending primarily upon the pressure drops across the warm and cold sea water pumping systems. The model is relatively insensitive to the choice of working fluid, although ammonia is used as the illustrative example. 相似文献
16.
Abstract. Sediment characteristics determining macrofauna communities were investigated on the continental shelf of Crete. The sedimentary environment of the outer continental shelf of Crete is characterized by a silty substrate with significant decrease in chlorophyll a and organic carbon concentration with depth. Redox potential values indicated an ample supply of oxygen at all depths. Values of most production-related parameters TOC, chlorophyll a , ATP were found at the low end of the range reported from the literature even though the sampling stations were very close to the coastline. Organic carbon to chlorophyll ratios in the sediments indicated that most of the organic material is of phytoplankton origin; the quality of the organic material in the outer shelf, however, seems to be of lower bioavailability. 相似文献
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Traditionally autonomous underwater vehicles (AUVs) have been built with a torpedo-like shape. This common shaping is hydrodynamically suboptimal for those AUVs required to operate at snorkeling condition near the free surface. In this case, the wave resistance associated to the wavy deformation of the sea surface induced by the motion of the platform is an important component of the drag. This work has investigated the optimum hull shape of an underwater vehicle moving near the free surface. Specifically a first-order Rankine panel method has been implemented to compute the wave resistance on a body of revolution moving close to the free surface. A simulated annealing algorithm was then employed to search those set of parameters defining the hull shape that minimize the wave resistance. The optimization was constrained to keep constant the total volume of the vehicle. The total drag of scaled models of the torpedo-like and resulting optimum shapes was measured in the naval tank of the University of Trieste. Measurements showed a smaller resistance of the optimized shape in the range of the considered Froude numbers. 相似文献