• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    The Use of Hydrogen as a Fuel for Inland Waterway Units

    2014-07-31 22:28:34MorsyElGoharyYousriWelayaandAmrAbdelwahabSaad

    M. Morsy El Gohary, Yousri M. A. Welayaand Amr Abdelwahab Saad

    The Use of Hydrogen as a Fuel for Inland Waterway Units

    M. Morsy El Gohary1,2*, Yousri M. A. Welaya1and Amr Abdelwahab Saad1

    1. Department of Naval Architecture and Marine Engineering, Faculty of Engineering, Alexandria University, Egypt
    2. Marine Engineering Department, Faculty of Maritime Studies, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia

    Escalating apprehension about the harmful effects of widespread use of conventional fossil fuels in the marine field and in internal combustion engines in general, has led to a vast amount of efforts and the directing of large capital investment towards research and development of sustainable alternative energy sources. One of the most promising and abundant of these sources is hydrogen. Firstly, the use of current fossil fuels is discussed focusing on the emissions and economic sides to emphasize the need for a new, cleaner and renewable fuel with particular reference to hydrogen as a suitable possible alternative. Hydrogen properties, production and storage methods are then reviewed along with its suitability from the economical point of view. Finally, a cost analysis for the use of hydrogen in internal combustion engines is carried out to illustrate the benefits of its use as a replacement for diesel. The outcome of this cost analysis shows that 98% of the capital expenditure is consumed by the equipment, and 68.3% of the total cost of the equipment is spent on the solar photovoltaic cells. The hydrogen plant is classified as a large investment project because of its high initial cost which is about 1 billion US$; but this is justified because hydrogen is produced in a totally green way. When hydrogen is used as a fuel, no harmful emissions are obtained.

    sustainable alternative energy sources; hydrogen fuel; hydrogen properties; hydrogen production; hydrogen storage; cost analysis; inland waterway units

    1 Introduction1

    The need for renewable or green energy sources, in addition to improving the efficiency of using current fossil fuels in the marine field, makes it necessary to replace or improve current fossil-fueled engines (Welaya et al., 2011).

    Renewable energy sources such as solar, wind, biomass, and hydrogen can provide sustainable energy services, based on the use of routinely available indigenous resources. A transition to renewable based energy systems is looking increasingly likely as their costs decline while the price of oil and gas continues to fluctuate. Fossil fuel and renewable energy prices, and social and environmental costs are heading in an opposite direction and the economic and policy mechanisms needed to support the widespread dissemination and sustainable markets for renewable energy systems are rapidly evolving (Herzog et al., 1999).

    The introduction of new fuel types like hydrogen into the field of maritime transport is considered to be a challenge due to the severe environmental conditions the marine power plant has to work in. Therefore, any attempts to introduce a new technology in this field must be accompanied by sufficient studies and experimental data to provide the ship designers and operators with enough information about the new type of fuel used. The demand on energy production will increase due to the growing population and sea borne trade. The use of other alternative fuels should start to replace diesel oil on board ships. Hydrogen is considered a good candidate for such replacement (El Gohary, 2012).

    Using hydrogen as a fuel has been investigated in several publications such as those by Welaya et al. (2012), El Gohary and El Sherif (2006) and El Gohary (2009, 2013a, 2013b and 2013c), so the hydrogen engine or gas turbine is a dream that will come true in the near future particularly in the inland waterways transportation sector due to its short trip characteristic.

    2 Marine conventional fuels

    Marine conventional fuels are normally fossil fuels which contain large quantities of carbon and sulfur leading to increased harmful emissions along with nitrogen oxides resulting from the high temperature combustion of these hydrocarbon fuels. Over the last 50 years, while consumption of fossil fuels grew substantially, the world undertook a transition in its usage of fossil fuels, from solids (coal), to liquids (oil) to gases (natural gas). The performance characteristics of a solar powered unit were analyzed at different operating conditions. It was found that the efficiency of solar collectors was increased by increasing the angle of inclination, increasing the area of solar collectors and decreasing the water flow rate (Elshazly et al., 2010).

    2.1 Fossil fuel reserves

    Oil reserves are the estimated quantities of crude oil that are claimed to be recoverable under existing economic and operating conditions. Fig. 1 shows the crude oil reserves worldwide (Thakur and Rajput, 2011).

    The total oil consumption per year is believed to becloseto 88 billion barrels which is about 2% of the international reserves. Thus by simple calculations it is clear that the international reserves will be consumed in about 50 years which makes these days the most crucial time to start developing new energies to avoid energy shortages like the one seen in 1973.

    Fig. 1 World crude oil reserves locations

    Worldwide use of petroleum and other liquids is estimated to grow from 85.7 million barrels per day in 2008 to 97.6 million barrels per day in 2020 and 112.2 million barrels per day in 2035 (Gaul et al., 2011).

    Fuel prices are very dynamic and vary widely with the worldwide political situations and decisions made. As the middle-east is the major supplier of oil and gas, it is believed that the fuel prices will continue to rise and drop since no stable political solutions are apparent in the near future.

    Most of the growth in liquids consumption is in the transportation sector, where, in the absence of significant technological advances, liquid fuels continue to provide much of the energy consumed. Liquid fuels remain an important energy source for transportation and industrial sector processes. Despite rising fuel prices, use of liquids for transportation will increase by an average of 1.4 percent per year, or 46 percent overall from 2008 to 2035 (U.S. Energy Information Administration, 2011).

    2.2 Fossil fuel prices

    As shown in Fig. 2, three different scenarios are expected for the variation of fossil fuel prices between 2010 and 2030 (Harlan and Stonecypher, 2011).

    Fig. 2 Oil prices scenarios

    (1) Low: The approach taken is to attempt to establish a price floor for oil prices based on the lowest estimates.

    (2) Central: For the central scenario, a simple supply and demand framework was used with assumed levels for the price elasticity of demand.

    (3) High: similar to the central scenario but without an increase in the supply.

    2.3 Fossil fuel prices

    Fossil fuel emissions are considered to be the major problem of this type of fuel. The main pollutants are carbon mono- and dioxides CO and CO2, oxides of nitrogen NOx, hydrocarbons and sulfur dioxide SO2(El Gohary, 2012). The two main ways to minimize the emissions, especially with carbon, are carbon capture from fuels or using alternative sources of fuel such as natural gas (nonrenewable source of energy) or hydrogen (renewable source of energy).

    3 The hydrogen fuel

    Hydrogen as an element was discoveredby the British scientist Henry Cavendish in 1766, but the name “hydrogen”did not appear until 1788 when the French chemist Antoine Lavoisier gave it the name which was derived from the Greek words “hydro” and “genes” meaning “water” and“born of”.

    3.1 Hydrogen fuel properties

    As diesel took several years to be trusted in and to replace steam, hydrogen is predicted to take a period of time before it can be used in our industrial activities. But this period will be definitely shorter than that of diesel and other petroleum fuels since the technological advance is much faster now than it was a hundred years ago, and this is due to the advanced tools used to optimize the performance of powering problems.

    Hydrogen fuel contains the lowest calorific value CV (120 kJ/gm) when compared to other fuel sources, where diesel has a calorific value of 45 kJ/gm, which means that hydrogen can provide almost triple the calorific value of diesel (Pierce, 1998). The comparison between these types has led to the reason why both hydrogen and natural gas are considerd to be the best alternatives for being applied to onboard ships specially from the view point of economic and environmental issues (Banawan et al., 2010).

    Regarding hydrogen fuel properties, it was found that hydrogen will be theoretically safer in operation than other fuel sources because it is lighter and has less density than other fuels, as shown in Table 1. This leads to a lighter weight, and consequently more cargo can be carried (Germain et al., 2006).

    Using computers in the marine field and the integration of the electronics and diesel engines has resulted in many benefits:

    (1)Lower SFOC and better performance parameters thanks to the variable electronically controlled timing of fuelinjection and exhaust valves at any load.

    (2)Improved emission characteristics, with lower NOx and smokeless operation(El Gohary and Abdou, 2011).

    Table 1 Combustion properties of different fuels

    3.2 Hydrogen production and storage

    Hydrogen is not available as a conventional fossil fuel like natural gas, diesel oil or coal. Therefore, it must be produced either from renewable energy driven from electrolysis or from fuel processing of hydrocarbons (El Gohary, 2009; El Gohary and Saddiek, 2013).

    3.2.1 Hydrogen production methods

    There are several methods that can be used for hydrogen production as listed below, but since the aim is to produce hydrogen with the highest purity and the least amount of emissions, the water electrolysis method is selected as steam reforming (SR), partial oxidation reforming (POX), auto thermal reforming (ATR) and electrolysis.

    3.2.2 Hydrogen storage methods

    Hydrogen is an extremely difficult gas to store, which will limit its use until convenient and cost effective storage technologies can be developed and commercialized. Many technologies are available currently or are undergoing research for hydrogen storage as stated below, but until now none of these technologies have the ability to store as much hydrogen as the liquid storage method. Hydrogen is, therefore, suggested to be stored in insulated cryogenic tanks at -253oC as high pressure tanks, material based storage, metal hydride storage, chemical based storage and carbon based storage (Veldhuis et al., 2005).

    4 Proposed hydrogen production plant (Case study)

    The schematic diagram in Fig. 3 shows the proposed structure of the hydrogen plant. The solar panels along with the DC to DC converter provide a constant DC voltage supply to the electrolysis. A constant supply of pure water is fed to the electrolysis from a tank after passing the water through a distiller.

    Fig. 3 Schematic diagram for a proposed solar hydrogen plant

    It should be understood that 95 percent of this hydrogen is sold and transported to various places to be used as a fuel. The remaining 5 percent of the hydrogen produced is fed into a turbine which powers a 3-phase generator that generates AC voltage. This is converted back into DC voltage using an AC to DC converter. The DC voltage helps power the electrolysis.

    The main storage methods include compressed gas, liquefaction and metal hydride methods. All these methods and technologies are applicable nowadays but the basis of our choice will be which option is the most economical.

    4.1 Hydrogen storage for one day

    The effects of increasing the hydrogen production rate on the storing cost for the three main storing methods (compressed hydrogen, liquid hydrogen and metal hydride storage), is illustrated in Fig. 4 for an assumed storing period of one day.

    Fig. 4 Effects of the hydrogen production rate on storage costs for one day of storage

    4.2 Hydrogen storage for two days

    It is also required, as shown in Fig. 5, to illustrate the effect of increasing the hydrogen production rate on the storing cost of the three main hydrogen storing methods assuming that the storing period will be two days.

    The river Nile navigation route between Alexandria and Aswan is taken as a case study. This route can be divided into five main points (Alexandria, Damietta, Cairo, Assiut and Aswan) where all the legs have equal navigation periods of 36 to 40 hours at a sailing speed of 12 knots. This leads us to choose storage tanks that can store hydrogen for 2 days (48 hours).

    Fig. 5 Effects of the hydrogen production rate on storage costs for two days of storage

    Based on Fig. (5), and from an economical view point, the compressed gas method is considered the optimum storage method.

    The results of calculating the CapEx, OpEx and profitability of the hydrogen production plant are discussed below.

    5 Calculation of results

    5.1 Capital cost (CapEx)

    As shown in Table 2, the equipment represents about 98 percent of the project CapEx.

    Table 2 Equipment cost breakdown

    5.2 Operating cost (OpEx)

    The OpEx of the plant will be divided into fixed costs which consists of license and insurance, manpower and depreciation, and the variable costs which consists of maintenance and other costs.

    (1) Fixed cost items.

    License and insurance are assumed to be 5 percent of the project CapEx value, which will amount to $5 566 945. The plant manpower is assumed to be made up of 150 people with an average salary $1 000 each. This will make the total manpower salaries cost $1 800 000 and the depreciation of the plant is assumed to be a 15 year period. This will make the depreciation cost $74 225 928 per year.

    (2) Variable cost items.

    Maintenance of the plant is considered to be an effective factor in the variable cost calculations, as it represents 6.7 percent of the total OpEx. Other costs are added to cover the other variable cost items and are assumed to be 1 percent of the total OpEx.

    5.3 Hydrogen plant profitability

    It is clear from the above calculations that the profitability degree of this project will depend mainly on the selling price of hydrogen in a direct proportional relation. However, this price should always be compared with the selling price of diesel as it is the main competitor of hydrogen.

    Fig. 6 Relationship between IRR, NPV and the selling price

    In Fig. 6 the relationship between IRR, NPV and the selling price is illustrated for the proposed hydrogen plant. As the selling price increases, both the IRR and NPVincrease. When the selling price becomes $1 000/t, the IRR becomes 51 percent which is acceptable from the financial point of view.

    6 Using hydrogen fuel in marine engines

    Using hydrogen as a fuel will directly affect the cost/h and the cost/trip, as all engine fuel consumption will decrease by 35 percent. Hydrogen consumption will be examined in two marine engines and two marine generators, installed on two Nile barges currently in service.

    (1) Doosan marine engine L126TIH.

    (2) Volvo marine engine D16.

    (3) Volvo marine generator D12.

    (4) Volvo marine generator D5.

    Figs.7-8 illustrate the effects of using hydrogen as a fuel on both cost/hr and cost/trip, for four different selling prices, on the selected engines and generators.

    (1) Case 1: $500, selling price/tonne.

    (2) Case 2: $750, selling price/tonne.

    (3) Case 3: $1 000, selling price/tonne.

    (4) Case 4: $1 250, selling price/tonne.

    Fig.7 Cost/hour in US$ for the selected engines

    Fig. 8 Cost/trip in US$ for the selected engines

    7 Conclusions

    The hydrogen production plant is classified as a large investment project due to its high initial cost; but this high cost is justified because hydrogen is produced in a totally green way.

    The massive increase in energy demand plus the limited available sources of energy and the stringent emissions measures forced by international regulations, will accelerate the search for alternative sources of energy, and hydrogen is expected to play an important role in the future.

    In order to use hydrogen as an alternative fuel for marine engines, a cost analysis of hydrogen production was carried out. The outcome of the current study showed that 98 percent of the capital expenditure was consumed by the equipment, and 68.3 percent of the equipment’s total cost was spent on the solar photovoltaic cells.

    The profitability of the hydrogen plant is totally dependent on the selling price of hydrogen. Since diesel is well subsidized by the Egyptian government, it is a very hard competitor for any other fuel, especially hydrogen. In order for hydrogen to replace diesel as the mass fuel, it is necessary for hydrogen to provide the same conveniences offered by diesel such as reasonable running costs and long range consumption on a single tank. Until the technology to achieve this is developed, diesel will continue to dominate the fuel market.

    8 Recommendation for the future

    The Egyptian government needs to support the implementation of using hydrogen as a fuel through a firm commitment to sell diesel at its international price to the industrial and commercial sectors and keep the subsidization for those who need it. This will guarantee a fare competition between hydrogen and diesel fuels.

    Abbreviations

    AC Alternate current

    DC Direct current

    CO Carbon monoxide

    CO2Carbon dioxide

    NOX Nitrogen oxides

    SO2Sulfur dioxide SFC

    SFC Specific fuel consumption (g/kW.hr)

    SR Steam reforming

    POX Partial oxidation reforming

    ATR Auto thermal reforming

    CapEx Capital cost

    OpEx Operating cost

    IRR Internal rate of return

    NPV Net present value

    Banawan AA, El Gohary MM, Sadek IS (2010). Environmental and economical benefits of changing from marine diesel oil to natural-gas fuel for short-voyage high-power passenger ships. Journal of Engineering for the Mari-time Environment, 224(2), 103-113.

    El Gohary MM, Saddiek I (2013). Utilization of alternative marine fuels for gas turbine power plant onboard ships. International Journal of Naval Architecture and Ocean Engineering, 5(1), 21-32.

    El Gohary MM (2013a). Overview of past, present and future marine power plants. Journal of Marine Science and Application, 12(2), 219-227.

    El Gohary MM (2013b). Economical analysis of combined fuel cell generators and absorption chillers. Alexandria Engineering Journal, 52(1), 151-158.

    El Gohary MM (2013c). Environmental analysis of present and future fuels in 2D simple model marine gas tubines. International Journal of Naval Architecture and Ocean Engineering, 5(4), 559-568.

    El Gohary MM (2009). Design of marine hydrogen internal combustion engine. Alexandria Engineering Journal, 48(1), 57-65.

    El Gohary MM (2012). The future of natural gas as a fuel in marine gas turbine for LNG carriers. Journal of Engineering for the Maritime Environment, 226(4), 371-377.

    El Gohary, MM, Abdou KM (2011). Computer based selection and performance analysis of marine diesel engine. Alexandria Engineering Journal, 50(1), 1-11

    El Gohary M, El Sherif H (2006). Future of hydrogen as green energy in marine applications. 9th World Renewable Energy Congress, Florence, Italy, 360-366.

    Elshazly AH, El Gohary MM, Ossman ME (2010). Performance characteristics of a solar humidification dehumidification unit using packed bed of screens as the humidifier. Desalination and Water Treatment, 16(1-3), 17-28.

    Germain J, Hradil J, Fréchet JM, Svec F (2006). High surface area nanoporous polymers for reversible hydrogen storage. Chemistry of Materials, 18(18), 4430-4435.

    Gaul D, Geagla A, Lindstrom P, Mayne L, McLeod B, Smith CL, Wells P, Yucel EM (2011). Monthly energy review 2011. US Energy Information Administration, US Department of Energy, Washington, DC, USA, Report No. 0484.

    Harlan B, Stonecypher L (2011). Concentrating solar power commercial. U.S Department of Energy, California, United States, Report no. 110-140.

    Herzog AV, Lipman TE, Kammen DM (1999). Renewable energy sources. University of California, Berkeley, USA.

    Pierce C, Adams KR, Stewart JD (1998). Determining the fuel constituents of ancient hearth ash via ICP-AES analysis. Journal of Archaeological Science, 25(6), 493-503.

    Thakur NK, Rajput S (2011). World’s oil and natural gas scenario. Springer-Verlag, Berlin/Heidelberg, 29-47.

    U.S. Energy Information Administration (2011). International energy outlook 2011. U.S. Department of Energy, Washinton, DC, USA.

    Veldhuis IJS, Richardson RN, Stone HBJ (2005). A hydrogen fuelled gas turbine powered high-speed container ship: A technical & economic investigation of the ship & associated port infrastructure. International Conference on Fast Sea Transportation. St. Ptersburg, Russia.

    Welaya YMA, El Gohary MM, Ammar NR (2011). A comparison between fuel cells and other alternatives for marine electric power generation. International Journal Naval Architecture and Ocean Engineering, 3(2), 141-149.

    Welaya, YMA, El Gohary MM, Ammar NR (2012). Steam and partial oxidation reforming options for hydrogen production from fossil fuels for PEM fuel cells. Alexandria engineering Journal, 51(2), 69-75.

    Author biographies

    M. Morsy Elgohary was born in 1969. He holds a PhD in diesel engines (2004) from Hannover University, Germany and he has written more than 30 academic papers. He is an associated professor at the marine engineering department at Alexandria University and works as a head of the Marine Engineering Department, King Abdulaziz University Saudi Arabia currently. His current research interests are green ship energy, marine diesel engines, marine alternative fuels and energy conservation onboard ships.

    Yousri M. A. Welaya is an emeritus professor at the Department of Naval Architecture and Marine Engineering, Alexandria University. Current research work includes the dynamic behavior of damaged semi-submersibles, environmental loading on offshore structures and energy management options in marine power plants.

    Amr Abdelwahab Saad holds a masters degree (2013) from the Faculty of Engineering, Alexandria University. He is an engineer at a Nile floating hotels company. His current research interests include hydrogen fuel applications in the marine field, renewable energy and modern marine power plants.

    1671-9433(2014)02-0212-06

    date: 2013-09-22.

    Accepted date: 2013-10-12.

    *Corresponding author Email: prof.morsy@gmail.com

    ? Harbin Engineering University and Springer-Verlag Berlin Heidelberg 2014

    欧美日韩av久久| 免费久久久久久久精品成人欧美视频| 大陆偷拍与自拍| 你懂的网址亚洲精品在线观看| 免费观看在线日韩| 国产精品av久久久久免费| 免费女性裸体啪啪无遮挡网站| 免费大片黄手机在线观看| 在线天堂中文资源库| 久久精品国产亚洲av涩爱| 久久亚洲国产成人精品v| 成年人免费黄色播放视频| 国产成人精品福利久久| 亚洲,欧美,日韩| 男女无遮挡免费网站观看| 亚洲三级黄色毛片| 午夜福利,免费看| 久热这里只有精品99| 久久久a久久爽久久v久久| 国产精品麻豆人妻色哟哟久久| 在线观看一区二区三区激情| 国产一级毛片在线| 99久久人妻综合| 精品亚洲成a人片在线观看| 伊人久久大香线蕉亚洲五| 国产日韩欧美亚洲二区| 巨乳人妻的诱惑在线观看| 午夜福利一区二区在线看| 欧美老熟妇乱子伦牲交| 人人妻人人爽人人添夜夜欢视频| 久久精品国产亚洲av涩爱| 精品少妇黑人巨大在线播放| 老司机影院毛片| 一级毛片黄色毛片免费观看视频| 人成视频在线观看免费观看| 看非洲黑人一级黄片| 国产精品亚洲av一区麻豆 | 欧美日韩成人在线一区二区| 美女国产视频在线观看| 中国国产av一级| 国产一区二区 视频在线| 免费av中文字幕在线| 亚洲色图综合在线观看| av女优亚洲男人天堂| 18禁动态无遮挡网站| 女人被躁到高潮嗷嗷叫费观| 天堂俺去俺来也www色官网| 亚洲精品成人av观看孕妇| 热re99久久精品国产66热6| 亚洲国产欧美日韩在线播放| 久久久久久久大尺度免费视频| 久久人人97超碰香蕉20202| 国产精品久久久久久精品古装| 男人舔女人的私密视频| 欧美激情 高清一区二区三区| 九草在线视频观看| 满18在线观看网站| 最黄视频免费看| 国产国语露脸激情在线看| 亚洲国产欧美在线一区| 18禁裸乳无遮挡动漫免费视频| 国产精品人妻久久久影院| 精品少妇久久久久久888优播| 成人18禁高潮啪啪吃奶动态图| 最近中文字幕高清免费大全6| 久久影院123| 人人澡人人妻人| 9色porny在线观看| 最近手机中文字幕大全| 国产片特级美女逼逼视频| 中文乱码字字幕精品一区二区三区| 亚洲精品中文字幕在线视频| 亚洲国产成人一精品久久久| 久热久热在线精品观看| 香蕉精品网在线| 久久狼人影院| 最近中文字幕2019免费版| 久久99一区二区三区| 国产精品偷伦视频观看了| 亚洲av.av天堂| 欧美中文综合在线视频| 两个人看的免费小视频| av国产久精品久网站免费入址| 国产日韩欧美视频二区| 丝瓜视频免费看黄片| 国产一区有黄有色的免费视频| 国产一区有黄有色的免费视频| 欧美变态另类bdsm刘玥| 国产av码专区亚洲av| 精品国产一区二区久久| 国产免费视频播放在线视频| 丝袜脚勾引网站| 热re99久久精品国产66热6| 国产精品国产av在线观看| 精品酒店卫生间| 国产免费福利视频在线观看| 青草久久国产| 在线观看三级黄色| 9色porny在线观看| 欧美人与性动交α欧美软件| 亚洲欧美一区二区三区国产| 丝袜在线中文字幕| 亚洲人成网站在线观看播放| 亚洲在久久综合| 99国产综合亚洲精品| 精品福利永久在线观看| 日韩中字成人| 国产97色在线日韩免费| 国产成人av激情在线播放| 精品少妇一区二区三区视频日本电影 | 最近的中文字幕免费完整| 少妇熟女欧美另类| 成年av动漫网址| 精品国产一区二区三区四区第35| 国产成人午夜福利电影在线观看| 伦精品一区二区三区| 欧美日韩一区二区视频在线观看视频在线| 久久人妻熟女aⅴ| 美女脱内裤让男人舔精品视频| 亚洲一区二区三区欧美精品| 在线观看免费日韩欧美大片| 国产亚洲欧美精品永久| 在线观看免费高清a一片| 超碰97精品在线观看| 精品一区二区三卡| 捣出白浆h1v1| 黑人巨大精品欧美一区二区蜜桃| 日日爽夜夜爽网站| 色播在线永久视频| 午夜激情av网站| 国产成人欧美| 一个人免费看片子| 国产不卡av网站在线观看| 国产精品二区激情视频| 国产免费现黄频在线看| 天天操日日干夜夜撸| 亚洲av.av天堂| 国产高清国产精品国产三级| 高清不卡的av网站| 日本欧美国产在线视频| 狂野欧美激情性bbbbbb| 精品99又大又爽又粗少妇毛片| 午夜福利一区二区在线看| 中文字幕人妻丝袜制服| 久久久久视频综合| 国产免费视频播放在线视频| 精品一区二区三卡| 国产 一区精品| 午夜日韩欧美国产| 久久毛片免费看一区二区三区| 91aial.com中文字幕在线观看| 大片免费播放器 马上看| 午夜影院在线不卡| 香蕉国产在线看| 国产成人a∨麻豆精品| 波多野结衣av一区二区av| 亚洲av欧美aⅴ国产| 天美传媒精品一区二区| 亚洲第一av免费看| 一区在线观看完整版| 国语对白做爰xxxⅹ性视频网站| 新久久久久国产一级毛片| 人成视频在线观看免费观看| 人人妻人人添人人爽欧美一区卜| 久久国产精品男人的天堂亚洲| 视频在线观看一区二区三区| 好男人视频免费观看在线| 巨乳人妻的诱惑在线观看| 国产精品偷伦视频观看了| 男男h啪啪无遮挡| 男女无遮挡免费网站观看| 国产 一区精品| 一本久久精品| 国产精品二区激情视频| 18禁裸乳无遮挡动漫免费视频| 一二三四在线观看免费中文在| 精品人妻熟女毛片av久久网站| 99热网站在线观看| 热re99久久精品国产66热6| 99精国产麻豆久久婷婷| 伦理电影免费视频| 欧美成人午夜免费资源| 亚洲av欧美aⅴ国产| 91在线精品国自产拍蜜月| 男女午夜视频在线观看| 一区在线观看完整版| 2021少妇久久久久久久久久久| 国产精品不卡视频一区二区| 一本—道久久a久久精品蜜桃钙片| 国产精品免费视频内射| 99国产综合亚洲精品| 久久ye,这里只有精品| 天天躁夜夜躁狠狠躁躁| 国产极品天堂在线| 免费在线观看视频国产中文字幕亚洲 | av免费在线看不卡| 国产精品久久久久久精品古装| 狠狠婷婷综合久久久久久88av| 中文字幕最新亚洲高清| 精品一区二区三卡| 99热国产这里只有精品6| 最近手机中文字幕大全| 黄色配什么色好看| 在线观看国产h片| 高清在线视频一区二区三区| 香蕉国产在线看| 不卡av一区二区三区| 久久久久精品人妻al黑| 亚洲综合色网址| 美女视频免费永久观看网站| 伊人亚洲综合成人网| 国精品久久久久久国模美| 国产精品香港三级国产av潘金莲 | 久久人妻熟女aⅴ| 在线观看美女被高潮喷水网站| 国产欧美日韩一区二区三区在线| 亚洲av国产av综合av卡| av不卡在线播放| 欧美人与善性xxx| 亚洲成国产人片在线观看| 日韩中文字幕欧美一区二区 | 国产欧美亚洲国产| 久久影院123| 午夜福利视频在线观看免费| 欧美日韩一级在线毛片| 国产亚洲一区二区精品| 午夜福利在线观看免费完整高清在| 观看美女的网站| 在线观看人妻少妇| 亚洲欧洲国产日韩| 另类精品久久| 一级,二级,三级黄色视频| 久久午夜福利片| 国产又色又爽无遮挡免| 一边亲一边摸免费视频| 久久精品国产亚洲av天美| 电影成人av| 亚洲婷婷狠狠爱综合网| 一本一本久久a久久精品综合妖精 国产伦在线观看视频一区 | 麻豆乱淫一区二区| 亚洲精品aⅴ在线观看| 久久97久久精品| 日韩欧美一区视频在线观看| 一本—道久久a久久精品蜜桃钙片| 婷婷成人精品国产| 亚洲精品视频女| 亚洲欧美一区二区三区久久| 亚洲中文av在线| 免费av中文字幕在线| 男女午夜视频在线观看| 搡女人真爽免费视频火全软件| 一边摸一边做爽爽视频免费| 满18在线观看网站| 高清欧美精品videossex| 十八禁网站网址无遮挡| 亚洲国产精品一区三区| 日韩欧美一区视频在线观看| 又粗又硬又长又爽又黄的视频| 久久久久久久大尺度免费视频| 1024视频免费在线观看| 国产老妇伦熟女老妇高清| 国产免费现黄频在线看| 久久综合国产亚洲精品| 国产又色又爽无遮挡免| 2018国产大陆天天弄谢| 久久精品国产亚洲av天美| 街头女战士在线观看网站| www日本在线高清视频| 90打野战视频偷拍视频| 国产精品女同一区二区软件| 亚洲欧美成人精品一区二区| 日韩不卡一区二区三区视频在线| 又黄又粗又硬又大视频| 美女中出高潮动态图| 少妇精品久久久久久久| 久久久久精品人妻al黑| 欧美激情高清一区二区三区 | 欧美bdsm另类| 亚洲国产欧美网| 狠狠精品人妻久久久久久综合| videosex国产| 亚洲欧美成人综合另类久久久| 亚洲精品av麻豆狂野| 精品亚洲乱码少妇综合久久| 精品人妻偷拍中文字幕| 伦理电影大哥的女人| 久久精品亚洲av国产电影网| 日本爱情动作片www.在线观看| 亚洲国产欧美日韩在线播放| 性高湖久久久久久久久免费观看| 久久久久久伊人网av| 99久久综合免费| 久久精品国产鲁丝片午夜精品| 久久亚洲国产成人精品v| 国产黄频视频在线观看| 校园人妻丝袜中文字幕| 在线免费观看不下载黄p国产| 久久精品aⅴ一区二区三区四区 | av片东京热男人的天堂| 超碰成人久久| 午夜福利视频在线观看免费| 一级片免费观看大全| 男女国产视频网站| 亚洲精品在线美女| 黄色配什么色好看| 亚洲欧洲国产日韩| 老司机影院成人| 成年人免费黄色播放视频| 夫妻午夜视频| 成年av动漫网址| 熟女电影av网| 久久国产亚洲av麻豆专区| 伦精品一区二区三区| 精品一区在线观看国产| 亚洲第一av免费看| 又粗又硬又长又爽又黄的视频| videos熟女内射| 国产麻豆69| 狠狠精品人妻久久久久久综合| 日本av免费视频播放| 欧美成人午夜精品| 母亲3免费完整高清在线观看 | 久久久国产精品麻豆| 欧美日韩视频高清一区二区三区二| 久久久精品免费免费高清| 国产成人精品婷婷| 久久婷婷青草| 午夜久久久在线观看| 国产色婷婷99| 中文精品一卡2卡3卡4更新| 日本91视频免费播放| 人人妻人人澡人人看| 婷婷成人精品国产| 99香蕉大伊视频| 久久精品久久久久久久性| 一级,二级,三级黄色视频| 美女国产高潮福利片在线看| 男女下面插进去视频免费观看| 99久久精品国产国产毛片| 波野结衣二区三区在线| 一级毛片我不卡| 久久久国产精品麻豆| 久久 成人 亚洲| 欧美日本中文国产一区发布| 国精品久久久久久国模美| 久久久久精品人妻al黑| 黄色毛片三级朝国网站| 亚洲中文av在线| 少妇的逼水好多| 免费久久久久久久精品成人欧美视频| 日韩欧美一区视频在线观看| 国产视频首页在线观看| 1024香蕉在线观看| 国产成人av激情在线播放| 黄片小视频在线播放| 精品一区在线观看国产| 亚洲,欧美精品.| 亚洲精品国产色婷婷电影| 久久这里有精品视频免费| 国产精品免费大片| 国产成人午夜福利电影在线观看| 久久人人爽av亚洲精品天堂| 精品人妻熟女毛片av久久网站| 黄色怎么调成土黄色| 一区二区日韩欧美中文字幕| 亚洲国产av影院在线观看| 国产亚洲一区二区精品| 捣出白浆h1v1| 久久久国产欧美日韩av| 黄频高清免费视频| 啦啦啦中文免费视频观看日本| 日韩制服丝袜自拍偷拍| 日本色播在线视频| 欧美日韩精品网址| 欧美最新免费一区二区三区| 制服人妻中文乱码| 男女午夜视频在线观看| 亚洲精品日韩在线中文字幕| 亚洲欧美一区二区三区久久| 国产成人一区二区在线| 日韩一卡2卡3卡4卡2021年| av女优亚洲男人天堂| 黄色配什么色好看| 有码 亚洲区| 如何舔出高潮| 久久女婷五月综合色啪小说| 搡老乐熟女国产| videos熟女内射| 大香蕉久久成人网| 男男h啪啪无遮挡| 巨乳人妻的诱惑在线观看| 久久久亚洲精品成人影院| 丰满迷人的少妇在线观看| 飞空精品影院首页| 99国产综合亚洲精品| 色视频在线一区二区三区| 亚洲国产毛片av蜜桃av| 少妇被粗大猛烈的视频| 国产精品久久久久久精品电影小说| 十八禁网站网址无遮挡| 久久久久国产一级毛片高清牌| 免费看av在线观看网站| 中文字幕另类日韩欧美亚洲嫩草| 中国国产av一级| av在线老鸭窝| 久久久久精品久久久久真实原创| 最近2019中文字幕mv第一页| 国产av码专区亚洲av| 亚洲 欧美一区二区三区| 日韩欧美一区视频在线观看| 七月丁香在线播放| 亚洲av综合色区一区| 亚洲激情五月婷婷啪啪| 国产精品嫩草影院av在线观看| 免费高清在线观看日韩| 啦啦啦在线免费观看视频4| 亚洲精品一二三| 黑人猛操日本美女一级片| 国产亚洲av片在线观看秒播厂| av免费在线看不卡| 精品一品国产午夜福利视频| 国产精品一区二区在线不卡| www.av在线官网国产| 午夜福利视频精品| 叶爱在线成人免费视频播放| 亚洲国产色片| 91国产中文字幕| 亚洲国产成人一精品久久久| 国产精品亚洲av一区麻豆 | 亚洲欧美成人精品一区二区| 91在线精品国自产拍蜜月| 国产成人精品在线电影| 精品少妇内射三级| 高清视频免费观看一区二区| 久久狼人影院| 韩国高清视频一区二区三区| 国产成人精品无人区| 咕卡用的链子| 黄色配什么色好看| 亚洲情色 制服丝袜| 少妇被粗大的猛进出69影院| 高清av免费在线| 一个人免费看片子| 国产熟女午夜一区二区三区| 精品少妇一区二区三区视频日本电影 | 亚洲精品国产av成人精品| 中文字幕亚洲精品专区| 伊人亚洲综合成人网| 日日摸夜夜添夜夜爱| 大香蕉久久网| 青青草视频在线视频观看| 亚洲视频免费观看视频| av国产精品久久久久影院| 成人免费观看视频高清| 我要看黄色一级片免费的| 天天躁夜夜躁狠狠久久av| 激情视频va一区二区三区| 国产国语露脸激情在线看| 天天躁狠狠躁夜夜躁狠狠躁| 欧美日韩亚洲国产一区二区在线观看 | 亚洲欧洲日产国产| 十八禁网站网址无遮挡| 一级毛片我不卡| 精品福利永久在线观看| 国产一级毛片在线| 十分钟在线观看高清视频www| 午夜免费观看性视频| 国产成人av激情在线播放| 午夜福利在线免费观看网站| 人妻少妇偷人精品九色| 欧美精品一区二区免费开放| 99久久人妻综合| 久久久国产一区二区| 欧美黄色片欧美黄色片| 嫩草影院入口| 伊人亚洲综合成人网| 超碰97精品在线观看| 精品一区二区免费观看| 两个人免费观看高清视频| 黄色怎么调成土黄色| 欧美日韩综合久久久久久| 人妻少妇偷人精品九色| 婷婷色综合大香蕉| 一个人免费看片子| 久久影院123| 成人亚洲精品一区在线观看| 女性被躁到高潮视频| 91国产中文字幕| 亚洲国产精品国产精品| 国产激情久久老熟女| 老汉色av国产亚洲站长工具| 性色avwww在线观看| 亚洲激情五月婷婷啪啪| 免费黄网站久久成人精品| 国产成人精品婷婷| 精品人妻熟女毛片av久久网站| 美国免费a级毛片| 久久久久久久久久久久大奶| 纯流量卡能插随身wifi吗| 18禁裸乳无遮挡动漫免费视频| 亚洲视频免费观看视频| 王馨瑶露胸无遮挡在线观看| 伊人亚洲综合成人网| 晚上一个人看的免费电影| 成年女人毛片免费观看观看9 | 国产精品国产av在线观看| 90打野战视频偷拍视频| av一本久久久久| 日韩欧美一区视频在线观看| 丰满乱子伦码专区| 午夜影院在线不卡| 日日撸夜夜添| 精品亚洲成国产av| 最近最新中文字幕免费大全7| 极品少妇高潮喷水抽搐| 久久精品久久久久久噜噜老黄| 亚洲图色成人| 99热网站在线观看| 午夜福利视频在线观看免费| 日韩三级伦理在线观看| 美女午夜性视频免费| 国产激情久久老熟女| 国产av一区二区精品久久| 中国国产av一级| 99国产精品免费福利视频| 91精品国产国语对白视频| 中文字幕另类日韩欧美亚洲嫩草| 女性被躁到高潮视频| 亚洲激情五月婷婷啪啪| 国产乱来视频区| 黄片无遮挡物在线观看| 纯流量卡能插随身wifi吗| 久久这里只有精品19| 波多野结衣av一区二区av| 午夜激情久久久久久久| 亚洲人成网站在线观看播放| 亚洲情色 制服丝袜| 不卡视频在线观看欧美| 久久国产亚洲av麻豆专区| 欧美日韩综合久久久久久| 欧美 亚洲 国产 日韩一| 国产女主播在线喷水免费视频网站| 日韩 亚洲 欧美在线| 亚洲精品,欧美精品| 欧美成人精品欧美一级黄| 搡女人真爽免费视频火全软件| videos熟女内射| 又粗又硬又长又爽又黄的视频| 国产精品国产av在线观看| 国产综合精华液| 国产白丝娇喘喷水9色精品| 日韩欧美精品免费久久| 国产成人精品久久久久久| 久久久久国产精品人妻一区二区| 久久99蜜桃精品久久| 国产一级毛片在线| 又粗又硬又长又爽又黄的视频| 黄色一级大片看看| 丝袜脚勾引网站| 一区二区av电影网| a级片在线免费高清观看视频| 一区二区三区乱码不卡18| 欧美日韩成人在线一区二区| 久久久久久久亚洲中文字幕| 看免费av毛片| 精品人妻偷拍中文字幕| 亚洲国产精品国产精品| 亚洲情色 制服丝袜| 男女免费视频国产| 国产精品蜜桃在线观看| 欧美国产精品一级二级三级| 99国产综合亚洲精品| 国产无遮挡羞羞视频在线观看| 啦啦啦在线观看免费高清www| 精品酒店卫生间| 精品少妇一区二区三区视频日本电影 | 最近中文字幕2019免费版| 国产亚洲一区二区精品| 777米奇影视久久| av有码第一页| 少妇熟女欧美另类| 可以免费在线观看a视频的电影网站 | 色94色欧美一区二区| 三级国产精品片| 精品久久蜜臀av无| 免费大片黄手机在线观看| 欧美 亚洲 国产 日韩一| 18在线观看网站| 狠狠精品人妻久久久久久综合| 大码成人一级视频| 久久亚洲国产成人精品v| av卡一久久| 亚洲av日韩在线播放| 一区二区三区激情视频| 少妇人妻久久综合中文| 欧美97在线视频| 久久久久人妻精品一区果冻| 在线精品无人区一区二区三| 男男h啪啪无遮挡| 大话2 男鬼变身卡| 麻豆精品久久久久久蜜桃| 26uuu在线亚洲综合色| av在线老鸭窝| 青春草亚洲视频在线观看| 国产白丝娇喘喷水9色精品| 女性被躁到高潮视频| 在线观看免费日韩欧美大片| 伊人久久国产一区二区| 男女边吃奶边做爰视频| 久久精品国产亚洲av涩爱| 咕卡用的链子| 一级,二级,三级黄色视频| 三上悠亚av全集在线观看| 自拍欧美九色日韩亚洲蝌蚪91| 国产伦理片在线播放av一区|