热能与动力工程专业英语论文(强化对流传热)

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热能与动力工程专业英语

如果我们忽视动能和势能变化，净工作输出是 T 的图下的区域。由图 1-5(b) ；区 1-2-3-4-1由于第一定律需要 W=Q.The 传热工作的实质内容由一-2-3-b-一区，情况也是如此。
因此，朗肯循环的热效率 n 是
(1-2).
所需的输出，即除以能量输入 (购买能源)。
Obviously,the thermal efficiency can be improved by increasing the numerator or by decreasing the denominator. This can be done by increasing the pump outlet pressure P2, increasing the boiler outlet temperature T3 or decreasing the turbine outlet pressure P4.
显然，通过增加分子或通过减小分母可以提高热效率。这可以通过增加泵出口压力 P2，锅炉出口温度 T3 的增加或减少涡轮出口压力 P4。
1.1。8 再热循环
很明显与高锅炉压力或低凝汽器压力朗肯循环中运行时很难防止液滴在低压涡轮的部分形成。由于大多数金属不能经受温度约 600 以上，再热周期通常用于防止液体滴形成：蒸汽涡轮机穿越在一些中间的压力，从而提高 5 中的状态 T 的图图 1-6 的温度加热。然后的蒸汽涡轮低压条经过和进入状态 6 冷凝器。这控制或完全消除了在涡轮中的水分问题。通常，涡轮分为高压涡轮和低压涡轮。再热循环不会显著影响热效率的周期，但它不会导致重大的额外工作输出，表示在图中的地区 4-5-6-4' 的图 1-6-4。再热循环要求额外的设备，在重大的投资和使用这类设备必须是从事经济工作增加的输出的 justifled。如果再热不用于避免液滴形成，凝汽器压力必须相当高，这会导致较低循环效率。在这个意义上，再热显著增大时没有再热，但较高的凝汽器压力相比，周期循环效率。

热能与动力工程英文文献3

Combustion and NO x emission characteristics of a retroﬁtted down-ﬁred 660MW e utility boiler at different loadsZhengqi Li ⇑,Guangkui Liu,Qunyi Zhu,Zhichao Chen,Feng RenSchool of Energy Science and Engineering,Harbin Institute of Technology,92,West Dazhi Street,Harbin 150001,Chinaa r t i c l e i n f o Article history:Received 7September 2010Received in revised form 23November 2010Accepted 20January 2011Available online 12February 2011Keywords:Down-ﬁred boiler RetroﬁtCarbon content in ﬂy ash Thermal efﬁciencya b s t r a c tIndustrial experiments were performed for a retroﬁtted 660MW e full-scale down-ﬁred boiler.Measure-ments of ignition of the primary air/fuel mixture ﬂow,the gas temperature distribution of the furnace and the gas components in the furnace were conducted at loads of 660,550and 330MW e .With decreasing load,the gas temperature decreases and the ignition position of the primary coal/air ﬂow becomes farther along the axis of the fuel-rich pipe in the burner region under the arches.The furnace temperature also decreases with decreasing load,as does the difference between the temperatures in the burning region and the lower position of the burnout region.With decreasing load,the exhaust gas temperature decreases from 129.8°C to 114.3°C,while NO x emissions decrease from 2448to 1610mg/m 3.All three loads result in low carbon content in ﬂy ash and great boiler thermal efﬁciency higher than 92%.Com-pared with the case of 660MW e before retroﬁt,the exhaust gas temperature decreased from 136to 129.8°C,the carbon content in the ﬂy ash decreased from 9.55%to 2.43%and the boiler efﬁciency increased from 84.54%to 93.66%.Ó2011Elsevier Ltd.All rights reserved.1.IntroductionReserves of anthracite and lean coal are abundant and globally distributed.The use of anthracite and lean coal,which have low-volatility contents,presents difﬁculties in ignition and burnout.More and more research has been conducted around the world to solve these problems.At present,down-ﬁred combustion is widely applied in the power industry to consume low-volatility coals,and its main merit is that it achieves a high degree of burn-out by prolonging the residence time of pulverized-coal in the fur-nace.However,a practical down-ﬁred boiler operation still suffers from the problems of high carbon content in the ﬂy ash and poor ﬂame stabilization at low load without oil support ﬁring.Precise understanding of the behavior of char particles in pul-verized-coal combustion systems is critical in determining funda-mental processes that occur during heterogeneous bustion data obtained for full-scale equipment can give the combustion and NO x emission characteristics of real combustors,in particular the turbulent ﬂow of industrial coal ﬂames.As a re-sult,studies using full-scale equipment are highly desirable and a necessity.In the surrounds of wall-ﬁred boilers,measurements are made of the local mean concentrations of O 2,CO,CO 2,and NO x ,gas temperatures,and char burnout through several observ-ing doors in the utility boilers [1–5].Experiments have also been performed for tangentially ﬁred boilers [6–9].However,for down-ﬁred boilers adopting Foster Wheeler technology,there has only been the work of Li et al.,who measured the gas temperature,gas species concentrations in the furnace and carbon content in the ﬂy ash in a 300MW e boiler before and after retroﬁt [10–14].In the present study,in situ experiments were carried out for a 660MW e down-ﬁred pulverized-coal boiler after retroﬁt;this unit has the maximum capacity of any currently used worldwide [15].Measurements of ignition of the primary air/fuel mixture ﬂow,the gas temperature distribution of the furnace and the gas compo-nents in the furnace were made for this full-scale boiler at the rated,middle and half loads.The collected data were used to deter-mine the combustion and NO x emissions characteristics of the boi-ler at different loads.The results obtained from these experiments help solve similar problems and beneﬁt the design and operation of 600MW e and 1000MW e down-ﬁred boilers,and the data can be used to support theoretical and numerical calculations.2.The utility boilerThe investigated 660MW e boiler,having the largest capacity of any down-ﬁred boiler in the world,was made by Foster Wheeler (FW)Corp.Fig.1a is a schematic diagram of the furnace.Arches di-vide the furnace into two:the lower furnace below the arches and the upper furnace above the arches.Originally,36cyclone burners were arranged on the arches to produce a W-shaped ﬂame.The fuel-rich ﬂow streaming from the cyclone nozzle is near the0306-2619/$-see front matter Ó2011Elsevier Ltd.All rights reserved.doi:10.1016/j.apenergy.2011.01.048Corresponding author.Tel.:+8645186418854;fax:+8645186412528.E-mail address:green@ (Z.Li).water-cooled wall while the fuel-leanﬂow jetting from the fuel-lean pipe faces the furnace center.Under the arches,there are three tiers of secondary air denoted D,E and F,all of which are fed into the furnace horizontally.Details of the speciﬁc structure of this kind of boiler can be found in the literature[10–13].During practical operation,the boiler suffers from great resis-tance and serious abrasion of the cyclone and high carbon content inﬂy ash up to7–10%.Fuel-richﬂows form after the separation of the coal/airﬂows in the cyclones.The swirl intensities of fuel-rich ﬂows decrease at the exits under the effect of the adjustable vane, which provides great resistance.The fuel-richﬂows with residual swirl have little rigidity and abrade the nozzles of the cyclones [16].The secondary air under the arches enters the furnace horizon-tally and mixes prematurely with the fuel-richﬂow.This reduces the down-forwardﬂow and space for combustion and decreases the temperature in the lower furnace,which causes a series of problems including the delayed ignition of pulverized-coal and high carbon content in theﬂy ash[13,17].There is fuel-leanﬂow with low momentum and shallow penetration depth near the furnace center, which readily shortens theﬂame and reduces upﬂow to the burnout region quickly.This is also a reason for the poor burnout degree of coal particles and high carbon content in theﬂy ash[18].In2009,Li et al.retroﬁtted the combustion system with many items.Fig.1b is a schematic diagram of the retroﬁtted combustion system.A fuel louver concentrator replaced the original cyclone as it has much lower resistance than the cyclone.The fuel/airﬂowﬁrst passes through the louver concentrator and separates into fuel-rich ﬂow and fuel-leanﬂow.The fuel-richﬂow further divides into two and is injected into the furnace through the original primary air ducts facing the furnace center while the fuel-leanﬂow as vent air is injected into the furnace near the wall.The vent air ducts are con-trolled by valves.The horizontal secondary air is modiﬁed by the F-tier secondary air with an angle of declination of20°.In this retroﬁtted boiler,measurements were conducted at loads of660,550and330MW e with a constant opening of the vent air valves.3.Data acquisition methods and experimental conditionsThe formal in situ experiments were carried out in the2026tph down-ﬁred pulverized-coal boiler to investigate certain aspects of the combustion process and NO x formation in the furnace.During the experiments,soot blowing and sewer bleeding were not per-mitted.The coal used in the experiments was a mixture of anthra-cite and lean coal.Sample characteristics of coals before and after retroﬁt are presented in Table1.The following parameters were measured:(1)The gas temper-ature of the furnace was measured with a leucoscope through observing doors in the front,rear and side walls.The layout of the observing doors is shown in Fig.2.The measurement error is 50°C.(2)The gas temperature of the furnace was measured with a nickel chromium–nickel silicon thermocouple through observing doors1,2and3.As shown in Fig.2,observing door1is in the air-ﬂow zone of the tier D and E slots,observing door2is in the airﬂow zone of the tier F slots,and observing door3is above the arches. The end of the bare thermocouple was exposed in the furnace,so the temperature measured should be higher than the local gas temperature because of highﬂame radiation.However,because of radiation between the bare thermocouple and the water-cooled wall,and the close proximity of the two,the temperature mea-sured should be lower than the local gas temperature.The calcula-tions have indicated that in the region of highest temperature the ‘‘true’’temperature do not exceed the measured one by more than 8%[3,19].The thermocouples used were thoroughly checked be-fore leaving the factory,giving high conﬁdence in the temperature measurement results.To minimize errors due to ash deposition,Table1Characteristics of the coal used in the experiments before and after retroﬁt.Quantity Before retroﬁt After retroﬁtProximate analysis,wt.%(as received)Volatile10.729.29Ash30.8431.51Moisture0.54 2.48Fixed carbon57.9056.72Net heating value(kJ/kg)23,53121,250Ultimate analysis,wt.%(as received)Carbon59.7059.48Hydrogen 2.95 2.52Oxygen 3.81 3.53Nitrogen0.820.83Sulfur 1.340.79Z.Li et al./Applied Energy88(2011)2400–24062401the thermocouples were frequently retracted from the furnace and, where necessary,any deposits were carefully removed.Moreover, the probes were replaced if there was any thermal distortion ob-served.(3)The primary air/ﬂow temperature distribution was measured with the same thermocouple inserted parallel to the axis of the fuel-rich pipe,as shown in Fig.1.(4)Gas compositions were sampled using a water-cooled stainless steel probe2.5m in length for analysis of the local mean O2,CO and NO x concentrations.As shown in Fig.3,the probe comprised a centrally located10mm (inner diameter)tube,through which quenched samples were evacuated,surrounded by a tube for probe cooling.The probe was cleaned frequently by blowing high-pressure air through it to maintain a constant suction rate.The water-cooled probe was inserted into the furnace through observing doors1–3(see Fig.2).The gases withdrawn were analyzed online using a Testo 350M system.Theﬂue gas after the air heater was also analyzed online.Calibrations with standard mixtures including zero concen-trations were performed before each measurement session.The measurement error for O2and CO2concentrations was1%,while that for CO and NO x concentrations was50ppm.(5)Unburnt car-bon inﬂy ash was determined by collectingﬂy ash using a particle-sampling device with constant suction speed.Values of the main operating parameters for the three operating loads are listed in Table2.4.Results and discussionFig.4shows the gas temperature distribution of the fuel-burn-ing zone along the cyclone axes of the burners;zero points were set at the tips of the burner nozzles in the furnace.With decreasing load,the gas temperature decreases and the ignition position of the primary coal/airﬂow becomes farther along the axis of the fuel-rich pipe in the burner region under the arches,especially as the load decreases from550to330MW e.For the rated load,the gas temperature rises rapidly as the measurement point extends to lower positions,exceeding1000°C at a position400mm from the end of the fuel-rich nozzle and exceeding1200°C at 1400mm.For the load of550MW e,the gas temperature is a little lower than that for the rated load in the burner region,exceeding 1000°C at a position800mm from the fuel-rich nozzle.For the half load,the gas temperature rises slowly and the temperature gradi-ent is lower than in the other two cases,barely reaching1000°C at 2400mm.The mass ratio of coal/air decreases as the load decreases,indi-cating that the concentration of pulverized-coal falls in the primary air and the momentum of coal/airﬂow decreases,resulting in aTable2Boiler operating conditions and measurement results.Quantity Before retroﬁt After retroﬁt660MW e660MW e550MW e330MW eTotalﬂux of the primary air(kg/s)121127110.574Temperature of the primaryair(°C)130124125114Totalﬂux of the secondaryair(kg/s)657620511396Temperature of thesecondary air(°C)398405397362 Coal feeding rate(ton/h)268.6282.7244.6147.7 O2at the furnace exit(dryvolume%)3.35 2.58 2.02 5.31O2inﬂue gases(dry volume%)4.76 3.99 3.047.27NO x inﬂue gas(mg/m3at6%O2dry)1181244821631610Carbon inﬂy ash(%)9.55 2.43 6.02 3.24 Exhaust gas temperature(°C)136129.8119.3114.3Thermal efﬁciency of the boiler(%)84.5493.6692.5992.862402Z.Li et al./Applied Energy88(2011)2400–2406shallower penetration depth and shorter residence time of the pri-mary coal/airﬂow in the lower furnace.For these reasons,the gas temperature measured along the axis direction of the fuel-rich pipe decreases and the ignition of the primary coal/airﬂow in the bur-ner region under the arches is farther along the axis.The mass ratio of coal/air is deﬁned to indicate the coal concen-tration in the primary air.As the load falls from660to330MW e, the mass ratio of coal/air drops from0.618to0.554,which indi-cates an obvious decrease in the coal concentration;thus,the heat and time needed for coal ignition increase.This is one of the rea-sons for the low gas temperature in the burner region and far igni-tion position of the coal particles at half load.For the load of 550MW e,the mass ratio of coal/air is0.615,which is little different to that for the rated load.Furthermore,the quantity of primary air and coal feed rate both decrease as the load decreases,as does the momentum of coal/airﬂow,leading to shallow penetration of the pulverized-coal in the lower furnace.The short residence times then lower the overall temperature of the burner zone to the ex-tent that the fuel-richﬂow cannot obtain sufﬁcient heat from the recirculating up-ﬂowing gases(see Fig.1).Fig.5presents furnace gas temperature variations as measured using the thermocouple inserted through observing doors1–3.On the whole,the gas temperature measured through observing doors 1–3decreases with decreasing load.In the case of the temperature distribution measured through observing door1,the gas tempera-tureﬁrst increases and then decreases because some of the high-temperature gas recirculates into the near-wall zone.As the measurement points move deeper into the furnace,the measured temperature begins to fall as the thermocouple enters the fuel-rich ﬂow.At the rated load,the gas temperature is steadily around 1000°C at points further than1400mm,while for the load of 550MW e,the measured temperature is a little lower.At the same position but for a load of330MW e,the temperature falls below 700°C gradually,indicating that the fuel-richﬂow has not ignited. This temperature sequence is the same as that for the temperature gradients of the fuel-richﬂow mentioned above,indicating that ignition conditions worsen as the load decreases.In the cases of measuring the temperature through observing doors2and3,once the temperature reached1250°C,no further measurements were taken at deeper positions for the simple rea-son of protecting the thermocouple from burnout.From the rela-tively limited temperature distribution,Fig.5shows that in the zone near observing door2,the temperature rises rapidly at loads of660and550MW e,and at400mm,temperatures already exceed 1250°C.This indicates that coal burns more intensely in the lower furnace in both cases.At the load of330MW e,the temperature rises to nearly1200°C at the position1800mm from the side wall, increasing more slowly than in the other two cases.As illustrated above for the gas temperature in the burner region,the momentum of coal/airﬂow at half load is low,which results in a shallow pen-etration depth and short residence time of the primary coal/air ﬂow and low furnace temperature in the lower furnace.Further-more,the F-tier air accounts for a large proportion of the secondary air entering the furnace under the arches;therefore,much of the air does not take part in combustion immediately,which decreases the temperature in the region near observing door2.In the zones near observing door3above the arches,the temperature increases to more than1100°C at a load of330MW e,which is just a little lower than the temperature near observing door2.This can be ex-plained by the delay in the fuel-richﬂow ignition causing much of the fuel to burn in the upper furnace.Fig.6presents furnace temperature variations measured through observing doors for the three loads.The furnace tempera-tures shown in Fig.6are averages of values measured through observing doors at the same level.In the three cases,gas tempera-ture peaks are all in the lower furnace,and the distances from the peak positions to the exit of the furnace are relatively large.Resi-dence times for coal burning in the higher-temperature zone are thus longer,which favors fuel burnout.The difference between temperatures in the burning region and the lower position of the burnout region decreases as the load decreases,and is just35°C at a load of330MW e.This is because the momentum of coal/air ﬂow decreases,which results in a shallower penetration depth and shorter residence time of the primary coal/airﬂow in the lower furnace;the ignition position becomes farther from the fuel-rich nozzle,and more pulverized-coal combusts completely in the upper furnace.Moreover,the temperature in the furnace decreases with the decreasing load.The reason for this is that the total heatZ.Li et al./Applied Energy88(2011)2400–24062403provided to the furnace also falls with decreasing load,decreasing the furnace temperature.Fig.7shows the variations in gas species concentrations in the zones near observing doors1–3.Gas species concentration mea-surements begin400mm from the side wall to avoid the effect of an air leak.In all three cases,the O2concentration sequence is C(door1)>C(door2)>C(door3),which describes well theﬂow of coal as illustrated in Fig.1b.Fuel-richﬂowsﬁrst inject down-ward into the furnace and then reverse their direction upwards in the down-ﬁred boiler.The coal/airﬂows pass sequentially through the observation doors1,2,and3and O2is consumed con-tinuously along the path of theﬂame.Thus,in each case,the O2 concentration in the zone near observation door1was the highest, that in the zone near observation door2was intermediate and that near observation door3was the lowest.In the airﬂowﬂow zone of the D and E tiers and in the zone near the wall,a great quantity of hot gas lowers the measured O2con-centration.When the measurement points are deeper and closer to the fuel-richﬂow,the measured value increases.O2concentra-tions near observing door1increase with decreasing load,espe-cially from550to330MW e.For loads of660and550MW e,at the position1800mm from the wall,O2concentrations are nearly 14%,suggesting that the fuel-richﬂow is beginning to react and a certain amount of O2is being consumed.For the load of 330MW e,however,O2concentrations are higher than18%,indi-cating that the fuel-richﬂow has not ignited,which agrees with the conclusion drawn from the temperature analysis.In the near-wall zone of observing doors2and3,O2concentrations at half load are higher than in the other two cases,even as high as8%in the near-wall zone of observing door3.At all three loads,CO concentrations strictly rule contrary to O2 concentrations.In the zones near observing doors1–3,the higher the O2concentration,the lower the CO concentration.In the air-ﬂowﬂow zone of the D and E tiers,CO concentrations decrease with decreasing load because of the delayed ignition of the fuel/ airﬂow.In the near-wall zone of observing doors2and3,CO con-centrations in the case of the half load are lower than in the other two cases because of the highly oxidizing atmosphere in the furnace.2404Z.Li et al./Applied Energy88(2011)2400–2406In the zone near port1at loads of660and550MW e,volatiles are released and form a certain amount of NO x.However,biased combustion restricts the formation of NO x,and hence,NO x concen-tration here is only645mg/m3and630mg/m3respectively at a position1800mm from the wall.However,for the load of 330MW e,the NO x concentration is as high as3706mg/m3at the same position,because the high O2concentrations form the strong oxidative atmosphere near the observing door1.Moreover,the fuel/airﬂows with weak rigidity mix with the fuel gas quickly in the furnace;these are the reason for the high NO x concentration. Compared with those measured through observing door1,NO x concentrations for660and550MW e operation increase rapidly in the airﬂow zone of observing door2because fuel–NO forms con-stantly with further combustion of the pulverized-coal and ther-mal NO increasingly forms under the high-temperature condition in the lower furnace.The NO x concentration at a load of 550MW e is lower than that for the rated load because of the re-duced fuel–NO formation with a lower coal feed rate and the low-er-furnace temperature in this zone.In the case of330MW e,NO x concentrations decrease sharply,because the reducing atmosphere become higher with a great amount of O2consuming.In the zone near observing door3,the NO x concentration decreases with decreasing load.Table2lists results obtained for theﬂue gas after the air hea-ter.It is obvious that as the load decreases,the exhaust gas tem-perature decreases from129.8°C to114.3°C,while NO x emissions decrease from2448to1610mg/m3.Overall,the NO x content in theﬂue gas at the three loads was at high levels, exceeding the proposed Chinese emission standard for anthracite (1100mg/Nm3).To decrease these emissions,further technolo-gies,such as over-ﬁre air[15,20],selective catalytic reduction and selective non-catalytic reduction[21,22]should be taken into account.All three loads result in low carbon content in theﬂy ash and great boiler thermal efﬁciency higher than92%.The O2 concentrations at the furnace exit when operating at660and 550MW e were2.58%and2.02%,respectively,with the small dif-ference between the two caused by theﬂuctuation of air supply during operation.The carbon in theﬂy ash at a load of550MW e was6.02%,which is higher than that at660MW e because the lower-furnace temperature was lower by as much as50°C than the temperature at the higher operating load.To enhance heat absorption in the reheater and to ensure sufﬁcient temperature of the reheat steam,the method of increasing the excess air coef-ﬁcient is commonly adopted when operated at330MW e.Thus, the O2concentration at the furnace exit at330MW e was5.31%, much higher than that at660or550MW e.Despite the high O2 concentration,the quantity of air supplied,including both pri-mary and secondary air,was low for the330MW e case,being only63%of the quantity supplied at660MW e and76%of the quantity supplied at660MW e,as shown in Table2.Therefore, the mean velocity of the fuel gas was lower and the residence time of pulverized-coal was longer in the furnace.These factors explain the high degree of burnout of pulverized-coal and low carbon content in theﬂy ash.Table2also shows the main operating parameters and mea-surement results at a load of660MW e before the combustion sys-tem retroﬁt.After retroﬁt,the exhaust gas temperature decreased from136to129.8°C,the carbon content in theﬂy ash decreased from9.55%to 2.43%and the boiler efﬁciency increased from 84.54%to93.66%.However,the NO x content in theﬂue gas (O2=6%)was higher than before the retroﬁt,because premature ignition of the pulverized-coal prolonged the residence time of coal particles in the lower furnace with high temperature.Furthermore, the O2concentration in theﬂue gas decreased from4.76%to3.99%, which increased the NO x concentration after conversion of O2at 6%.5.ConclusionIndustrial experiments were performed in a retroﬁtted 660MW e full-scale down-ﬁred boiler.Measurements of ignition of the primary air/fuel mixtureﬂow,gas temperature distribution of the furnace and the gas components in the furnace were con-ducted at loads of660,550and330MW e.The results were as follows.With decreasing load,the gas temperature decreases and the ignition position of the primary coal/airﬂow becomes farther along the axis of the fuel-rich pipe in the burner region under the arches, especially as the load decreases from550to330MW e.With decreasing load,the gas temperature measured through observing doors1–3decreases,the ignition conditions worsen. Moreover,the combustion intensity of pulverized-coal reduces in the lower furnace.The furnace temperature also decreases with decreasing load,as does the difference between temperatures in the burning region and in the lower position of the burnout region.O2concentrations near observing door1increase with decreas-ing load,while O2concentrations at half load are higher than in the other two cases in the near-wall zone of observing doors2and3. CO concentrations strictly rule contrary to O2concentrations.The higher the O2concentration,the lower the CO concentration near observing doors1–3.NO x concentrations(O2=6%)near observing door1were low at loads of660and550MW e than at the load of 330MW pared with those measured through observing door 1,NO x concentrations for660and550MW e operation increase rapidly in the airﬂow zone of observing door2while NO x concen-trations at the load of330MW e decrease.In the zone near observ-ing door3,the NO x concentration decreases with decreasing load.With decreasing load,the exhaust gas temperature decreases from129.8°C to114.3°C,while NO x emissions decrease from 2448to1610mg/m3.All three loads result in low carbon content in theﬂy ash and great boiler thermal efﬁciency higher than92%.Compared with the case of660MW e before retroﬁt,the exhaust gas temperature decreased from136to129.8°C,the carbon con-tent in theﬂy ash decreased from9.55%to2.43%and the boiler efﬁciency increased from84.54%to93.66%.AcknowledgmentThis work was sponsored by the Hi-Tech Research and Development Program of China(863Program)(Contract No. 2006AA05Z321).References[1]Li ZQ,Jing JP,Liu GK,Chen ZC,Liu CL.Measurement of gas species,temper-atures,char burnout,and wall heatﬂuxes in a200-MWe lignite-ﬁred boiler at different loads.Appl Energy2010;87:1217–30.[2]Li ZQ,Jing JP,Chen ZC,Ren F,Xu B,Wei HD,et bustion characteristicsand NO x emissions of enhanced ignition-dual register and central-fuel-rich swirl burners in a300-MWe wall-ﬁred pulverized coal utility bust Sci Technol2008;180:1370–94.[3]Costa M,Azevedo JLT,Carvalho bustion characteristics of a front-wall-ﬁred pulverized coal300MW e utility bust Sci Technol 1997;129:277–93.[4]Costa M,Silva P,Azevedo JLT.Measurements of gas species,temperature,andchar burnout in a low-NO x pulverized coal-ﬁred utility bust Sci Technol2003;175:271–89.[5]Costa M,Azevedo JLT.Experimental characterization of an industrialpulverized coal-ﬁred furnace under deep staging bust Sci Technol2007;179:1923–35.[6]Kouprianova VI,Tanetsakunvatanab V.Optimization of excess air for theimprovement of environmental performance of a150MW boilerﬁred with Thai lignite.Appl Energy2003;74:445–53.[7]Li S,Xu TM,Hui SE,Wei XL.NO x emission and thermal efﬁciency of a300MW eutility boiler retroﬁtted by air staging.Appl Energy2009;86:1797–803.Z.Li et al./Applied Energy88(2011)2400–24062405[8]Toshikazu T,Hirofumi O,Dernjatinc P,Savolainenc K.Reducing the minimumload and NO x emissions for lignite-ﬁred boiler by applying a stable-ﬂame concept.Appl Energy2003;74:415–24.[9]Li ZQ,Yang LB,Qiu PH,Sun R,Chen LZ,Sun SZ.Experimental study of thecombustion efﬁciency and formation of NO x in industrial pulverized coal combustion.Int J Energy Res2004;28:511–20.[10]Li ZQ,Ren F,Zhang J,Zhang XH,Chen ZC,Chen LZ.Inﬂuence of vent air valveopening on combustion characteristics of a down-ﬁred pulverized-coal 300MW e utility boiler.Fuel2007;86:245–62.[11]Ren F,Li ZQ,Jing JP,Zhang XH,Chen ZC,Zhang JW.Inﬂuence of the adjustablevane position on theﬂow and combustion characteristics of a down-ﬁred pulverized-coal300MW e utility boiler.Fuel Process Technol2008;89: 1297–305.[12]Li ZQ,Ren F,Chen ZC,Wang JJ,Chen Z,Zhang JW.Inﬂuence of oil atomized aironﬂow and combustion characteristics in a300MW e down-ﬁred –Pac J Chem Eng2010;5:488–96.[13]Li ZQ,Ren F,Chen ZC,Chen Z,Wang JJ.Inﬂuence of declivitous secondary air oncombustion characteristics of a down-ﬁred300-MWe utility boiler.Fuel 2010;89:410–6.[14]Li ZQ,Ren F,Chen ZC,Liu GK,Xu ZX.Improved NO x emissions and combustioncharacteristics for a retroﬁtted down-ﬁred300-MWe utility boiler.Environ Sci Technol2010;44:3926–31.[15]Garcia-Mallol JA,Steitz T,Chu CY,Jiang PZ.Ultra-low NO x advanced FW archﬁring:central power station applications.In:2nd US China NO x and SO2 control workshop,Dalian;2005.[16]Zhang J.Experimental study and numerical simulation on separation char-acteristics of cyclone separator of downﬁred boiler.Harbin:School of Energy Science and Engineering,Harbin Institute of Technology;2006[in Chinese]. [17]Ren F,Li ZQ,Chen ZC,Wang JJ,Chen Z.Inﬂuence of the down-draft secondaryair on the furnace aerodynamic characteristics of a down-ﬁred boiler.Energy Fuels2009;23:2437–43.[18]Ren F,Li ZQ,Chen ZC,Xu ZX,Yang GH.Experimental investigations into gas/particleﬂows in a down-ﬁred boiler:inﬂuence of the vent air ratio.Energy Fuels2010;24:1592–602.[19]De DS.Measurement ofﬂame temperature with a multi-elementthermocouple.J Inst Energy1981;54:113–6.[20]Li ZQ,Ren F,Liu GK,Shen SP,Chen ZC.Inﬂuence of the overﬁre air ratio on theNO x emission and combustion characteristics of a down-ﬁred300MW e utility boiler.Environ Sci Technol2010;44:6510–6.[21]Sounak R,Hegde MS,Giridhar M.Catalysis for NO x abatement.Appl Energy2010;86:2283–97.[22]Liang ZY,Ma XQ,Lin H,Tang YT.The energy consumption and environmentalimpacts of SCR technology in China.Appl Energy2010.doi:10.1016/ j.apenergy.2010.10.010.2406Z.Li et al./Applied Energy88(2011)2400–2406。

热能动力专业毕业论文

热能动力专业毕业论文热能动力专业毕业论文摘要随着国家的繁荣发展，人们对于能源的需求也越来越大。

热能动力作为现代化的热能系统，受到了人们的广泛关注。

本文对热能动力在能源领域的广泛应用进行了研究。

通过对热能动力原理、设备结构及相关理论知识的分析，阐述了在现代化热能系统中，热动力学方程以及各类热能动力传递方式的应用。

此外，结合实例，介绍了热能动力系统的实际应用和发展现状，展望了未来的发展前景。

关键词：热能动力；能源领域；实际应用；发展前景。

AbstractWith the prosperity and development of the country, people's demand for energy is increasing. As a modern thermal system, thermal power has been widely concerned by people. This paper studies the extensive application of thermal power in the field of energy. Through the analysis of the principle, equipment structure and related theoretical knowledge of thermal power, this paper expounds the application of thermodynamic equations and various types of thermal power transmission modes in modern thermal systems. Inaddition, combined with examples, the practical application and development status of thermal power system are introduced, and the future development prospect is prospected.Keywords: thermal power; energy field; practical application; development prospects.引言热能动力是一种实用型热能系统，具有广泛的应用领域。

热能与动力工程专业英语1

(Heat transfer is the science)传热学是一门试图预测热量传递可以发生在温差存在的两个物体之间的科学。

(Thermodynamics teaches that this)热力学告诉我们能量的传递以热量的形式。

传热学不仅可以解释热能怎样被传送,同样可以预测在某种特殊的情况下产生的热交换率。

实际上热交换率的客观分析指出了传热学和热力学之间的差异。

热力学研究对象是处于平衡状态的系统,他可能被用于预测一个系统从一种平衡状态改变到另一种状态所需要的能量的多少,他可能不被用于预测发生在非平衡状态下的系统的热的交换量有多快。

传热学通过提供了可以作为科学中的热力学被用作传热项目基础的实验法则是非常简单的并且容易扩展到各种各样的实际情况当中。

(When a temperature gradient)当温度梯度存在于一个物体中时,经验显示能量将会从高温区域传递到低温区域,我们说能量是通过导热传递并且单位面积的传热效率于法向温度梯度成正比。

(When a fluid at rest or in motion)当流体以不同的温度与一块平板的表面接触且处于静止或运动时据热力学法则规定能量将朝低温区域流动,我们说热量被交换走了并且我们把这个过程称为对流换热过程。

(For both situations shown in fig,1.2)对于表1.2所示的两种情况我们用牛顿冷却定律来表述对流的整体作用。

(The temperature Tw is that)温度Tw是直接与平板表面接触的温度,温度T∞是为了确保平板表面温度不产生明显影响而使流体远离平板表面的所在区域的温度,面积A是与流体接触的表面区域,并且我们应该注意A与热流方向垂直。

比例因子h被叫做传热系数(也是单位面积的导热量或对流换热量)并且取决于几何布置、方向和表面状况(光滑或粗糙)、还有流体的物性和速度。

(There are two convection modes)有两种对流换热模型:强制对流换热和自然对流换热,如果一块被加热的平板暴露一个周围没有额外动因的房子里,空气的流动将经验的被认为是平板附近存在密度梯度的结果,我们称之为自然对流或是无常对流,强制对流与此相反,经验的认为是在风扇吧空气吹到平板上的情况。

热能,动力工程节能技术英文文献

热能,动力工程节能技术英文文献Energy is essential for human life and the development of society. However, the excessive use of energy has resulted in environmental degradation and climate change. As a result, there is an urgent need for the development and implementation of energy-saving technologies, particularly in the field of thermal and power engineering.One of the key areas in which energy-saving technologies can make a significant impact is in the field of heat transfer. Heat transfer is the process of transferring thermal energy from one material to another. In thermal and power engineering, heat transfer is crucial for the efficient operation of machinery and equipment, such as boilers, heat exchangers, and refrigeration systems. By improving the efficiency of heat transfer processes, energy consumption can be reduced, leading to cost savings and environmental benefits.There are several energy-saving technologies that can be applied in the field of heat transfer. One such technology is the use of heat exchangers. Heat exchangers are devices that transfer heat between two or more fluids at different temperatures. By using heat exchangers, the energy that is generated during heating or cooling processes can be recoveredand reused, reducing energy waste and improving overall efficiency.Another energy-saving technology that can be applied in thermal and power engineering is the use of insulation materials. Insulation materials are used to reduce heat transfer between different materials, such as walls, pipes, and equipment. By insulating these materials, heat loss can be minimized, leading to energy savings and improved thermal efficiency.In addition to heat exchangers and insulation materials, there are other energy-saving technologies that can be applied in thermal and power engineering, such as energy-efficient heat pumps, cogeneration systems, and waste heat recovery systems. By integrating these technologies into existing thermal and power systems, energy consumption can be reduced, leading to cost savings and environmental benefits.Overall, energy-saving technologies play a crucial role in the field of thermal and power engineering. By implementing these technologies, energy consumption can be reduced, leading to cost savings and environmental benefits. As the global demand for energy continues to rise, the development and implementation of energy-saving technologies will be essential for a sustainable future.。

热能与动力工程专业外语

UNIT2热对流For both situation shown in Fig.1.2,we express the overall effect of convection,we use New-ton”s law of cooling: Q=Ha(Tw-T8横)在图 1.2所示的两种情况，我们对对流的整体效果，我们使用的冷却新吨级“定律为: Q=Ha(Tw-T8横)UNIT3热辐射Thermodynamic considerations show that an idea thermal radiator ,or blackbody ,will emit energy at a rate proportional to the fourth power of the absolute temperature of the body and directly proportional to its surface area. Thus q(emitted)=σAT4 (1-6)热力学规律揭示出一个理想的热辐射体或黑体，所散发出能量的速度与其自身的绝对温度的四次方和其表面积成正比。

即（公式）Where σ is the proportionality constant and is called the Stefan-Boltzmann constant with the value of 5.669*10-8 W/m2k4. Equation(1-6)is called the Stefan-Boltzmann law of thermal radiation, and it applies only to blackbodies. It is important to note that this equation is valid only for thermal radiation; other types of electromagnetic radiation may not be treated so simply.其中σ是比例常数，值为5.669*10-8 W/m2k4称为斯蒂凡玻尔兹曼常数。

热能与动力工程专业英语

Chapter 1 Introduction to Thermal Science第一章热科学基础Acoustic flow meter 声波流量计Corrugated fin 波状散热片Adiabatic []绝热的Cross product 矢量积Aerodynamics 空气动力学Denominator 分母Affiliation 联系Developed flow 充分发展流Airfoil 机翼，螺旋桨Diffusion 扩散Alternative 替代燃料Doppler effect 多普勒效应Anemometer 风速计Double-pipe heat exchanger 套管式换热器Angular speed 角速度Dry saturated vapor 干饱和蒸汽Area density 表面密度Electrode 电极Baffle 挡板Electrolyte 电解，电解液Bifurcation 分形Electrostatic 静电的Blackbody 黑体Emissivity 发射率Blade 浆叶，叶片Equilibrium 平衡Boiler 锅炉Fluid mechanics 流体力学Boundary layer 边界层Forced convection 强制对流Carnot Cycle 卡诺循环Free convection 自然对流Cartesian coordinates 笛卡尔坐标系Friction loss 摩擦损失Celsius Degree 摄氏度Glass ceramic 微晶玻璃，玻璃陶瓷Heat engine 热机Compact heat exchanger 紧凑式换热器Composition 成分，合成物Heat pump 热泵Compressed liquid 压缩液体Hydrofoil 水翼Compressibility 可压缩性，压缩率Hypersonic speed 高超音速Condensation 凝结Infinitesimal 无穷小的Condenser 冷凝器Inflating/deflating 充气/压缩Conduction 导热Internal combustion engine 内燃机Control volume 控制体Isentropic 等熵的Convection 对流Isobaric 等压的Coriolis-accelaration flowmeter 科Isolated system 孤立体系的氏加速流量计Isometric 等容的Rough-wall tube 粗糙管Isothermal 等温的Saturation 饱和Kinematic viscosity 运动黏度Shear stress 剪切力、切应力Laminar 层流Shell-and-tube heat exchanger管壳式换热器Manuscript 手稿，原稿Specific volume 比容Moisture 湿度，水分Steady 稳态的，定常的Molecule (化学)分子Stifling engine 斯特林机Molten polymer 熔融聚合物Strain rate 变形速度，应变率Muti-disciplinary 多学科的Streamline 流线Newtonian Fluid 牛顿流体Strut 支撑，支柱Nominal temperature gradient 法向Subcooled liquid过冷液体温度梯度Numerator （数学）分子Superheated vapor 过热蒸汽Parallel flow 平行流动，并流Surrounding 环境，外界Pathline迹线Thermal conductivity 热传导率Phase change 相变Thermal efficiency 热效率Plane flow 平面流，二元流Thermodynamics 热力学Torsional 扭力的，扭转的Plate and flame heat exchanger板式换热器Polymer solution 胶浆Trailing edge 机翼后缘、尾缘Proof 校样Transmitter 传送装置、发送器Propeller 螺旋桨，推进器Turbine meter 涡轮流量计Pump泵Turbulent 湍流的Qulity 干度Ultrosonic 超声波的Qusi-equilibrium 准平衡、准静态Uniform flow 均匀刘Radiation 辐射Vacuum 真空Rankin Cycle 朗肯循环View factor 角系数Regenerative heat exchangerViscous 黏性的蓄热/再生式换热器Reservoir 水库，蓄水池Cortex shedding 漩涡脱落Reversible 可逆的Water faucet 水龙头，水嘴Rotameter 转子流量计Bi Biot number 比澳数NPSH 汽蚀余量CFD 计算流体力学NTU 传热单元数CHF 临界热流量Nu 努谢尔特数COP 制冷系数PE 势能Eu 欧拉数Pr 普朗特数Fo 富立叶数Ra 瑞利数Fr 弗劳德数Re 雷诺数Gr 格拉晓夫数Sc 施密特数KE 动能St 斯坦顿数，斯特劳哈数LMTD对数平均温差We 韦伯数1.1Fundamental of Engineering Thermodynamics1.1工程热力学基础Thermodynamics is a science in which the storage, transformation and transfer of energy are studied. Energy is stored as internal energy (associated with temperature), kinetic energy (du to motion), potential energy (due to elevation) and chemical energy (due to chemical composition); it is transformed from one of these forms to another; and it is transferred across a boundary as either heat or work.热力学是一门研究能量储存、转换及传递的科学。

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Enhancement of Forced Convection Heat TransferRongzhen YouClass 1202 of Power EngineeringIn my College Students Innovative Project, we are supposed to adopt some methods to enhance the forced convection heat transfer on the plain surface. Although we have taken several technical methods into consideration, most of them are too difficult for us to apply in our project. Therefore, I would like to make an introduction to these methods here.Firstly, machining some grooves or dimples on the plain plates is one of important methods to enhance the convection heat transfer. The grooves or dimples can change the flow field of the fluid near the surface, for which the fluid would be turbulent than before. In this way, the Nusselt number of the near surface fluid would be raised, and than the convection heat-transfer coefficient would increase. This method can enhance the convection heat transfer on the plain plate to some extent, but it’s still ineffective for the reason that the improvement of heat-transfer coefficient of the fluid in the near wall region can not enhance the heat-transfer of the mainstream.Secondly, some researchers come up with an idea that using spiral fine ribs (SFRs) in plate channel to enhance the convection heat transfer. They equally placed the SFRs in the channel, which can form a packing layer resembling a kind of quasi-porous media with large porosity and can produce efficient disturbance both to the boundary layer and the mainstream. The operation principle of SFRs is that the multi-longitudinal vortices induced by SFRs can significantly increase the tangential velocity components in the cross section, which is helpful to promote the micro-fluctuation in the fluid. What’s more, the transport action caused by the longitudinal vortices can improve the mass exchange between the boundary layer and the mainstream. These two factors can not only speed up the heat migration from the channel walls, but also enhance the heat diffusion in the mainstream. This improves the temperature distribution uniformity in channel.Thirdly, the most efficient way to enhance the convection heat transfer is installing fins on the plain plate. Base on this thought, some researchers have fabricated many different types of fins, such as columned pin fins, conical pin fins, elliptical pin fins, cross-cut pin fins and longitudinal vortex generator arrays (LVG). Nowadays, fins with geometric shape pins have been commonly used to in the engineering. As for the vortex generator, it can disturb the flow field by the vortex and generate vortex after the generator, which can break the boundary lay on the surface and transfer the heat into mainstream quickly. Nowadays, many researchers have proved that the LVG effect is much better than the straight fins within a certain limit of Reynolds number, as well as that the multi rows LVG can improve the whole heat transfer effect.The methods mentioned above sounds pretty advanced, but it’s quiet difficult for us, regular college students, to apply these methods in our project. Because we couldn’t analysis the complex flow field in these special structure, unless we use the FLUENT software to build up their mathematic model. As the advanced usage of FLUENT is out of our ability, we have no choices but to install the straight fins on the heat transfer surface. Some researchers have found that the overall thermal resistance of straight fins is lower than other geometric pin fins, due to the combination effect of enhanced later conduction along the fins and the lower flow bypass characteristics. At last, our experiment also proved that the straight fin can meet the requirement of the enhancement of forced convection heat transfer.References1. Christopher L. Chapman, and Seri Lee, Thermal Performance of an Elliptical Pin Fin Heat Sink, Silicon Graphics Computer Systems Mountainview, California, 940392. Pradeep Salapakkam, Ri Li, Mehmet Arik, Bill Gerstler, Augmenting Forced Convection Heat Transfer Coupled with an Aerodynamic Surface and a Synthetic Jet, One Research Circle, Niskayuna, NY 123093. Zhang Xiang, Research on Forced Convection Heat Transfer of Parallel Plate with Grooves, China Academic Journal Electronic Publishing House, TK 1234. Tang Yufeng, Research on Heat Transfer Enhancement Mechanism and Heat Transfer Characteristic of Spiral Fine Ribs in Plate Channel, China Academic Journal Electronic Publishing House, TK1245. K.W. Low, and C. Yap,The Enhanced Cooling of IC Chip Arrays On Printed Circuit Boards, Electronics Packaging Technology Conference, Singapore, 1192606. Gaowen Liu, Peng zhao, Zongwei zhang, Tao Liu, Transient Infrared Heat Transfer Measurements and Surface Flow Visualization on a Single Dimpled Wall, Journal of Propulsion Technology, Feb. 2009, V ol.30 No.11.。

热能与动力工程专业英语论文(强化对流传热)

热能与动力工程专业英语

热能与动力工程英文文献3

热能动力专业毕业论文

热能与动力工程专业英语1

热能,动力工程节能技术英文文献

热能与动力工程专业外语

最新热能与动力工程专业英语(整理版)

热能与动力工程专业英语