板式換熱器畢業(yè)設(shè)計(jì)外文翻譯

1、<p>　　DESIGN OF HEAT EXCHANGER FOR HEAT RECOVERY IN CHP SYSTEMS</p><p><b>　　ABSTRACT </b></p><p>　　The objective of this research is to review issues related to the design o

2、f heat recovery unit in Combined Heat and Power (CHP) systems. To meet specific needs of CHP systems, configurations can be altered to affect different factors of the design. Before the design process can begin,

3、product specifications, such as steam or water pressures and temperatures, and equipment, such as absorption chillers and heat exchangers, need to be identified and defined. The Energ</p><p&

4、gt;　　INTRODUCTION </p><p>　　Combined Heat and Power (CHP), also known as cogeneration, is a way to generate power and heat simultaneously and use the heat generated in the process for various

5、purposes. While the cogenerated power in mechanical or electrical energy can be either totally consumed in an industrial plant or exported to a utility grid, the recovered heat obtained from the thermal ene

6、rgy in exhaust streams of power generating equipment is used to operate equipment such as ab</p><p>　　The Mechanical Engineering Department and the Industrial Assessment Center at the Universit

7、y of Louisiana Lafayette has been donated an 800kW diesel turbine and a 100 ton absorption chiller from industries. This equipment needs to be integrated to work as a Combined Heat and Power system fo

8、r the University which will supplement the chilled water supply and electricity. The design constraints of the heat recovery unit are the specifications of the turbine and </p><p>　　Integrating

9、equipment to form a CHP system generally does not always present the best solution. In our case study, the absorption chiller is not able to utilize all of the waste heat from the turbine exhaust. This is b

10、ecause the capacity of the chiller is too small as compared to the turbine capacity. However, the need for extra space conditioning in the buildings considered remains an issue which can be resolved

11、through the use of this CHP system. </p><p>　　BACKGROUND LITERATURE </p><p>　　The decision of setting up a CHP system involves a huge investment. Before plunging into one, any ind

12、ustry, commercial building or facility owner weighs it against the option of conventional generation. A dynamic stochastic model has been developed that compares the decision of an irreversib

13、le investment in a cogeneration system with that of investing in a conventional heat generation system such as steam boiler combined with the option </p><p>　　CHP systems demand that the

14、performance of the system be well tested. The effects of various parameters such as the ambient temperature, inlet turbine temperature, compressor pressure ratio and gas turbine combustion efficiency

15、are investigated on the performance of the CHP system and determines of each of these parameters [1]. Five major areas where CHP systems can be optimized in order to maximize profits have been iden

16、tified as optimization of h</p><p>　　Another example of a commercial CHP set-up is the Mississippi Baptist Medical Center. First the energy requirement of the hospital was assessed and the potenti

17、al savings that a CHP system would generate [10]. CHP applications are not limited to the industrial and commercial sector alone. CHP systems on a micro-scale have been studied for use in residential appli

18、cations. The cost of UK residential energy demand is calculated and a study is performed that compares </p><p>　　The search for different types of fuel cells in residential homes finds that a

19、dominant cost effective design of fuel cell use in micro – CHP exists that is quickly emerging [3]. However fuel cells face competition from alternate energy products that are already in the market. Us

20、e of alternate energy such as biomass combined with natural gas has been tested for CHP applications where biomass is used as an external combustor by providing heat to par</p><p>　　Inte

21、gration of a CHP system is generally at two levels: the system level and the component level. Certain trade-offs between the component level metrics and system level metrics are required to achie

22、ve optimal integrated cooling, heating and power performance [18]. All CHP systems comprise mainly of three components, a power generating equipment or a turbine, a heat recovery unit and a cooli

23、ng device such as an absorption chiller.</p><p>　　There are various parameters that need to be considered at the design stage of a CHP project. For instance, the chiller efficiency together with t

24、he plant size and the electric consumption of cooling towers and condenser water pumps are analyzed to achieve the overall system design [20]. Absorption chillers work great with micro turbines. A

25、 good example is the Rolex Reality building in New York, where a 150 kW unit is hooked up with an absorption chiller t</p><p>　　Exhaust gas at 800°F comes out of the turbine at a flow rate of 4

26、8,880 lbs/h [7]. One important constraint during the design of the CHP system was to control the final temperature of this exhaust gas. This meant utilizing as much heat as required from the exh

27、aust gas and subsequently bringing down the exit temperature. After running different iterations on temperature calculations, it was decided to divert 35% of the exhaust air to the heat exchanger </p>

28、;<p>　　A diverter valve can also used at the inlet side of the heat exchanger which would direct the exhaust gas either to the heat exchanger or out of the bypass stack. This takes care of variable load

29、s requirement. Inside the heat exchanger, exhaust gas enter the shell side and heats up water running in the tubes which then goes to the absorption chiller. These chillers run on either steam or hot water.<

30、/p><p>　　The absorption chiller donated to the University runs on hot water and supplies chilled water. A continuous water circuit is made to run through the chiller to take away heat from

31、 the heat input source and also from the chilled water. The chilled water from the absorption chiller is then transferred to the existing University chilling system unit or for another use.</p><

32、;p>　　Thermally Activated Devices </p><p>　　Thermally activated technologies (TATs) are devices that transform heat energy for useful purposed such as heating, cooling, humidity control

33、etc. The commonly used TATs in CHP systems are absorption chillers and desiccant dehumidifiers. Absorption chiller is a highly efficient technology that uses less energy than conventional chilling

34、equipment, and also cools buildings without the use of ozone-depleting chlorofluorocarbons (CFCs). These </p><p>　　Desiccant dehumidifiers are used in space conditioning by removing

35、 humidity. By dehumidifying the air, the chilling load on the AC equipment is reduced and the atmosphere becomes much more comfortable. Hot air coming from an air-to-air heat exchanger removes wate

36、r from the desiccant wheel thereby regenerating it for further dehumidification. This makes them useful in CHP systems as they utilize the waste heat. </p><p>　　An absorption chiller is mec

37、hanical equipment that provides cooling to buildings through chilled water. The main underlying principle behind the working of an absorption chiller is that it uses heat energy as input, instead of

38、 mechanical energy.</p><p>　　Though the idea of using heat energy to obtain chilled water seems to be highly paradoxical, the absorption chiller is a highly efficient technology and cost effec

39、tive in facilities which have significant heating loads. Moreover, unlike electrical chillers, absorption chillers cool buildings without using ozone-depleting chlorofluorocarbons (CFCs). These chillers

40、 can be powered by natural gas, steam or waste heat.</p><p>　　Absorption chiller systems are classified in the following two ways: </p><p>　　1. By the number of generators.</p

41、><p>　　i) Single effect chiller – this type of chiller, as the name suggests, uses one generator and the heat released during the absorption of the refrigerant back into the solution is rej

42、ected to the environment. </p><p>　　ii) Double effect chiller – this chiller uses two generators paired with a single condenser, evaporator and absorber. Some of the heat released during

43、 the absorption process is used to generate more refrigerant vapor thereby increasing the chiller’s efficiency as more vapor is generated per unit heat or fuel input. A double effect chiller requires a hig

44、her temperature heat input to operate and therefore its use in CHP systems is limited by the type </p><p>　　iii) Triple effect chiller – this has three generators and even higher effi

45、ciency than a double effect chiller. As they require even higher heat input temperatures, the material choice and the absorbent/refrigerant combination is limited. </p><p>　　2. By type o

46、f input: </p><p>　　i) Indirect-fired absorption chillers – they use steam, hot water, or hot gases from a boiler, turbine, engine generator or fuel cell as a primary power input. Indir

47、ect-fired absorption chillers fit well into the CHP schemes where they increase the efficiency by utilizing the otherwise waste heat and producing chilled water from it. </p><p>　　ii) Direct-

48、fired absorption chillers – they contain burners which use fuel such as natural gas. Heat rejected from these chillers is used to provide hot water or dehumidify air by regenerating the desiccant wheel. </p

49、><p>　　An absorption cycle is a process which uses two fluids and some heat input to produce the refrigeration effect as compared to electrical input in a vapor compression cycle in the mor

50、e familiar electrical chiller. Although both the absorption cycle and the vapor compression cycle accomplish heat removal by the evaporation of a refrigerant at a low pressure and the rejection of heat by

51、the condensation of refrigerant at a higher pressure, the method of c</p><p>　　The primary working fluids ammonia and water in the vapor compression cycle with ammonia acting as the refrigerant

52、 and water as the absorbent are replaced by lithium bromide (LiBr) as the absorbent and water (H2O) as the refrigerant in the absorption cycle. The process occurs in two shells - the upper shell

53、 consisting of the generator and the condenser and the lower shell consisting of the evaporator and the absorber.</p><p>　　Heat is supplied to the LiBr/H2O solution through the generator

54、 causing the refrigerant (water) to be boiled out of the solution, as in a distillation process. The resulting water vapor passes into the condenser where it is condensed back into the liquid state

55、using a condensing medium. The water then enters the evaporator where actual cooling takes place as water is passes over tubes containing the fluid to be cooled.</p><p>　　Heat Exchanger&l

56、t;/p><p>　　A very low pressure is maintained in the absorber-evaporator shell, causing the water to boil at a very low temperature. This results in water absorbing heat from the medium to be

57、 cooled and thereby lowering its temperature. The heated low pressure vapor then returns to the absorber where it mixes with the LiBr/H2O solution low in water content. Due to the solution’s lo

58、w water content, vapor gets easily absorbed resulting in a weaker LiBr/H</p><p>　　The heat recovery steam generator (HRSG) is primarily a boiler which generates steam from the waste he

59、at of a turbine to drive a steam turbine. The heat recovery boiler design for cogeneration process applications covers many parameters. The boiler could be designed as a fire-tube, water tube or combi

60、nation type. Further for each of these parameters, there is a variety of tube sizes and fin configurations. For a given boiler, a simplif</p><p>　　The shell and tube heat exch

61、anger is the most common and widely used heat exchanger in different industrial applications [13]. It is compared to a classic instrument in a concert playing all the important nodes in different comp

62、lex system set-ups and can be improved by using helical baffles. There are other ways to augment the heat transfer in a shell and tube exchanger such as through the use of wall-radiation [25].The design of a sh

63、ell and tube heat exchanger</p><p>　　This involves listing assumptions at the beginning of the procedure, obtaining fluid properties, calculation of Reynolds number and the flow are

64、a to obtain the shell and tube sizes. Once U is calculated, the heat balances are calculated. This study also compares the theoretical U values with the actual experimental ones to prove the theoretical assum

65、ptions and to obtain the optimum design model [18].</p><p>　　A mathematical simulation for the transient heat exchange of a shell and tube heat exchanger based on energy conservation and mass balance can b

66、e used to measure the performance. The design of the heat exchanger is optimized with the objective function being the total entropy generation rate considering the heat transfer and the flow resistanc

67、e [20].</p><p>　　Once a heat exchanger is designed, a total cost equation for the heat exchanger operation is deduced. Based on this, a program is developed for the optimal selection of shell-tube he

68、at exchanger [24].</p><p>　　The heat exchanger to be used in the CHP system in the end needs to be tested for its performance. A heat recovery module for cogeneration is tested bef

69、ore use for CHP application through a microprocessor based control system to present the system design and performance data [19]. </p><p>　　The basis of a CHP system lies in efficiently capturi

70、ng thermal energy and using it effectively. Generally in CHP systems, the exhaust gas from the prime mover is ducted to a heat exchanger to recover the thermal energy in the gas. The commonly used heat

71、recovery systems are heat exchangers and Heat Recovery Steam Generators depending on whether hot water or steam is required.</p><p>　　The heat exchanger is typically an air-to-water kind where

72、 the exhaust gas flows over some form of tube and fin heat exchange surface and the heat from the exhaust gas is transferred to make hot water. Sometimes, a diverter or a flapper damper is used to maintain

73、a specific design temperature of the hot water or steam generation rate by regulating the exhaust flow through the heat exchanger.</p><p>　　The HRSG is essentially a boiler that captures

74、the heat from the exhaust of a prime mover such as a combustion turbine, gas or diesel engine to make steam. Water is pumped and circulated through the tubes which are heated by exhaust gases

75、at temperatures ranging from 800°F to 1200°F. The water can then be held under high pressure to temperatures of 370°F or higher to produce high pressure steam [21].</p><p>

76、;　　The Delaware method is a rating method regarded as the most suitable open-literature available for evaluating shell side performance and involves the calculation of the overall heat trans

77、fer coefficient and the pressure drops on both the shell and tube side for single-phase fluids [12]. This method can be used only when the flow rates, inlet and outlet temperatures, pressures and

78、other physical properties of both the fluids and a minim</p><p>　　Emission Control</p><p>　　Emission control technologies are used in the CHP systems to remove SO2 (sulphur dioxide)

79、, SO3 (sulphur trioxide) NOx (nitrous oxide) and other particulate matter present in the exhaust of a prime mover. Some common emission control technologies are: </p><p>　　1、Diesel Oxidation

80、 Catalyst (DOC) – They are know to reduce emissions of carbon monoxide by 70 percent, hydrocarbons by 60 percent, and particulate matter by 25 percent (Emissions Control : CHP Technologies Gulf Co

81、ast CHP 2007) when used with the ultra-low sulfur diesel (ULSD) fuel. Reductions are also significant with the use of regular diesel fuel. </p><p>　　2、Diesel Particulate Filter (DPF) - DPF can reduce e

82、missions of carbon monoxide, hydrocarbons, and particulate matter by approximately 90 to 95 percent (Emissions Control : CHP Technologies Gulf Coast CHP 2007). However, DPF are used only in conjunction with ul

83、tra-low sulfur diesel (ULSD) fuel. </p><p>　　3、Exhaust Gas Recirculation (EGR) – They have a great potential for reducing NOx emissions. </p><p>　　4、Selective Catalytic Reduction (SCR) – SCR

84、cuts down high levels of NOx by reducing NOx to nitrogen (N2) and oxygen (O2).</p><p>　　5、NOx absorbers – catalysts are used which adsorb NOx in the exhaust gas and dissociates it to nitrogen

85、. </p><p>　　CONCLUSIONS </p><p>　　The various components needed in a CHP system have been presented. Important parameters such as the mass flow rates of the exhaust gas and

86、water can then be defined. The CHP system has been integrated by the use of a heat recovery unit, the design of which has been discussed. A shell and tube configuration is commonly selected based on li

87、terature survey. The pressure drops at both the shell and the tube side can be calculated after the exchanger ha</p><p>　　Integrating equipment to form a CHP system generally does not always

88、 present the best solution. In our case study, the absorption chiller is not able to utilize all of the waste heat from the turbine exhaust. Approximately 65% goes is left to go out the stack. This is becau

89、se the capacity of the chiller is too small as compared to the turbine capacity. However, the need for extra space conditioning in the buildings considered remains an issue which can </p><p

90、>　　The heat exchanger designed can either be constructed following the TEMA standards or it can be built and purchased from an industrial facility. The design that is used is based on the methodolog

91、y of the Bell-Delaware method and the approach is purely theoretical, so the sizing may be slightly different in industrial design. Also the manufacturing feasibility needs to be checked.</p><p>　

92、　After the heat exchanger is constructed, the CHP equipment can be hooked together. Again since the available equipment is integrated to work as a system, the efficiency of the CHP system needs to be calcul

93、ated. Some kind of control module needs to be developed that can monitor the performance of the entire system. Finally, the cost of running the set-up needs to be determined along with the air-conditioning r

94、equirements. </p><p>　　關(guān)于在熱電聯(lián)產(chǎn)（CHP）系統(tǒng)中廢熱回收的熱交換器的設(shè)計(jì) Kozman Bimaldeep Kaur吉姆·李</p><p><b>　　研究助理教授副教授</b></p><p><b>　　機(jī)械工程學(xué)系</b></p><p>　　441

95、70信箱,244房間CLR大廳</p><p>　　拉斐特的路易斯安娜大學(xué)</p><p>　　拉斐德,湖人70504 - 2250,美國(guó)</p><p><b>　　摘要 </b></p><p>　　本次研究的目的是回顧熱電聯(lián)產(chǎn)（CHP）系統(tǒng)中廢熱回收裝置的設(shè)計(jì)的相關(guān)問(wèn)題。為了滿足熱電聯(lián)產(chǎn)（CHP)系統(tǒng)的特殊需求，可

96、以通過(guò)改變配置來(lái)影響設(shè)計(jì)的各種因素。在設(shè)計(jì)過(guò)程開(kāi)始之前，產(chǎn)品參數(shù)(如蒸汽或水壓力、溫度)和設(shè)備(又如吸收式冷水機(jī)和熱交換器)需要被明確確定。實(shí)業(yè)公司向位于拉斐特的路易斯安那大學(xué)機(jī)械工程系的能源工程實(shí)驗(yàn)室和路易斯安那州的工業(yè)評(píng)估中心捐贈(zèng)一個(gè)800千瓦柴油渦輪機(jī)和100噸吸收式制冷機(jī)。該設(shè)備需要聯(lián)合熱交換器工作，作為一個(gè)聯(lián)合熱動(dòng)力系統(tǒng)，為大學(xué)供應(yīng)冷卻水和電力。不改變的渦輪機(jī)和制冷機(jī)的規(guī)格是熱回收裝置設(shè)計(jì)的約束條件。</p>&

97、lt;p>　　引言 熱電聯(lián)產(chǎn)（CHP）也稱(chēng)為廢熱發(fā)電，是一種通過(guò)利用在使用過(guò)程中所產(chǎn)生的熱量來(lái)同時(shí)發(fā)電和發(fā)熱的方法。在機(jī)械或電氣能量中利用工業(yè)廢熱所產(chǎn)生的電能，可以被一個(gè)工業(yè)工廠完全消耗或被輸出到一個(gè)公用電網(wǎng)，從發(fā)電設(shè)備的排氣流中產(chǎn)生的熱能里得到的高溫回收熱能，被操作設(shè)備（如吸收冷水機(jī)、除濕設(shè)備）或是熱能回收裝置（用于生產(chǎn)蒸汽，熱水，空間或過(guò)程制冷、制熱，又或是控制濕度)所使用?；谒褂玫脑O(shè)備，CHP也有其它的縮寫(xiě)，例

98、如CHPB（冷卻建筑物的供暖和電力），CCHP（聯(lián)合冷熱電），BCHP（建筑冷熱電聯(lián)產(chǎn)）和IES（綜合能源系統(tǒng)）。熱電聯(lián)產(chǎn)（CHP）系統(tǒng)要比單獨(dú)的生產(chǎn)電力和火力發(fā)電的效率要高很多。根據(jù)商業(yè)建筑物能耗調(diào)查，1995年在美國(guó)有460萬(wàn)的商業(yè)建筑[14]，這些建筑消耗能量是總能源四分之一的5.3倍，大約有一半來(lái)自電力。調(diào)查數(shù)據(jù)的分析表明，熱電聯(lián)產(chǎn)只滿足商業(yè)領(lǐng)域需要總能量的3.8%。盡管日益增長(zhǎng)的能源需求，自1960年以來(lái)，平均發(fā)電效率一直保持