换热器中英文对照外文翻译文献

1、 中英文对照外文翻译(文档含英文原文和中文翻译)换热器的优化选型【摘要】板式换热器的优化选型是根据换热器的用途和工艺过程中的参数和NTUKAMCttm，即传热单元数 NTU和温差比（对数平均温差换热的动力）选择板片形状、板式换热器的类型和结构。【关键词】平均温差 NTU 板式蒸发器 冷凝器1 平均温差tm从公式 QKtmA，tm （tt）dA 中可知，平均温差tm 是1AA12传热的驱动力，对于各种流动形式，如能求出平均温差，即板面两侧流体间温差对面积的平均值，就能出换热器的传热量。平均温差是一个较为直观的概念，也是评价板式换热器性能的一项重要指标。 1.1 对数平均温差的计算当换热器传热量为

2、 dQ，温度上升为 dt 时，则 CdQdt，将 C 定义为热容量，它表示单位时间通过单位面积交换的热量，即 dQK（t t ）dAKtdA，hc两种流体产生的温度变化分别为 dt dQC ，dt dQC ，dtd（t t ）chhchcdQ（1C 1C ）,则 dA1k（1C 1C ）（dtt），当从 Acchh0 积分至 AA 时，A 1k（1C 1C ）（t t ）（t t ），ci00chhohico由于两种流体间交换的热量相等，即 QC （t t ）C （t t ），经简化后可chhihococi知，QKA （t t ）（t t ）（t t ）（t t ），若ci0hocihicoh

3、ohicot t t ，t t t ，则 QKA （t t ）（t t ）KA 21hico2hoci01120tm，式中的tm（t t ）（t t ）。1122顺流 tm（t t ）（t t ） （t t ）（t t ）cihicihocohihoci逆流 tm（t t ）（t t ） （t t ）（t t ）cohicohocihihoci对于各种流动型式，在相同的进口、出口温度条件下，逆流的平均温差最大。当板式换热器入口和出口两流体的温差t 和t 之间的差不大时，可采21用算术平均温差（t t ）2，一般t t 小于 1.5 时，可采用，若t1122t 为 3 时，则误差约为 10%。2

4、1.2 传热单元数法在传热单元数法中引入一个无量纲参数 NTU，称为传热单元数，它表示板式换热器的总热导（即换热器传热热阻的倒数）与流体热容量的比值 NTUKAMC，它表示相对于流体热容流量，该换热器传热能力的大小，即换热器的无量纲“传热能力”。对于板式换热器来说，KAMCttm，式中ttm 称为温差比，上式中的右边的工艺过程用 NTUp 表示，左边的换热设备的条件用 NTU 表示。NTUp 是E流体温度的变化与平均温差的比值，表示的是用1tm 的变化引起几度流体温度变化的值，当tm 大时，NTUp 则小；当tm 小时，它有变大的倾向。相反，在 NTUp变大的过程中，tm 的温度变化较大，NT

5、Up 较小时，其tm 的温度变化较小（见表 1）。表 1 tm，NTUp 的关系 NTUp 大NTUp 小tm 的温度变化大tm 的温度变化小板式换热器的优化设计计算，就是在已知温差比NTU 的条件下，合理地确定其E型号、流程和传热面积，使 NTUp 等于 NTU 。E1.3 换热过程和 NTU与供热空调相关的换热过程如下如示： 用蒸汽加热水 水水换热a. 蒸汽 133133水 565（生活热水）c. 一次水 6560二次水 4540（采暖）b. 蒸汽 133133水 5565（采暖）d. 一次水 149二次水 137（制冷）e. 一次水 2924二次水 2621（制冷机的冷却）以上 5 例工

6、艺过程的 NTUp（见表 2）表 2 供热空调工艺过程的 NTUp（655）94.860.632（6555）72.880.1320.001.44（4540）200.25（137）1.444.17d149 292426211.4 板式换热器和 NTUENTU 表示板式换热器的能力，换热器的面积是具有一定传热长度的单位传热体E的组合，总传热长度是单位长度和流程数的乘积。当NTU 是总数时，若每 1 流程数E为 NTU 时，则 NTU nNTU （其中 n 是流程数）。eeE当 NTU NTU NTUp 时，换热器为单程。若 NTU NTUp 时，则换热器应为多流eeE程，故设计时应先预定 n。由于

7、每种板片单程的 NTU 值基本上是定值，如适合表 2e中 e 的流量为 25m h 的单程板式换热器的 NTU 为 17 。从NTU AKMC 可知，3ee当 NTU 为定值时，AK 成反比，仍以 e 为例，当 K500kcalh时，Ae1.672500050083.5 ，流程数 n83.5175。当 K2500kcalh时，A16.7 ，流程数 n1。每一流程的 NTU 如下所示：K500，NTU NTU nEee0.33，K2500 时，NTU 1.67。由此可知，根据NTU 即可求出换热器的流程数，ee传热系数和传热面积。从以上可知，若板式换热器设计不合理，可能使换热面积过大，也可能使板

8、间流速太高，阻力过大。1.5 板式换热器制造技术的进步，板片种类的增加，提高了板式换热器对各种工艺过程的适应性。 大 NTU（8），小tm（12）的板式换热器满足了区域供冷和热泵机组蒸发器、冷凝器的要求。从以上分析可知，tm 是换热的驱动力，若tm 小，即意味着驱动力小，要实现两种流体之间的换热，必须增大传热系数，增大传热面积，为了使传热面积不至过大，唯一的是增大传热系数 K。 浅密波纹板片是北京市京海换热设备制造有限责任公司开发的新型板片，它的传热系数约为 7000WK，是水平平直波纹板的 2 倍，是人字形波纹板的 1.5 倍，在区域供冷中时，检测的tm 约为 1.2。在作为冰蓄冷的乙二醇和

9、冷冻水的换热器使用中，tm 约为 1.5。 板式蒸发器、板式冷凝器也是北京市京海换热设备制造有限责任公司开发的适应于热泵机组的新型换热器。与管壳式蒸发器、冷凝器相比，它具有如下优点：单 位体积内板式蒸发器、板式冷凝器的传热面积约是管壳式换热器的 3倍；板式蒸发器的传热系数约为 10001200 WK，板式冷凝器的传热系数约为 15002000WK均为管壳式换热器的 23倍；在板式蒸发器上采用了使制冷剂液体分布均匀的分配器装置，当蒸发器板片数较多时，可能会出现制冷剂液体分配不均的，不能充分利用所有蒸发传热面积，使蒸发温度低于设计计算温度。采用分配器后即能克服上述问题。有关单位检测数据说明，板式蒸

10、发器、板式冷凝器的传热系数在tm 约为 2.53时，在 15002000 WK 之间，且阻力小，满足了热泵机组的要求。 小 NTU（0.32），大tm（4090）的板式换热器满足了热回收工艺和工艺加热、冷却的要求。当工艺过程在大tm的条件下进行换热时，说明驱动力大，所需的传热面积较小，对传热系数要求也不高，但，这种工艺过程或者工作压力高，或者工作温度高，或者工艺加热、冷却过程的液体中含有纤维或直径较大的颗粒，对板式换热器的承压、耐温能力提出了要求，对换热器的板间距提出了要求。 排（烟）气水板壳式换热器（省能器），排（烟）气空气板壳式换热器（空气预热器）是北京市京海换热设备制造有限责任公司和兰石

11、化共同开发出来的新型板式换热器，全焊接板式换热器中介质的换热是通过板管束来实现的，组成板管束的板片由专用模具压制成型，全焊接式板束装在压力壳内。波纹板片具有静搅拌作用，能在很低的雷诺数下形成湍流，且污垢系数低，传热系数是管壳式换热器的 23倍。为了适应换热量大，流体压降小的要求，板间距大，当量直径约为28。为了满足工艺的要求板束工作压力（反压） P4.5Mpa，板束工作压力（正压）同壳体工作压力，不受限制；工作温度 t550。乌鲁木齐石化分公司 40万吨年连续重整采用了进料（冷介质）和出料（热介质）的板壳式换热器，进料流量 50th，进、出口温渡 88，470。出料流量 50th，进、出口温度

12、 100，500，对数平均温差约 38，总传热系数约为 380kcalh，热负荷达 2310 kcal6h，进料压降 20Kpa，出料压降 50Kpa。 多效蒸发板式加热器（换热器），这种换热器既是工艺加热装置，又是重要的热回收装置。以前由于板式换热器的流道小（板间距 1.55.0 ），不适宜 于气气换热和蒸气冷凝；且易堵塞，故不宜用于含悬浮物的流体。为了尽量地发挥板式换热器的长处，克服存在问题，适应工艺的要求，北京市京海换热设备制造有限责任公司开发出了新型的多效蒸发板式换热器，这种板式换热器属宽流道型，其板间距为 8.0 ，适合于蒸气冷凝，适合于含悬浮物的流体，且不易堵塞，最大处理量达 12

13、00m h。3 原文New plate heat exchanger optimization SelectionAbstract: The plate heat exchanger Selection is based on the optimization of the use of heatexchangers and in the process of the parameters and NTU = KA / MC = t / tm, that is, transferunits of NTU and the temperature difference than (the aver

14、age temperature difference - Heat transferin power) choose plate shapes, plate heat exchanger and the type of structure.Key words: the average temperature difference between NTU plate evaporator condenser1 average temperature difference tmWhen the heat exchanger to heat-dQ, when the temperature rose

15、 to dt, C = dQ / dt, C will bedefined as heat capacity, it said units of time through the exchange of heat per unit area, dQ = K (th-tc)dA = K tdA, two of the fluid temperature changes were dth =- dQ / Ch, dtc =- dQ / Cc, d t = d(th-tc) = dQ (1/Cc-1/Ch), while dA = 1 / k (1/Cc-1/Ch) (d t / t), when

16、the A = 0 points to A =A0 when, A0 = 1 / k (1/Cc-1 / Ch) (tho-tci) / (thi-tco), because of two fluid exchangebetween the heat equivalent, that is, Q = Ch (thi-tho) = Cc (tco-tci), the simplified Know, Q = KA0(tho-tci) - (thi-tco) / (tho-tci) / (thi-tco), if t1 = thi-tco, t2 = tho-tci , Q = KA0 ( t1-

17、 t2) / ( t1 / t2) = KA0 tm, in- tm = ( t1- t2) / ( t1 / t2) .Down tm = (thi-tci) - (tho-tco) / (thi-tci) / (tho-tci)Countercurrent tm = (thi-tco) - (tho-tci) / (thi-tco) / (tho-tci)For various flow patterns in the same import, export under the conditions of temperature,the average temperature differ

18、ence between the largest counter-current.When the plate heat exchanger import and export of the fluid temperature differencebetween the two t1 and the difference between t2 not available when arithmetic averagetemperature ( t1 + t2) / 2, General t1 / t2 less than 1.5, May be, if t / t2 for 3:00, the

19、error is about 10 percent.1.2 the number of transfer unitsIn the heat transfer unit of the introduction of a few dimensionless parameters NTU, known as the number of transfer units, it said plate heat exchanger of the total thermal conductivity (heatexchanger heat resistance of the countdown) and th

20、e ratio of fluid heat capacity NTU = KA / MC, itsaid in relation to heat fluid flow, heat transfer capacity of the heat exchanger of the size of the heatexchanger that is, non-dimensional heat transfer capability. The plate heat exchanger for, KA / MC= t / tm, where t / tm known as the temperature d

21、ifference than, on the right side of theprocess used NTUp that left the conditions of heat transfer equipment used NTUE said. NTUp is fluidtemperature changes in temperature and the average ratio that is used 1 tm of several changes inthe value of fluid temperature changes, when tm large, NTUp is sm

22、all when tm hours, it hasbecome bigger The tendency. On the contrary, in NTUp larger in the process, tm of the largertemperature changes, NTUp smaller, its tm small changes in temperature (see table 1).Table 1 tm, NTUp relationslargeinintmtemperaturePlate heat exchanger, the optimal design, is known

23、 NTUE temperature difference than theconditions, to determine a reasonable model, processes and heat transfer area, equivalent to NTUpNTUE.1.3 heat transfer process and the NTUHeating and air-conditioning related to the heat transfer process if theshow are as follows: steam heating watera. steam 133

24、 133 Water 5 65 (hot water)b. Steam 133 133 water - water heat exchangerc. a water 65 60 Secondary water 45 40 (heating)d. a water 14 9 Water 55 65 (heating) secondary water 13 7 (refrigeration) e. a water 29 24 Secondary water 26 21 (refrigerator cooling)More than five cases of the process NTUp (se

25、e table 2)Table 2 heating air-conditioning process of NTUpNTUp（655）94.860.632（6555）72.880.13（4540）200.25（137）1.444.17（2621）31.67292426211.4 plate heat exchanger and NTUENTUE plate heat exchanger that the capacity of heat exchanger is the size of a certainlength of the heat and the combination of hea

26、t transfer units, the total length of heat transfer process isthe length and number of units of the product. When the total number of NTUE is, if the number ofprocesses for every 1 NTUe, then NTUE = n NTUe (where n is the number of processes).When NTUe = NTUE = NTUp, the heat exchanger for one-way.

27、If NTUe NTUp, the heatexchanger for many processes, it should be designed to target n. As each plate of one-way NTUevalue is essentially fixed value, such as in e Table 2 for the flow of 25 m3 / h of the one-way NTUeplate heat exchanger for 17 square meters. From NTUe = A K / MC tells us that when N

28、TUe to beon duty, A K is inversely proportional, still e example, when K = 500kcal / h time, A =1.67 25000/500 = 83.5 , the process of n = 83.5/17 5. When K = 2500kcal / h time,A = 16.7 square meters, the flow of n = 1. Each process NTUe as follows: K = 500, NTUe = NTUE / n = 0.33, K = 2500 when, NT

29、Ue = 1.67. So, can be obtained under NTUe the flow of heat exchangers,heat transfer coefficient and heat transfer area. From the above we can see that if the plate heatexchanger design unreasonable and likely to heat transfer area is too large, may also be partitioned sothat flow is too high, too mu

30、ch resistance.1.5 plate heat exchanger manufacturing and technological progress, plate type of increase,raising the plate heat exchanger of the various processes of adaptation. the NTU ( 8), small tm ( 1 2) the plate heat exchanger to meet the districtcooling and heat pump units evaporator, condense

31、r requirements. From the above analysis know, tm is the driving force of heat transfer, if tm small, means that the driver of small, to achieve theheat transfer between the two fluid, we must increase heat transfer coefficient, increasing heat transferarea, in order to Heat to make up too large, is

32、the only increase heat transfer coefficient K. shallow plate of corrugated Beijing, Beijing is the heat transfer equipment manufacturers limitedliability company developed a new type of plate, the heat transfer coefficient of about 7000 W / K, is the level of the flat corrugated board two times, is

33、chevron Corrugated sheets of 1.5 times, in theregional cooling, the detection of tm is about 1.2. As in ice storage of ethylene glycol and chilledwater use in the heat exchanger, tm is about 1.5. plate evaporator, condenser plate Beijing, Beijing is also the heat transfer equipmentmanufacturers limi

34、ted liability companies adapt to the development of a new type of heat pump unitsin the heat exchanger. And the shell-and-evaporator, compared to the condenser, which has thefollowing advantages: unit volume in the evaporator plate, the plate condenser is a heat transfer areaof shell and tube heat e

35、xchanger of three times the plate evaporator heat transfer coefficient About1000 1200 W / K, the condenser plate heat transfer coefficient of about 1500 2000 W / K are shell heat exchanger two to three times the plate on the evaporator used to Refrigerantdistributor of liquid evenly distributed devi

36、ces, when the evaporator plate a few more, may be unevendistribution of liquid refrigerant and can not take full advantage of all the heat and evaporation area,evaporation temperature lower than the calculated design temperature. After a distributor overcomethese problems. Detection of data on the r

37、elevant units, evaporator plate, the plate condenser in the heat transfer coefficient tm about 2.5 3 , in 1500 2000 W / K between the resistanceand small, satisfying the heat pump units Requirements. small NTU ( 0.3 2), the tm ( 40 90 ) of the plate heat exchanger to meetthe heat recovery process an

38、d the process heating and cooling requirements. When the process in the tm conducted under conditions of heat transfer, that driving force, the heat and the smaller, the heattransfer coefficient demand is not high, but that this process or high-pressure work, or work Hightemperature, or process heat

39、ing and cooling process in the liquid containing fiber diameter or largerparticles, the plate heat exchanger, the pressure, temperature and ability to request, the heat exchangerto the plate spacing requirements. Pai (breathing) gas - water shell heat exchanger (Province can), Pai (breathing) gas -

40、shell-air heatexchangers (air preheater) is a heat exchanger in Beijing Beijing-equipment manufacturers limitedliability Portland petrochemical companies and co-developed a new type of plate heat exchanger, allwelded plate heat exchanger in the heat transfer through the medium to achieve the control

41、 board,composed of board control by the plate for forming mold suppression, all-welded - Beam installed inthe pressure shell. Corrugated plate with static mixing, in a very low Reynolds number formed underthe turbulence, and low coefficient of dirt, the heat transfer coefficient is the shell and tube heatexchanger of the two or three times. In order to adapt to the heat transfer, fluid pressure on the request,board space, equivalent diameter of about 28 mm. In order to meet the demands of work pressureplate beam (Anti-pressure) P 4.5 Mpa, the pressure plate