化工原理填空與選擇 答案版

1、化工原理填空與選擇 答案版1, choice (1 point, 10 points)In a rectangular tube with a length of 3m or 2m, the diameter of the rectangular tube is (C).A. 1.2 m; B. 0.6 m; C. 2.4 m; D. 4.8 m.When the fluid flows in a circular, straight tube, the friction coefficient lambda is associated with the Reynolds number Re

2、(C) when entering the resistance square.A. Re increases, lambda increases B. Re increases, lambda decreases c. Re increases, and lambda increases basically the sameD. Re increases, the lambda goes up and then decreasesThe thinner the laminar layer, the following conclusion is correct (D).The lower t

3、he velocity gradient of the near wall, the lower the flow of turbulenceD. The greater the flow resistance4, in a certain line, when the pore diameter of orifice flow and the throat area of venturi meter phase at the same time, the same flow conditions, the orifice flow coefficient of venturi meter C

4、V and the size of orifice meter C0 orifice flow coefficient (D).A. CV = C0 B. C 0 C5, in the level of A variable diameter pipe, in the small tube cross section and fill section B connect A U tube differential pressure gauge, when the fluid flows through the section, the differential pressure meter r

5、eading R value response (A).A. the pressure differential between A and B two section b. flow resistance between A and B two section c. A and B the dynamic head changes between the two section d. sudden increase or decrease of local resistance6 fluid flows through two parallel lines, 1 and 2, both of

6、 which are stagflation. The pipe length L1 = 2L2, the inner diameter d1 = 2d2, the volume flow V1 / V2 is (C). .A. 1/2 B. 1/4 c. 1/8 d. 1/16The velocity value should be (C) when calculating the sudden expansion of the piping system and the local resistance of sudden reduction.A. the flow velocity in

7、 the downstream section of the sectionThe air is in a steady flow in the inner diameter of the tube, and if the air quality flux remains the same, when the temperature rises, the Re value will (B).A. increase b. reduce c. change d. uncertaintyThe following flowmeter does not belong to the throttling

8、 flowmeter (A)A. The rotameter B. Orifice flowmeter C. Venturi meterThe flowmeter should be (A) when measuring the flow with the rotor flowmeter.A. the vertical installation, flow to the bottom-up b. vertical installation, flow to the top-down c. horizontal installation, flow with convenient operati

9、on for the principle d. horizontal vertical installation, depending on site conditions1, using centrifugal pump will be low exposure container liquid to high airtight container, if change one of the following conditions, wont make the change pipeline characteristic curve, (B).A. The pressure of the

10、centrifugal pump of the centrifugal pump. The pressure DTransfer liquid between two open containers with centrifugal pump. If the liquid level of the two containers remains constant, the total resistance will be (B) when the valve in the pipeline is small.A. increase b. change c. reduce d. uncertain

11、ty3, in the determination of centrifugal pump performance, the table if the pressure after regulating valve, the pressure p2 readings will (B), pressure table, wrapped in regulating valve, the pressure p2 readings will be (A).As the traffic increases, the increase in traffic increases the CThe recip

12、rocating pump applies to (C).A. large flow and require extremely uniform flow rate of b. mediumC. low volume of traffic and high pressure head5, and some students used in the determination of centrifugal pump characteristic curve, start the pump, water outlet pipe is very small, pump inlet vacuum ga

13、uge indicates a high vacuum degree, he gave a correct judgment of the cause of the problem, ruled out fault, do you think the following possible reasons,Which is the real reason (C).A. the water is too hot b. the vacuum is too hotBefore the reciprocating pump is started, the outlet valve (A) must be

14、 set.A. open b. close c. close d. open7, self-absorbable pumps are (B).A. centrifugal b. reciprocation pump c. vortex pump d. axial pumpThe smaller the residual amount of the centrifugal pump, the anti-cavitation performance (A).A. the stronger B. The weaker c. noThe dust gas is deposited in the dus

15、t chamber by stokes law. Can completely remove 30 microns particles in theory, the gas capacity is doubled, the subsidence is still in the stokes zone, then the dust chamber theory can completely remove the smallest diameter (D).A. b. b. c. d.The following statement is correct (B).A. filtering rate

16、is proportional to the A (filter area) b. filtration rate is proportional to the A2 c. filtration rate is proportional to the volume of filtrate d. filtration rate is inversely proportional to the resistance of filter cloth3, constant pressure plate frame filter, when operating differential pressure

17、 doubled, at the same time the filtrate volume will (ignoring medium resistance) (A).To increase the size of A. Increase to 2 times the original.Increase to four times as much as before; D. the same4, the dust gas passes through the side length 4m, the width is 2m, the high ground 1m is in the dust

18、chamber, if the settlement velocity of the particle is, the production capacity of the dust chamber is (D).A. b. b. c. d.If the operating pressure difference is the same as in the filtration and washing, the viscosity of the wash water is the same as the viscosity of the filtrate. The plate frame fi

19、lter is used to wash the filter cake through the washing method, and the rate of washing is equal to (D) the rate at the end of the filter. The leaf filter adopts the displacement washing method, and the washing rate is equal to (A) the rate at which the filter ends.A. 1; B. 2; C. 0.5; D. 0.25The la

20、w of the relation between the radiation capacity of an object and its efficiency is (B).A. Stephen boltzmanns law of c. refractionB. kirchhoffs law d. universal lawBetween 2, A casing heat exchanger, tube with A saturated vapor turbulent flow of air is heated to the specified temperature, if need to

21、 further improve the outlet temperature of the air, will double heating tube diameter (length, flow state, and other conditions are the same), what do you think are the measures (A).A. not feasible b. feasibleIn the condenser, water condensing benzene steam, the water pipe, its Reynolds number, the

22、convection heat transfer coefficient is. If the flow of water is halved, its convection heat transfer coefficient (B).A. (1/2) B.C. = (1/2) D4, through the partition of cold hot water heat exchanger heat, hot water inlet temperature of 90 C, the outlet temperature of 50 C, cold water tube side, the

23、cold water inlet temperature is 15 C, outlet temperature of 53 C, hot and cold water flow is the same, and the physical properties of hot and cold water assumed to be the same, the heat loss of heat transfer in (A).A. 5.26% b. 5% c. 6% d. 7%In the process of heat transfer in the steam air, the follo

24、wing scheme is feasible for the following scheme (A).A. increase the air speed b. improve the steam flowC. use superheated steam to improve the steam temperatureAdd the fins to the side of the steam side, increase the condensation area and guide the condensation fluid in time6, a tube heat exchanger

25、 is 10 meters long, and the tube is heated with saturated water vapor. A certain flow of air flowing through the inner tube flows, and the temperature can rise to the specified temperature. Now to double air flow, and the approximate think heated side wall temperature is constant, to make the air ou

26、tlet temperature remains the original specified temperature, the length of the pipe heat exchanger as the original (C).A. twice b. 1.75 c. 1.15 times d. 2.30 timesIn the steam heat transfer, the presence of the non-condensable gas is (A) the effect of alpha.A. the presence of noncondensate causes al

27、pha to greatly reduce b. the presence of noncondensable gas increases alphaC. the presence of noncondensable gases has no effect on alpha8, double steady-state heat conduction of wall thickness are the same, the coefficient of thermal conductivity of each layer and, respectively, the corresponding t

28、emperature difference and, if , and the relationship between as (A).A. B. C. D. not sureGet pointsexaminers2, fill in the blanks (1 point, 20 points)The expression for the Reynolds number is _ Re = du rho/mu _. When the density of rho = 1000 kg. M , mu = 1 CPS viscosity of water, for d = 100 mm in d

29、iameter, flow velocity for 1 m. s flow in the tube, the Renault numeral equals _105_, the flow type is _ _ turbulence.When the atmospheric pressure is 750mmHg, the measured pressure of the system is 100mmHg, and the absolute pressure of the system is _113. 4_ _kPa, and the vacuum is _ -13.3 _ _Pa.3,

30、 when the 20 glycerin (rho = 1261 kg/m3, mu = 1499 centipoise) flow in the inner diameter of 100 mm tube, when the velocity of 1.0 m/s, the Renault numeral Re for _84. 1 _, the friction coefficient of lambda is _0. 761 _ _.4, the oil of rice bran is flowing in the tube, if the flux is constant, the

31、tube length is changeless, the diameter of the tube is doubled, and the friction resistance loss is _1/16_.When the flow of the fluid flows in the tube, the friction coefficient lambda =, if the flow is in the turbulent region, the lambda is,The function of; If the flow is in a completely turbulent

32、area, the friction coefficient of the rough tube is only related to.The flow of the fluid in the circular direct tube, if the diameter of the tube must be doubled, the energy loss of the laminar flow is originalTwice as much, the energy loss is four times as big as it was when it was completely turb

33、ulent. (ignoring epsilon/d changes)7, fluid flow in the circular straight pipe, if the flow rate decreases the diameter must be doubled, the laminar flow energy loss is 16 times, fully turbulent energy loss is 32 times. (ignoring epsilon/d changes)8, reducing pipeline section, as shown in the tube w

34、ith fluid from A to B, and the measured U type differential pressure meter readings for R1, when fluid flow from B to A place, the measured U type differential pressure meter readings for R2, try to compare the size of the R1 and R2:R1 R2.1, the pump system of a water transmission, the calculation o

35、f the tube road, the pressure head for the pump is H = 19m water column, and the water capacity is 20kg. S-1, the effective power of the pump is _3728w_.The method of regulating centrifugal pump discharge is: changing the opening of the valve; Change the speed of the pump; The diameter of the turnin

36、g impeller.The fluid density of the centrifugal pump is greater, and when the flow is certain, the output of the pump is constant, the efficiency is constant, and the shaft power _ is greater.Use centrifugal pumps to transport water from the river to a high exposure slot. Now the water is rising in

37、the river, and if the channel is not changing, the centrifugal pump is flowingThe shaft power, the total energy loss of the line.Transfer liquid to high-pressure containers with centrifugal pump. If the pressure vessel to atmospheric pressure, other things being equal, the centrifugal pump flow, sha

38、ft power, line the total energy loss.The flow rate of the pump, such as the reciprocating pump and the vortex pump, depends on the pump characteristics, and the pressure head depends on the piping characteristics.7, if be conveying fluid viscosity increases, the head of centrifugal pump is reduced,

39、the flow is reduced, the efficiency drop, shaft power increased.If the height of the dust chamber increases, the settlement time increases, the flow rate decreases, and the production capacity remains unchanged.The room is 8m long, 4m wide, 1.5m high, with 14 partitions in the centre and 0.1 m apart

40、. Now, minimum diameter is 12 m, the settling velocity of 0.02 m/s, intends to minimum diameter of particle settling down, all the dust gas maximum velocity cannot be more than 1.6 m/s.In the cyclone,A spherical particle has a radius of 0.4 m, which is 15 m/s. When the relative motion of the particl

41、e and fluid is a laminar flow, the separation factor is 57.4, the filter method is mainly, and.Two fluidized forms of fluidized bed are sum.The abnormal phenomenon of fluidized bed is and.1, fluid flow in vertical tube from top to bottom is heated at the same time, the convection heat transfer coeff

42、icient than ordinary numeral calculation result of correlations.The heat resistance of convection heat transfer is mainly concentrated in the stagnant inner layer, therefore, the thickness of the inner layer of thinning turbulence is an important way to enhance convection heat transfer.3, the surfac

43、e of the blackbody temperature from 300 to 600 , its radiation ability increases to 5.39 times.The organic solution for 440kg/h is preheated in a heat exchanger. After a period of operation, the solution generates a scale of deposit in the tube, which increases the total heat resistance of the heat

44、exchanger by 10%. If the temperature of the temperature of the temperature of the cold and hot medium is constant, the amount of the solvent should be changed to 400kg/h.The three basic methods of heat transfer are: heat conduction, convection, heat radiation.The two basic forms of liquid boiling ar

45、e:.A pack of steam pipes with asbestos clay insulation layer, which is less effective when the asbestos is damp. The reason is that the conductivity of water is greater than that of asbestos.8, composed of multilayer flat after wall thermal insulation layer, the greater the thermal conductivity of m

46、aterials if a layer, the layer is the smaller thermal resistance, the smaller the temperature difference on both sides of the.9, water turbulent flow in pipe, if the velocity of up to 2 times, is the convection heat transfer coefficient is about 1.74, if half of the pipe diameter is changed to the o

47、riginal, is the convection heat transfer coefficient is about 3.48.10, through a heat exchanger, with saturated steam heating water, can make the temperature of water increased from 20 to 80 . Found water outlet temperature reduced, check the water inlet temperature and flow rate has no change, satu

48、rated vapor temperature also has no change, then the causes of water temperature decline might be non-condensable gas no emissions, condensate not discharge in time, the surface of the heat exchange tube fouling11, a certain quality of fluid in the inner diameter is 25 * 2.5 force turbulent flow in

49、the straight pipe, the convection heat transfer coefficient a = 1000, if flow rate is unchanged, and physical properties change, including the 19 * 2 straight pipe flow, it is 1678.4 a.No, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no, no.The readings R of the U tube differe

50、ntial pressure gauge indicates the difference between the static pressure of the two pressure points and the difference of the position (y,).The fluid particles in the turbulent boundary layer are all turbulent motion (x).No matter how the fluid flows, the ratio of the mosa factor to the flow is rel

51、ated to the relative roughness of the pipe wall (x).5, regardless of the flow state of the fluid, the ratio of the mosa to the flow is related to the Reynolds number at the time of flow (x).The energy loss of each branch of the pipe is equal (y).The energy loss of each branch of the branch line is t

52、he same. (x)8, pitot tube can be read directly measuring the average speed of cross-section (x)The orifice flowmeter belongs to the fixed section and the differential flowmeter. For the measured system, its flow coefficientIs a constant (x)The rotor flowmeter is a constant pressure differential and

53、cross-sectional flow meter. When measured, the value read on the flowmeter is itsReal traffic (x)When measuring the flow with a rotameter, the value of the rotor on the top of the rotor is the value to read. (x)Before the centrifugal pump is started, it will not be injected into the conveyor flow. (yes,)No gas erosion occurs before the c