Description : Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both ... steam on shell side (D) Shell and tube heat exchanger with air on shell side and steam inside tubes
Last Answer : (B) Finned tube heat exchanger with air outside and steam inside
Description : Is there a quick rule-of-thumb to estimate a gas side heat-transfer rate inside the tubes of a shell and tube heat exchanger?
Last Answer : If you need to estimate a gas heat transfer rate or see if a program is getting a reasonable gas rate, use the following: h = 75 X Sq. Root(Op. pressure/100) The operating pressure is ... will be lower for the shell side or if there is more than one exchanger. Source: Gulley Computer Associates
Description : The critical radius of insulation for cylindrical pipe is (where, hi = heat transfer coefficient at inside of the pipe) (A) K/h0 (B) 2K/h0 (C) hi /K (D) 2hi /K
Last Answer : (A) K/h0
Description : Overall heat transfer co-efficient for cooling of hydrocarbons by water is about (A) 50 -100 Kcal/hr.m2 .°C (B) 50 -100 W/m2 .°K (C) 50 -100 BTU/hr. ft. 2°F (D) 1000 - 1500 BTU/hr. ft. 2°F
Last Answer : (C) 50 -100 BTU/hr. ft. 2°F
Description : Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone. (A) Laminar (B) Transition (C) Both 'a' & 'b' (D) Highly turbulent
Last Answer : (D) Highly turbulent
Description : In a shell and tube heat exchanger, floating head is used for (A) Large temperature differentials (B) High heat transfer co-efficient (C) Low pressure drop (D) Less corrosion of tubes
Last Answer : (A) Large temperature differentials
Description : A coal with high ash content is undesirable, as (A) It is abrasive to the coal pulveriser (i.e. ball mill) and the combustion chamber (B) The ash in molten condition gets absorbed in the pores of the ... and stick to the boiler tubes thereby reducing the heat transfer (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : Pick out the wrong statement. (A) Longer tubes are less expensive per unit heat transfer area as compared to shorter tubes (B) A cost index is merely a number for a given year ... butt welded joints are less expensive compared to lap welded joints, because squaring of plates is not necessary
Last Answer : (D) Plates with butt welded joints are less expensive compared to lap welded joints, because squaring of plates is not necessary
Description : Baffles provided on the shell side of a shell and tube heat exchanger are meant for (A) Providing support for the tubes (B) Improving heat transfer (C) Both 'a' & 'b' (D) Preventing the fouling of tubes & stagnation of shell side fluid
Last Answer : C) Both 'a' & 'b'
Description : Condensing film co-efficient for steam on horizontal tubes ranges from 5000 to 15000 Kcal/hr.m2 .°C. Condensation of vapor is carried out inside the tube in a shell and tube heat ... drop through the exchanger is desired (D) Temperature of the incoming vapor is very high
Last Answer : (B) Supersaturated
Description : In an extended surface heat exchanger, fluid having lower co-efficient (A) Flows through the tube (B) Flows outside the tubes (C) Can flow either inside or outside the tubes (D) Should not be used as it gives very high pressure drop
Last Answer : (B) Flows outside the tubes
Description : A metal wire of 0.01 m dia and thermal conductivity 200 W/m.K is exposed to a fluid stream with a convective heat transfer coefficient of 100 W/m2 .K. The Biot number is (A) 5.6 (B) 0.025 (C) 3.5 (D) 0.0035
Last Answer : (B) 0.025
Description : The critical radius of insulation for a spherical shell is (where, K = thermal conductivity of insulating material h0 = heat transfer coefficient at the outer surface) (A) K/h0 (B) 2K/h0 (C) h0 /K (D) h0 /2K
Last Answer : (B) 2K/h0
Description : Overall heat transfer co-efficient of a particular tube is U1 . If the same tube with some dirt deposited on either side has coefficient U2 , then (A) U1 = U2 (B) U2 > U1 (C) U1 > U2 (D) U1 = dirt factor - U2
Last Answer : (A) U1 = U2
Description : For the same heat load and mass flow rate in the tube side of a shell and tube heat exchanger, one may use multipass on the tube side, because it (A) Decreases the pressure drop (B) ... the outlet temperature of cooling medium (C) Increases the overall heat transfer coefficient (D) None of these
Last Answer : (C) Increases the overall heat transfer coefficient
Description : For a heat exchanger, will the overall heat transfer coefficient increase along with an increase in LMTD (log mean temperature difference) around the unit?
Last Answer : The overall heat transfer coefficient is generally weakly dependent on temperature. As the temperatures of the fluids change, the degree to which the overall heat transfer coefficient will be affected depends ... with temperature as I've noted and the U-value will decrease over time with fouling).
Description : What is heat transfer coefficient ?
Last Answer : The method by which the molecules of a substance do not change their own position but simply give a molecule heat to its adjacent molecule by vibration and transfer heat from the warmer part to the cooler part of the substance is called heat transfer coefficient.
Description : Give the unit of overall heat transfer coefficient in SI and MKS.
Last Answer : Unit of overall heat transfer coefficient 1. In SI : W/m2K 2. In MKS : kcal/hr m2K
Description : Define film heat transfer coefficient.
Last Answer : Film heat transfer coefficient: Film heat transfer coefficient h is defined as the quantity of heat transferred in unit time through unit area at a temperature difference of 10 between the surface and surrounding.
Description : Plastic tubes & pipes are generally made by __________ moulding. (A) Injection (B) Transfer (C) Extrusion (D) Compression
Last Answer : (C) Extrusion
Description : . If all the conditions and dimensions are same, then the ratio of velocity through the tubes of a double pass heat exchanger to that through the single pass heat exchanger is (A) 1 (B) 2 (C) 1/2 (D) 4
Last Answer : (B) 2
Description : The purpose of floating head in a heat exchanger is to (A) Avoid buckling of tubes (B) Provide support for tubes (C) Decrease the pressure drop (D) Facilitate its lengthening, if needed
Last Answer : (A) Avoid buckling of tubes
Description : Pick out the wrong statement: (A) The capacity of an evaporator is reduced by the boiling point elevation (B) Corrosive liquid is normally passed through the tubes in a ... recompression evaporator (D) Heat sensitive materials should be concentrated in high pressure evaporators
Last Answer : (D) Heat sensitive materials should be concentrated in high pressure evaporators
Description : The main function of baffles provided in a shell and tube heat exchanger is to (A) Facilitate the cleaning of outer tube surface (B) Enhance turbulence (C) Hold the tubes in position (D) All 'a', 'b' & 'c'
Last Answer : (B) Enhance turbulence
Description : Vibrations in the tubes of a shell and tube heat exchanger is induced due to the (A) Flow of fluid on the tube and shell sides (B) Oscillations in the flow of shell/tube sides fluid (C) Vibrations ... piping and/or supports due to external reasons (D) All (A), (B) and (C)
Description : Heat exchanger tubes are never made of (A) Plain carbon steel (B) Stainless steel (C) Lead (D) Copper
Last Answer : (C) Lead
Description : In a gas-liquid shell and tube heat exchanger, the (A) Presence of a non-condensable gas decreases the condensing film coefficient (B) Gases under high pressure are routed through the tube side, because high pressure ... water or steam condensate remain localised to the tubes (D) All 'a', 'b' & 'c'
Last Answer : (D) All 'a', 'b' & 'c'
Description : In a heat exchanger with steam outside the tubes, a liquid gets heated to 45°C, when its flow velocity in the tubes is 2 m/s. If the flow velocity is reduced to 1 m/s, other things remaining ... than 45°C (B) More than 45°C (C) Equal to 45°C (D) Initially decreases and remains constant thereafter
Last Answer : (B) More than 45°C
Description : How can one estimate how the friction factor changes in heat exchanger tubes with a change in temperature?
Last Answer : Seider and Tate recommended the following for determine friction factors inside heat exchanger tubes with varying temperatures: First, determine the average, bulk mean temperature in the processing line. For example if ... 0.11 and for heating, it's divided by (bulk viscosity/wall viscosity)0.17.
Description : Pick out the wrong statement. (A) The Reynolds analogy for mass transfer is given by Lewis relation and is applicable, when Schmidt number is one (B) Sherwood number for flow in pipes can be expressed ... flux of a component A in binary mixture of A and B is given by - Dab'.dCA/dz
Last Answer : (C) According to film theory for equimolar counter diffusion, the mass transfer coefficient is given by DAB(B)P - 3, Q - 2
Description : Mass transfer co-efficient is defined as (A) Flux = Co-efficient/concentration difference (B) Co-efficient = Flux/concentration difference (C) Flux=concentration difference/coefficient (D) None of these
Last Answer : (B) Co-efficient = Flux/concentration difference
Description : H2S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of H2S ... by, y = 5x + 0.001 is (A) 2.0 (B) 1.56 (C) 1.0
Last Answer : (A) 2.0
Description : Heat transfer co-efficient (h) for a fluid flowing inside a clean pipe is given by h = 0.023 (K/D) (DVρ/µ) 0.8 (CP .µ/k) 0.4 . This is valid for the value of NRe equal to (A) < 2100 (B) 2100-4000 (C) > 4000 (D) > 10000
Last Answer : (D) > 10000
Description : A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer coefficient for turbulent flow conditions is proportional to (A) d 0.8 (B) d -0.2 (C) d -1 (D) d -1.8
Last Answer : (B) d -0.2
Description : The inside heat transfer co-efficient in case of turbulent flow of liquid in the tube side in a 1-2 shell and tube heat exchanger is increased by __________ times, when the number of tube passes is increased to 8. (A) 2 0.8 (B) 4 0.8 (C) 4 0.4 (D) 2 0.4
Last Answer : (B) 4 0.8
Description : Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is 3k/l'. If the wall temperature ... wall temperature in degree centigrade? (A) 35.5 (B) 43.75 (C) 81.25 (D) 48.25
Last Answer : (C) 81.25
Description : A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place (A) The better insulation material should be put just ... to which insulating material is to be put inside (i.e., just next to the pipe)
Last Answer : (A) The better insulation material should be put just next to pipe (i.e., inside)
Description : Why are hydrocarbons currently the main source of world’s electrical energy and heat source?
Last Answer : The energy produced when burnt often this energy is used directly as heat as in home heaters which use either oil or natural gas.
Description : Size of boiler tubes is specified by a) Mean diameter and thickness b) Inside diameter and thickness c) Outside diameter and thickness d) Outside diameter and inside diameter
Last Answer : c) Outside diameter and thickness
Description : What is procedure of calculation for the volume of certain objects, one of 10 kg and another of 100 kg, with an approximation of 10%?
Last Answer : You need to know the density of what you are measuring. 1 litre of water = 1kg. 1 litre of oil is less than 1kg. 1 litre of mercury = more than 1kg. Volume measures are NOT weight measures. ... litre of rice vs 1 litre of sugar, or packed brown sugar. They are all going to be different weights.
Description : Where can I find the detailed information about Successive Approximation method and discrete newton method？?
Last Answer : answer:A DISCRETE NEWTON ALGORITHM FOR MINIMIZING A FUNCTION OF MANY VARIABLES SUCCESSIVE APPROXIMATIONS
Description : What mathematical equation do I use relating to normal approximation to the binomial?
Last Answer : answer:@peachfuzz I see you are new here so I will try to explain this without getting into a fight with you. I see that has happened already with another member. No need to call names from either of us. On ... of thought. Do you know the answer to part A? If so, we can go from there. Good luck.
Description : When a smooth curve is approximated through the data points, then the curve is knownas a.approximation curve b.pitch curve c.data curve d.interpolant curve
Last Answer : a.approximation curve
Description : When the curve passes through all the data points, then the curve is known as a.approximation curve b.pitch curve c.data curve d.interpolant curve
Last Answer : d.interpolant curve
Description : When a smooth curve is approximated through the data points, then the curve isknown as a.interpolant curve b.approximation curve c.pitch curve d.data curve
Last Answer : b.approximation curve
Description : What the area of each circle. Use 3.14 as an approximation for π?
Last Answer : That depends on its radius which has not been given but the area of a circle is pi*radius squared
Description : Which of the following surgical techniques lead to improved wound healing? a. Atraumatic handling of tissue b. Approximation of underlying fatty tissue to obliterate dead space c. Protecting the wound from water for at least one week d. Meticulous hemostasis
Last Answer : Answer: a, d There are numerous practical implications for the care of wounds and surgical incisions. Meticulous hemostasis reduces the inflammation of phagocytosis necessary to clear the wound of ... or shower one or two days after surgery actually serves useful purpose in debriding the wound
Description : Which of the following tissues contain significant collagen useful for placing sutures to allow the prolonged tension necessary to maintain tissue approximation? a. Dermis b. Intestinal submucosa c. Muscular fascia d. Blood vessel wall
Last Answer : Answer: a, b, c, d It takes at least three weeks for collagen to undergo sufficient remodeling and cross linking to attain moderate strength. Since most skin sutures are removed at one to ... , Scarpa's fascia, and blood vessel wall represent a partial list of tissues with high collagen content
Description : Which causes a quantization noise in PCM system? A. Serial transmission errors B. The approximation of the quantized signal C. The synchronization between encoder and decoder D. Binary coding techniques
Last Answer : B. The approximation of the quantized signal
Last Answer : The approximation of the quantized signal