Chemical Heat Transfer Quiz 1
1 / 50
200 kg of solids (on dry basis) is subjected to a drying process for a period of 5000 seconds. The drying occurs in the constant rate period with the drying rate as, Nc = 0.5 ? 10-3 kg/m2.s. The initial moisture content of the solid is 0.2 kg moisture/kg dry solid. The interfacial area available for drying is 4 m2/1000 kg of dry solid. The moisture content at the end of the drying period is (in kg moisture/kg dry solid)?
2 / 50
________ paint has the maximum absorption coefficient ?
3 / 50
A ______ surface has the maximum thermal emissivity out of the following ?
4 / 50
?The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium?. This is _______ law?
5 / 50
According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor) ?
6 / 50
A diathermanous substance ________ the thermal radiation completely?
7 / 50
A dephlegmator is a_______?
8 / 50
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 _______?
9 / 50
______ paint has the minimum absorption co-efficient?
10 / 50
A black body when hot, emits heat radiation of ______ wavelengths?
11 / 50
A long iron rod initially at a temperature of 20?C has one end dipped in boiling water (100?C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40?C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time _____?
12 / 50
An ejector is used to___________?
13 / 50
A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?
14 / 50
Absorptivity and reflectivity of a perfect black body are respectively ________?
15 / 50
Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ?
16 / 50
A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is plotted against time. The plot will be very nearly a/an_____?
17 / 50
All analogy equations connecting friction factor and heat transfer co-efficient apply only to _____?
18 / 50
A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of___________?
19 / 50
A 2-4 heat exchanger involves___________?
20 / 50
A composite wall consists of two plates A and B placed in series normal to the flow of heat. The thermal conductivities are kA and kB and the specific heat capacities are CPA and CPB for plates A and B respectively. Plate B has twice the thickness of plate A. At steady state, the temperature difference across plate A is greater than that across plate B, when__________?
21 / 50
A process stream of dilute aqueous solution flowing at the rate of10 Kg.s-1 is to be heated. Steam condensate at 95?C is available for heating purpose, also at a rate of 10 Kg.s-1. A 1 ? 1 shell and tube heat exchanger is available. The best arrangement is________?
22 / 50
1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is___________?
23 / 50
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 the cases. The recommended arrangement is_________?
24 / 50
Analogy between mass and heat transfer is not applicable in case of______?
25 / 50
A body cools down from 75?C to 70?C in 10 minutes. It will cool down from 70? C to 65? C in _______ minutes?
26 / 50
An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a__________?
27 / 50
A ______ evaporator employs an annular downtake?
28 / 50
_____ chart is known as transient heat conduction chart?
29 / 50
A hot body will radiate heat most rapidly, if its surface is_____?
30 / 50
A multiple effect evaporator has a capacity to process 4000 kg of solid caustic soda per day, when it is concentrating from 10% to 25% solids. The water evaporated in kg per day is___________?
31 / 50
A steel sphere of radius 0.1 m at 400?K is immersed in an oil at 300?K. If the centre of the sphere reaches 350?K in 20 minutes, how long will it take for a 0.05 m radius steel sphere to reach the same temperature (at the centre) under identical conditions? Assume that the conductive heat transfer co-efficient is infinitely large ?
32 / 50
?Fouling factor? used in the design of a multipass shell and tube heat exchanger is a_______?
33 / 50
A black body does not _____ radiation?
34 / 50
A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case ?
35 / 50
A perfect black body is a perfect ______ of radiation?
36 / 50
A multiple effect evaporator as compared to a single effect evaporator of the same capacity has __________?
37 / 50
A graph between ______ is called Wilson plot?
38 / 50
An evaporator while concentrating an aqueous solution from 10 to 40% solids evaporates 30000 kg of water. The amount of solids handled by the system in kg is_____?
39 / 50
Air is best heated with steam in a heat exchanger of___________?
40 / 50
A dilute aqueous solution is to be concentrated in an evaporator system. High pressure steam is available. Multiple effect evaporator system is employed, because___________?
41 / 50
1 BTU/hr.ft.?F is equal to ______ kcal/hr. m.?C?
42 / 50
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 co-efficient for turbulent flow conditions is proportional to_______?
43 / 50
A BTU/hr.ft.2 ?F is equal to__________?
44 / 50
______ heat exchanger is used for chilling oil to be dewaxed?
45 / 50
A measure of the extent to which viscous heating is important relative to the heat flow resulting from the impressed temperature difference is represented by the ________ number?
46 / 50
?Duhring?s plot? is of use in__________?
47 / 50
Among liquids, water has a comparatively high value of thermal conductivity, due to its___________?
48 / 50
A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides ___________?
49 / 50
A body is called grey if the monochromatic emissivity of the body is_____?
50 / 50
______ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side?
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