Chemical Heat Transfer Quiz 1

1 / 50

**A ______ evaporator employs an annular downtake?**

2 / 50

**A hot body will radiate heat most rapidly, if its surface is_____?**

3 / 50

**According to Reynolds analogy, Stanton number is equal to (where, f = Fanning friction factor) ?**

4 / 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)?**

5 / 50

**Analogy between mass and heat transfer is not applicable in case of______?**

6 / 50

**A ______ surface has the maximum thermal emissivity out of the following ?**

7 / 50

**A 2-4 heat exchanger involves___________?**

8 / 50

**______ heat exchanger is used for chilling oil to be dewaxed?**

9 / 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__________?**

10 / 50

**A multiple effect evaporator as compared to a single effect evaporator of the same capacity has __________?**

11 / 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_________?**

12 / 50

**Air is best heated with steam in a heat exchanger of___________?**

13 / 50

**A black body when hot, emits heat radiation of ______ wavelengths?**

14 / 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?**

15 / 50

**_____ chart is known as transient heat conduction chart?**

16 / 50

**A graph between ______ is called Wilson plot?**

17 / 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 _____?**

18 / 50

**A dephlegmator is a_______?**

19 / 50

**Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity ?**

20 / 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 _______?**

21 / 50

**A diathermanous substance ________ the thermal radiation completely?**

22 / 50

**A black body does not _____ radiation?**

23 / 50

**?Fouling factor? used in the design of a multipass shell and tube heat exchanger is a_______?**

24 / 50

**1 BTU/hr.ft.?F is equal to ______ kcal/hr. m.?C?**

25 / 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 ?**

26 / 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___________?**

27 / 50

**A hollow sphere and a solid sphere of the same material and equal radii are heated to the same temperature. In this case ?**

28 / 50

**A BTU/hr.ft.2 ?F is equal to__________?**

29 / 50

**Absorptivity and reflectivity of a perfect black body are respectively ________?**

30 / 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___________?**

31 / 50

**Among liquids, water has a comparatively high value of thermal conductivity, due to its___________?**

32 / 50

**An equipment which converts the latent or sensible heat of one fluid into the latent heat of vaporisation of another, is called a__________?**

33 / 50

**An ejector is used to___________?**

34 / 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________?**

35 / 50

**All analogy equations connecting friction factor and heat transfer co-efficient apply only to _____?**

36 / 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_______?**

37 / 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___________?**

38 / 50

**A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides ___________?**

39 / 50

**?The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium?. This is _______ law?**

40 / 50

**A perfect black body is a perfect ______ of radiation?**

41 / 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___________?**

42 / 50

**______ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side?**

43 / 50

**?Duhring?s plot? is of use in__________?**

44 / 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?**

45 / 50

**A tank painted with which of the following coloured paints, would heat up maximum by radiation from sun ?**

46 / 50

**________ paint has the maximum absorption coefficient ?**

47 / 50

**______ paint has the minimum absorption co-efficient?**

48 / 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_____?**

49 / 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_____?**

50 / 50

**A body is called grey if the monochromatic emissivity of the body is_____?**

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