Description : Pick out the correct statement. (A) 1 kcal/hr.m.°C is equal to 1 BTU/hr. ft.°F (B) In steady state heat conduction, the only property of the substance which determines the ... in the direction of temperature rise (D) In heat transfer by forced convection, Grashoff number is very important
Last Answer : (B) In steady state heat conduction, the only property of the substance which determines the temperature distribution, is the thermal conductivity
Description : Three materials A, B and C of equal thickness and of thermal conductivity of 20, 40 & 60 kcal/hr. m. °C respectively are joined together. The temperature outside of A and C are 30°C and 100°C respectively. The interface ... C will be at a temperature of __________ °C. (A) 40 (B) 95 (C) 70 (D) 50
Last Answer : (C) 70
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 : 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 : The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the ... temperature of the right face in °C is (A) 77.2 (B) 71.2 (C) 63.8 (D) 48.7
Last Answer : (D) 48.7
Description : 1 BTU/hr.ft.°F is equal to __________ kcal/hr. m.°C. (A) 1.49 (B) 1 (C) 4.88 (D) None of these
Last Answer : (A) 1.49
Description : A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0 ... that of the un-insulated steam pipe (D) Less than the steam pipe with 5 cms insulation
Last Answer : (B) Less than that of the un-insulated steam pipe
Description : A BTU/hr.ft. 2 °F is equal to (A) 1 kcal/hr. m2°C (B) 4.88 kcal/hr. m. 2°C (C) 1 kcal/hr. m2 .°K (D) None of these
Last Answer : (B) 4.88 kcal/hr. m. 2°C
Description : Pick out the wrong statement: (A) With change in temperature, the radiant energy emitted by a black body remains unchanged (B) Absorptivity of a body approaches unity in case of diffuse reflection (C) Absorptivity of ... unity (D) Value of Stefan-Boltzmann constant is 4.876 10 -8 KCal/m2 .hr.°K4
Last Answer : (A) With change in temperature, the radiant energy emitted by a black body remains unchanged
Description : Thermal diffusivity of a material (A) Has the unit m2 /sec (B) Is defined as K/ρ . Cp (C) Is the ratio of thermal conductivity to thermal capacity (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C
Last Answer : (C) 35°C
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 : In SI units, thermal conductivity is expressed in (A) Watt/m.°K (B) Watt/m2 . °K (C) Watt/m2 . °K (D) Watt/m4 . °K
Last Answer : (A) Watt/m.°K
Description : What is the critical radius of insulation (cms) for a metallic cylinder, if the convective heat transfer co-efficient with the ambient atmosphere is 5 W/m2. °K? Thermal conductivity of metal and insulation material are 40 and 0.1 W/m.°K respectively. (A) 2 (B) 8 (C) 10 (D) 40
Last Answer : (A) 2
Description : A wall has two layers of materials A and B; each made of a different material. Both the layers have the same thickness. The thermal conductivity of material A is twice that of B. Under the equilibrium, the temperature ... difference across the layer A is __________ °C. (A) 6 (B) 12 (C) 18 (D) 24
Last Answer : (B) 12
Description : Heat required to raise the temperature of a body by 1 °C is called its (A) Heat capacity (B) Specific heat capacity (C) Thermal conductivity (D) Water equivalent
Last Answer : (A) Heat capacity
Description : A thin, flat & square plate measuring 2 m 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will ... heat transfer co-efficient is __________ W/m2 °C. (A) 50 (B) 100 (C) 150 (D) 200
Last Answer : (B) 100
Description : Pick out the wrong statement. (A) Bubble size increases with the dynamic viscosity of the liquid in case of nucleate pool boiling (B) Thermal conductivity of a dry material is more than ... in kg/hr in an evaporator (D) Vaporisation of organic substances in evaporator mostly causes foam formation
Last Answer : (B) Thermal conductivity of a dry material is more than that of the damp material
Description : In fluid flow, and heat and mass transfer, one encounters (i) kinematic velocity (μ), (ii) molecular diffusivity (θ) and thermal diffusivity (α). The units of these quantities are. (A) μ , α and θ all have units of m/ ... μ has unit of m/s (D) α and θ have units of m/s, while μ has unit of m2/s
Last Answer : Option C
Description : In a heat exchanger, one transfer unit means (A) A section of the exchanger in which change in temperature of one stream equals the average driving force in the section (B) The size of the exchanger in which heat transfer rate is 1 kcal/hr (C) Both (A) and (B) (D) None of these
Last Answer : (A) A section of the exchanger in which change in temperature of one stream equals the average driving force in the section
Description : Compound A is extracted from a solution of A + B into a pure solvent S. A Co-current unit is used for the liquid-liquid extraction. The inlet rate of the solution containing A is 200 moles of B/hr.m2 and the ... extraction achieved in the unit is (A) 25% (B) 50% (C) 70% (D) 90%
Last Answer : (B) 50%
Description : Unit of furnace loading is (A) Ton stock/hr/m2 hearth area (B) Ton stock/hr (C) Ton stock/m2 hearth area (D) Both (B) and (C)
Last Answer : (A) Ton stock/hr/m2 hearth area
Description : Unit of mass velocity is (A) kg/hr (B) kg/m2 . hr (C) kg/m2 (D) kg/m3 . hr
Last Answer : (B) kg/m2 . hr
Description : The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area in m2 , V = rising velocity of fluid in m/sec, S = percentage of solids in the suspension by volume, ρ = density of solids in kg/m3 ) (A) 3.6 AVS.ρ (B) 3.6 A.V.ρ (C) 3.6 A.S. ρ (D) 3.6 AVS/ρ
Last Answer : (A) 3.6 AVS.ρ
Description : 1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m2 and the overall heat transfer co-efficient to the ... will be (A) 15 min (B) 22 min (C) 44 min (D) 51 min
Last Answer : (D) 51 min
Description : Normal values of overflow rate for plain sedimentation tank using coagulants, is (A) 750 to 1000 litres/hr/m2 (B) 1000 to 1250 litres/hr/m2 (C) 1250 to 1500 litres/hr/m2 (D) 1500 litres/hr/m
Last Answer : (B) 1000 to 1250 litres/hr/m2
Description : Normal values of overflow rate for plain sedimentation tank, is (A) 250 to 500 litres/hr/m2 (B) 500 to 750 litres/hr/m2 (C) 750 to 1000 litres/hr/m2 (D) 1000 to 1250 litres/hr/m
Last Answer : (B) 500 to 750 litres/hr/m
Description : . The inner wall of a furnace is at a temperature of 700°C. The composite wall is made of two substances, 10 and 20 cm thick with thermal conductivities of 0.05 and 0.1 W.m-1.°C-1 respectively. The ambient air is at 30°C ... from the outer surface in W.m-2 is (A) 165.4 (B) 167.5 (C) 172.5 (D) 175
Last Answer : (A) 165.4
Description : The temperature at which the magnetic property of iron disappears (i.e., it becomes non-magnetic) and its electrical conductivity & specific heat also changes, is called the 'Curie point', which is __________ °C. (A) 768 (B) 908 (C) 1400 (D) 1539
Last Answer : Option A
Description : Heat load in a cooling tower (A) Means the amount of heat thrown away (KCal/hr.) by the cooling tower (B) Is equal to the number of kg, of water circulated times the cooling range (C) Both (A) & (B) (D) Neither (A) nor (B)
Last Answer : (C) Both (A) & (B)
Description : Steam side heat transfer co-efficient in an evaporator is in the range of __________ kcal/hr.m2°C. (A) 10-50 (B) 100-500 (C) 1000-1500 (D) 5000-15000
Last Answer : (D) 5000-15000
Description : Rate of heat release in a furnace, which is the measure of heat intensity, is defined as (A) kcal/hr/m3 combustion space (B) kcal/m3 combustion space (C) kcal/hr (D) None of these
Last Answer : (A) kcal/hr/m3 combustion space
Description : One ton of refrigeration capacity is equivalent to the heat removal rate of (A) 50 kcal/hr (B) 200 BTU/hr (C) 200 BTU/minute
Last Answer : (C) 200 BTU/minute
Description : Pick out the wrong statement. (A) Reciprocal of the resistance to heat flow is called thermal conductance (B) Unit of thermal conductance is W/°K (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A (D) None of these
Last Answer : (C) Thermal conductance of a wall of thickness 'L', thermal conductivity 'k' and heat flow area 'A' is kL/A
Description : Heat transfer rate per unit area is called (A) Thermal conductivity (B) Heat flux (C) Heat transfer co-efficient (D) Thermal diffusivity
Last Answer : (B) Heat flux
Description : Water filtration rate in a rapid sand filter ranges from __________ kilolitres/m2 /hr. (A) 0.1 to 1 (B) 3 to 6 (C) 10 to 15 (D) 15 to 20
Last Answer : (B) 3 to 6
Description : Water filtration rate in a slow sand filter ranges from __________ litres/m2 /hr. (A) 10 to 20 (B) 100 to 200 (C) 1500 to 2500 (D) 4000 to 5000
Last Answer : (B) 100 to 200
Description : The variation of thermal conductivity of a metal with temperature is often correlated using an expression of the form K = K0 + at, where, K is the thermal conductivity and T is the temperature (in °K). The units of 'a' in SI system will be (A) W/m.k (B) W/m (C) W/m.k
Last Answer : (C) W/m.k
Description : A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of ... and thickness __________ metre. (A) 0.01 (B) 0.1 (C) 0.25 (D) 0.5
Last Answer : (B) 0.1
Description : One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is (A) 100 (B) 900 (C) 9000 (D) 10000
Last Answer : (D) 10000
Description : A rod 3 m long is heated from 10°C to 90°C. Find the expansion of rod. Take Young’s modulus = 1.0 x 10^5 MN/m2 and coefficient of thermal expansion = 0.000012 per degree centigrade. 1. 0.168 cm 2. 0.208 cm 3. 0.288 cm 4. 0.348 cm
Last Answer : 3. 0.288 cm
Description : One tonrefrigeration corresponds to (a) 50 kcal/min (b) 50 kcal/kr (c) 80 kcal/min (d) 80 kcal/hr
Last Answer : Ans: a
Description : Calculate the recoverable waste heat (Q, in kCal/hour) from flue gases using the followingparameters: V (flow rate of the substance) 2000 m3/hr r (density of the flue gas): 0.9 kg/m3 Cp (specific heat ... (temperature difference): 120 oC h (recovery factor): 50% a. 21600 b. 43200 c. 25600 d. 34000
Last Answer : 21600
Description : What refers to the rate of thermal radiation emitter per unit area of a body? A. Thermal conductivity B. Absorptivity C. Emissivity D. Emissive power
Last Answer : Emissive power
Description : The unit of conductance in SI unit is (A) W/m (B) W/m2 (C) W/°K (D) W/m°K
Last Answer : (C) W/°K
Description : . One stoke (unit of kinematic viscosity) is equivalent to (A) 1 cm2 /second (B) 1 m2 /second (C) 1 gm/cm. second (D) 1 kg. m/second
Last Answer : (A) 1 cm2 /second
Description : The unit of bulk modulus of elasticity for a liquid in S.I. unit is (A) N (B) N/m (C) N/m2 (D) N/m3
Last Answer : (C) N/m2
Description : The unit of dynamic viscosity in SI unit is (A) kg/m. sec (B) N/m2 (C) m2 /sec (D) m/N. sec
Last Answer : (A) kg/m. sec
Description : 5. Unit of surface tension in S.I. unit is (A) Watt/m (B) Joule/m2 (C) Newton/m2 (D) Joule/m
Last Answer : Option B
Description : Normal values of overflow rate for sedimentation tanks using coagulants in litres/hr/m2 , generally range between (A) 250 to 500 (B) 500 to 750 (C) 750 to 1000 (D) 1000 to 1250
Last Answer : (D) 1000 to 1250