Question: 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 liquid is 1500 W/m2.°C. Assuming

• 1. 15 min
• 2. 22 min
• 3. 44 min
• 4. 51 min

Question: For evaporation of viscous solution in a multiple effect evaporator, the preferred feeding scheme is _________________?

• 1. Forward
• 2. Backward
• 3. Parallel
• 4. None of these

Question: A backward feed multiple effect evaporator is better than forward feed for concentrating cold feed, because it provides __________________?

• 1. Higher economy
• 2. Lower capacity
• 3. Both A & B
• 4. Lower economy

Question: Pick out the wrong statement?

• 1. The capacity of an evaporator is reduced by the boiling point elevation
• 2. Corrosive liquid is normally passed through the tubes in a shell and tube heat exchanger
• 3. Steam jet ejector is used for vapor compression in a thermal recompression evaporator
• 4. Heat sensitive materials should be concentrated in high pressure evaporators

Question: Pick out the wrong statement ?

• 1. Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient
• 2. In a shell and tube heat exchanger, the shell pressure drop is maximum for orifice baffles
• 3. S.I. unit of fouling factor is Watt/m2.°K
• 4. Longitudinal fins are used in extended surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Question: Which of the following is correct ?

• 1. Rate = Driving force × Resistance
• 2. Driving force = Rate × Resistance
• 3. Resistance = Driving force × Rate
• 4. Rate = Resistance/Driving force

Question: Pick out the wrong statement ?

• 1. Heat transfer by radiation cannot occur across an absolute volume
• 2. In case of a shell and tube heat exchanger, the pressure drop through the shell is proportional to the number of times the fluid crosses the bundle between baffles
• 3. Propagation velocity for travel of heat radiation through vacuum is equal to the velocity of the light
• 4. The amount of heat involved in the condensation or vaporisation of 1 kg of a fluid is the same

Question: Pick out the wrong statement?

• 1. Swenson-Walker crystalliser is a batch crystalliser
• 2. Super saturation of the solution is the driving potential for a crystal growth
• 3. The liquor left after the removal of crystals from a solution is called mother liquor
• 4. The first stage of crystal formation is called nucleation

Question: Pick out the wrong statement?

• 1. Reciprocal of the resistance to heat flow is called thermal conductance
• 2. Unit of thermal conductance is W/°K
• 3. Thermal conductance of a wall of thickness ‘L’, thermal conductivity ‘k’ and heat flow area ‘A’ is kL/A
• 4. None of these

Question: Pick out the wrong statement ?

• 1. The controlling resistance in case of heating of air by condensing steam is in the air fil
• 2. The log mean temperature difference (LMTD) for counter flow and parallel flow can be theoretically same when any one of the fluids (hot or cold fluid) passes through the heat exchanger at constant temperature
• 3. In case of a 1 – 2 shell and tube heat exchanger, the LMTD correction factor value increasessharply, when a temperature cross occurs
• 4. Phase change in case of a pure fluid at a given pressure from liquid to vapor or vice-versa occurs at saturation temperature