A. Remove condensate from the steam pipelines
B. Create vacuum
C. Superheat the steam
D. None of these
Correct Answer: Create vacuum ✔
Last Updated: March 03, 2019
Related MCQs
- Steam is to be condensed in a shell and tube heat exchanger, 5 m long with a shell diameter of 1 m. Cooling water is to be used for removing the heat. Heat transfer co-efficient for the cooling water, whether on shell side or tube side is the same. The best arrangement is__________?
- Which of the following is generally considered as opaque surface towards radiations ?
- Fourier’s law of heat conduction applies to __________ surfaces?
- 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)?
- Harmonic mean temperature difference is given by__________?
- If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length__________?
- The rate of heat transfer from a vertical plate by natural convection depends upon the temperature differences (ΔT) between wall and outside bulk. The proportionality is given as__________?
- Heat transfer occurs by natural convection because change in temperature causes difference in__________?
- A metal ball of radius 0.1 m at a uniform temperature of 90°C is left in air at 30°C. The density and the specific heat of the metal are 3000 kg/m3 and 0.4 kJ/kg.K respectively. The heat transfer co-efficient is 50 W/m2.K Neglecting the temperature gradients inside the ball, the time taken (in hours) for the ball to cool to 60°C is__________?
- The ratio of momentum diffusivity to thermal diffusivity is the __________ number?
- What is the thermal conductivity of a perfect heat insulator ?
- The value of Stefan-Boltzmann constant in SI unit is__________?
- 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 __________?
- Air is best heated with steam in a heat exchanger of__________?
- Which is the most suitable for the concentration of foamy & frothy liquors ?
- The thermal radiative flux from a surface of emissivity = 0.4 is 22.68 kW/m2. The approximate surface temperature (K) is (Stefan-Boltzmann constant = 5.67 × 10-8 W/m2.K4) ?
- Boiling point elevation of an ideal solution__________?
- The main function of baffles provided in a shell and tube heat exchanger is to__________?
- Steam side heat transfer co-efficient in an evaporator is in the range of __________ kcal/hr.m2°C?
- The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoff‟s law?
- For small temperature difference, the heat transfer rate as per Newton’s law of cooling is proportional to (where, Δt = excess temperature) ?
- Overall heat transfer co-efficient for cooling of hydrocarbons by water is about__________?
- Intermittent tube cleaning is possible to be done in case of a __________ evaporator?
- In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient__________?
- In evaporators, lowering the feed temperature__________?
- Shell side pressure drop in a shell and tube heat exchanger does not depend upon the__________?
- The most conducive surface for dropwise condensation to occur is the __________ surface?
- Out of 100 kcal/second of incident radiant energy on the surface of a thermally transparent body, 300 kcal/second is reflected back. If the transmissivity of the body is 0.25, the emissivity of the surface will be__________?
- 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) ?
- Analogy between mass and heat transfer is not applicable in case of__________?
- 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__________?
- Steady state one dimensional heat flow by conduction as given by Fourier’s low does not assume that__________?
- Heat transfer co-efficient (h1) for liquids increases with__________?
- Multiple effect evaporators ar used to__________?
- In natural convection heat transfer, the correlating parameter is the__________?
- Correction is applied to LMTD for __________ flow?
- Increasing the liquor level in the evaporator results in the__________?
- In case of a shell and tube heat exchanger, the minimum and maximum baffle spacing is respectively (where, D = inside diameter of the shell) ?
- Double pipe heat exchangers are used__________?
- A body is called grey if the monochromatic emissivity of the body is__________?
- While the total emissivity of a perfect black body is unity, the same for a real body is__________?
- Crystal size in a continuous crystalliser depends upon the__________?
- Boiling of milk in an open vessel is an example of __________ boiling?
- Black liquor generated during paper manufacture is concentrated in a__________?
- What is Nusselt number ?
- In the equation Q = UAΔt; Δt is__________?
- For a cold dilute feed to produce thick viscous liquor, backward feeding as compared to forward feeding results in__________?
- Hot water (0.01 m3 /min) enters the tube side of a counter current shell and tube heat exchanger at 80°C and leaves at 50°C. Cold oil (0.05 m3/min) of density 800 kg/m3 and specific heat of 2 kJ/kg.K enters at 20°C. The log mean temperature difference in °C is approximately ?
- Graetz number is given by__________?
- Reynold’s analogy states that__________?
- Which of the following has the minimum thermal conductivity ?