Chemical Heat Transfer

The outlet temperature of cooling water in a heat exchanger is generally not allowed to exceed above 50°C in industrial practice mainly to avoid_________________? A. Its evaporation lossB. Excessive corrosion C. Uneconomic LMTD D. Decrease in heat exchanger efficiency

The Fourier number (defined as a.t/L2) is used in the analysis of problem involving heat transfer by_______________? A. Forced convection B. Natural convectionC. Transient conduction D. Steady state conduction

Three solid objects of the same material and of equal mass-a sphere, a cylinder (length = diameter) and a cube are at 500°C initially. These are dropped in a quenching bath containing a large volume of cooling oil each attaining the bath temperature eventually. The time required for 90% change in temperature is the smallest…

Which of the following forced convection heat transfer equation accounts for the liquid viscosity effect for viscous liquids ? A. Dittus-Boelter equationB. Sieder-Tate equation C. Nusselt equation D. None of these

For condensation of pure vapors, if the heat transfer co-efficients in filmwise and drop-wise condensation are respectively hf and hd, then__________________? A. hf = hd B. hf > hdC. hf < hd D. hf could be greater or smaller than hd

Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by__________________? A. Eddies currentB. Conduction C. Convection D. None of these

_____________ heat exchanger is the most suitable, when the temperature of shell side fluid is much higher than that of tube side? A. Single pass, fixed tube sheetB. U-tube C. Three pass, fixed tube sheet D. None of these

Evaporation of 1kg of water from a solution in a single effect evaporator requires about ________________ kg of steam? A. 0.4 – 0.6B. 1-1.3 C. 1.8-2 D. 2 – 2.4

Thermal conductivities of most of the liquids _______________ with rise in temperature? A. IncreasesB. Decreases C. Remains unchanged D. May increase or decrease; depends on the liquid

The purpose of providing a ‘catchall’ in the vapor line of an evaporator is to__________________? A. Create vacuum B. Regulate the vapor flow C. Vent the non-condensable gasesD. Arrest the entrained liquid