Heat Transfer Questions

• 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
• 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
• In case of vertical tube evaporator, with increase in liquor level, the overall heat transfer co-efficient
• The number of kg vaporised per kg of steam fed to the evaporator is defined as
• For an ideal black body
• In a heat exchanger, floating head is provided to
• When vaporisation takes place directly at the heating surface, it is called
• The steam ejector is used to
• In the equation Q = UAΔt; Δt is
• 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 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be
• In Joule's experiment, an insulated container contains 20 kg of water initially at 25°C. It is stirred by an agitator, which is made to turn by a slowly falling body weighing 40 kg through a height of 4 m. The process is repeated 500 times. The acceleration due to gravity is 9.8 ms-2. Neglecting the heat capacity of agitator, the temperature of water (in °C) is
• Fouling factor
• With increase in temperature, the thermal conductivity of non-metallic amorphous solids
• Which of the following is concerned with both heat and mass transfer?
• 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
• With increase in porosity, the thermal conductivity of a solid substance
• Heat waves
• Presence of a non-condensing gas in a condensing vapour
• Which of the following is not used as a medium for high temperature heating?
• Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the __________ zone.