HEAT AND THERMODYNAMICS

Result in temperature difference with no phase change.

• Sensible Heat

• Latent Heat

• Heat

• Specific Heat

Resulted from the substance changing its phase.

• Sensible Heat

• Latent Heat

• Heat

• Specific Heat

The energy required to raise the temperature of a unit mass of a substance by one degree.

• Sensible Heat

• Latent Heat

• Specific Heat

• BTU

1 Calorie is equal to:

• 4.16J

• 1.05J

• 4.18J

• 1.15J

Type of convection in which the substance moves because of the decrease in its density which is caused by increase in temperature.

• Free Convection

• Forced Convection

• Radiation

• Flow Convection

Calculate the heat transfer per hour through a solid brick

wall 6m long, 2.9 m high, and 225 mm thick, when the

outer surface is at 5°C and the inner surface 17°C, the

coefficient of thermal conductivity of the brick being 0.6

W/m-K.

• 3,400.48 kJ

• 3,004.48 kJ

• 2,004.48 kJ

• 2,400.48 kJ

Calculate the quantity of heat conducted per minute

through a duralumin circular disc 127 mm diameter and

19 mm thick when the temperature drop across the

thickness of the plate is 5°C. Take the coefficient of

thermal conductivity of duralumin as 150 W/m-K.

• 30 kJ

• 40 kJ

• 35 kJ

• 45 kJ

A dry ice storage chest is a wooden box lined with glass

fiber insulation 5 cm thick. The wooden box (k=0.069) is 2cm thick and cubical 60 cm on an edge. The inside

surface temperature is -76°C and the outside surface

temperature is 18°C. Use k=0.035 for glass fiber

insulation. Determine the heat gain per day.

• 10,208 kJ

• 11,195 kJ

• 12,211 kJ

• 9,185 kJ

A pipe with an outside diameter of 2.5 in is insulated with a 2 in layer asbestos (k=0.396 Btu-in/hr-ft2-°F), followed by a layer of cork 1.5 in thick (k=0.30 Btu-in/hr-ft2-°F). If the temperature of the outer surface of the cork is 90 °F and inner temperature of 290 °F, calculate the heat lost per 100 ft of insulated pipe

• 847.64 Btu/hr

• 2847.42 Btu/hr

• 1847.14 Btu/hr

• 3847.51 Btu/hr

Hot gases at 280°C flow on one side of a metal plate of 50mm thickness and air at 35°C flows on the other side. The heat transfer coefficient of the gases is 31.5 W/m2-K and that of the air is 32 W/m2-K. Calculate the overall heat transfer coefficient if the value of thermal conductivity is 0.01.

• 0.1795 W/m2-K

• 0.1975 W/m2-K

• 0.1957 W/m2-K

• 0.1759 W/m2-K