Chapter 1, Problem 1.62P

A plane wall, 7.5 cm thick, generates heat internally at the rate of 105 W/m3. One side of the wall is insulated, and the other side is exposed to an environment at 90C. The convection heat transfer coefficient between the wall and the environment is 500 W/m2 K. If the thermal conductivity of the wall is 12 W/m K, calculate the maximum temperature in the wall.

energy can be conserved when your home heating/cooling system works less during the heating and cooling seasons. in fact/ a one degree celsius difference in your thermostat setting can reduce energy consumption by up to 5%

The fin efficiency is defined as the ratio of the actual heat transfer from the fin to   a. The heat transfer from an equivalent fin which is infinitely long b. The heat transfer through the base area of the same fin c. The heat transfer from the same fin with an adiabatic tip d. The heat transfer from the same fin if the temperature along the entire length of the fin is the same as the base         temperature

Q. 1.2: Consider heat loss through the two walls of a house on a winter night. The walls are identical, except that one of them has a tightly fit glass window. Through which wall will the house lose more heat? Explain.

Calculate the amount of energy required to heat the air in a house 30 by 50 by 40 feet from 10 to 70°F. The density of air is about 0.080 lbs/ft3, and its specific heat at constant pressure is about 0.24 BTU/lb-°F

Consider two concentric spheres of radii R1​ and R2​ (R1<R2​). The inner sphere has a temperature of T1​=20°C and the outer sphere has a temperature of T2​=100°C. The material between the two spheres has a thermal conductivity of k=0.5 W/(m⋅K). Calculate the heat flow from the outer sphere to the inner sphere. Determine the equation of the thermal Ohm's law for this system.

A 75-hp (shaft output) motor that has an efficiency of 91.0 percent is worn out and is replaced by a high-efficiency 75-hp motor that has an efficiency of 95.4 percent. Determine the reduction in the heat gain of the room due to higher efficiency under full-load conditions.

An electric heater with the total surface area of 0.25 m2 and emissivity 0.75 is in a room where the air has a temperature of 20°C and the walls are at 10°C. When the heater consumes 500 W of electric power, its surface has a steady temperature of 120°C. Determine the temperature of the heater surface when it consumes 700 W. Solve the problem (a) assuming negligible radiation and (b) taking radiation into consideration. Based on your results, comment on the assumption made in part (a).

The rate of heat conduction through a plane wall is proportional to the average thermal conductivity, the wall area, and the temperature difference, but is inversely proportional to the ---------------.