During a plant visit, it was observed that a 1.5-m-high and 1-m-wide section of the vertical front section of a natural gas furnace wall was too hot to touch. The temperature measurements on the surface revealed that the average temperature of the exposed hot surface was 110°C, while the temperature of the surrounding air was 25°C. The surface appeared to be oxidized, and its emissivity can be taken to be 0.7. Taking the temperature of the surrounding surfaces to be 25°C also, determine the rate of heat loss from this furnace. The furnace has an efficiency of 79 percent, and the plant pays $1.20 per therm of natural gas. If the plant operates 10 h a day, 310 days a year, and thus 3100 h a year, determine the annual cost of the heat loss from this vertical hot surface on the front section of the furnace wall.
Energy transfer
The flow of energy from one region to another region is referred to as energy transfer. Since energy is quantitative; it must be transferred to a body or a material to work or to heat the system.
Molar Specific Heat
Heat capacity is the amount of heat energy absorbed or released by a chemical substance per the change in temperature of that substance. The change in heat is also called enthalpy. The SI unit of heat capacity is Joules per Kelvin, which is (J K-1)
Thermal Properties of Matter
Thermal energy is described as one of the form of heat energy which flows from one body of higher temperature to the other with the lower temperature when these two bodies are placed in contact to each other. Heat is described as the form of energy which is transferred between the two systems or in between the systems and their surrounding by the virtue of difference in temperature. Calorimetry is that branch of science which helps in measuring the changes which are taking place in the heat energy of a given body.
During a plant visit, it was observed that a
1.5-m-high and 1-m-wide section of the vertical front section
of a natural gas furnace wall was too hot to touch. The temperature
measurements on the surface revealed that the average
temperature of the exposed hot surface was 110°C, while
the temperature of the surrounding air was 25°C. The surface
appeared to be oxidized, and its emissivity can be taken to
be 0.7. Taking the temperature of the surrounding surfaces to
be 25°C also, determine the rate of heat loss from this furnace.
The furnace has an efficiency of 79 percent, and the
plant pays $1.20 per therm of natural gas. If the plant operates
10 h a day, 310 days a year, and thus 3100 h a year,
determine the annual cost of the heat loss from this vertical
hot surface on the front section of the furnace wall.
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