Compare thermal resistance of three walls.xls

KNOWN: Configurations of exterior wall. Inner and outer surface conditions.

FIND: Heating load for each of the three cases.

ASSUMPTIONS: 1) Steady-state conditions.

2) One-dimensional conduction .

3) Constant properties.

4) Negligible radiation effects.

Calculation Reference

Fundamentals of Heat and Mass Transfer - Frank P. Incropera

To compare the thermal resistance and heating load for three different wall configurations, considering the inner and outer surface conditions, you can follow these steps:

1. Determine the thermal resistance of each wall: The thermal resistance (R) of a wall is a measure of its resistance to heat flow and can be calculated using the formula:

   R = (Thickness) / (Thermal Conductivity * Area)

   Where the thickness is the thickness of the wall, the thermal conductivity is the thermal conductivity of the wall material, and the area is the cross-sectional area of the wall.

2. Calculate the overall thermal resistance: For each wall configuration, sum the thermal resistances of the individual layers to obtain the overall thermal resistance (R_total) of the wall.

   R_total = R1 + R2 + R3 + ... (for multi-layered walls)

3. Calculate the heating load: The heating load (Q) is the amount of heat that needs to be supplied to maintain the desired indoor temperature and can be calculated using the formula:

   Q = (Temperature Difference) / R_total

   Where the temperature difference is the difference between the desired indoor temperature and the outdoor temperature.

By following these steps, you can compare the thermal resistance and heating load for three different wall configurations based on the given inner and outer surface conditions. The assumptions of steady-state conditions, one-dimensional conduction, constant properties, and negligible radiation effects allow for simplified analysis.