HW6 ChE 350 F11

# HW6 ChE 350 F11 - ChE 350 Fall 2011 Homework 6(Due Thursday...

This preview shows pages 1–3. Sign up to view the full content.

ChE 350 Fall 2011 Homework 6 (Due Thursday, Dec. 1) Name:________________________ 1 1. The thermal conductivities of metals are known to closely follow the Wiedemann-Franz law that states that the thermal conductivity k and the electrical conductivity are related to each other and the temperature T : T k L (a) Determine the value of L for silver at room temperature: (b) Determine the value of L for silicon at room temperature. How close is this to the theoretical value of L is  2 8 K W 10 44 . 2 ? Explain why silicon does or does not follow the Wiedemann-Franz law: 2. You find a large sheet of gold, that weighs 1 kg and is 1 cm thick sitting in your backyard. You want to pick it up, but it’s been sitting in the sun for the past hour and it may be too hot to handle. Calculate the temperature of the gold. The room temperature heat capacity of gold is 128 J/kg K. At noon, the sun is illuminating 100 mW/cm 2 of energy. Assume that the gold does not lose any heat to the surrounding environment (i.e., that it’s adiabatic…this is probably not a great assumption, but it will give you an estimate of the maximum possible temperature of the gold).

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
ChE 350 Fall 2011 Homework 6 (Due Thursday, Dec. 1) Name:________________________ 2 3. (a) Consider a house that is being cooled in the summer. Calculate the heat transferred per m 2 of surface area through an insulating wall composed of 25 mm thick fiber insulating board
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 6

HW6 ChE 350 F11 - ChE 350 Fall 2011 Homework 6(Due Thursday...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online