The heat diffusion equation.

Question

Want to see the full answer?

Answer 1

Question

Chapter 2, Problem 2.33P

To determine

The heat diffusion equation.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Students have asked these similar questions

Heat transfer to and from a reaction flask is often a critical factor in controlling reaction rate. The heat transferred (q) depends on a heat transfer coefficient (h) for the flask material, the temperature difference (∆T) across the flask wall, and the commonly “wetted” area (A) of the flask and bath, q = hA∆T. When an exothermic reaction is run at a given T, there is a bath temperature at which the reaction can no longer be controlled, and the reaction “runs away” suddenly. A similar problem is often seen when a reaction is “scaled up” from, say, a half-filled small flask to a half-filled large flask. Explain these behaviors.

a) First, let's start with the steady-state analysis for the cable. What is the steady-state temperature of the wire surface if this current has been passing through the cable for a long period of time in these underwater conditions? Enter only a numeric value (with no units entered) and express your answer in ∘C. b) Now, let's think about the transient case. Assume that the cable starts at the same uniform temperature as the water and then the electrical current is passed through the cable. We're now interested in the amount of time it takes to heat up. Start by calculating the Biot number for this scenario. Enter only a numeric value (your answer should be unitless). c)

A hollow aluminum sphere, with an electrical heater in the center, is used in tests to determine the thermal conductivity of insulating materials. The inner and outer radii of the sphere are o.18 and o.21 m, respectively, and testing is done under steady-state conditions with the inner surface of the aluminum maintained at 250°C. In a particular test, a spherical shell of insulation is cast on the outer surface of the sphere to a thickness of o.15 m. The system is in a room for which the air temperature is 20°C and the convection coefficient at the outer surface of the insulation is 30 W/m2. K. If 80 W is dissipated by the heater under steady-state conditions, what is the thermal conductivity of the insulation?