Furnace Heat transfer question

In summary, the question is asking for the rate of heat transfer through a furnace wall with an area of 3m^2, thickness of 250mm, and a thermal conductivity of 1.5 W m^-1 K^-1 at a temperature of 40K. The equation Q/t=KxAx(T2-T1)/L is provided but without knowing T2 or the transfer rate, it is impossible to solve. However, assuming a temperature difference of 40K may not be accurate as furnaces typically have very high temperatures.
  • #1
ash-kennard
16
0

Homework Statement



a furnace wall has an area of 3m^2. a thickness of 250mm and a thermal conductivity of 1.5 W m^-1 K^-1. calculate the rate of heat transfer through it when the temperature is 40K

Homework Equations



Q/t=KxAx(T2-T1)/L

The Attempt at a Solution



This isn't homework as such, it was given in a list of questions aimed at helping with revision for my module exam. I've done the other 11 questions but this one is doing my head in. the furthest I've gotten to is (Q/18t)-40=T2 but without knowing T2 or the transfer rate is it impossible to progress to an answer?

please help. don't want to be revising something incorrectly for the exam
 
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  • #2
40K must be the temperature difference (delta T) it surely isn't -233 C for a furnace.
 
  • #3
i was talking to my dad about it earlier today too. but that's the exact question, haven't re worded it at all. a furnace implies very hot temperatures, and the 40k must have to be a difference. but i wanted to see if i was overlooking something so posted on here.

is there anyway to get any further on this question with the lack of information?
 
  • #4
I don't see any other way to solve this problem rather than to assume a delta T of 40 K. But actually that value seems to low. Furnace temperatures get very high, I would have expected a delta T of about 350 K assuming an exterior surface temperature of about 40 C (100 F) and an inside wall temperature of 380 C (800 F). Might be a typo.
 
  • #5
right cheers for that then. i know how to do it providing that is is delta 40, i also know how to do it given 2 temperatures so cheers for the help. was annoying me greatly

much appreciated, ash
 

1. How does heat transfer occur in a furnace?

Heat transfer in a furnace occurs through three main mechanisms: convection, conduction, and radiation. Convection is the transfer of heat through the movement of a fluid, such as air or gas. Conduction is the transfer of heat through direct contact between objects. Radiation is the transfer of heat through electromagnetic waves.

2. Why is heat transfer important in a furnace?

Heat transfer is important in a furnace because it is the primary way in which heat is distributed throughout the furnace. This ensures that the desired temperature is reached and maintained within the furnace, allowing for efficient and effective operation.

3. How is heat transfer calculated in a furnace?

Heat transfer in a furnace is calculated using the principles of thermodynamics. This involves determining the temperature difference between the heat source (such as the burning fuel) and the object being heated (such as the surrounding air or material). The rate of heat transfer is then calculated using the thermal conductivity and surface area of the objects involved.

4. What factors affect heat transfer in a furnace?

Several factors can affect heat transfer in a furnace, including the type and quality of fuel being burned, the design and construction of the furnace, the temperature and flow rate of the fluid or gas, and the presence of any insulating materials. Additionally, the size and composition of the objects being heated can also impact heat transfer.

5. How can heat transfer be optimized in a furnace?

To optimize heat transfer in a furnace, it is important to ensure that the furnace is designed and operated in a way that maximizes the surface area available for heat transfer. This can be achieved through proper insulation and construction, as well as maintaining optimal temperatures and flow rates. Additionally, using high-quality fuel and regularly maintaining the furnace can also help to optimize heat transfer.

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