Heat transfer rate to heating time

In summary, the conversation discusses the setup of an equation to calculate the heat transfer rate Q for a combined system, where heat is transferred from a cylindrical outer wall set at 500 C. The wall heats a gas, which in turn heats a solid block of cylindrical metal positioned in the center of the heated walls with a starting temperature of 20 C. The equation provided gives a result of 11.3213 Watts for the given situation. The speaker is concerned about the small value and asks for clarification on how to relate this heat transfer to time. They also mention difficulties with using an equation editor and provide a hand-written version of the equation. The conversation ends with a request for more details and a request for the equation submitter's email
  • #1
gemt
7
0
i have set up an equation to get the heat transfer rate Q for a combined system where heat is transferred from a cylindrical outer wall set at 500 C. the wall heats a gas, which in turn heats a solid block of cylindrical metal positioned in the centre of the heated walls with a starting temperature of 20 C.

the equation i have is

Q=[1]\frac{}{}[/(A0/(h*Alm1))+((r*A0)/(k*A2))+(A0/(h*Alm3))+((r*A0)/(k*A4))+(A0/(h*Alm5))]*A0*[tex]\Delta[/tex]T

and it give a result of 11.3213 Watts or the situation above.

but too me this seems small?? am i right in thinking this?

also can anyone tell me how i can relate this heat transfer to time. ie. know how long it would take to heat the central metal part.

Thank you in advance.
 
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  • #2
could you fix the latex?
 
  • #3
i could not get the equation editor to work properly (probaly the user to be fair) but i am included a hand written version as an attachment. i have managed to modifie it a bit which is giving me more sensible answers. But to get a value for time (in seconds#) i am using the below equation to get a value for q in joulse and then dividing q by Q.

q=cm[tex]\Delta[/tex]T

c = specific heat of the gas
m = mass of gas
delta T = the change in temperature

Thanks
 

Attachments

  • equation1.bmp
    291.2 KB · Views: 547
  • #4
Hi, can you send me eveything about this equation including details the of model, description of the variable and sketch, I will look into this...
My email address is riscy00@googlemail.com
 

1. What is heat transfer rate?

Heat transfer rate is the amount of heat that is transferred per unit time. It is typically measured in units of watts (W) or joules per second (J/s).

2. How is heat transfer rate calculated?

Heat transfer rate can be calculated by dividing the amount of heat transferred (in joules) by the time it took for the transfer to occur (in seconds). Mathematically, it can be expressed as Q/t, where Q is the heat transferred and t is the time.

3. What factors affect heat transfer rate?

The rate of heat transfer is affected by several factors, including the temperature difference between the two objects, the thermal conductivity of the materials involved, the surface area of contact between the objects, and the distance between the objects.

4. How does heating time affect heat transfer rate?

The longer the heating time, the greater the heat transfer rate. This is because as the heating time increases, the amount of heat transferred also increases. However, there may be a point of diminishing returns where further increases in heating time do not significantly impact the heat transfer rate.

5. How can heat transfer rate be increased?

Heat transfer rate can be increased by increasing the temperature difference between the two objects, using materials with higher thermal conductivity, increasing the surface area of contact, and decreasing the distance between the objects. Additionally, using methods such as convection or radiation can also increase the heat transfer rate.

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