Calculating time taken to boil water

  • Context: High School 
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    Boil Time Water
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Discussion Overview

The discussion revolves around calculating the time required to boil off 50 liters of water in a sealed tank placed inside a kiln operating at 800°C. Participants explore the necessary conditions, equations, and factors influencing the evaporation process, including the initial temperature of the water, heat transfer, and the design of the kiln and tank.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants note that water cannot be heated to 800°C under normal conditions since it boils at 100°C, suggesting the need for more information about the setup.
  • Others propose that the initial temperature of the water, heat transfer function, and ambient pressure are critical for determining the time to boil off the water.
  • A participant mentions that the kiln's design and the thermal power it can deliver are essential factors, as the water may cool the kiln if placed inside when hot.
  • Some participants express uncertainty about the appropriate equations to use, with one referencing a specific equation related to evaporation but questioning its applicability to a sealed tank.
  • Concerns are raised about the potential for damaging the kiln due to rapid cooling and thermal gradients caused by the introduction of water.
  • Participants discuss the dimensions and specifications of the kiln and water tank, emphasizing the need for detailed parameters to model the situation accurately.

Areas of Agreement / Disagreement

Participants generally agree that the problem is complex and lacks a straightforward solution, with multiple competing views on the necessary parameters and equations. The discussion remains unresolved regarding the exact time it would take to evaporate the water.

Contextual Notes

Limitations include missing assumptions about heat transfer rates, the influence of the kiln's design on evaporation, and the lack of a clear equation applicable to the specific scenario of a sealed tank.

  • #31
Chestermiller said:
Is there a concern about moisture affecting the curing of the paint?

This is the big one, in my opinion. If you're putting this in an oven with curing paint, you'll be dramatically raising the humidity in the oven as the water evaporates. I'd be worried that this would affect the paint curing.

Is there any reason the device can't stay outside of the oven, with wires running to the inside of the oven where the thermocouples are?
 
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  • #32
Steam in ovens: If I want really crusty bread, I put a tray of water in the bottom of the oven. It certainly makes a difference - and it hits you right in the face if you open the door. Better check with the paint people.

But, there are plenty ways of remote monitoring of those sorts of temperatures. Do you just need extension leads on your thermocouples? You may be letting the tail wag the dog, as they say.
 

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