Water heating

[gar]

181201-2352 EST

ActionDave:

Yes, you did ask a question early on, and I did not respond at that point because I wanted to see how responses would flow. Had I responded at the time of your question it would have prevented the other responses that followed in the form that they took. Later, when drcampbell provided his response, it matched what I was expecting to see.

On the subject of an induction heater --- my guess it is less efficient than a direct resistive heater for heating a pot of water, and more efficient than microwave. I don't have an induction heater to test. If I had a chunk of steel to heat the induction heater would be faster, and probably more efficient than resistive heating of that chunk.

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[ActionDave]

181201-2352 EST

ActionDave:

Yes, you did ask a question early on, and I did not respond at that point because I wanted to see how responses would flow. Had I responded at the time of your question it would have prevented the other responses that followed in the form that they took. Later, when drcampbell provided his response, it matched what I was expecting to see.

On the subject of an induction heater --- my guess it is less efficient than a direct resistive heater for heating a pot of water, and more efficient than microwave. I don't have an induction heater to test. If I had a chunk of steel to heat the induction heater would be faster, and probably more efficient than resistive heating of that chunk.

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That's interesting because a lot of the posts I see you making on this forum chide the person asking the question for not providing enough information or asking the question incompletely by your assessment.

 

[gar]

181202-0604 EST

ActionDave:

I can agree with your point.

I chose to not provide a precise description of the hot pot to make the question as simple as possible. I was going for basics in the question. An integrated water heating pot using induction heating would make no sense. There is greater cost and less efficiency in such a design to use it for water heating. I doubt there is any hot pot designed for heating water that is based on induction heating. My use of the words "hot pot" may not have been the best descriptor.

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[Adamjamma]

181201-2148 EST

I did not define a microwave more accurately than the electric pot. drcampbell understood the concept of the question, and added some additional comment.

There were some assumptions in my question that did not need to be presented. Had altitude been a factor, then other information would have come into play. The temperature range indicated was to get away from both freezing and boiling, and to somewhat imply standard pressure conditions. Whether one method was faster or more convenient was not in the question. The difference in efficiency is so great that the container was not of great consequence.

The purpose of my question was not that I needed an answer, but to stimulate some thought.

If you thought the question was impossible to solve, or you did not undcerstand the question, then the obvious thing to do is ask a question to try to get clarity.

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nd to think I thought it might be someone considering how much power they needed if power went out?
a

 

[drcampbell]

... To be a fair comparison, one must know the mass and material of the pot if just μwave to cooktop comparison. For the electric pot, you gotta heat the pot so for just 1 cup, you are heating the pot also. 1 cup in a styrofoam cup in microwave you are pretty much only heating the water.
If the μWave oven is only 50% efficient, the mass of the electric pot and cup needs to be less than 16 oz times pot+ heater mass x pot/heater specific heat.

Your analysis seems to be correct. (albeit seeming to omit the mass & specific heat of the μwave oven components that heat up) Why don't you continue this line of thought, make some reasonable estimates of each parameter, calculate the result and see if it offers any new or different insight first?

... If you thought the question was impossible to solve, or you did not understand the question, then the obvious thing to do is ask a question to try to get clarity. ... .

That, or STFU.

 

[junkhound]

μwave oven components that heat up

that heat is part of the 50% uwave loss, already in the basis for comparison.

Hmm could gold plate the cup and put in a vacuum to eliminate other factors, how far to take modeling?

Thermal analysis of spacecraft electronics does take all that into account, but those who do it get paid for the effort /g

 

[gadfly56]

181201-1500 EST

Is it more efficient to heat a cup of water from 70 F to 180 F in a microwave, an electric pot, or are they the same?

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I would think an immersion heater would be the top choice, hands down. Insanely dangerous if you have children in the house, but IIRC the couple of times I used one I had boiling hot water in about 15 seconds and all the energy goes into the water.

 

[MAC702]

... an immersion heater ... all the energy goes into the water.

Yeah, but are your mains powered by coal, nuclear, or solar? :lol:

 

[sameguy]

I had, had, one at college until my roommate saw me make hot water one day; he walked over and plugged it in holding in his hand open air where it melted. Then he looks at me and said "junk!". I made him get me coffee for a week until he said "that piece of sxxx didn't cost that much!". Same guy left my hot plate on the tile floor running until the tile curled up and turned black.

 

[gar]

181203-2005 EST

gadfly56:

Your direct immersion heater is going to be one of the most efficient means of heating the water. My guess is above 99% with an appropriate container.

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