It SEEMS I can heat water faster in my microwave than I can on my stovetop.
Is a microwave "more efficient" at heating water ?
If so, can anyone see a time where the heat source for a home water heater would be microwave rather than heating elements ?
The microwave heats faster cause there is no warm-up time.
No AND be carefull to never heat plain water in a MW as it may damn near "explode" when you go to use it due to surface tension issue. I.E. put cocoa in before heating, ditto tea bag.
Lou
And because it's usually not heating the container either. You can put food in it on a paper plate, plastic container, neither of which get heated up much, and even if they do, have a very small thermal mass compared to a metal pot on a stove. And there is less loss to the surrounding environment. The microwave directly vibrates the water molecules transferring energy to them. With a pot on the stove a lot of the heat goes to the air, surrounding stove metal, etc.
It definitely uses less electricity to warm the cup of water in the microwave than on the stove. However, an electric water heater is
100% efficient at converting the incoming electricity to heat because it's a simple resistance heating element surrounded by water. Microwaves would offer no advantage in a storage tank water heater. In fact, it would use MORE electricity, because the electronics that create the microwaves are not 100% efficient.The kitchen version of the water heater is an electric kettle. It's basicly a metal teapot type appliance that has a 1500W heater inside. I can have a quart of water boiling in just a few minutes, much faster than on the stovetop. Again, it's going to be more efficient because most of the heat is going directly to the water.
Agree. If you're going to heat water to near boiling, it should have something in it. If it's pure water, it can become super heated, where it's actually just a tiny bit above the boiling point without actually boiling. Then the slightest disturbance can trigger it all to suddenly boil at once.
Excellent advice, if you like cocoa all over the inside of the microwave. Otherwise - not so much.
Excellent advice, if you like cocoa all over the inside of the microwave. Otherwise - not so much.
However, an electric water heater is
100% efficient at converting the incoming electricity to heat because......Oh hell..... You had to say it.....
Well, I have used the microwave for years to heat my coffee. As a lapsed lab. chemist, I have a fair handle on volumes and just pour the required amount of instant coffee from the jar straight into my mug, top up with water and zap in the MW for the relevant time (depending upon the power of the MW). IIRC, I haven't had a volcanic eruption to date. I might regret having said that!
It saves energy rather than using the kettle and I don't use a spoon, (not using milk or sugar). Very efficient, I find it.
The key here is not to over heat it. Use your brain if you have one. I use it to head a cup of hot water all the time. I learned what is just right. We don't need blanket moronic regulations.
I heard someone put a plastic coil in the microwave and circulated water into a tank and made hot water just fine. Don't try it if you're an idiot.
No microwave is NOT more 'efficient' at heating water.
It may be 'faster' at heating small quantities of water in small containers that themselves do not absorb much heat.
But from basic physics the question makes no sense. It is all a matter of how quickly the units of heat from watts of electrcity get into the water by some means, so as to raise the temperature of the water.
A typical microwave uses maybe 1200 watts (1.2 kilowatts per hour); and takes maybe a minute or so to heat a cup of water to say same temperature as hot water out of the tap.
So that''s 1/60 of 1.2 kilowatt hour. Ignoring the losses in the inefficiency of the magnetron, the little light that comes on inside and the small amount of electrcity used by the controller module with its display etc.
Less total amount of electrcity would be used in a properly insulated hot water tank, more slowly, by its 3000 watt heater; or alternatively one of those 'instant on' heaters; to heat the same amount (cup) of water. Some of those instant hot water heaters can use 9 kilowatts or more for the short periods they are on.
Compared to water heating on stove top: Element has to heat up, the pan or kettle has to absorb the heat and there is heat loss to the room, so it is a 'slower' process. But it is a 'convenient' way to heat water for tea or coffee or cooking despite the heat losses.
There is a complete difference between 'how fast' and 'how efficient' something is.
There are some ceramics designed to absorb microwaves, heat up and help heat the contents. Those are more efficient. Some microwave foods place a microwave "magnet" in the bottom of the tray to heat the food faster.
As Dick Cheney said to a protester: "Put a lid on it*."
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I made what appears to be a rash assumption for some folks. That the user is smart enough to not run the MW for too long a period.
Lou
LouB wrote in news: snipped-for-privacy@invalid.com:
Actually, superheating is a wellknown phenomenon. For water to boil, it has to go to vapor phase (steam). That usually (in a pan on a fire of some kind) at very hot places on the pan's surface. That's when the water is starting to "sing". In a MW there is no such hot surface and boiling has to start somewhere. This is then usually on a floating speck of dust. The MW energy has heated the water in the meantime to higher than the boiling temperature, so when a teensy "boil" starts, suddenly this is the seed for much more water to become steam. Steam is also much, muc more voluminous than water, hence the force of the boiling water and steam.
When a chem student having to heat solvents on a heated water bath, it was official policy to add "boiling stones" to the containers in order to have a controlled boiling, rather than a little explosion. But that is another story ...
Oh, yeah. 1 mole of water is 18 grams, just over half an ounce. Visualize that volume. At "normal" conditions (0degrees C, 1 atmosphere pressure), the volume of an ideal gas is 22.4 liters. Since pV=RT, that volume would be 373/273 times as much at 100 degree C (boiling), or about
31 L, or close to 8 gallons. Visualize 18 milliliters expanding to 31 liters, roughly 2000 fold. That's the power of steam.That explains why you eed be careful pulling the Saran wrap off of a microwaved food container. Less than 4 tablespoons of water will convert to 8 gallons of steam when overheated to boiling.
Han wrote in news:Xns9BF1463D7B65Cikkezelf@216.151.153.41:
Hope I got the facts right
Ridiculous. Only a moron puts a tea bag into cold water. Yuck.
Or using a MW for tea at all. Even when boiled, if you drop a tea bag into the water it does not taste the same as a properly brewed cup. Of course, you should be using loose tea anyway.
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