Idea!! Stupid or Genius??

[berksrunner]

Has anyone thought of inventing a hot water heater for mobile applications based upon microwave technology????

 

[Speedr56]

Sounds like very high watts?

 

[John Frum]

Has anyone thought of inventing a hot water heater for mobile applications based upon microwave technology????

I can boil water in my microwave.
That is proof of concept.

Why mobile applications?
I mean, if its a good idea for mobile wouldn't it also be a good idea for stationary applications?

 

[BiduleOhm]

How can you beat the 100 % efficiency and simplicity and low cost of a resistor? (excluding heat pumps of course) well, you can't. That's why everything that needs to heat water, and which doesn't use a heat pump, uses a resistive element.

 

[berksrunner]

How can you beat the 100 % efficiency and simplicity and low cost of a resistor? (excluding heat pumps of course) well, you can't. That's why everything that needs to heat water, and which doesn't use a heat pump, uses a resistive element.

hmmmm. I think we need more context. Let's assume a hot water tank approach, something like the Bosch units, as opposed to propane-fueled on demand. My van has a Bosch 7 gallon tank. If I want hot water (as opposed to lukewarm) I need to crank it to the highest setting, which draws a steady 1,400-1,600 Watts for 40-50 minutes depending on ambient temps. I'm willing to bet that microwaves, while drawing a similar amount, would draw for a significantly smaller period of time.

 

[berksrunner]

hmmmm. I think we need more context. Let's assume a hot water tank approach, something like the Bosch units, as opposed to on propane-fueled on demand. My van has a Bosch 7 gallon tank. If I want hot water (as opposed to lukewarm) I need to crank it to the highest setting, which draws a steady 1,400-1,600 Watts for 40-50 minutes depending on ambient temps. I'm willing to bet that microwaves, while drawing a similar amount, would draw for a significantly smaller period of time.

I should also state: It's only 40-50 minutes when heating from ambient -- the maintenance of an already-not tank of water is far less (otherwise the draw would truly make the fully electric tank-based Bosch unfeasible for most battery banks/systems, at least at its highest setting.

 

[snoobler]

Simple math exercise:

1500W of power consumption applied as direct heating = almost 1500W of power applied to the water.
1500W of power consumption applied as microwave = about 1000W of power applied to the water.

Microwaving water is one of the most inefficient ways to heat water. Direct heat application is highly efficient.

As you mentioned yourself, the microwave takes a similar 1400-1600W of power, but it only heats the water with 1000W due to the gross inefficiencies of the microwave. In your 40-50 minute example, a microwave would run for well over an hour.

The answer to the question is "stupid" if the goal is to use less power to heat a given volume of water.

 

[berksrunner]

Simple math exercise:

1500W of power consumption applied as direct heating = almost 1500W of power applied to the water.
1500W of power consumption applied as microwave = about 1000W of power applied to the water.

Microwaving water is one of the most inefficient ways to heat water. Direct heat application is highly efficient.

As you mentioned yourself, the microwave takes a similar 1400-1600W of power, but it only heats the water with 1000W due to the gross inefficiencies of the microwave. In your 40-50 minute example, a microwave would run for well over an hour.

The answer to the question is "stupid" if the goal is to use less power to heat a given volume of water.

That makes total sense if your presumptions are true. How sure are you about those presumptions? Also, just thinking logically: a microwave can be applied to the entire mass of water at once, whereas a heating element is limited to a degree by its locality within the water -- hearing the molecules immediately nearby first and then relying upon those molecules to transfer the heat further on down the line.

 

[snoobler]

You should ask yourself if you're okay with putting this out into the world with so little thought. You don't even bother with basic research before thinking you have the potential for genius. My presumptions aren't presumptions. They are facts. Opinion or fantasy does not change facts. A microwave uses 50-60% more power than it can output as microwaves. Period. The conversions necessary to take electrical input to microwave output are grossly inefficient. Microwaves are used because they are convenient. Their efficiency sucks.

No you can't apply it to the entire volume. Matter is a barrier to microwaves. Water is the best barrier of all for a microwave tuned to heat water. When heating water in the microwave, the water closest to the emitter gets warmer first and shields the water "behind" it relative to the emitters. The water below it heats through conduction from the adjacent molecules and what little natural convection can occur... JUST LIKE A TRADITIONAL WATER HEATER - the water at the element heats first and it radiates outward. One could argue that this more efficient because the heating element radiates in all directions vs. the microwave heating radiating only in the direction opposite the emitter.

In what would you house this magical device? Metal blocks microwaves. Would you put the entire microwave including its 5600V magnetron INSIDE the water heater?

Again, to answer the question: Stupid. I'm trying to be polite by not using colorful adjectives.

 

[John Frum]

I think its fine to offer up quarter baked ideas.
In my experience it spurs others on to come up with better ideas.
I'm gonna change my avatar again.
That should settle @snoobler's hash.

 

[snoobler]

My limit is half baked.

EDIT: I've started to become disappointed if I can recognize you by your avatar. Excellent choice BTW.

 

[John Frum]

Nobody got injected with bleach, so that's good.

 

[snoobler]

The day is young.

 

[BiduleOhm]

hmmmm. I think we need more context. Let's assume a hot water tank approach, something like the Bosch units, as opposed to propane-fueled on demand. My van has a Bosch 7 gallon tank. If I want hot water (as opposed to lukewarm) I need to crank it to the highest setting, which draws a steady 1,400-1,600 Watts for 40-50 minutes depending on ambient temps. I'm willing to bet that microwaves, while drawing a similar amount, would draw for a significantly smaller period of time.

To do that you need a magnetron who takes energy from somewhere else in addition to the electric power you feed it. Not only it doesn't exist but magnetrons will waste some part (educated guess: 30 %) of the electricity into heat. So then you can say I'll heat water with that heat in addition to the microwaves; well yes, but then you just better off using a resistor...

And @snoobler already answered the other questions (this one too actually, but I already wrote my answer before seeing he already answered it...), even if he's a bit rude he's totally right on the scientific level. Energy is always conserved, never created or destroyed.

 

[berksrunner]

You should ask yourself if you're okay with putting this out into the world with so little thought. You don't even bother with basic research before thinking you have the potential for genius. My presumptions aren't presumptions. They are facts. Opinion or fantasy does not change facts. A microwave uses 50-60% more power than it can output as microwaves. Period. The conversions necessary to take electrical input to microwave output are grossly inefficient. Microwaves are used because they are convenient. Their efficiency sucks.

No you can't apply it to the entire volume. Matter is a barrier to microwaves. Water is the best barrier of all for a microwave tuned to heat water. When heating water in the microwave, the water closest to the emitter gets warmer first and shields the water "behind" it relative to the emitters. The water below it heats through conduction from the adjacent molecules and what little natural convection can occur... JUST LIKE A TRADITIONAL WATER HEATER - the water at the element heats first and it radiates outward. One could argue that this more efficient because the heating element radiates in all directions vs. the microwave heating radiating only in the direction opposite the emitter.

In what would you house this magical device? Metal blocks microwaves. Would you put the entire microwave including its 5600V magnetron INSIDE the water heater?

Again, to answer the question: Stupid. I'm trying to be polite by not using colorful adjectives.

I feel sufficiently flamed. Thank you!

 

[berksrunner]

You should ask yourself if you're okay with putting this out into the world with so little thought. You don't even bother with basic research before thinking you have the potential for genius. My presumptions aren't presumptions. They are facts. Opinion or fantasy does not change facts. A microwave uses 50-60% more power than it can output as microwaves. Period. The conversions necessary to take electrical input to microwave output are grossly inefficient. Microwaves are used because they are convenient. Their efficiency sucks.

No you can't apply it to the entire volume. Matter is a barrier to microwaves. Water is the best barrier of all for a microwave tuned to heat water. When heating water in the microwave, the water closest to the emitter gets warmer first and shields the water "behind" it relative to the emitters. The water below it heats through conduction from the adjacent molecules and what little natural convection can occur... JUST LIKE A TRADITIONAL WATER HEATER - the water at the element heats first and it radiates outward. One could argue that this more efficient because the heating element radiates in all directions vs. the microwave heating radiating only in the direction opposite the emitter.

In what would you house this magical device? Metal blocks microwaves. Would you put the entire microwave including its 5600V magnetron INSIDE the water heater?

Again, to answer the question: Stupid. I'm trying to be polite by not using colorful adjectives.

Again, thank you for the flaming...as if titling my own post as potentially stupid at the outset -- implying beforehand that I was NOT informed prior to making the post -- was not enough. Again, thank you!

 

[efficientPV]

My friend is a patent attorney. He often sent me patents, mind you they actually paid a lot of money to get these, that were questionable. One was a giant rotating horn that would microwave an orange orchard to keep it from freezing. Another was a hot water idea, sticking a propeller in a water tank driven by a motor to heat it.

 

[snoobler]

Again, thank you for the flaming...as if titling my own post as potentially stupid at the outset -- implying beforehand that I was NOT informed prior to making the post -- was not enough. Again, thank you!

You're welcome. Whimsical musings are not logic. When facts are readily available, but they are ignored and assumed otherwise, logic can't happen. Logic starts with what you KNOW, then proceeds to extrapolate the unknown.

In re-reading my posts, I clearly came off as a dick. My apologies to you and all who read it.

 

[Gazoo]

Has anyone thought of inventing a hot water heater for mobile applications based upon microwave technology????

If it was more efficient than a heating element then some company would have jumped on this years ago possibly before microwaves became popular. That was my first thought when you asked the question.

 

[John Frum]

I still want to know why this idea is specific to mobile applications.
I wonder if you can boil water with serious look down radar.