Author Topic: Electric stovetops are superior to gas ones  (Read 5929 times)

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Offline Marco

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Re: Electric stovetops are superior to gas ones
« Reply #25 on: October 27, 2022, 04:03:14 pm »
In theory an induction cooktop due to easy closed loop temperature control would always be a valuable addition, it can do some things easily a gas burner likely never would. I wouldn't mind an extra portable cooktop with continuously/smoothly variable power, a temperature sensor below the pan for constant temperature cooking/frying, with 2 concentric coils (outer coil kicking in for skillets and other large pans). Unfortunately most of what's available seems trash and/or overly expensive trash. I haven't been able to find anything truly well built as a cooktop, the Miele/etc hobs might be good but that's not what I'm looking for for the moment.

My sister wanted an induction cooktop to use as an extra, I ordered the latest version of the Xiaomi Mija (actually the UK TOKIT rebrand, specifically UK because for some reason mainland Europe gets a cheaper version). Coil still looks tiny, but at least it seems to have smooth power control and a temperature sensor, two out of three ain't bad I guess. I'll give it a try myself.
 

Offline Teledog

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Re: Electric stovetops are superior to gas ones
« Reply #26 on: October 28, 2022, 01:40:30 am »
Dumped out the third electric coil range in 20 years.
Gas would be exceedingly difficult & ugly to put in.
Bought a Fulgor induction range, but $$$.
It will heat a cast iron pan to well over 300F within 30 seconds (boost mode).
Boils water faster than anything I've ever used.
It DOES heat up "supposedly" non- magnetic things (ie: stainless mixing bowls {chocolate} and disposable aluminum pie tins{melting paraffin wax})
Oven has dual convection & the pizza mode actually heats up to 585F.
Ideally, if I had my dream come true..induction AND gas in one.
My 2 cents anyway.
 

Offline onsenwombat

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Re: Electric stovetops are superior to gas ones
« Reply #27 on: October 28, 2022, 09:20:56 am »
Kind of yes.. and no I'd say. Will leave the conventional electric hobs out of the discussion here as they're just complete rubbish.
Induction is lovely if you're mostly just boiling water. Quick and pretty much negligible residual heat. When actually cooking something, I'd take gas almost every time. Can adjust the heat with ~infinite accuracy, you can wiggle with the cookware as you please, the range can be cleaned with a jackhammer and a stick of dynamite after your cooking session without worrying about damaging the surfaces. And... and above anything else on this planet - NO GOD-AWFUL TOUCH BUTTONS. Fucking hate them.
For most everyday cooking, though, induction is pretty neat mainly for the lack of residual heat.
 

Offline Marco

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Re: Electric stovetops are superior to gas ones
« Reply #28 on: October 28, 2022, 04:24:53 pm »
Can adjust the heat with ~infinite accuracy
That's a result of most of the market cheaping out, probably using a fixed frequency quasiresonant control loop and just switching it complete on or off. Many ways to make it continuously variable.
Quote
can wiggle with the cookware as you please, the range can be cleaned with a jackhammer and a stick of dynamite after your cooking session without worrying about damaging the surfaces.
You could get this this and cement some thin granite ribs on top of your granite countertop. Pretty abuse proof.

In theory it's even possible to make a pan which you could tilt and baste with (by putting a receiving coil in the bottom of the pan).
 

Offline james_s

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Re: Electric stovetops are superior to gas ones
« Reply #29 on: October 28, 2022, 04:49:40 pm »
That's a result of most of the market cheaping out, probably using a fixed frequency quasiresonant control loop and just switching it complete on or off. Many ways to make it continuously variable.

While it's technologically possible to make an electric burner that works like that, every one that I've seen just cycles on and off, most of them use a crude control designed ~100 years ago with a bimetal strip and an internal heater with the knob mechanically pressing on the strip to adjust the duty cycle. Even if you have continuous control you still lack the instant feedback of gas.
 

Offline Marco

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Re: Electric stovetops are superior to gas ones
« Reply #30 on: October 28, 2022, 05:15:09 pm »
Even if you have continuous control you still lack the instant feedback of gas.
Some hobs already use lightguides to light up the edge of the pan, guess they should add some woosh too.
 

Offline james_s

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Re: Electric stovetops are superior to gas ones
« Reply #31 on: October 28, 2022, 05:26:00 pm »
Even if you have continuous control you still lack the instant feedback of gas.
Some hobs already use lightguides to light up the edge of the pan, guess they should add some woosh too.

The light is a neat idea, I've never seen one that did that.
 

Offline JohnG

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Re: Electric stovetops are superior to gas ones
« Reply #32 on: October 30, 2022, 05:13:20 pm »
That's a result of most of the market cheaping out, probably using a fixed frequency quasiresonant control loop and just switching it complete on or off. Many ways to make it continuously variable.

Yes, this is true. They are cheaping out. Even worse, many just run off of a rectified AC, but the cost savings are large. It's a shame for induction, because it is possible to get nearly infinite control.

While it's technologically possible to make an electric burner that works like that, every one that I've seen just cycles on and off, most of them use a crude control designed ~100 years ago with a bimetal strip and an internal heater with the knob mechanically pressing on the strip to adjust the duty cycle. Even if you have continuous control you still lack the instant feedback of gas.

I worked on one of these that went into a high-end electric cooktop, so it is possible. Note that you are still limited in what you can do at a reasonable cost. We used a variation of cycle-skipping. This is trickier than it seems if you want relatively fast and fine control. The total number of half-cycles per control period must be even so you don't pull any dc and unbalance the utility transformer (doesn't take a lot of dc to push the core flux average away from zero), and there are issues with subharmonics if you are not careful. You also need to avoid generating frequency components near 8-10 Hz to avoid issues with power line flicker.

Phase control with a triac is a non-starter because the power factor is atrocious and EMI is a nightmare (in the US, a high end electric cooktop might top out near 10 kW at full load). When I worked on this, this was not regulated at a residential level in the US, but that didn't mean we could do it. If you filled an apartment complex or a new subdivision with something like this, you would get an unpleasant call from the nearest utility, and word gets around. Not good for sales.

Finally, the ambient environment is brutal inside a cooktop and thermal insulation costs money...

John
« Last Edit: October 30, 2022, 05:23:09 pm by JohnG »
"Reality is that which, when you quit believing in it, doesn't go away." Philip K. Dick (RIP).
 
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Offline Marco

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Re: Electric stovetops are superior to gas ones
« Reply #33 on: October 30, 2022, 05:43:49 pm »
Yes, this is true. They are cheaping out. Even worse, many just run off of a rectified AC
The output being AC modulated isn't really a problem, 100/120 Hz modulation is well beyond the thermal response.

Hard switched buck boost with a steady duty cycle to follow rectified AC, just scaled, then QR would work fine AFAICS. The buck boost doesn't have to deal with a terrible inductor, so it works a little simpler.
« Last Edit: October 30, 2022, 05:51:23 pm by Marco »
 

Offline JohnG

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Re: Electric stovetops are superior to gas ones
« Reply #34 on: October 30, 2022, 06:19:54 pm »
100/120 Hz or it's harmonics are annoying to a subset of customers, and the cooking vessel can vibrate. But, even a little filtering or another converter costs money that appliance companies don't want to spend.

When I was involved, the product marketing teams often had little or no idea what it was like to use their own employer's cooking products. The test kitchen did a much better job, but they only got a little more respect than the engineers.

John
"Reality is that which, when you quit believing in it, doesn't go away." Philip K. Dick (RIP).
 
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Offline Alti

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Re: Electric stovetops are superior to gas ones
« Reply #35 on: October 30, 2022, 06:33:45 pm »
An induction electric range is probably more efficient then the usual one with resistive heating elements.
My electric range is a sheet of glass and under it there is a heater element insulated from the back. All the energy goes through the glass, all but some tiny fraction that is hard to measure. It is absolutely quiet, does not squeak and has no fan.

I am an advocate of resistive transfer heating.

Whether it is faster to cook a meal with resistive, inductive or gas stove is a matter of powers delivered and heat capacities that take part in this process.

For gas flame burners you do not need a bottom surface of the pot to lay flush with flames. It can be arbitrarily thin and curvy.
For resistive heat, coupling through the glass, bottom of the pot needs to be super planar or you get huge thermal resistance. Small pot is a lesser problem and can have thinner bottom but thin bottom pans would flex, start to bulge when expand and "dance" on glass.
Inductive pots need to have magnetic coupling, bottom thickness does affect energy transfer but flatness is not critical.
 

Offline JohnG

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Re: Electric stovetops are superior to gas ones
« Reply #36 on: October 31, 2022, 10:42:19 pm »
Glass with resistive heating underneath is often called "radiant electric" in the industry. If you have a very flat pot with lowish emissivity, you can transfer heat to the pot very well. But, if you have a shiny aluminum pot with a concave bottom, the same burner can barely boil water.

The problem with the latter is two-fold. First, the heat transfer is poor for obvious reasons. The second, less obvious reason, is that the resistive heaters must be thermally limited. If the glass (actaully a glass-ceramic composite with near zero TCE) gets to hot, it will fail. I forget the temperature (~700 deg C comes to mind), but it is within reach of the heating element. So, if you dump full power into the element, and your shiny, non-flat pot doesn't absorb it, the temperature of the glass starts to climb. Hence, the thermal limit kicks in to prevent that from happening. If the pot is bad enough, you can hardly bring water to a simmer.

Other downsides are the long thermal time constant (that glass stays hot for a long time), and better not burn too much sugar on it or it sometimes it can pit the glass.

John
"Reality is that which, when you quit believing in it, doesn't go away." Philip K. Dick (RIP).
 

Offline JohnG

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Re: Electric stovetops are superior to gas ones
« Reply #37 on: October 31, 2022, 10:52:54 pm »
A few more bits of cooktop trivia:

The coil element cooktops (Calrod burners) can actually get response times a lot closer to gas, if you can estimate and cancel the thermal pole. This can give very responsive cooking performance. The glass cooktop cooling time constant is too long for this too work well.

The problem is, coil cooktops are the cheapest and have a unshakeably cheap reputation. Because of the reputation, a manufacturer won't put the money into it because they probably will never get it back. Most people with more money to spend will get gas or induction.

One other thing is that many mid-tier and above cooktops with electronic controls (in US) have a "showroom mode" that is activated when you connect power to one of the lines and neutral, and leave the other line disconnected. That way, the controls can light up and emulate function on the showroom floor without any danger of turning on a heating element. A lit-up big appliance will sell better than a dark one, even if otherwise identical.

John
« Last Edit: November 01, 2022, 08:23:21 pm by JohnG »
"Reality is that which, when you quit believing in it, doesn't go away." Philip K. Dick (RIP).
 


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