Because of the Second Law of Thermodynamics, like I said. The turbines in power stations are heat engines. Hot gas in one end; cooler gas out. The maximum efficiency is the temperature difference between the hot and the cold gases expressed as a percentage of the hot gas temperature, using an absolute temperature scale like Kelvin.
Nice one! Thanks for posting :-)
Useful if you want to know whether LR44 cells that cost £2 for 10 are good value compared to ones that are £2 each.
Because the exhaust gasses can not be colder than the hot water output. For heating a house 60°C or less is good. For hot water, 45°C is enough. For a power station, you need to boil the water at elevated pressures.
The electricity companies do their own checking.
At least a fine, which is order of magnitude higher than paying it back.
At six months, I would be in trouble with the company, they would be sending inspectors and asking the police.
Maybe there never was such a problem in Spain. We did things right from the start.
LOL.
Not enough people would do.
Look, I am very happy with my smart meter and with everybody having them.
Of course it is.
Don't you know Doctor Zhivago was filmed here, with all that snow?
You can be without in areas of the south of Spain, but in winter everybody needs something.
Yeah, sure.
I do.
Consider a "100% efficient" gas or electric heater. A very hot element warms room air.
But one could add a thermoelectric generator between the heat source and the room air and get just as much hot air, but free electricity too! Use that to make more heat.
Water used to be unmetered at our cabin, but then they installed smart meters. I got an email from TDPUD that they suspected a leak, based on the usage pattern. They sent me graphs and we saw a constant low-level flow when nobody was there. It was a leaking shutoff+drain valve.
Realtime metering catches stuff like that.
No? What about:
No, you couldnt.
The energy from the electricity would subtract from the heat output of the device. Unless the electricity all ends up as heat, anything else - like mechanical power - has to be exchanged for heat.
That is equivalent to saying that heat pumps can't work.
It's an impedance matching problem. It's inefficient to use a 1900C gas flame to directly heat air to 25C.
No it isnt.
No, it isnt
It's just an exercise in design
California has mandated that future water heaters must be heat pumps.
A heat pump can deliver a given amount of space heating or hot water at about 1/3 the cost of direct gas or resistive electric heating.
Suppose you have 120 VAC and want to charge a 24 volt battery. You could rectify and filter to 150 VDC, and connect that to the battery through a resistor. Or you could use a transformer or a switching regulator. Your engineering decision.
Yes. Try it. You can Spice a thermal system assuming
ELECTRICAL THERMAL
1 amp 1 watt 1 farad 1 gram aluminum 1 volt 1 degree C 1 second 1 second 1 ohm 1 K/wattwhich is accurate to about 10%.
Note that current is not power, as integrated heat flow is not energy.
A thermoelectric generator is just another heat engine, it COOLS the hot end and warms the cold one. It'll never 'make more heat' because it's a heatpump cooler in its primary function.
mandag den 14. november 2022 kl. 17.51.21 UTC+1 skrev John Larkin:
heat pumps move heat
inefficient how? A condensing gas boiler is ~95% efficient the exhaust is ~50'C
Irrelevaqnt
But not without an external heat source like the air or round.
granndmither eggs suck
I dint know how to spice a thermal system I do know because I am an engineer, everything below
Jesus Christ, I have a masters in electrical engineering and an ordinary degree in general engineering including thermal energy design.
Go and patronise your hamster
As has been pointed out to you thermal transfer efficiency is a function of how hot the working fluid gets and how cold the final exhaust is, And infinitely large heat exchanger that heats to in infinitesimal amount over ambient is 100% efficient.
The hotter the input to a heat exchanger the more efficient it is, the colder the outflow from it the more efficient it is, so a warm condensing boiler is more efficient all other things being equal to one that gets water to over 100°C. Like wise the hotter the combustion temperature the more efficient it will be as well. Which is why gas turbines are once they are a attached to stream turbines,more efficient than steam turbines alone.
On Monday, 14 November 2022 at 09:30:48 UTC-8, John Larkin wrote: ...
...
If the objective is to provide space heating at relatively low temperature it doesn't make any difference which solution you choose. They are still 100% efficient.
Any heat developed in the resistor dropper in your simulation is creating desired output inanition to any that is delivered to the battery (In this case it is a heat sink at the output temperature).
If your definition of 'efficiency' includes entropy then it would indeed be better to use a heat engine with its source as the high temperature and discard waste heat to the hot water or other area needing space heating. Some of the input heat would then be converted to a more valuable form such as mechanical or electrical power.
kw
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