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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#41
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O.T. electric cars - do they have gearboxes?
On 21-Apr-17 8:51 AM, harry wrote:
On Thursday, 20 April 2017 16:39:29 UTC+1, Brian Reay wrote: On 19/04/2017 19:47, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. We looked at the Tesla and were told it didn't have a gear box. We decided against all electric, we don't like the idea of being stuck with a 'flat' battery on a journey. The idea of stopping for 'top ups' on a long journey is fine until you consider the practical aspects. The practical aspects are 1. The charge point(s) are in use. 2. The charge point has been vandalised. 3. Some idiot has parked an ICE car in the charge bay. 4 The council has removed the charge points from the car park, because nobody has been using them, which is what has been happening around here. -- -- Colin Bignell |
#42
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O.T. electric cars - do they have gearboxes?
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#43
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O.T. electric cars - do they have gearboxes?
On 20-Apr-17 11:41 PM, Tim Streater wrote:
In article , Nightjar wrote: On 20-Apr-17 6:18 PM, Tim Streater wrote: In article , Nightjar wrote: On 20-Apr-17 8:18 AM, harry wrote: On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. Internal combustion engines are inherently unsuitable for traction, hence the need for gearboxes/clutches etc. Electric motors can be designed to be ideal for traction. Max torque at zero rpm. I could get that with a steam engine. And a small one at that for a car. But AIUI, it's the condenser that's the problem. With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and it could move off from cold in under 30 seconds. http://www.popularmechanics.com/cars...le-steam-cars/ Presumably it needed fuel as well as water. What was that, and how much was needed, and how was the boiler kept stoked etc. According to the link I gave, they usually burned kerosene, but, being an external combustion engine, almost anything would do. However, my main point was that if they managed to get that range from one tank of water in 1924, we should expect better today. -- -- Colin Bignell |
#44
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O.T. electric cars - do they have gearboxes?
On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote:
On 21-Apr-17 8:47 AM, harry wrote: On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote: On 20-Apr-17 6:18 PM, Tim Streater wrote: In article , Nightjar wrote: On 20-Apr-17 8:18 AM, harry wrote: On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. Internal combustion engines are inherently unsuitable for traction, hence the need for gearboxes/clutches etc. Electric motors can be designed to be ideal for traction. Max torque at zero rpm. I could get that with a steam engine. And a small one at that for a car. But AIUI, it's the condenser that's the problem. With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and it could move off from cold in under 30 seconds. Drivel. Water is not fuel. I was answering the point about the condenser. However, recent advances in catalytic splitting of water could make it feasible to use water as fuel, if you really wanted to. Drivel. Have you never heard of the Law of Conservation of Energy? All steam engines and boilers are inherently inefficient. They will never come anywhere near the ICE efficiency wise. I spent forty years running them. And getting rid of them where possible. |
#45
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O.T. electric cars - do they have gearboxes?
On Friday, 21 April 2017 10:13:17 UTC+1, Nightjar wrote:
On 21-Apr-17 8:51 AM, harry wrote: On Thursday, 20 April 2017 16:39:29 UTC+1, Brian Reay wrote: On 19/04/2017 19:47, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. We looked at the Tesla and were told it didn't have a gear box. We decided against all electric, we don't like the idea of being stuck with a 'flat' battery on a journey. The idea of stopping for 'top ups' on a long journey is fine until you consider the practical aspects. The practical aspects are 1. The charge point(s) are in use. 2. The charge point has been vandalised. 3. Some idiot has parked an ICE car in the charge bay. 4 The council has removed the charge points from the car park, because nobody has been using them, which is what has been happening around here. -- -- Colin Bignell Very possible.The government has mishandled the whole business. Most EV drivers charge their car at home far more cheaply. I SummerI pay nothing mostly, due to PV panels. 99% of my journeys are in range. The others, I use my other car. |
#46
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O.T. electric cars - do they have gearboxes?
"harry" wrote in message
... Most EV drivers charge their car at home far more cheaply. I Summer I pay nothing mostly, due to PV panels. 99% of my journeys are in range. The others, I use my other car. Is there enough time to charge the car, given that you will probably have it away from home during most of the daylight hours and hence there are only a few hours of light at the end of the day and the beginning of the day when the car can charge off free electricity; during hours of darkness you'll need to use electricity that you have to pay for, from the grid. How much does gradient affect range? I imagine that a few 1:5 (or steeper) hills on a journey would reduce the range quite significantly. Do you keep your car outside or in a garage? If it's kept outside, how do you protect against moisture (eg early morning dew) and someone maliciously disconnecting the supply (either to use your electricity or just for the hell of it)? How do car parks guard against malicious disconnections? If you can manage to keep your journeys to within the daily range of the car, you don't need to worry about recharge time because you've got loads of "dead" time either when you are at work or else overnight. But you need a second car (maybe not used normally, but still needing to be taxed and insured) for holidays and other times when you will want to travel vastly in excess of the electric car's range. It is the need for two cars, each suited to a particular type of journey, where a single IC-engined car would suffice, which is a big problem with EVs. I don't see a way around the recharge time, unless cars use batteries that are exchanged at fuel stops, because the rate at which energy is taken on board with petrol or diesel is tremendous: within a couple of minutes I can fill my 60-litre tank and have another 700 miles of range. Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 = 56 MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power transfer of 56*60/300 = 11 MW (!) Try supplying electricity to a battery at that rate :-) Watch the lights go dim in the neighbourhood while you are charging :-) |
#47
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O.T. electric cars - do they have gearboxes?
On 21/04/2017 08:55, harry wrote:
Wait until it breaks. Then try and find someone to fix it. The dealers lie BTW. That's hardly unique to electric cars... (Just found out the reason the mechanics have taken a week and not fixed my IC car was they didn't have authorisation, and the **** paper pushers hadn't asked me) Andy |
#48
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O.T. electric cars - do they have gearboxes?
On 21/04/17 19:48, NY wrote:
Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 = 56 MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power transfer of 56*60/300 = 11 MW (!) Well diesels are at best 40% efficient and leccy motors at least 80%, so halve that to 5.5MW. Not that big a deal. similar to a train starting up I'd say. Its about 7000 bhp. So 10 formula one cars in qualifying trim... So very doable at a custom built motorway service station, if not in yer garage. But thats where the car is kept and charged overnight innit? -- "The great thing about Glasgow is that if there's a nuclear attack it'll look exactly the same afterwards." Billy Connolly |
#49
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O.T. electric cars - do they have gearboxes?
"NY" wrote in message o.uk... "harry" wrote in message ... Most EV drivers charge their car at home far more cheaply. I Summer I pay nothing mostly, due to PV panels. 99% of my journeys are in range. The others, I use my other car. Is there enough time to charge the car, given that you will probably have it away from home during most of the daylight hours He's unemployed and is hardly ever out. and hence there are only a few hours of light at the end of the day and the beginning of the day when the car can charge off free electricity; during hours of darkness you'll need to use electricity that you have to pay for, from the grid. How much does gradient affect range? I imagine that a few 1:5 (or steeper) hills on a journey would reduce the range quite significantly. Do you keep your car outside or in a garage? If it's kept outside, how do you protect against moisture (eg early morning dew) and someone maliciously disconnecting the supply (either to use your electricity or just for the hell of it)? How do car parks guard against malicious disconnections? If you can manage to keep your journeys to within the daily range of the car, you don't need to worry about recharge time because you've got loads of "dead" time either when you are at work or else overnight. But you need a second car (maybe not used normally, but still needing to be taxed and insured) for holidays and other times when you will want to travel vastly in excess of the electric car's range. It is the need for two cars, each suited to a particular type of journey, where a single IC-engined car would suffice, which is a big problem with EVs. I don't see a way around the recharge time, unless cars use batteries that are exchanged at fuel stops, because the rate at which energy is taken on board with petrol or diesel is tremendous: within a couple of minutes I can fill my 60-litre tank and have another 700 miles of range. Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 = 56 MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power transfer of 56*60/300 = 11 MW (!) Try supplying electricity to a battery at that rate :-) Watch the lights go dim in the neighbourhood while you are charging :-) |
#50
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O.T. electric cars - do they have gearboxes?
On 20/04/2017 19:24, Nightjar wrote:
On 20-Apr-17 6:18 PM, Tim Streater wrote: In article , Nightjar wrote: On 20-Apr-17 8:18 AM, harry wrote: On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. Internal combustion engines are inherently unsuitable for traction, hence the need for gearboxes/clutches etc. Electric motors can be designed to be ideal for traction. Max torque at zero rpm. I could get that with a steam engine. And a small one at that for a car. But AIUI, it's the condenser that's the problem. With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and it could move off from cold in under 30 seconds. http://www.popularmechanics.com/cars...le-steam-cars/ Ta. And a video of it https://www.youtube.com/watch?v=rUg_ukBwsyo -- Adam |
#51
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O.T. electric cars - do they have gearboxes?
On Friday, 21 April 2017 21:50:10 UTC+1, Vir Campestris wrote:
On 21/04/2017 08:55, harry wrote: Wait until it breaks. Then try and find someone to fix it. The dealers lie BTW. That's hardly unique to electric cars... (Just found out the reason the mechanics have taken a week and not fixed my IC car was they didn't have authorisation, and the **** paper pushers hadn't asked me) Andy Consider yourself lucky It took them over three months to fix mine. Under guarantee. |
#52
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O.T. electric cars - do they have gearboxes?
On Friday, 21 April 2017 19:48:45 UTC+1, NY wrote:
"harry" wrote in message ... Most EV drivers charge their car at home far more cheaply. I Summer I pay nothing mostly, due to PV panels. 99% of my journeys are in range. The others, I use my other car. Is there enough time to charge the car, given that you will probably have it away from home during most of the daylight hours and hence there are only a few hours of light at the end of the day and the beginning of the day when the car can charge off free electricity; during hours of darkness you'll need to use electricity that you have to pay for, from the grid. How much does gradient affect range? I imagine that a few 1:5 (or steeper) hills on a journey would reduce the range quite significantly. Do you keep your car outside or in a garage? If it's kept outside, how do you protect against moisture (eg early morning dew) and someone maliciously disconnecting the supply (either to use your electricity or just for the hell of it)? How do car parks guard against malicious disconnections? If you can manage to keep your journeys to within the daily range of the car, you don't need to worry about recharge time because you've got loads of "dead" time either when you are at work or else overnight. But you need a second car (maybe not used normally, but still needing to be taxed and insured) for holidays and other times when you will want to travel vastly in excess of the electric car's range. It is the need for two cars, each suited to a particular type of journey, where a single IC-engined car would suffice, which is a big problem with EVs. I don't see a way around the recharge time, unless cars use batteries that are exchanged at fuel stops, because the rate at which energy is taken on board with petrol or diesel is tremendous: within a couple of minutes I can fill my 60-litre tank and have another 700 miles of range. Diesel is 45 MJ/kg. Its density is 0.8 kg/l, so the energy is 45/0.8 = 56 MJ/l. So if I fill up with 60 litres in 5 minutes, that's a power transfer of 56*60/300 = 11 MW (!) Try supplying electricity to a battery at that rate :-) Watch the lights go dim in the neighbourhood while you are charging :-) I am retired so it can be charged through the day. But even on mains electricity, the cost is negligable compared with petrol. Often you can arrange to charge up at destination. You get used to range estimations after a while. Gradient has a big effect. But you get about half back descending the other side. The heater has a big effect too. My cars are indoors, I also have an ICE car. But no tax and cheap to insure as it's a heritage vehicle. |
#53
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O.T. electric cars - do they have gearboxes?
On 21-Apr-17 6:46 PM, harry wrote:
On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote: On 21-Apr-17 8:47 AM, harry wrote: On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote: On 20-Apr-17 6:18 PM, Tim Streater wrote: In article , Nightjar wrote: On 20-Apr-17 8:18 AM, harry wrote: On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. Internal combustion engines are inherently unsuitable for traction, hence the need for gearboxes/clutches etc. Electric motors can be designed to be ideal for traction. Max torque at zero rpm. I could get that with a steam engine. And a small one at that for a car. But AIUI, it's the condenser that's the problem. With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and it could move off from cold in under 30 seconds. Drivel. Water is not fuel. I was answering the point about the condenser. However, recent advances in catalytic splitting of water could make it feasible to use water as fuel, if you really wanted to. Drivel. Have you never heard of the Law of Conservation of Energy? The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. All steam engines and boilers are inherently inefficient. They will never come anywhere near the ICE efficiency wise. Petrol cars achieve a tank to wheel thermal efficiency of about 16%. Non-condensing third generation steam locomotives achieve a drawbar thermal efficiency of about 16%. I spent forty years running them. And getting rid of them where possible. I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. -- -- Colin Bignell |
#54
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O.T. electric cars - do they have gearboxes?
Nightjar wrote:
The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. Eh? Now who's talking drivel? A fuel cell that magically splits water or in some other way converts *only* water into electrical energy? This greatest, most fabulous discovery was made a few years ago and nobody has heard of it? This one perhaps? https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0 "Fabulous" seems like an apt description, stuff of fables. Tim -- Please don't feed the trolls |
#55
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O.T. electric cars - do they have gearboxes?
On 22/04/17 09:45, Nightjar wrote:
On 21-Apr-17 6:46 PM, harry wrote: On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote: On 21-Apr-17 8:47 AM, harry wrote: On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote: On 20-Apr-17 6:18 PM, Tim Streater wrote: In article , Nightjar wrote: On 20-Apr-17 8:18 AM, harry wrote: On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. Internal combustion engines are inherently unsuitable for traction, hence the need for gearboxes/clutches etc. Electric motors can be designed to be ideal for traction. Max torque at zero rpm. I could get that with a steam engine. And a small one at that for a car. But AIUI, it's the condenser that's the problem. With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and it could move off from cold in under 30 seconds. Drivel. Water is not fuel. I was answering the point about the condenser. However, recent advances in catalytic splitting of water could make it feasible to use water as fuel, if you really wanted to. Drivel. Have you never heard of the Law of Conservation of Energy? The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. All steam engines and boilers are inherently inefficient. They will never come anywhere near the ICE efficiency wise. Typical modern steam power station 37%. More with supercritical steam Typical diesel. 25%. Petrol cars achieve a tank to wheel thermal efficiency of about 16%. Non-condensing third generation steam locomotives achieve a drawbar thermal efficiency of about 16%. No use telling harry anything. The thermodynamics are all well understood, but not by harry I spent forty years running them. And getting rid of them where possible. I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Exatamondo. I cant remember what the law is called, but the hotter the working fluid (steam in this case) is to start with, and the colder the final exhaust, the more efficient is the engine. Which is why a combined cycle gas turbine that starts with 1000C gases in the jet engine, then heats a boler to get steam, and has a final after condenser temp of around 50C, willnet you over 60% thermal efficiency. Whether you call that an IC or a steam engine is up to you. -- "Corbyn talks about equality, justice, opportunity, health care, peace, community, compassion, investment, security, housing...." "What kind of person is not interested in those things?" "Jeremy Corbyn?" |
#56
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O.T. electric cars - do they have gearboxes?
On 22/04/17 10:36, Chris Hogg wrote:
On Sat, 22 Apr 2017 09:21:33 -0000 (UTC), Tim+ wrote: Nightjar wrote: The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. Eh? Now who's talking drivel? A fuel cell that magically splits water or in some other way converts *only* water into electrical energy? This greatest, most fabulous discovery was made a few years ago and nobody has heard of it? This one perhaps? https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0 "Fabulous" seems like an apt description, stuff of fables. Tim Sadly, the Green world is full of such nonsense. Anything is possible if you know nothing. Anything *seems* to be possible if you know nothing. I have often said - and it bears repeating - that my education in hard science and engineering doesn't tell me ultimately how to build stuff that works, but it is incredibly effective at telling me what cannot work, so I don't waste time trying. This 'negative knowledge' is hugely useful. Greens call it 'being negative' :-) -- "If you dont read the news paper, you are un-informed. If you read the news paper, you are mis-informed." Mark Twain |
#57
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O.T. electric cars - do they have gearboxes?
On 22/04/17 11:44, Chris Hogg wrote:
On Sat, 22 Apr 2017 10:48:32 +0100, The Natural Philosopher wrote: On 22/04/17 09:45, Nightjar wrote: On 21-Apr-17 6:46 PM, harry wrote: On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote: On 21-Apr-17 8:47 AM, harry wrote: On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote: On 20-Apr-17 6:18 PM, Tim Streater wrote: In article , Nightjar wrote: On 20-Apr-17 8:18 AM, harry wrote: On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. Internal combustion engines are inherently unsuitable for traction, hence the need for gearboxes/clutches etc. Electric motors can be designed to be ideal for traction. Max torque at zero rpm. I could get that with a steam engine. And a small one at that for a car. But AIUI, it's the condenser that's the problem. With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and it could move off from cold in under 30 seconds. Drivel. Water is not fuel. I was answering the point about the condenser. However, recent advances in catalytic splitting of water could make it feasible to use water as fuel, if you really wanted to. Drivel. Have you never heard of the Law of Conservation of Energy? The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. All steam engines and boilers are inherently inefficient. They will never come anywhere near the ICE efficiency wise. Typical modern steam power station 37%. More with supercritical steam Typical diesel. 25%. Petrol cars achieve a tank to wheel thermal efficiency of about 16%. Non-condensing third generation steam locomotives achieve a drawbar thermal efficiency of about 16%. No use telling harry anything. The thermodynamics are all well understood, but not by harry I spent forty years running them. And getting rid of them where possible. I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Exatamondo. I cant remember what the law is called, but the hotter the working fluid (steam in this case) is to start with, and the colder the final exhaust, the more efficient is the engine. Carnot cycle or Carnot's law. https://en.wikipedia.org/wiki/Carnot_cycle Not to be confused with Fred Karno, who had an 'army' IIRC! That's the bugger! Which is why a combined cycle gas turbine that starts with 1000C gases in the jet engine, then heats a boler to get steam, and has a final after condenser temp of around 50C, willnet you over 60% thermal efficiency. Whether you call that an IC or a steam engine is up to you. -- All political activity makes complete sense once the proposition that all government is basically a self-legalising protection racket, is fully understood. |
#58
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O.T. electric cars - do they have gearboxes?
In article ,
Nightjar wrote: Petrol cars achieve a tank to wheel thermal efficiency of about 16%. Non-condensing third generation steam locomotives achieve a drawbar thermal efficiency of about 16%. A steam locomotive generally operates under carefully controlled conditions. Like all railways. Cars don't. -- *When a man opens a car door for his wife, it's either a new car or a new Dave Plowman London SW To e-mail, change noise into sound. |
#59
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O.T. electric cars - do they have gearboxes?
In article , Tim Streater
wrote: In article , The Natural Philosopher wrote: I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Exatamondo. I cant remember what the law is called, but the hotter the working fluid (steam in this case) is to start with, and the colder the final exhaust, the more efficient is the engine. Which is why a combined cycle gas turbine that starts with 1000C gases in the jet engine, then heats a boler to get steam, and has a final after condenser temp of around 50C, willnet you over 60% thermal efficiency. One of the laws of thermodynamics IIRC - efficiency is related to the difference between input and output temps - in degrees K, not C. my elementary physics suggests that if you are only refering to a temperature difference the answer is the same in °K and in °C.° -- from KT24 in Surrey, England |
#60
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O.T. electric cars - do they have gearboxes?
On 22-Apr-17 10:21 AM, Tim+ wrote:
Nightjar wrote: The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. Eh? Now who's talking drivel? A fuel cell that magically splits water or in some other way converts *only* water into electrical energy? This greatest, most fabulous discovery was made a few years ago and nobody has heard of it? This one perhaps? https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0 "Fabulous" seems like an apt description, stuff of fables. That looks like it. I only recall the publicity of its launch and didn't follow up on what happened to it. However, MIT and Stanford University have both demonstrated low energy water splitters that can run from low voltage sources. -- -- Colin Bignell |
#61
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O.T. electric cars - do they have gearboxes?
Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote: Nightjar wrote: The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. Eh? Now who's talking drivel? A fuel cell that magically splits water or in some other way converts *only* water into electrical energy? This greatest, most fabulous discovery was made a few years ago and nobody has heard of it? This one perhaps? https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0 "Fabulous" seems like an apt description, stuff of fables. That looks like it. I only recall the publicity of its launch and didn't follow up on what happened to it. However, MIT and Stanford University have both demonstrated low energy water splitters that can run from low voltage sources. "Didn't follow up" is a lame excuse for believing in fairies! Do you believe in other perpetual motion machines? Tim -- Please don't feed the trolls |
#62
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O.T. electric cars - do they have gearboxes?
On 22/04/2017 12:23, Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote: Nightjar wrote: The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. Eh? Now who's talking drivel? A fuel cell that magically splits water or in some other way converts *only* water into electrical energy? This greatest, most fabulous discovery was made a few years ago and nobody has heard of it? This one perhaps? https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0 "Fabulous" seems like an apt description, stuff of fables. That looks like it. I only recall the publicity of its launch and didn't follow up on what happened to it. However, MIT and Stanford University have both demonstrated low energy water splitters that can run from low voltage sources. You can split water with an AAA battery, the voltage doesn't matter much its how much energy it takes. Rule one: you cannot get more energy out than you put in. This means that all these split water put it through a fuel cell and re-split it while taping off energy are scams, every one. There are no exceptions no matter how many youtube likes they get. I know its hard to understand but its the truth, in this reality anyway. |
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O.T. electric cars - do they have gearboxes?
On 22/04/17 12:23, Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote: Nightjar wrote: The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. Eh? Now who's talking drivel? A fuel cell that magically splits water or in some other way converts *only* water into electrical energy? This greatest, most fabulous discovery was made a few years ago and nobody has heard of it? This one perhaps? https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0 "Fabulous" seems like an apt description, stuff of fables. That looks like it. I only recall the publicity of its launch and didn't follow up on what happened to it. However, MIT and Stanford University have both demonstrated low energy water splitters that can run from low voltage sources. well I am sorry, but unless the laws of physics have changed the energy required to split a molecule of water into hydrogen and oxygen is the same whatever method you use, and about three times what you are likely to get back recombining them to make mechanical or electrical power. -- If I had all the money I've spent on drink... ...I'd spend it on drink. Sir Henry (at Rawlinson's End) |
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O.T. electric cars - do they have gearboxes?
On 22/04/17 12:13, charles wrote:
In article , Tim Streater wrote: In article , The Natural Philosopher wrote: I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Exatamondo. I cant remember what the law is called, but the hotter the working fluid (steam in this case) is to start with, and the colder the final exhaust, the more efficient is the engine. Which is why a combined cycle gas turbine that starts with 1000C gases in the jet engine, then heats a boler to get steam, and has a final after condenser temp of around 50C, willnet you over 60% thermal efficiency. One of the laws of thermodynamics IIRC - efficiency is related to the difference between input and output temps - in degrees K, not C. my elementary physics suggests that if you are only refering to a temperature difference the answer is the same in °K and in °C.° Well its not actually the temperature difference, its the *ratio* of the temperatures. The total input energy in heat is proportional to the absolute temperature. The lost output energy as heat is proportional to the output temperature in absolute degrees. Theres a bit of a fudge in that you start with ambient to do your heating of course. -- If I had all the money I've spent on drink... ...I'd spend it on drink. Sir Henry (at Rawlinson's End) |
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O.T. electric cars - do they have gearboxes?
In article ,
Chris Hogg wrote: t always sup rises me that seemingly intelligent people who claim to have invented the perpetual motion machines that they proudly display on Youtube, aren't multi-millionaires, having solved the world's energy and AGW problems at a stroke with their carbon-free, non-nuclear methods of electricity generation, such as cars that run on water or spinning magnet arrangements to make electricity. The fact that they aren't multi-millionaires says it all. Rather like someone trying to sell you a money making scheme. If it were good, they'd keep it to themselves, and make all the money they want. -- *I'm reading a book about anti-gravity. I just can't put it down.* Dave Plowman London SW To e-mail, change noise into sound. |
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O.T. electric cars - do they have gearboxes?
On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote:
In article , Tim Streater wrote: In article , The Natural Philosopher wrote: I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Exatamondo. I cant remember what the law is called, but the hotter the working fluid (steam in this case) is to start with, and the colder the final exhaust, the more efficient is the engine. Which is why a combined cycle gas turbine that starts with 1000C gases in the jet engine, then heats a boler to get steam, and has a final after condenser temp of around 50C, willnet you over 60% thermal efficiency. One of the laws of thermodynamics IIRC - efficiency is related to the difference between input and output temps - in degrees K, not C. my elementary physics suggests that if you are only refering to a temperature difference the answer is the same in °K and in °C.° The main benefit of using deg K instead of Deg C is the complete and utter absence of negative numbers by which to confuse the mathematics. :-) It's true enough that as far as steam engines are concerned, this is unlikely to effect calculations involving deg C, but there are other heat engines designs based on fluids with much lower freezing and boiling points than zero deg C (the triple point of water to within an accuracy of one decimal place). -- Johnny B Good |
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O.T. electric cars - do they have gearboxes?
On Saturday, 22 April 2017 09:45:40 UTC+1, Nightjar wrote:
On 21-Apr-17 6:46 PM, harry wrote: On Friday, 21 April 2017 09:58:50 UTC+1, Nightjar wrote: On 21-Apr-17 8:47 AM, harry wrote: On Thursday, 20 April 2017 19:24:26 UTC+1, Nightjar wrote: On 20-Apr-17 6:18 PM, Tim Streater wrote: In article , Nightjar wrote: On 20-Apr-17 8:18 AM, harry wrote: On Wednesday, 19 April 2017 19:47:29 UTC+1, Murmansk wrote: I've just been for a ride in someone's Nissan Leaf - it was impressive, so quiet and amazing acceleration. Do electric cars have a gearbox (an automatic one I presume)? Or does the motor just run faster the faster you go? I was told by the owner the optimum speed for economy of battery usage is about 55mph. It doesn't sound like it's changing gear. Internal combustion engines are inherently unsuitable for traction, hence the need for gearboxes/clutches etc. Electric motors can be designed to be ideal for traction. Max torque at zero rpm. I could get that with a steam engine. And a small one at that for a car. But AIUI, it's the condenser that's the problem. With a 24 gallon water tank, the 1924 Doble E had a 1500 mile range and it could move off from cold in under 30 seconds. Drivel. Water is not fuel. I was answering the point about the condenser. However, recent advances in catalytic splitting of water could make it feasible to use water as fuel, if you really wanted to. Drivel. Have you never heard of the Law of Conservation of Energy? The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. All steam engines and boilers are inherently inefficient. They will never come anywhere near the ICE efficiency wise. Petrol cars achieve a tank to wheel thermal efficiency of about 16%. Non-condensing third generation steam locomotives achieve a drawbar thermal efficiency of about 16%. I spent forty years running them. And getting rid of them where possible. I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Total drivel. Steam locomotive efficiency, typically 5%. The most efficient power stations use rejected heat for district heating. But that only applies in Winter. In Summer the heat is dumped. And it only works if the heat is needed nearby. Higher steam temperatures results in less efficient boilers because the exiting combustion gases can be at no lower temperature than the stem. If you look at the picture, there are cooling towers. What do you suppose they are for? (Clue,dumping excess heat) http://cornerstonemag.net/setting-th...-power-plants/ The problem of what to do with rejected low grade heat has proved insurmountable. Flash steam boilers are suited for rapid start up, cheapness and low weight. But are notoriously inefficient, high maintenance and short life. Yes,I have run these too. |
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O.T. electric cars - do they have gearboxes?
On Saturday, 22 April 2017 12:23:33 UTC+1, Nightjar wrote:
On 22-Apr-17 10:21 AM, Tim+ wrote: Nightjar wrote: The principle has been demonstrated. A few years ago the Japanese demonstrated a fuel cell car that ran entirely on water. Eh? Now who's talking drivel? A fuel cell that magically splits water or in some other way converts *only* water into electrical energy? This greatest, most fabulous discovery was made a few years ago and nobody has heard of it? This one perhaps? https://www.greenoptimistic.com/gene.../#.WPshDlTTWf0 "Fabulous" seems like an apt description, stuff of fables. That looks like it. I only recall the publicity of its launch and didn't follow up on what happened to it. However, MIT and Stanford University have both demonstrated low energy water splitters that can run from low voltage sources. -- -- Colin Bignell You don't get anything for nothing. In theory it take the same amount of energy to split hydrogen and oxygen as you get burning the hydrogen. In practice, splitting the hydrogen is very inefficient. So the whole concept is/was doomed. |
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O.T. electric cars - do they have gearboxes?
On 22-Apr-17 12:47 PM, Chris Hogg wrote:
.... Splitting water only requires 1.23v in theory. If it's low energy, as opposed to low voltage, you only get low amounts of H2 and O2. And with the usual systematic energy losses, you'll get even lower amounts of energy back when you recombine them. The idea that you can split water, recombine the products, and get more energy out than you put in, is pure fantasy, like the thinking on any other perpetual motion machine. As they are working on ways of reducing the cost of producing hydrogen, they have been working on getting the same amount while using less energy. Both claim to have made breakthroughs in doing that. As these are processes with commercial applications, no details have been given, but I assume that the use of catalysts implies that there is some chemical reaction involved as well as pure electrolysis. -- -- Colin Bignell |
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O.T. electric cars - do they have gearboxes?
On 23/04/17 09:19, Nightjar wrote:
On 22-Apr-17 12:47 PM, Chris Hogg wrote: .... Splitting water only requires 1.23v in theory. If it's low energy, as opposed to low voltage, you only get low amounts of H2 and O2. And with the usual systematic energy losses, you'll get even lower amounts of energy back when you recombine them. The idea that you can split water, recombine the products, and get more energy out than you put in, is pure fantasy, like the thinking on any other perpetual motion machine. As they are working on ways of reducing the cost of producing hydrogen, they have been working on getting the same amount while using less energy. Both claim to have made breakthroughs in doing that. As these are processes with commercial applications, no details have been given, but I assume that the use of catalysts implies that there is some chemical reaction involved as well as pure electrolysis. You can assume what you like mate, but the fact remains that the binding energy has to be overcome, and that sets a limit on the process. You cant magically create energy out of nothing. The energy you get be recombining hydrogen and oxygen will never exceed what you put in to split them in the first place. And in fact is usually a whole lot less. Using electricity to make hydrogen and then burning that to create electricity is a round trip efficiency of probably less than 30% as batteries go, that's crap. If basic physics wer mandatory like English is supposed to be there wouldn't be as single renewable/alternative energy company in operation. They all survive because of grants granted by the technically illiterate. -- Karl Marx said religion is the opium of the people. But Marxism is the crack cocaine. |
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O.T. electric cars - do they have gearboxes?
On 23-Apr-17 8:13 AM, harry wrote:
.... I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Total drivel. Steam locomotive efficiency, typically 5%.... Third generation steam locomotives are not typical. They have been specifically designed to use modern technology. The 5AT project failed to get the target funding, but the calculation of drawbar efficiency is given he http://5at.co.uk/index.php/definitio...fficiency.html Flash steam boilers are suited for rapid start up, cheapness and low weight. But are notoriously inefficient, high maintenance and short life. Yes,I have run these too. Using 21st century or 19th century materials? Whatever you want to think, an R&D subsidiary of IAV Gmbh developed a small, lightweight steam engine, using modern technology throughout, that could be fitted into motor vehicles, although they see the initial application as being in auxiliary power units, particularly in third world countries. They claim fuel efficiency as being similar to a diesel engine. It uses catalytic heating to avoid flames, which keeps emissions down to very low levels, and can burn a very wide range of fuels. Steam is viable, even if that does not sit well with your world view. -- -- Colin Bignell |
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O.T. electric cars - do they have gearboxes?
On 23/04/17 09:49, Nightjar wrote:
Steam is viable, even if that does not sit well with your world view. Technically perhaps ...but economically? IC engines are good because you don't have to lug the fuel oxidant or the working fluid around. Its in huge supply as atmospheric oxygen and gases respectively. Once you are building a static installation though, steam predominates and is more efficient, because you can run huge condensers on the back end. And you have a variety of thermal sources that you can hook up - coal, oil gas, nuclear. -- The New Left are the people they warned you about. |
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O.T. electric cars - do they have gearboxes?
On Fri, 21 Apr 2017 10:08:00 +0100, Muddymike
wrote: On 21/04/2017 10:01, Tim Streater wrote: In article , Muddymike wrote: Or like my Peugeot ICE drives front wheels, Electric motor drives rear wheels. So I have 4WD when I need it, and silent running when in town just to scare the natives:-) Can you put the ICE in reverse while the electric is going forwards? To get a stretched limo? Wouldn't it get you a city car? ;-) Cheers, T i m |
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O.T. electric cars - do they have gearboxes?
On 22/04/2017 22:43, Johnny B Good wrote:
On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote: In article , Tim Streater wrote: One of the laws of thermodynamics IIRC - efficiency is related to the difference between input and output temps - in degrees K, not C. my elementary physics suggests that if you are only refering to a temperature difference the answer is the same in °K and in °C.° The main benefit of using deg K instead of Deg C is the complete and utter absence of negative numbers by which to confuse the mathematics. :-) It's true enough that as far as steam engines are concerned, this is unlikely to effect calculations involving deg C, but there are other heat engines designs based on fluids with much lower freezing and boiling points than zero deg C (the triple point of water to within an accuracy of one decimal place). Freezing points are irrelevant. So are boiling points. It's just gases and absolute temperatures. -- Max Demian |
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O.T. electric cars - do they have gearboxes?
On 23-Apr-17 10:10 AM, Tim Streater wrote:
In article , Nightjar wrote: ..... Whatever you want to think, an R&D subsidiary of IAV Gmbh developed a small, lightweight steam engine, using modern technology throughout, that could be fitted into motor vehicles, although they see the initial application as being in auxiliary power units, particularly in third world countries. They claim fuel efficiency as being similar to a diesel engine. It uses catalytic heating to avoid flames, which keeps emissions down to very low levels, and can burn a very wide range of fuels. Steam is viable, even if that does not sit well with your world view. As I hinted at before, where is the condenser and how big does it have to be? You would have to ask the developers that. However, they have said that the engine could be fitted into a car, so they obviously don't think it is a serious problem. -- -- Colin Bignell |
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O.T. electric cars - do they have gearboxes?
On 23/04/17 16:39, Chris Hogg wrote:
On Sat, 22 Apr 2017 22:46:33 +0100, Tim Streater wrote: In article , Johnny B Good wrote: On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote: In article , Tim Streater wrote: In article , The Natural Philosopher wrote: I suspect that the boilers and engines you are familiar with are more nineteenth century technology than twenty-first century. A titanium tube flash boiler can supply steam at up to 4,000 psi and 650C. Ceramics allow engines to work at those temperatures and pressures and achieve efficiencies not even dreamed of with conventional materials. Exatamondo. I cant remember what the law is called, but the hotter the working fluid (steam in this case) is to start with, and the colder the final exhaust, the more efficient is the engine. Which is why a combined cycle gas turbine that starts with 1000C gases in the jet engine, then heats a boler to get steam, and has a final after condenser temp of around 50C, willnet you over 60% thermal efficiency. One of the laws of thermodynamics IIRC - efficiency is related to the difference between input and output temps - in degrees K, not C. my elementary physics suggests that if you are only refering to a temperature difference the answer is the same in °K and in °C.° The main benefit of using deg K instead of Deg C is the complete and utter absence of negative numbers by which to confuse the mathematics. :-) It's true enough that as far as steam engines are concerned, this is unlikely to effect calculations involving deg C, but there are other heat engines designs based on fluids with much lower freezing and boiling points than zero deg C (the triple point of water to within an accuracy of one decimal place). The formula for efficiency *requires* K. +1 From the wiki entry for the Carnot cycle I posted elsewhere in this thread, the theoretical maximum efficiency of a heat engine is given as 1 - Tc/Th, where Tc is the lower temperature and Th is the higher temperature, both in kelvins http://tinyurl.com/alle4tg (Equation 3). For a heat engine where the operating temperature is say 600°C (873K) and exhausting into ambient of say 20°C (293K), you get very different results if you attempt the calculation in °C compared to calculating in kelvins, 0.97 for the former, 0.66 for the latter. It is the latter which is correct. A quote from that article: "Carnot realized that in reality it is not possible to build a thermodynamically reversible engine, so real heat engines are even less efficient than indicated by Equation 3. In addition, real engines that operate along this cycle are rare. Nevertheless, Equation 3 is extremely useful for determining the maximum efficiency that could ever be expected for a given set of thermal reservoirs". Note that the basis for the formula depends on a relationship between energy and temperature that is not necessarily obeyed if you go through a phase change. -- Truth welcomes investigation because truth knows investigation will lead to converts. It is deception that uses all the other techniques. |
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O.T. electric cars - do they have gearboxes?
On 23/04/2017 08:13, harry wrote:
Higher steam temperatures results in less efficient boilers because the exiting combustion gases can be at no lower temperature than the stem. This turns out not to be the case. You can, for example, use the warm exhaust to preheat the incoming air & fuel. Andy |
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O.T. electric cars - do they have gearboxes?
On 22/04/2017 22:43, Johnny B Good wrote:
On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote: In article , Tim Streater wrote: One of the laws of thermodynamics IIRC - efficiency is related to the difference between input and output temps - in degrees K, not C. my elementary physics suggests that if you are only refering to a temperature difference the answer is the same in °K and in °C.° The main benefit of using deg K instead of Deg C is the complete and utter absence of negative numbers by which to confuse the mathematics. :-) It's true enough that as far as steam engines are concerned, this is unlikely to effect calculations involving deg C, but there are other heat engines designs based on fluids with much lower freezing and boiling points than zero deg C (the triple point of water to within an accuracy of one decimal place). FFS Kelvins aren't degrees. And it must be absolute temperature for the equations to work. Just consider what the results would look like for Tin-Tout/Tout if Tout was negative. Andy |
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O.T. electric cars - do they have gearboxes?
On Sun, 23 Apr 2017 21:42:59 +0100, Vir Campestris wrote:
On 22/04/2017 22:43, Johnny B Good wrote: On Sat, 22 Apr 2017 12:13:31 +0100, charles wrote: In article , Tim Streater wrote: One of the laws of thermodynamics IIRC - efficiency is related to the difference between input and output temps - in degrees K, not C. my elementary physics suggests that if you are only refering to a temperature difference the answer is the same in °K and in °C.° The main benefit of using deg K instead of Deg C is the complete and utter absence of negative numbers by which to confuse the mathematics. :-) It's true enough that as far as steam engines are concerned, this is unlikely to effect calculations involving deg C, but there are other heat engines designs based on fluids with much lower freezing and boiling points than zero deg C (the triple point of water to within an accuracy of one decimal place). FFS Kelvins aren't degrees. Well, assuming by "Kelvins" you meant Degrees Kelvin and by "degrees" you meant degrees Celcius, they are! If the standard atmospheric pressure had been a higher value than it's currently assumed, those degrees Celcius would simply have been a larger sized increment across the arbitrary 100 degrees Mr Celcius had chosen to span the freezing and boiling points of pure water and a smaller starting volume of gas than the 273cc's worth at zero degrees Celcius would have been determined as the basis for establishing where absolute zero would be in the (now) larger scale units of degrees Celcius. Anyhow, putting that aside, degrees Kelvin are directly based on degrees Celcius no matter that there is an element of arbitrariness in the Celcius scale. The difference is merely in where the zero point is set on the scales. In the case of degrees Kelvin, this was based on an Absolute Zero derived from the behaviour of gases which all exhibited the same expansion coefficient throughout their gas phase, allowing the Absolute Zero point to be extrapolated beyond the limits set by each particular gas's liquifaction points at NTP. And it must be absolute temperature for the equations to work. My bad, I just assumed that mere temperature differences would suffice. :-( Just consider what the results would look like for Tin-Tout/Tout if Tout was negative. Obviously, I *didn't* consider negative temperatures, just temperature differences. :-( -- Johnny B Good |
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O.T. electric cars - do they have gearboxes?
On Sun, 23 Apr 2017 21:37:06 +0100, Vir Campestris wrote:
On 23/04/2017 08:13, harry wrote: Higher steam temperatures results in less efficient boilers because the exiting combustion gases can be at no lower temperature than the stem. This turns out not to be the case. You can, for example, use the warm exhaust to preheat the incoming air & fuel. Mother nature has beaten us to this 'trick' as can be seen in the anatomy of penguins' feet where the veins and arteries in their legs run side by side so as to allow the veins to recover heat from the arteries before it gets lost by contact with the ice upon which they roost or walk. The feet themselves are little more than bones, ligaments and tendons acting as remote controlled low temperature tolerant appendages. In the case of the flash boiler, the hot combustion products are routed in a contra-flow to the direction of the feed water flow from the condenser and the boiler unit itself is extremely well insulated to minimise unproductive heat loss through the casing. Getting back to the original question, most electric vehicle designs eliminate the mechanical variable ratio gearbox, electing instead to use high power handling switching converters to control the motor speed instead. Even when a design uses a fixed gear ratio box to better match the loading on the drive motor, electronic drive voltage control is still the method by which modern electric road vehicles are speed regulated. In an ideal setup, you would have hub motors in each wheel which could be arranged as a series wired pair on each axle to provide a built in differential and halving of the current required to drive each axle's worth of hub motors. However, in order to maximise efficiency and power to weight performance of electric traction motors, you get the best performance using a high rpm motor[1] which basically precludes direct drive hub motor designs unless you're prepared to sacrifice top end performance for improved battery economy at more modest urban traffic speeds (you replace mechanical transmission losses with much lower electric cabling losses). [1] High rpm on account it uses less turns of heavier gauge copper in its windings, meaning reduced I squared R losses. -- Johnny B Good |
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