How could battery powered trains (such as Class 230) be heated?

[Bletchleyite]

Storage heating might be an option? Some Swiss funiculars are heated that way.

 

[superkev]

Storage heating might be an option? Some Swiss funiculars are heated that way.

Storage heaters equals lots of bricks. Not something you want on a limited powered train me thinks.
K

 

[Bletchleyite]

Storage heaters equals lots of bricks. Not something you want on a limited powered train me thinks.

Insignificant when compared to the weight of a train.

 

[Harpers Tate]

Electric Heat Pumps plus waste heat from the battery seem more appropriate nowadays. Any extra battery weight needed to support the heat pump is, I'd suggest, going to be less than the equivalent bricks. With the added benefit of being able to be used for a cooling system (if it's warm) and for traction if its neither warm nor cold.

 

[reddragon]

The battery tech is moving so fast, capacity & cost will not be an issue in a few years

 

[Xenophon PCDGS]

The battery tech is moving so fast, capacity & cost will not be an issue in a few years

I am sure that Vivarail will have hoped to have sold all their Class 230 units long before the "few years" scenario stated above.

 

[Charlie Smythe]

I am sure that Vivarail will have hoped to have sold all their Class 230 units long before the "few years" scenario stated above.

Do you know how many battery units are currently going to be made?

 

[samuelmorris]

Electric Heat Pumps plus waste heat from the battery seem more appropriate nowadays. Any extra battery weight needed to support the heat pump is, I'd suggest, going to be less than the equivalent bricks. With the added benefit of being able to be used for a cooling system (if it's warm) and for traction if its neither warm nor cold.

That would be the answer I'd expect them to use - lightweight equipment and very energy efficient. As long as temperatures don't fall below -10°C, they work very well indeed and would also double as air conditioning. The issues really are, as suggested, the cost of leasing battery packs and the amount of time spent charging, even with fast charging solutions.

 

[big all]

yes battery cooling transferred internally if required or externally if not required would seem the most efficient use providing the added mechanism or channeling are cost effective or practical
sometimes micromanaging things add extra costs extra failure possibilities far in excess off any benefits

 

[Charlie Smythe]

Insignificant when compared to the weight of a train.

How much would the weight of these bricks be?

 

[Bletchleyite]

How much would the weight of these bricks be?

Well, this domestic storage heater:
https://www.tlc-direct.co.uk/Produc...MIjZjj0obP3wIVBEPTCh3ttwarEAQYBCABEgJ1HfD_BwE

weighs 155kg, which is about the same as two fairly small passengers (or one very fat one).

 

[Charlie Smythe]

Well, this domestic storage heater:
https://www.tlc-direct.co.uk/Produc...MIjZjj0obP3wIVBEPTCh3ttwarEAQYBCABEgJ1HfD_BwE

weighs 155kg, which is about the same as two fairly small passengers (or one very fat one).

Is that enough for a whole carriage? If so then it isn't a lot in the grand scheme of things.

 

[Bletchleyite]

Is that enough for a whole carriage? If so then it isn't a lot in the grand scheme of things.

I doubt 1.5kW would be enough for a whole carriage (it's the kind of thing you'd have in a bedroom or hallway), but even if you needed a few of them it's still not huge compared with a crush-load of passengers.

Of course, what you're doing is maintaining temperature, so you don't need as much as to heat up from freezing or below. So you could combine storage heating with direct heating when "on the juice".

That said, using fossil fuel (i.e. diesel heaters or similar) solely to heat doesn't exactly use loads of it and is quite efficient when compared to using it to move something, hence why we still mostly use gas at home (and it won't be on at all for half the year). It does just seem oddly amusing to have an electric bus with a diesel heater.

 

[samuelmorris]

1.5kW isn't a lot - I believe car heaters are in the 3-6kW range. Even a 230 vehicle should be expected to have sufficient heat for 10 times that volume.

 

[edwin_m]

I think the heating required for trains is somewhere around 20kW per coach (think 20 single bar electric fires). However the amount of heat storage depends on how long it needs to be stored as well as how much heat output is required - a domestic heater will need to provide heat for a whole day but one on a battery train would only need endurance similar to that of the traction batteries.

According to the below link bricks have a specific heat capacity of 0.9kJ/kg/K. As a very ball park calculation:
20kW for 1hr would be 72000kJ
If the storage heaters can cool by 10K (or 10degC), this would need 8 tonnes of bricks, which sounds quite significant. Always assuming I haven't lost a factor of 10 somewhere!

https://www.engineeringtoolbox.com/specific-heat-solids-d_154.html

Probably better to look for something that melts at about 30degC, as the phase change releases more heat.

 

[krus_aragon]

1.5kW isn't a lot - I believe car heaters are in the 3-6kW range. Even a 230 vehicle should be expected to have sufficient heat for 10 times that volume.

Car heaters are, of course, designed to heat a car up from cold as quickly as possible on a winter's day.

 

[Bletchleyite]

Car heaters are, of course, designed to heat a car up from cold as quickly as possible on a winter's day.

Indeed, whereas if you also had direct electric heating the train heaters would just need to keep the coach warm for the period the train is off the juice.

 

[Charlie Smythe]

Does anyone actually know the heating system they have chosen for this unit? The easiest thing to do is to wait until it is in service and then see what system they are using

 

[Harpers Tate]

My (electric) car's heater consumes about 0.5kW and warms the (obviously relatively much much smaller) interior to very hot, if I want it to, very quickly. Heat Pump technology is very, very efficient - I believe the statistic is that the heat output is 4x the electrical input; counter-intuitive, I know, but there it is. No need for bricks.

 

[Bletchleyite]

My (electric) car's heater consumes about 0.5kW and warms the (obviously relatively much much smaller) interior to very hot, if I want it to, very quickly. Heat Pump technology is very, very efficient - I believe the statistic is that the heat output is 4x the electrical input; counter-intuitive, I know, but there it is. No need for bricks.

An air source heat pump is a very interesting idea. I wonder how easy it would be to apply that to a train.

 

[samuelmorris]

My (electric) car's heater consumes about 0.5kW and warms the (obviously relatively much much smaller) interior to very hot, if I want it to, very quickly. Heat Pump technology is very, very efficient - I believe the statistic is that the heat output is 4x the electrical input; counter-intuitive, I know, but there it is. No need for bricks.

Just one point, that 0.5kW is the electrical draw. When being compared with a storage heater I believe you'll need to state the actual heat output, which is usually 4-5 times the electrical draw. I definitely feel it's the right solution for a battery unit though.

 

[Bletchleyite]

Just one point, that 0.5kW is the electrical draw. When being compared with a storage heater I believe you'll need to state the actual heat output, which is usually 4-5 times the electrical draw. I definitely feel it's the right solution for a battery unit though.

All electric heaters are basically 100% efficient. The heat output is (give or take a small "on" light, a slight red glow of the element and maybe a quiet buzz) exactly the same as the power input. The output cannot be more than the input in kWh, though I suppose a storage heater can output it quicker (or slower) than it was inputted, unlike a regular one, though normally you want slower output as otherwise you'll find your house rather cold for half the day (you want a charge for about 7 hours then output for about 17 - hence "Economy 7").

 

[samuelmorris]

All electric heaters are basically 100% efficient. The heat output is (give or take a small "on" light, a slight red glow of the element and maybe a quiet buzz) exactly the same as the power input. The output cannot be more than the input in kWh, though I suppose a storage heater can output it quicker (or slower) than it was inputted, unlike a regular one, though normally you want slower output as otherwise you'll find your house rather cold for half the day (you want a charge for about 7 hours then output for about 17 - hence "Economy 7").

The volume of air you'd have to heat on a train though, I wouldn't have thought you could store sufficient heat - yes the power requirement drops off considerably once the vehicle is up to temperature but I think you'd still need a fairly hefty amount of power to be able to heat the area in a reasonable amount of time. Using an online A/C calculator for the rough dimensions of a 230 carriage based on 40 occupants provides a 6.2kW rating without occupants. Given A/C is normally designed with a slightly higher heating rating than cooling, let's say 7.5kW. That'd be quite a hit on battery life with electric heating whereas with a heat pump you'd probably get away with a 1.5-2kW load per vehicle.

 

[Bletchleyite]

You wouldn't heat from zero using the battery or bricks, you'd do that while on the 25kV. I do think the heat pump idea is interesting though. As air source heat pumps require large radiators, perhaps this could be underfloor or overhead rather than the annoying bodyside conduits?

 

[Charlie Smythe]

An air source heat pump is a very interesting idea. I wonder how easy it would be to apply that to a train.

I think they are quite bulk systems so i maybe not too easy.

 

[samuelmorris]

Indeed, but part of the reason I use the A/C figures is they're continuous. The more people onboard of course, the lower the heat requirement. The space requirement for the radiator could be a little problematic to fit in among the battery packs, but they shouldn't need be too large, large cars have A/C systems rated for 5kW+ and their radiators aren't too large.

 

[Bletchleyite]

I think they are quite bulk systems so i maybe not too easy.

I thought an *air* source unit was basically like a slightly big aircon unit so could be fitted in the roof space like an actual aircon unit.

 

[samuelmorris]

I thought an *air* source unit was basically like a slightly big aircon unit so could be fitted in the roof space like an actual aircon unit.

To do that you would need to lower the ceiling though, as I don't imagine there'd be much clearance above the existing roofs within the UK loading gauge.

 

[Bletchleyite]

To do that you would need to lower the ceiling though, as I don't imagine there'd be much clearance above the existing roofs within the UK loading gauge.

Most if not all third generation EMU and DMU stock has either one or two aircon units per coach mounted in the roof. So yes, it is feasible.

 

[samuelmorris]

Of course, but they were built from the outset to have such fitted. At the risk of joining the 'it's an old tube train' brigade, you can't just slap one on top of a unit that never had one fitted, or even provision for one, to begin with. Some Renatus-style re-engineering of the ceiling inside would need to be done. It's certainly doable, but it isn't simple or cheap.