Car air condition power ratings?
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From: Michael Kilpatrick on 9 Apr 2010 16:05 Would anyone happen to have a vague idea of the power rating of a typical car air condition system (such as that in a Rover SD1)? I'd like to have a ball-park figure for the wattage (or any scalar equivalent such the British Thermal Units per hour) as a measure of the heat transfer that such a system is capable. For example, I think I've read somewhere that the radiator for a typical car engine water-cooling system might dissipate about 3kW (or maybe that was the figure for a tractor, not sure). But obviously cooling air at 30C requires a considerably lower transfer of energy than cooling water at 90C... Michael
From: Dave Plowman (News) on 9 Apr 2010 19:51 In article <bIidnfm3qeAHFSLWnZ2dnUVZ7o-dnZ2d(a)pipex.net>, Michael Kilpatrick <michael(a)mtkilpatrick.SPAMfsnet.co.uk> wrote: > Would anyone happen to have a vague idea of the power rating of a > typical car air condition system (such as that in a Rover SD1)? I'd like > to have a ball-park figure for the wattage (or any scalar equivalent > such the British Thermal Units per hour) as a measure of the heat > transfer that such a system is capable. > For example, I think I've read somewhere that the radiator for a typical > car engine water-cooling system might dissipate about 3kW (or maybe that > was the figure for a tractor, not sure). But obviously cooling air at > 30C requires a considerably lower transfer of energy than cooling water > at 90C... I don't have an exact figure, but the main rad dissipates a great deal more than 3 kW. I read of one chap using a Jag one as the heat exchanger for a warm air system in a house. So more like 20-30 kW. A decent car heater produces maybe 5 kW. I also remember reading a tech article about the then new Rolls Silver Shadow. It said the AC took about the same power as a Mini at full belt... -- *I took an IQ test and the results were negative. Dave Plowman dave(a)davenoise.co.uk London SW To e-mail, change noise into sound.
From: Kevin Poole on 10 Apr 2010 08:00 Michael Kilpatrick wrote: > Would anyone happen to have a vague idea of the power rating of a > typical car air condition system (such as that in a Rover SD1)? I'd like > to have a ball-park figure for the wattage (or any scalar equivalent > such the British Thermal Units per hour) as a measure of the heat > transfer that such a system is capable. > My books tend to stop at about the time air-conditioning became common. Presumably they have a coefficient of refrigeration of 2 or 3(?), so several times the input power to the compressor is being dissipated. > For example, I think I've read somewhere that the radiator for a typical > car engine water-cooling system might dissipate about 3kW Greene & Lucas "Testing of Internal Combustion Engines", 1969 show typically 30-odd percent of the input energy being dissipated through the radiator, so rather more than the maximum mechanical output of the engine. An SD1, with a power of 150-ish bhp, would have a radiator capable of getting rid of at least 150kW, or whatever that is in ton-acres/cubic fortnight. -- Kevin Poole ****Use current date to reply (e.g. apr2010(a)mainbeam.co.uk)****
From: Steve Firth on 10 Apr 2010 15:30 Michael Kilpatrick <michael(a)mtkilpatrick.SPAMfsnet.co.uk> wrote: > Would anyone happen to have a vague idea of the power rating of a > typical car air condition system (such as that in a Rover SD1)? I'd like > to have a ball-park figure for the wattage (or any scalar equivalent > such the British Thermal Units per hour) as a measure of the heat > transfer that such a system is capabl Typical car aircon uses around 5 bhp / 4kW. The thermal efficiency is about 3.42 (i.e. for each kilowatt of input mechanical energy the aircon can pump out 3.42 kW of heat. So at full output the aircon could be extracting around 14kW of heat from the incoming air.
From: Michael Kilpatrick on 10 Apr 2010 18:28
Dave Plowman (News) wrote: > > I don't have an exact figure, but the main rad dissipates a great deal > more than 3 kW. I read of one chap using a Jag one as the heat exchanger > for a warm air system in a house. So more like 20-30 kW. A decent car > heater produces maybe 5 kW. Ah, I imagine the figure must have been 30kW for the radiator in question, and I must have stripped off the zero. Michael |