Electric Air-conditioning capacity?

Technical discussion on converting internal combustion to electric
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juk
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Electric Air-conditioning capacity?

Post by juk » Tue, 20 Sep 2011, 06:48

Has anyone used the electric aircon compressors to hook up air-conditioning to their car? If so i was wondering what kW or BTU rating you went for and whether on reflection you thought it was sufficient?

My car is a little hotbox, heatsoak, unstoppable ventilation, radiator lines and the sun all combine to make it a nightmare if you get stuck in a traffic jam so i want to make sure i get sufficient cooling.

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Electric Air-conditioning capacity?

Post by gmacd33 » Tue, 20 Sep 2011, 14:41

I'm installing the Masterflux 2kW unit in 3 vehicles that I am working on, as it is the only one I've found that's suitable for EVs. Haven't experienced performance as yet...
http://evworks.com.au/index.php?product=AIR-SIERRA00055
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Electric Air-conditioning capacity?

Post by Jeff Owen » Tue, 20 Sep 2011, 16:14

Greg
Are you using the air-conditioning for heating?

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Electric Air-conditioning capacity?

Post by gmacd33 » Tue, 20 Sep 2011, 22:42

Yes, for some I will use the reverse cycle solenoid valve to enable heating; this may require changing an orifice valve to 2-way valves etc as well.


For some vehicles I won't bother with heating for Queensland weather.

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Electric Air-conditioning capacity?

Post by PlanB » Wed, 21 Sep 2011, 17:46

Is that little orange thing in the photo your EV Craig? If so I'm curious what make it is & the weight?

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Electric Air-conditioning capacity?

Post by Renard » Wed, 21 Sep 2011, 18:18

Considering this question, I found this article on the web:
http://www.nrel.gov/docs/fy99osti/26615.pdf
which discusses a/c loads, cooling requirements, effect on EV range etc. In particular, it makes the obvious point that a car left in the sun should be first cooled by -- wait for it -- opening the windows! Otherwise, you need a big system to get the temperature down to normal levels.
It suggests a power in/heat extraction factor of 2.3, and a suggested input power of 1kw.
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Electric Air-conditioning capacity?

Post by Thomas » Wed, 21 Sep 2011, 22:32

I notice that nobody even suggests keeping the belt-driven ICE accessories and running them off an extra motor of 2kw or so.

Anybody suggest how big an auxiliary motor for power steering, brakes and aircon should be and how much improvement I would get by using 12v components for these?

Thanks a lot :)

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Electric Air-conditioning capacity?

Post by juk » Wed, 21 Sep 2011, 22:56

"Is that little orange thing in the photo your EV Craig? If so I'm curious what make it is & the weight?"

No, It's '99 lotus elise with a 2L engine from a honda civic type R putting out about 170kW. It's a seriously competetive car given it's 750kg weight.

It's my consolation prize for the GFC killing my electric car. But if i find the spare cash, i'll convert it, but i wont lose performance. Target would be over 200kW peak and 200km range to convert it, that way i can keep racing it.

The Radiator pipes are aluminium and they run up the chassis rails which are aluminium and they radiate heat at you from the side. The radiator heat soak is fierce, and you can't put the HVAC on recirc. Then if you have the roof off, you get the sun as well. The windows are at shoulder height, so you dont get much through breeze. If you get stuck in traffic in summer it's a sauna.

The honda compressor doesn't fit anymore, so i'm looking at electric, hence the question about how much is required. I might be the first. If so i'll report back.

Thanks for your help guys.

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Electric Air-conditioning capacity?

Post by coulomb » Thu, 22 Sep 2011, 14:27

gmacd33 wrote: I'm installing the Masterflux 2kW unit in 3 vehicles that I am working on, as it is the only one I've found that's suitable for EVs. Haven't experienced performance as yet...
http://evworks.com.au/index.php?product=AIR-SIERRA00055

I was wondering if the 2 kW is electrical or thermal. From the above site, it seems to consume 1930 W (1.93 kW), and the output in British Thermal Units per hour seems to come to 4.19 kW. So that makes the COP (Coefficient Of Performance) 4.19/1.93 = 2.17. In other words, you put in just under 2 kW of electrical power, and it moves heat from one side to the other at a rate of just over 4 kW (plus losses go to the hot side, of course).

Presumably, this would compare quite favourably with a window A/C unit that you would plug into the mains. So I'd say it would have plenty of cooling power.

When I do a quick search, I see that window air conditioners seem to output about 5500 to 14000 BTU/hr (how did that horrible unit become standard?). That's fine, but they claim an energy efficiency ratio of over 10. From this Wikipedia page, EER = COP x 3.413 (it's the ratio of powers in different units). So the most efficient units with a EER of say 10.7 correspond to a COP of 10.7/3.413 = 3.1. So the Masterflux would appear to be less efficient than the latest window units. This possibly has something to do with its compactness.

[ Edit: then again, considering how marketing works, this may be the efficiency of heating, which means the cooling COP for the 10.7 unit would really be 2.1, which is about the same as the Masterflux. Man, I wish they would just quote actual power consumption.

I also fixed a mangling of energy and power, one of my pet peeves. ]
Last edited by coulomb on Thu, 22 Sep 2011, 04:32, edited 1 time in total.
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Electric Air-conditioning capacity?

Post by coulomb » Thu, 22 Sep 2011, 14:48

coulomb wrote:
gmacd33 wrote: I'm installing the Masterflux 2kW unit in 3 vehicles that I am working on, as it is the only one I've found that's suitable for EVs. Haven't experienced performance as yet...
http://evworks.com.au/index.php?product=AIR-SIERRA00055

I was wondering if the 2 kW is electrical or thermal. From the above site, it seems to consume 1930 W (1.93 kW), and the output in British Thermal Units per hour seems to come to 4.19 kW. So that makes the COP (Coefficient Of Performance) 4.19/1.93 = 2.17. In other words, you put in just under 2 kW of electrical power, and it moves heat from one side to the other at a rate of just over 4 kW (plus losses go to the hot side, of course).

Presumably, this would compare quite favourably with a window A/C unit that you would plug into the mains. So I'd say it would have plenty of cooling power.

When I do a quick search, I see that window air conditioners seem to output about 5500 to 14000 BTU/hr (how did that horrible unit become standard?). That's fine, but they claim an energy efficiency ratio of over 10. From this Wikipedia page, EER = COP x 3.413 (it's the ratio of powers in different units). So the most efficient units with a EER of say 10.7 correspond to a COP of 10.7/3.413 = 3.1. So the Masterflux would appear to be less efficient than the latest window units. This possibly has something to do with its compactness.

[ Edit: then again, considering how marketing works, this may be the efficiency of heating, which means the cooling COP for the 10.7 unit would really be 2.1, which is about the same as the Masterflux. Man, I wish they would just quote actual power consumption.

I also fixed a mangling of energy and power, one of my pet peeves. ]


[ Edit 2: I finally found a photo of a nameplate, and it would seem that the EER is for cooling. So the Masterflux would appear to be less efficient than typical modern window air conditioners. ]
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Electric Air-conditioning capacity?

Post by Rob M » Fri, 23 Sep 2011, 00:18

There is often some confusion when it comes to calculating efficiency of air conditioning units. The problem is caused by the difference between inside and outside teperatures or more correctly the difference between the condeser and evaporator temperatures. On a very hot day for instance the unit will draw a lot more current than on a cold day. An extra fan on the condenser can actually give you better cooling for the same or less power consumption. The efficiency is more to do with the configuration of the condenser and evaporator than with the compressor itself.
The masterflux unit which draws 6-7 amps at 144 volts is quite adequate for the average car even on a hot day.
The same unit provides more than enough heating if a reversing valve is used.

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Re: Electric Air-conditioning capacity?

Post by Dan007a » Thu, 27 Dec 2018, 15:09

juk wrote:
Tue, 20 Sep 2011, 06:48
Has anyone used the electric aircon compressors to hook up air-conditioning to their car? If so i was wondering what kW or BTU rating you went for and whether on reflection you thought it was sufficient?

My car is a little hotbox, heatsoak, unstoppable ventilation, radiator lines and the sun all combine to make it a nightmare if you get stuck in a traffic jam so i want to make sure i get sufficient cooling.
In going to try use a 6.5 hp forklift motor to that

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Re: Electric Air-conditioning capacity?

Post by francisco.shi » Fri, 28 Dec 2018, 05:07

Has anyone ever used an inverter split system compressor?
I was thinking of using one with a 3ph inverter.

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Re: Electric Air-conditioning capacity?

Post by jonescg » Fri, 28 Dec 2018, 07:06

http://www.wurzcompressor.com/en/produc ... essor.html
I got one of these for the Prelude.
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Re: Electric Air-conditioning capacity?

Post by Dan007a » Sat, 12 Oct 2019, 12:32

Hows the unit working

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