An Idea to Make Car AC Work Better

[angel82]

AoA,

I have an Idea to make your AC Work better (specially for small cars like Mehran, Alto, Coure, Cultus etc.) It just came in my mind I haven't yet tried it myself. I thought I should share it with you people to get your point of view first.

All the cars have wind screen shower in it and we seldom use it. What if we divert the shower water pipe to the condenser and shower water on it when there is a lot of heat out side in rush hour and AC isn't working that much good. I guess it will help alot to cool down the condenser and AC will work better. We can repeat it after 5-10 Minutes interval.

So what do you think? Will it work? I'll give it a try soon and let you people know. Please share if anyone else had tried it.

Waiting for your response.

[hash4u]

in places like 40 degree plus, u will need a lot of water. in this heat a drop of water will evaporate in a second. so u need a reasonable supply of water to shower it off so it only temperorarily cools down

[asad_scorpio21]

wat about alteration for this little quantity of water.

[system]

it is better to get it done by any service station they will charge 10- 20 rupees thats it

[manofpk]

your idea is good... though i would like to suggest something good...instead of changing the windsheild washer... we should add another shower providing the water that comes out of the condenser during the ac cooling. all we need to do is add a reservior instead it throws out of the car, cool water will work... but the quantity will be less.... or we can top it up before leaving for ride.

[VCheng]

Here is a very rough calculation:

It will take approximately 600 cal/gm of water to heat it from 50 degrees Centigrade and convert it into steam at 100 degrees Centigrade. This will theoretically absorb heat from the AC condenser and thus improve the efficiency.

One BTU is 250 cal, so a typical 20,000 BTU AC of a small car is putting out about 5 million cal/hr of heat into the air. To improve the heat efficiency by only 10%, you will need to absorb 500,000 cal/hr by the water spray, or about 833 gm of water per hour.

Some water will be lost by dripping down rather than evaporating completely. So you can estimate about 1 kilogram (equal to 1 liter) of water per hour to improve efficiency by 10% if the temperature in the engine bay is 50 degrees Centigrade. So, the spray output should be about 16 cc per minute sustained.

I can see that the practicalities will prevent even that gain.

Good idea, but it is likely to be not cost-effective in what you are trying to do.

[suzukialtomehran]

@Vcheng
Nice Calculation Bro you are genius.

[VCheng]

@Vcheng
Nice Calculation Bro you are genius.

Thank you, but any idiot can make these rough calculations. I just happen to be a bigger idiot than most!

[cracked]

putting water wont make it rusty?
plus wen its hot,it wud be in its expanded state,lyk things expand in heat,so wen water is showered on it,it will try to condense,so this phenomena mite damage some parts of whr water is showered..
its just my guess...

[daniyalahmad]

Here is a very rough calculation:

It will take approximately 600 cal/gm of water to heat it from 50 degrees Centigrade and convert it into steam at 100 degrees Centigrade. This will theoretically absorb heat from the AC condenser and thus improve the efficiency.

One BTU is 250 cal, so a typical 20,000 BTU AC of a small car is putting out about 5 million cal/hr of heat into the air. To improve the heat efficiency by only 10%, you will need to absorb 500,000 cal/hr by the water spray, or about 833 gm of water per hour.

Some water will be lost by dripping down rather than evaporating completely. So you can estimate about 1 kilogram (equal to 1 liter) of water per hour to improve efficiency by 10% if the temperature in the engine bay is 50 degrees Centigrade. So, the spray output should be about 16 cc per minute sustained.

I can see that the practicalities will prevent even that gain.

Good idea, but it is likely to be not cost-effective in what you are trying to do.

VCheng I,ve become your fan (Y)

[VCheng]

VCheng I,ve become your fan (Y)

Thank you. I need a lot more ceiling fans and a few more pedestal fans, but no exhaust fans. Which type are you?

[daniyalahmad]

Thank you. I need a lot more ceiling fans and a few more pedestal fans, but no exhaust fans. Which type are you?

LoL you are one funny bloke

[Ch_Hammas]

@Vcheng
Nice Calculation Bro you are genius.

he has to be genius...cux he is now a MOD..........:-$:-#:-#:-$:-#

[formula2012]

@all
cant an extra fan can be added in alto???to improve its performance

[VCheng]

Let's briefly review how the AC works so that we can see what ideas might work.

The compressor forces the refrigerant from a gaseous to a liquid state. This fluid becomes hot. It travels to the condenser. Airflow across the coils transfer heat from the refrigerant to the air. The much less hot (relatively cooled) refrigerant travels to the evaporator inside the cabin. There it is allowed to expand rapidly into a gaseous state. This rapid expansion cools down the coils. Airflow across the coils transfers heat from the air to the refrigerant. This sudden cooling effect also causes the temperature of the air to drop below its dew point, causing the moisture to condense on the coils and drip down.

So, to improve the AC performance means increasing the heat transfer. Some methods that can be used:

1. Increasing the size of the compressor and volume of refrigerant.

2. Increase the heat transfer across the condensor by increasing the size, density of the coils, and/or more airflow.

3. Increase the heat transfer across the evaporator by increasing the size, density of the coils, and/or more airflow.

The key here is that all these things must be done in a balanced fashion, and having one component or aspect outsized relative to others will not increase efficiency drastically as another component that is already maxxed out will become the weak link limiting the total heat trasnfer i.e. the capacity of the system.

[shahid217]

Thank you. I need a lot more ceiling fans and a few more pedestal fans, but no exhaust fans. Which type are you?

No use of fans... Ask for UPS

[angel82]

@VCheng
I agree with your calculation but i think my idea is harmless so why don't we give it a try may be it will give different results. Sometimes baseless ideas become very useful in such heat if we could improve 10% efficiency it would be great i guess.

[angel82]

@ cracked
I don;t thing it will crack the condenser because there isn't much difference between water temperature and condenser temperature. water will cool it down bcs fan will evaporate it quickly. for your 2nd concern it wont make it rusty bcs condenser is rust proof i guess.
@ VCheng
Don't forget that fan is also running at full speed it will evaporate water drops this will help to cool it down.

[VCheng]

@VCheng
I agree with your calculation but i think my idea is harmless so why don't we give it a try may be it will give different results. Sometimes baseless ideas become very useful in such heat if we could improve 10% efficiency it would be great i guess.

Oh, your idea has merit to be sure. And I like the way you are thinking to solve a real technical issue. That I admire too.

My post was to give only a rough calculation to give you a better idea of how to refine your thoughts. I hope you can now see better what the potential issues might be.

Your idea is not baseless. Increasing the heat loss in the condenser will help. If you are happy with even a few percent improvement, and at a cost that is reasonable, then that is a good thing.

Oh, the condenser won't crack, don't worry. It might show salt deposition after years and years if you use a hard water for the spray but that's about it. However, the water draining off will need to be routed so that it doesn't ruin the rest of your engine bay.

[Vaqas1]

Hmm its better to work on your ac than using these totkas.

Most cars with bad ac got old and weak components so ac dun work upto its mark.

Now when we talk about small cars like mehran there is no condensor fan so that also decreases ac performance.

If you got good compressor with newer technology multi flow or they call it multi aisle condensor the a/c will work fine.