Vapour Absorption Refrigeration System

your next question if water enter in vapour compression system..

1) it will damage your compressor

2) water will condensate at expansion valve, at evaporate line result in damage to whole line may be busting of copper piping.

check out the freezing point of R12 and freezing point of water.

Another question obviously looking beyond the given structure of things. I like that way of thinking and seeing.

I'm not a refrigeration specialist but I learn from your questions.

As far as introducing water with the refrigerant my guess would be it pre-loads the system making it less efficient.

Now I'll have to look up ammonia systems because you have peaked my curiosity.

No doubt somebody will answer your question more fully, and if my guess is wrong more accurately.

j.

If water carries into the condenser with the ammonia, the temp will fall during evaporation to probably -20 or -30C.

Any water present becomes ice at this temp and will clog up your evaporator until it ceases working.

The reason for water is that it dissolves a lot of ammonia (about 700x by volume at atmospheric pressure and ambient temperature I think). It is also cheap, as is ammonia.

Dear Friend,,

The water presnetage in the earh is about 70% in the world.

hence it is easily available so no need to take onther alternative.

bye

regards,

Pankaj Darji

Is there any practical application of vapor absorption system in automobile air conditioning .

Please specify the details if possible also teh cost involved in the same .

Exhaust system of an automobile can be used for air conditioning of an automobile. I did theoretical study on this subject back subject 26 years back. Please refer the discussion forum Air conditioning automobile using heat of exhaust.Automobiles are one of main sources of emitting Co2 into the atmosphere. Usually vapour compression refrigeration system is employed in automobile air-conditioning. In the present system the compressor derives power from the engine, resulting in a higher power engine and the exhaust gas pollutes the atmosphere. The exhaust gas temperature from automobile engine is approximately 300 C. This heat can be used to operate the vapour absorption system. Utilization of waste heat from the automobile exhaust, lesser power consumption from the engine and noise reduction are few of the salient features of this project.

Dear Sir,

Thanks for your valuable input.

I am Lokesh Jeswani currently working inTCSL Mumbai India last 1.5 years .

I am B.E (Mechanical 2007) I am really interrested in knowning the detail of this project and just have few questions.

1.I have read on internet that this technology (automobile air conditioning using exhaust gas)is possible but still ,I havent find the single actual working application of same .Is there any serious drawback of this technology.

I have lot of question on this

Is it ok If I post you by this forum.

Thanks in advance .

Thanks and Regards

Lokeah Jeswani

Hi,

You raise an interesting idea.

I can tell you this.

I have been around long enough to be familiar with cars going back to Ford's Model T.

I have never, in all those years in this country (US) at least, seen or heard of a car that sought to use exhaust heat for air conditioning. I suspect that is why you have not come across anything.

There have been many good ideas concerning automotive transportation; many of them left behind for one reason or another. Steam cars is one good example; left behind because boiler technology had not caught up.

You can of course today design flash boilers to burn all sorts of trash. The rub now is regular distribution of fuel.

There are other areas of technology left behind, for instance Edison's direct current generation and distribution. In that regard Tesla was, at that time, right; there is less loss transmitting alternating current over long distances.

Now, with local generation coming on line with the development of mini-turbines, it seems to me that question is once again open since you could, if you wished, generate power on a building by building basis especially with the wide network of fuel pipelines available.

Power companies faced with spot power shortages these days resort to installation of small turbine plants running on gas which can be cranked up to meet moments of peak load, and then shut down again pending the same drill on the morrow.

Thinking about this it seems to me that NY's Con Edison, faced with seriously antiquated and failing transmission systems, instead of expending large amounts of money replacing them, could instead install small turbine systems all over the city, as they have in a few places, and supply the bulk of their power from those.

Indeed, their service to parts of NYC has gotten so bad that large buildings and institutions are installing their own mini-turbines and selling excess to Con-Ed.

Seems to me there would be situations where it is beneficial to generate both AC and DC to serve more efficiently diverse needs.

I remember years ago, below Manhattans 14th Street, being startled by friends of mine who charged automotive batteries from a 110 Volt Direct Current line in the hallway. Although the building had an AC service the old DC line driven by Edison's plant in lower Manhattan was still in place and that, along with a lamp bank to reduce voltage, was how they charged batteries.

Perhaps it would be a good idea to systematically go back over the history of the development of technology looking for what might be nowadays gems, left behind because other technical issues had not yet matured.

Your question as to car air conditioning strikes me as one of those issues, not because it was left behind but because nobody it appears has ever thought of it.

I am curious. What got you thinking along those lines?

j.

We did design of air conditioning of an automobile using Li- Br - water absorption system as a part of undergraduate project work during the year 1982. (Madras University) .We did the calculations for the Indian make Ambassador car. It is a good idea even now to develop it. I do not know any commercial absorption units for car air conditioners are available. I am not able to guess any reasons why leading auto manufacturers are not taking any initiatives to develop this concept. It needs further discussions and debate from the like minded people. Dr. Ram

I am realy interested in working in this area .

Just want to understand the fact that why this feasible tecnology is not developed so far in world .

It might have some constraints and want to know them and then work on the same .

In this world of power crises if we utilize this huge exhaust energy it will be a great advantage .

There are many reasons why this concept is not commercialized. Generally vapor absorption system is preferred for large installations where waste heat is available freely/chiefly. COP ( Coefficient of Performance)of the vapor absorption system is another factor. But I am sure soon this concept will be commercialized and absorption unit of an automobile using exhaust gas will be available in the market.

Dear Sir,

Hope soon we can see this .

As I have search a lot on this found this technology is possible on paper as I found various paper on the same .

I am still wondering about the cost of the same .

Will this technology will be economically feasible.

Will it wont create the space problem in vehicle where packaging of all component is very tight.

I am very much interested to develop this project initially as a pilot study followed by mass production. I do not have facility here to fabricate the required components for the development of the new pilot system. I will be very happy to associate with design and development calculations with the team. Interested can contact me directly through my e mail.

Dr.Ram

Dear Sir,

I am a fresher and have ineterest in this field and want to develop the system which is practically feasible.

I am in the initall stage of developing the a.c system my vapor absorption system for automobiles .

Is it ok if I contact you for my querries.

Sir , one more question is it possible to have a hybrid technology in motorbikes.?

Thanks in advance .

Lokesh Jeswani

Hi lokesh, I am Ganesh doing my final year in mechanical dept,I wondered by seeing ur discussion in the topic RE-Vapour absorption in automobiles.I am ailso interste in doing project in this area.Now I am doing the project "Thermal storage device[using PCM]" to store the waste heat.If you give details of vapour absorption in cars it helps for further development of my project.

Vapour absorption on small scale used to be used here in US for residential refrigeration.

j.

Absorption systems are difficult to make efficient.

As the exhaust heat on a car is wasted anyway, this shouldn't be a problem.

The system heats the solution and in the process some of the working gas is expelled from the solution. It is passed into a separator (distillation column in the case of ammonia, simple separator for LiBr/water)

This gas, and the solvent then pass through heat exchangers to preheat the incoming stream as well as to start cooling the working fluid. If this heat exchanger is eliminated, the demands on the cooling circuit become very large. (Efficiency is not a worry as our heat is free, but heat to reject is a concern having a direct bearing on size and cost of the plant)

The gas and solvent are further cooled by the cooling circuit (eventually the heat is rejected into the air), and the gas, still at high pressure (relative to the pressure when it is evaporated), condenses. This liquid is now our refrigerant

The refrigerant is passed through an expansion valve and fed into the evaporator, where it evaporates, dropping the temperature. This cold vapor stream is now used to provide air conditioning or refrigeration.

The vapor stream is then passed into the absorber where it is reabsorbed into the solvent. The solvent needs to be as cool as possible as this has a direct bearing on how much of the refrigerant it can absorb. Heat is liberated during the absorption.

The solution then passes to the feed pump to increase the pressure then to the boiler via the heat exchangers.

As you can see, there is quite a collection of gear needed. When you add the cost of all this and compare it with a standard refrigerant cycle, the absorption cycle will be more expensive, especially as the cooler has to reduce things to around ambient, whereas a normal car radiator operates above 100C, so the cooling circuit tends to be expensive.

The fact that you have virtually no power drain to operate it isn't a factor as far as the car makers are concerned. They don't believe people will pay extra to get the resultant reduced power demand.

With increased emphasis on fuel economy now happening, this situation may well change.

my dear friend water is the best absorbent and i will tell another reason for using water is temprature difference of boiling pt. between absorber and refrigerant must be greater than 100 degree... if condenser contain water then it will cause choking problem.....