Einstein Cycle: Analysis of Low Temperature Refrigeration Performance

[willib]

CONCLUSIONS
The Einstein cycle is a three temperature thermal heat
pump with no work input or output. It receives high temperature
driving heat which is used to pump heat from a low
refrigeration temperature to an ambient rejection temperature.
The refrigeration application analyzed in this study uses
butane-ammonia-water working fluids with the driving heat
input temperature varying from 325 K to 375 K. The entropic
average temperature for this driving heat input is 342 K. This
is a relatively low driving heat source temperature. The
refrigeration temperature from which heat is pumped was
selected to be 266 K and the single heat rejection temperature
was selected to be 315 K. The COP of this cycle is low relative
to two-pressure absorption cycles, which require a liquid
solution pump. A second law analysis gives insight into the
fundamental reasons for the low COP.
The reversible COP was found to be at 0.57. This means
that even if the cycle could be made reversible, it still could not
reach the COP of advanced two-pressure absorption cycles.

This is due primarily to the low generator heat input entropic
average temperature of 342 K.
This reversible COP is degraded by three primary
irreversibilities: 1) the generator internal regenerative heat
exchanger, 2) the evaporator mixing, and 3) the absorber
mixing. They degrade the reversible COP by 0.17, 0.12, and
0.11 respectively, down to 0.17.
The cycle demonstrates a creative approach to achieving
refrigeration with no work requirement, though at a relative
low COP. The second law analysis shows the source of this
low performance to be primarily due to a low generator
temperature. This should be investigated to determine how the
cycle and working fluids might be changed to raise the
generator heat input temperature and various achieve
temperature lifts.
These developments could make the cycle competitive
with current commercial technology in various applications
such as residential heat pump space cooling and heating. The
cycle can achieve first law heating efficiencies over 100
percent, and reduce summer peak air conditioning loads on
electrical power plants. Other applications are possible where
low cost and reliability are important, such as remote
installations and developing countries without an electrical
infrastructure. Silent operation is also a benefit.

I'm sure most of you have heard of the Einstein Referigeration Cycle .
For those who have not I've listed the references for further reading..
http://www.me.gatech.edu/energy/pubs/SLA_2.pdf
ok 342 K is about 156 F ,for anyone with an attic , it seems to me that this is the perfect solution to keeping all of us cool in the summer..

REFERENCES
Alefeld, G., 1990, “What Are Thermodynamic Losses and
How to Measure Them,” A Future For Energy, J. Necco, ed.,
World Energy Symposium, Firenze, Italy.

Alefeld, G., and Radermacher, R., 1993, Heat Conversion
Systems, CRC Press, Boca Raton, FL, p. 64.
Delano, A., 1998, “Design Analysis of the Einstein
Refrigeration Cycle,” Ph.D. Thesis, Georgia Institute of
Technology, Atlanta, Georgia.

Einstein, A., and Szilard, L., 1930, “Refrigeration” (Appl:
16 Dec. 1927; Priority: Germany, 16 Dec. 1926) Pat. No.
1,781,541 (United States).

Gillespie, P.C., Wilding, W.V. and Wilson,G.M., 1987,
“Vapor-liquid equilibrium measurements on the ammoniawater
system from 313 K to 589 K,” Experimental Results
From the Design Institute for Physical Property Data, C.
Black, ed., AIChE Symposium Series, Vol. 83, No. 256.
Herold, K., Radermacher, R., and Klein, S. A., 1996,
Absorption Chillers and Heat Pumps, CRC Press, Boca Raton,
FL, p. 13.
Klein, S.A., and Alvarado, F.L., 1997, Engineering Equation
Solver, Version 4.4, F-Chart Software, Middleton, Wisconsin.
Palmer, S.C. and Shelton, S.V., 1996, “Effect of Evaporator
Design Pressure on Dual-Pressure Absorption Heat Pump
Performance” Proceedings of the International Ab-Sorption
Heat Pump Conference, R. Radermacher, ed., Vol. 1, pp. 231-
236.
Patel, N.C., 1980, “The Calculation of Thermodynamic
Properties and Phase Equilibria Using a New Cubic Equation
of State,” Ph.D. Thesis, Loughborough University of
Technology, Loughborough, Leicestershire, United Kingdom.
Pangiotopoulos, A.Z., and Reid, R.C., 1986, “New Mixing
Rule for Cubic Equations of State for Highly Polar,
Asymmetric Systems,” Equations of State: Theories and
Applications, K.C. Chao and R. Robinson, ed., American
Chemical Society, Washington, D.C., pp. 571-585.
Wilding, W.V., Giles, N.F., and Wilson, L.C., 1996, “Phase
Equilibrium Measurements on Nine Binary Mixtures,”
Journal of Chemical Engineering Data, Vol. 41, pp. 1239-
1251.

 

[Clausius2]

The cycle demonstrates a creative approach to achieving
refrigeration with no work requirement, though at a relative
low COP

Interesting information, willib. I will take a look at the pdf document. Anyway there are lots of traditional absorption chillers (LiBr-H20) which don't need any pump. The pumping process is made via gravitational force. We have one in a laboratory of my university.

 

[willib]

Clausius2 have you got any info on the (LiBr-H20) absorption chillers.?
the only thing on them i could find on google was on the IEEE site , and not being a member , i wasnt able to access the document..
i'll try registering ..

 

[Clausius2]

When I studied them I had to take a look at Trane and Yazaki web catalogs. Google them.

 

[quark]

My experience with LiBr+water VAS is very bad. Industrial systems do require a pump for LiBr solution and a pump for refrigerant(water) as well. The power consumed by these two pumps are not considered while calculating COP(to get a high COP). Some manufacturers claim a COP of 1.5 with double effect systems but I was never able to get beyond 1. Further, you have to provide more cooling water flowrate, when compared to vapor compression systems, as LiBr is to be cooled down for better water absorption.

LiBr is highly corrosive and yearly cleaning of the solution and internals is compulsory. Capacity control is almost nill with these systems and evaporator flooding is the most common trouble at low loads. Cooling water temperature below 21deg.C is well enough to crystallize the strong solution(about 61%). When you operate chilled water at 5deg.C, vacuum in the system should be 4mm Hg abs. Air ingress into the system will deteriorate the capacity and causes severe corrosion.

I recommend these systems if and only if you have waste heat, otherwise you will be the happiest guy with a vapor compression system.

Fundamentals of Air Conditioning by Shan K Wang has good description and design principles about these systems.

 

[willib]

The Einstein cycle

 

[willib]

Does anyone know if Einstein used a bubble pump ??
Being more of an electonic type guy , and the fact that water is a magnetic dipole molecule. i am wondering wether or not you could help the process along by using electro-magnetic induction ( a coil of wire wrapped around the tube), in place of the bubble pump...

 

[Clausius2]

I recommend these systems if and only if you have waste heat, otherwise you will be the happiest guy with a vapor compression system.

Great. If every people think as you, we will have a great amount of atmospheric pollution in a near future. You are forgetting the great enviromental impact that compression systems have. They have three main impacts: i)the Ozone Depletion Potential, ii)the indirect global warming effect caused by the fossil fuel burned in a power plant to feed the compressor power, and iii)the direct global warming effect caused by the refrigerant released into the atmosphere. Yeah, some time ago the people began to be afraid about this stuff, they were "happy guys" with compression systems till a NASA study gave us the information of the ozone layer depletion. From then to nowadays there have been a great effort to develop clean refrigeration systems, and absorption chillers are some of them.

Although you are not going to be a happy guy with an absorption chiller, at least you are not collaborating to destroy the environment.

 

[quark]

It is a wrong notion that absorption chillers are eco friendly. Infact, bromine is 50times more destructive, to ozone layer, than chlorine. Perhaps, you forgot that CO2 plays a substantial role in global warming. The electricity used for vapor compression systems is generated from good many sources apart from burning fuels, where as there is no alternative for vapor absorption systems except burning fuel and releasing CO2 into the atmosphere. At any capacity, if we presume power is generated from burning fuels alone, the amount of CO2 released will be higher for a VAS than VCS, for the COP of a VAS is much less than a VCS. Cooling water flowrates required for a VAS is more, so more treatment chemicals and more pollution.

The capacity control of a VAS is virtually nill, so the power consumption at lower loads is extremely high when compared to a VCS.

If you go into the trivials, the size of a VAS is much bigger, for any capacity, than a VCS and this requires more metal to be put into the manufacturing and so more duration of operation of a furnace which results in further CO2 release into the atmosphere. When LiBr fully crystallizes in the system, which is very common to VAS, you have to externally heat the low temperature heat exchangers. LiBr is a carcinogen. The part replacement for a VAS is more frequent when compared to a VCS.

No, I am not corroborating the destruction of environment. What I am suggesting is to judge the overall scenario. On personal front, I never used an air conditioner in my home nor I will in future.

Regards,

 

[willib]

Butane Water and Ammonia are the three ingrediants I'm interrested in.
and to my knowledge cooling water isn't required in the Einstein cycle..

 

[Clausius2]

At any capacity, if we presume power is generated from burning fuels alone, the amount of CO2 released will be higher for a VAS than VCS, for the COP of a VAS is much less than a VCS. Cooling water flowrates required for a VAS is more, so more treatment chemicals and more pollution.

,

For running an absorption chiller is not needed any CO2 at all. Although the COP is much less, there is no global indirect warming effect caused by the electricity generated for running the compressor. I don't know about the cancerigen capacity of LiBr, but let's try with NH3. Although NH3 is very dangerous when it is released to ambient, it has zero Ozono Depletion Potential.

 

[willib]

how difficult do you thing it would be to construct a working model of the Einstein referigerator.?

 

[willib]

this doesn't look that difficult..