Ph.D. Proposal Presentation by Andy Delano

(Dr. Sam Shelton, advisor)

"Design Analysis of the Einstein Refrigeration Cycle"

Currently, electric motor driven vapor compression refrigeration cycles dominate air conditioning, heat pump, and refrigeration applications. However, direct thermally driven refrigeration cycles are receiving increasing attention for several reasons: environmentally benign refrigerants, reducing electric utility summer peak demand, silent operation, and efficient utilization of waste heat.

The thermally activated refrigeration cycles receiving the most attention are dual pressure cycles requiring an electric pump to move the liquid solution from low pressure to high pressure. An uncovered patent by Albert Einstein issued Nov. 11, 1930 discloses a single pressure thermally driven refrigeration cycle which does not require a mechanical pump. It accomplishes this by using a triple mixture of butane, ammonia, and water. Butane acts as the refrigerant, and ammonia acts as an inert gas creating low partial pressure for the butane in the evaporator to provide low temperature refrigeration. Water serves as the absorbent to separate the ammonia from the butane. A literature search has provided only two brief references to this unique cycle.

A simple thermodynamic analysis of this cycle has been performed and relatively promising COPs as high as 0.40 were found to exist (Delano, 1997). This study provided insight on the processes of the cycle and its operating characteristics. It is proposed to further analyze the cycle and carry out design studies to improve its performance. The previous model will be improved by taking a more realistic fluid mixture property model, finite size heat exchangers, and including the bubble pump effects. In addition, other fluid triplets will be investigated. A component second law analysis will be carried out to determine how the cycle irreversibilities are distributed. Finally, the Einstein cycle will be compared to the similar ammonia-water-hydrogen used in some applications today.