Optimization of Two-Stage Peltier Modules: Structure and Exergetic Efficiency

The exergy method, based on the maximum exergetic efficiency criterion, is applied to a two-stage irreversible combined refrigeration system. The exergetic efficiency defined as the ratio of rate of exergy output to rate of exergy input is taken as the objective index to be maximized. The related cycle temperature parameters are first solved. The maximum exergetic efficiency is then obtained analytically. Comparisons between the exergetic efficiency and the coefficient of performance of the combined refrigeration system are performed. The influences of various parameters on the system performances are discussed. It shows that the exergy method is practical and effective when operating or designing the combined refrigeration system.

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Optimum coefficient of performance and exergetic efficiency of a two-stage vapour compression refrigeration system

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/095440603322407263 ◽

2003 ◽

Vol 217 (9) ◽

pp. 1027-1037 ◽

Cited By ~ 3

Author(s):

J S Tiedeman ◽

S A Sherif

Keyword(s):

Performance Optimization ◽

Geometric Mean ◽

Coefficient Of Performance ◽

Second Law ◽

Refrigeration System ◽

Exergetic Efficiency ◽

Two Stage ◽

Optimization Study ◽

The Common ◽

Vapour Compression

This paper presents the results of an optimization study for a two-stage vapour compression refrigeration system based on the coefficient of performance (COP) and exergetic efficiency. Traditional studies have focused on the first-law performance, while those studies dealing with the second law have primarily been limited to performance analysis as opposed to performance optimization. The results of this study indicate that the use of the common approximation of the geometric mean to find the optimum interstage pressure can lead to significant errors in interstage pressure. However, an optimum COP or exergetic efficiency based on the same interstage pressure has relatively little error. This trend is valid as long as the isentropic compressor efficiencies are ‘reasonable’. Second-law optimization revealed that the optimum data curves themselves have a maxima for each set of conditions tested. This leads to the conclusion that for a given system there is an optimum set of conditions that lead to the lowest amount of exergy destruction for that system. This is shown to occur consistently for reasons that are, as yet, undetermined. Finally, polynomial equations have been fitted to the resultant optimum data for the interstage pressure, COP and exergetic efficiency. These equations allow for the reproduction of optimum points based on high-and low-pressure compressor efficiencies and condenser and evaporator pressures.

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Two-stage self-seeding method for preparation of single crystals of poly(phenylene sulfide)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153816 ◽

1989 ◽

Vol 47 ◽

pp. 368-369

Author(s):

Sengshiu Chung ◽

Peggy Cebe

Keyword(s):

Single Crystals ◽

High Performance ◽

Dilute Solution ◽

Two Stage ◽

Annealing Behavior ◽

High Performance Polymers ◽

Seeding Method ◽

Phenylene Sulfide

We are studying the crystallization and annealing behavior of high performance polymers, like poly(p-pheny1ene sulfide) PPS, and poly-(etheretherketone), PEEK. Our purpose is to determine whether PPS, which is similar in many ways to PEEK, undergoes reorganization during annealing. In an effort to address the issue of reorganization, we are studying solution grown single crystals of PPS as model materials.Observation of solution grown PPS crystals has been reported. Even from dilute solution, embrionic spherulites and aggregates were formed. We observe that these morphologies result when solutions containing uncrystallized polymer are cooled. To obtain samples of uniform single crystals, we have used two-stage self seeding and solution replacement techniques.

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