The performance of a multi-couple thermoelectric device as a generator is inverstigated. The general expressions of two important performance parameters, the efficeiency and power output, are given. The η-K characteristic curves of a thermoelectric generator are presented for some differently constrained conditions, where η is the efficiency of the thermoelectric system and K is total thermal conductance of the multi-couple thermoelectric device. The mazimum efficeiency of the system if calculated. The structure parameters of the device are optimized. The effect of the thermal conductances between the thermoelectric device and the external heat reservoirs on the performance of the system is expounded by using some representative numerical examples. The results obtained here will be useful for a more detiled investigation and for the optimal design of real thermoelectric generators.

A thermodynamic model including four irreversiblilities is used to investigate the optimal Performance a solar-driven thermoelectric generator. The efficiency of the system is derived and taken as and objective function for optimiztion. Some important curves, such as the efficiency of the system versus the operating temperature of the solar collector, the reduced current, and the load resistance, are obtained. These curves can reveal the performance charaterisistics of solar-driven thermoelectric generators. the maximum efficeiency of the system and the corresponding reduced current are derived for some special cases. The optimal matching of load resistance which is one of the kdy problems in the optimal design of solar-driven thermoelectric generators is discussed. New bounds of the key performance parameters, such as the efficiency, power output, and load resistance, are determined.

On the basis of the probability distribution of the various values of the fluctuation and the fundamental equation of thermodynamics of any given system, a simple and useful method of calculating the fluctuations is presented. By using the method, the fluctuations of thermodynamic quantities can be directly determined from the fundamental equation of thermodynamics. Finally, some examples are given to illustrate the use of the method.

The thermostatistic properties of a q-generalized boson system trapped in an n-dimensional harmonic oscillator potential are studied, based on the generalized statistic distribution derived from Tsallis' entropy. The density of states, total number of particles, critical temperature at which Bose-Einstein condensation occurs, internal energy, and heat capacity at constant volume are derived. The characteristics of Bose-Einstein condensation of the system are discussed in detail. It is found from the results obtained here that the thermostatistic properties of such a system depend closely on parameter q, dimensional number of the space, and frequency of the harmonic oscillator; and the external potential has a great influence on the thermostatistic properties of the system.

The thermodynamic properties of a q-generalized ideal boson system with the general energy spectrum ε=aps in a D-dimensional space are investigated, based on the q-generalized statistical distributive function derived by Tsallis entropy. Several important parameters of the system such as the critical temperature tha Bose-Einstein condensation (BEC) occurs, the specifie heat at constant volume, etx. are derived analytically. It is found that the conditions that BEC may occur and the continuity of the specific heat at critical temperature are the same as those of an ordinary boson system. However, the thernodynamic properties of a q-generalized ideal boson system are closely depend on q and D/s and consequently there are some novel results.