Lixuan Chen

Efficiency bound of a solar-driven Stirling heat engine system

A solar-driven Stirling engine is modelled as a combined system which consists of a solar collector and a Stirling engine. The performance of the system is investigated, based on the linearized heat loss model of the solar collector and the irreverisible cycle model of the Stirling engine affected by finite-rate heat transfer and regenerative losses. The maximum efficiency of the system and the optimal operating temperature of the solar collector are determined. Moreover, it is pointed out that the investigation method in the present paper is valid for other heat loss models of the solar collector as well, and the results obtained are also valid for a solar-driven Ericsson engine system using an ideal gas as its engine work substance.

Density of states and thermodynamic properties of an ideal system trapped in any dimension

The density of states and thermodynamic properties of an ideal gas system trapped in a generic power-law potential in an n-dimensional space are studied. A unified description for the Bose, Fermi and classical gases is given by using the grand potential of the system. Consequently, not only the results in current textbooks of statistical mechanics but also some new general important conclusions, such as the conditions for the occurence of Bose-Eisntein condensation in a trapped Bose system in any dimensional space, can be derived directly using the results of this paper.

Thermostatistical properties of q-deformed bosons trapped in a D-dimensional power-law potential

The thermostatistical properties of an ideal gas of q-deformed bosons trapped in a D-dimensional power-law potential are studied, based on the q-deformed Bose–Einstein distribution. The effects of q-deformation on the properties of the system are discussed. It is shown that q-deformed bosons (q ≠ 1) possess many different characteristics from those of ordinary bosons, which include the condition that Bose–Einstein condensation (BEC) occurs, the critical temperature and the continuity of heat capacity.

Low-temperature behavior of a weakly interacting Fermi gas trapped in a power-law potential

The low-temperature behavior of a weakly interacting Fermi gas trapped in a power-law potential is studied, based on the pseudopotential method and local-density approximation (LDA). The expressions of several thermodynamic quantities, which include the chemical potential, total energy, entropy and heat capacity, are derived analytically. The corrections to the thermodynamic quantities due to the interactions between the particles are presented explicitly. The incorporative effects of the external potentials and interatomic interactions on the properties of the system are discussed.

Bose-Einstein condensation of a relativistic Bose gas trapped in a general external potential

Bose–Einstein condensation of an ideal relativistic Bose gas trapped in a generic power-law potential is investigated. The analytical expressions for some important parameters such as the critical temperature, ground-state fraction and heat capacity are derived. The general criteria on the occurrence of Bose–Einstein condensation and the discontinuity of heat capacity at the critical temperature are obtained. The results obtained here present a unified description for the Bose–Einstein condensation of a class of ideal Bose systems so that many important conclusions in the literature are included in this paper.

An analytical description of the low temperature behaviour of a weakly interacting Bose gas

An analytical description of the low temperature behaviour of a trapped interacting Bose gas is presented by using a simple approach that is based on the principle of the constancy of chemical potentials in equilibrium and the local-density approximation. Several thermodynamic quantities, which include the ground-state fraction, chemical potential, total energy, entropy and heat capacity, are derived analytically. It is shown that the results obtained here are in excellent agreement with the experimental data and the theoretical predictions based on the numerical calculation. Meanwhile, by selecting a suitable variable, the divergent problem existing in some papers is solved.