Prsented in this paper are a systematic study on the global exergy consumption in the earth and a budget and a budget of the exergy consumption with respect to main terrestrial processes. Based on Szargut's definition of exergy for thermal radiation, a global exergy balamce of the thermodynamic system of the earth, driven by cosmic exeryflow originated from the temperature difference between the sun and the cosmic background, is carried out to give the global cosmic exergy consumption as the multiplication of the cosmic background microwave (CBM) radiation temperature and the global entropy generation due to irreversibility in the earth system. Concrete formulae are derived for cosmic exergy, with emphasis on generalization of a simple blackbody relationship between entropy and energy flux densities to the cases of gray body radiation with moderate or large emissivity associated with the earth system. Global entropy generation is evaluated with a result compared very with a widely accepted datum based on satellite observations in earth science. A budget of the global entropy generation is made with respect to the terrestrial radiation processes associated with the atmosphere and the earth's surface and to the molecular transport phenomena in the material earth. A mechanism of multiplication goveming transformation between cosmic exergy and terrestrial exergy is developed. An overall exergy budget of the earth system, based on the entropy budget by means of the Gouy-Stodola law, are presented with essential implication to the problem of global sustainability.

Thepresent work discusses coupled heat and mass transfer during freeze-drying of a rigid product, as well as accelerated freeze-drying where sublimation and desorption occur concurrently. A desorption mushy zone model was developed to describe the desorption drying. An exaxt solution was obtained for coupled heat and mass transfer with one discrete sublimation moving interface and one desorption mushy zone where mass transfer is controlled by both Fick and Darcy laws. The effects of several parameters on the sublimation and desorption are analyzed and discussed.

A perturbational h4 compact exponential finite difference scheme with diagonally dominant coefficient matrix and upwind effect is developed for the convective diffusion equation. Perturbations of second order arerted on the convective coefficients and source term of an h2 exponential finite difference scheme proposed in this paper based on a transtormation to eliminate the upwind effect of the convective diffusion equation. Four numerical examples including one to three-dimensional model equations of fluid flow and a problem of natural convective heat transfer are given to illustrate the excellent behavior of the present exponential schemes. Besides, the h4 accuracy of the perturbational scheme is vernfied using double precision arithmetic.

The time evolution of a line puff, a turbulent non-buoyant element with significant momentum, is studied using the renormalization group (RNG) K-∈ model. The numerical results show that the puff motion is characterized by a vortex pair flow; the computed flow details and scalar mixing characteristies can be described by self-similar relations beyond a dimensionless time of around 30. The added mass coefficient of the puff motion is found to be approximately unity, The predicted puff flow and mixing rate are substantially similar to those obtained from the standard K-∈ model and are well supported by experimental data. The computed scalar field reveals significant significant secondary concentration peaks trailing behind in the wake fo the puff. The present results suggestthat the overall mixing rate of a puff is primarily detenmined by the large-scale motion and that stremline curvature probably plays a minor role.