Papers by Keyword: Concentrating

Abstract: Aiming at the problem of the concentrating solar cell efficiency restricted by the temperature. The closed two-phase thermosyphon could be used for heat dissipation in concentrat- ing solar cell with high heat flux, then water was selected as the working fluid. Numerical computation methods were adopted to study heat transfer performance of the finned heat pipe radiator in free convection. The temperature field, velocity field, total heat dissipating capacity of different fin pitch and side length as well as free convection heat transfer coefficient under the condition of constant temperature of parent tube were obtained. As a result, the fin side length had greater impact on the natural convection heat transfer coefficient and average total heat flux per unit area; the fin pitch had greater impact on the finned heat pipe radiator total heat dissipating capacity per unit length; the finned heat pipe radiator was the best when fin pitch was 3mm and fin side length was 90mm.

Abstract: Using a multi-effect evaporation system to concentrate the effluent from alkaline peroxide mechanical pulping (APMP) plants is known to require a high energy consumption. In order to improve the situation, a polyethersulfone (PES) membrane was used to concentrate the effluent of APMP plants beforehand. An orthogonal experimental design was applied and a mathematical model was established to optimize the filtration parameters. An estimation of potential energy and water savings from this new concentration process was developed. The optimal filtration conditions obtained were: molecular weight cut-off at 10,000 Dalton, trans-membrane pressure at 3 bar, feed temperature at 50oC, cross-flow velocity at 420 rpm, and volume reduction factor at 0.93. The average permeate flux under these conditions was 45.31 l/m2.h. The total solids content was increased from 14.74 g/l in the feed to 95.04 g/l in the concentrate. The permeate had low total solid contents of 8.75 g/l, Chemical Oxygen Demand of 6696 mg/l, and Biochemical Oxygen Demand of 4383 mg/l. Such qualities would allow the permeate to be reused in the alkaline peroxide mechanical pulping process. With this new concentration process, about 4840.6 kWh energy can be saved and 23.3 m3 effluent discharge can be reduced for each ton of pulp produced.