Performance Analysis of a Twin Rotary Compressor
For a twin rotary compressor, a computer simulation program has been developed. With R22, predicted cooling capacity, compressor input and EER were found to be in good agreement with experimental results. Calculated P-V diagram was also compared well to that of measurement. With the simulation program, parametric study has been performed to investigate effects of cylinder dimensions on R410A twin rotary compressor performance. Over the ranges of cylinder dimensions studied, some variations were found for volumetric, adiabatic and mechanical efficiencies, but overall compressor performance did not change much. Discharge port configuration was found to have large effect on adiabatic efficiency, but not much on volumetric efficiency.
Simulations on the performance of a vapor-injection heat pump for different cylinder volume ratios of a twin rotary compressor
Abstract In residential air-source heat pump systems, the refrigerant injection technique has rapidly developed in recent years due to its outstanding performance at low ambient temperatures. A numerical simulation model of a flash tank vapor-injection heat pump with a twin rotary compressor is newly presented in this paper. The performance of the twin rotary compressor with refrigerant injection was simulated using a loss and efficiency model. The model was validated by comparing the predictions with measured data. In addition, the model was used to analyze the performance characteristics of the vapor-injection heat pump according to the cylinder volume ratio of the twin rotary compressor. Based on the simulation results, optimum cylinder volume ratios were suggested for various design conditions, including for the fixed first cylinder volume, the fixed total cylinder volume, and the fixed heating capacity.
Denitrification of PVA-immobilized denitrifying photosynthetic bacterium, Rhodobacter sphaeroides
Abstract A newly isolated denitrifying strain, Rhodobacter sphaeroides NII2 was immobilized in polyvinyl alcohol (PVA) gel, and the properties of the cells in the gel were examined. The immobilized cells had low or almost no denitrification activity, but the cells were activated by incubation in light with culture medium for denitrification containing 0.5% nitrate and no other nitrogen source. Cells grown in the dark were activated by incubation at an earlier stage and to a higher rate than the light-grown cells. The activation was markedly enhanced in the PVA gel with a low cell concentration. The immobilized cells consumed nitrate with a temporary accumulation of NO 2 and evolved nitrogen gas. The immobilized cells could use various organic compounds as electron donors for denitrification. Thus, the immobilized cells were applied to a continuous treatment of synthetic wastewater using an aparatus devised by this laboratory. The results showed an efficient removal of NO 3 -N from the test water.