Improvement of environmental quality in intensive pig farming through an integrated bioactivation program for the control and prevention of swine mycoplasmal pneumonia

The decline of pig health status is the effect of a bad air quality inside breeding facilities related to the concentration of biogases derived from the action of faecal microbial flora on urine nitrogen. Bioactivation of the environment with bacterialenzymatic mixtures is able to reduce this chemical emanation. An experimental trial has been performed to evaluate the efficacy of the bioactivation treatment to prevent mycoplasmal pneumonia in finishing pigs. Treated and untreated groups, different treatment schemes and different floors have been compared. The ammonia concentration was checked by a chemical method. M. hyopneumoniae infection was evaluated through seroprevalence and by a quantitative lung-scoring system. For all slaughter-lots average carcass weight was recorded. The decrease of the environmental ammonia concentration resulted in lower lungscores and higher carcass weight

Experimental study of a R290 variable geometry ejector

Ejectors are classified as fluid-dynamics controlled devices where the “component-scale” performances are imposed by the local-scale fluid dynamic phenomena. For this reason, ejector performances (measured by the pressure-entrainment ratio coordinate of the critical point) are determined by the connection of operation conditions, working fluid and geometrical parameters. Given such a connection, variable geometry ejector represents a promising solution to increase the flexibility of ejector-based systems. The present study aims to extend knowledge on variable geometry systems, evaluating the local and global performances of the R290 ejector equipped with a spindle. The prototype ejector was installed at the R290 vapour compression test rig adapted and modified for the required experimental campaign. The test campaign considered global parameter measurements, such as the pressure and the temperature at inlets and outlet ports together with the mass flow rates at both inlet nozzles, and the local pressure drop measurements inside the ejector. In addition, the experimental data were gathered for different spindle positions starting from fully open position the spindle position limited by the mass flow rate inside the test rig with the step of 1.0 mm