Compound effect of EHD and surface roughness in pool boiling and CHF with R-123

This article is a post-print version of the fianl published article which may be accessed at the link below.Saturated pool boiling of R-123 at 1 bar, including the critical heat flux (CHF), was enhanced by modifying the surface characteristics and applying a high intensity electrostatic field, the latter termed electrohydrodynamic (and abbreviated EHD) enhancement. The heat flux was varied from very low values in the natural convection regime up to CHF. Experiments were performed with increasing and decreasing heat flux to study boiling hysteresis without and with EHD. Boiling occurred on the sand blasted surface of a cylindrical copper block with embedded electrical heating elements, with standardized surface parameter Pa = 3.5 μm. The electric field was generated by a potential of 5 kV to 25 kV, applied through a 40 mm diameter circular electrode of ss-304 wire mesh, aperture size 5.1 mm, located at distances of 5 - 60 mm from the surface, with most of the data obtained for 20 mm. The data for the rough surface were compared with earlier data for a smooth surface and indicated a significant increase in the heat transfer rates. EHD produced a further increase in the heat transfer rates, particularly at low heat flux values and near the CHF. Boiling hysteresis was reduced progressively by EHD and eliminated at high field strength.This work was supported by Government of Pakistan under a scholarship programme

The Impact of Simulation Training on Call Center Agent Performance: A Field-Based Investigation

The most prevalent form of training call center agents is via classroom instruction coupled with role-plays. Role-play training has a theoretical base in behavior modeling that entails observation, practice, and feedback. Emerging simulation-based technologies offer enhancements to behavior modeling that are absent in role-play training. This study evaluates the effectiveness of simulation-based training (henceforth, simulation training) as a behavior modeling technique vis-à-vis role-play training in a real-world call center environment across tasks of different levels of complexity. We collaborate with call centers at two Fortune 50 firms and examine on-job performance metrics to evaluate the effectiveness of simulation training. The performance measures of interest are call accuracy and call duration because these are two important factors that influence customer satisfaction and productivity in call center operations. After controlling for factors such as trainee's learning and technology orientation, age, education, and call center experience, results show that simulation training outperforms role-playing-based training in terms of both accuracy and speed of processing customer calls. Further, the relative superiority of simulation training improves at higher levels of task complexity.call centers, simulation training, behavior modeling, field experiments, performance measurement