An ideal Brayton refrigeration cycle has air entering at 100 kPa, 270 K. The compressor pressure ratio is 3, and the temperature at the turbine inlet is 310 K. The isentropic efficiencies of the compressor and turbine are 82% and 85 % respectively. Determine a. Net work input, per unit mass of air flow, in kJ/kg. b. Refrigeration capacity, per unit mass of air flow, in kJ/kg. c. Coefficient of performance. d. Coefficient of performance of a Carnot refrigeration cycle operating between thermal reservoirs at TC = 270 K and TH = 310 K, respectively.

Burgers vector is generally parallel to the dislocation line. a)-true b)-false

The flow rate of air through a through a pipe is 0.02 m5/s. a pitot static tube is placed in the flow. the radius of the pitot static tube is 1 mm. assuming the flow to be steady and the air to be at 300k, calculate the difference in total and static pressure if the diameter of the pipe is: (a) d 0.1 m d 0.05 m (c) d 0.01 m

Ashielded metal arc-welding operation is accomplished in a work cell by a fitter and a welder. the fitter takes 5.5 min to load components into the welding fixture at the beginning of the work cycle, and 1.5 min to unload the completed weldment at the end of the cycle. the total ength of the weld seams 1200 mm, and the travel speed used by the welder averages 300 mm/min. every 600 mm of seam length, the welding stick must be changed, which takes 0.8 min. while the fitter is working, the welder is idle (resting): and while the welder is working the fitter is idle. (a) determine the average arc-on time as a fraction of the work cycle time. (b) how much improvement in arc-on time would result if the welder used flux-cored arc welding (manually operated), given that the spool of weld wire must be changed every 10 weldments, and it takes the welder 5.0 min to accomplish the change? (c) what are the production rates for these two cases (weldments completed per hour)? attach your work and solutions.