Ashworth lesson 2: careers for mechanics and technicians exam

Different types of steels contain different elements that alter the characteristics of the steel. for each of the following elements, explain what the element does when alloyed with steel.

Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 mpa and -10°c at a rate of 0.05 ka/s and leaves at 0.8 mpa and 50°c. the refrigerant is cooied in the condenser to 0.72 mpa and 26'c. it is then throttled to 0.15 mpa. sketch the t-s diagram for the system and evaluate: 6) the rate of heat removai from the refrigerated space (kw), it) the power input to the compressor (kw), ii) the isentropic efficiency of the compressor (%), and iv) the cop of the refrigerator.

The catalogue for a refrigerant 22, four-cylinder, hermetic compressor operating at 29 r/s. a condensing temperature of 40°c and an evaporating temperature of -4°c shows a refrigeration capacity of 115 kw. at this operating point, the motor (its efficiency is 90 percent) draws 34.5 kw. the bore of the cylinders is 87 mm and the piston stroke is 70 mm. the performance data are based on 8°c of sub-cooling of the liquid leaving the condenser. compute (a) the actual volumetric efficiency and (b) the compression efficiency.