Acooper object that can be modeled as cube with 10 cm edges is soaking at uniform temperature of 260 c. it was suddenly placed in an environment maintained at 35 c and having heat transfer coefficient h=20 w/m2. c. the properties of the copper are as follows: rho = 8900 kg/m^3, cp=0.38 kj/kg. °c, and k=370 w/m-c. a)- calculate the time required for the center temperature to reach 90°c. b)-calculate the total heat transfer over the time period required for the center temperature to become 90°c.

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.