Aradiator may be treated as a block body with a true surface area of 6m2 and an envelope area of 4m2. it has a surface temperature of 40°c and is situated in a dark room at 20°c. the surface heat transfer coefficient is 4w/m²k. calculate the radiated heat transfer and the convected heat transfer rate. calculate the radiated surface heat transfer coefficient and obtain the same answer using it.

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.