Furphy

An old ammonia refrigerator is found in the stores. The compressor is sized as 2 kW and someone can remember that the fridge used to operate between 3.691 bar and 8.570 bar. Using this information and the steam tables calculate:

a) The temperature of the NH3 leaving the compressor

b) The mass flowrate of the ammonia,

c) The evaporator heat load and,

d) The condenser-desuperheater heat load.

Any help would be appreciated.

A cast iron central heating pipe has an inner radius of 50 mm and a wall thickness of 5 mm. The pipe feeds a radiator with water at a temperature of 85 oC and the inner wall temperature of the pipe may be assumed equal to the water temperature.

The thermal conductivity of cast iron is 52 W/m K and the outside surface of the pipe is exposed to air at 19 oC with a convective individual heat transfer coefficient of 20 W/m2 K. Resistance due to inside film heat transfer is negligible. Assuming the water temperature remains constant at 85 oC.

I need to find the overall heat transfer coefficient and know that i need to use the formula that starts with 1/U but i dont know how to apply it when you only have the outer heat transfer coefficient.

how do you find acceleration?

i have a samsung dvd burner and burn dvds, however i have not made one dvd free of errors, they are only small but irritating it there anyway to get rid?