Aheat pump with refrigerant-134a as the working fluid is used to keep a space at 25
o
c by absorbing heat from geothermal water that enters the evaporator at 60
o
c at a rate of 0.065 kg/s and leaves at 40
o
c. refrigerant enters the evaporator at 12
o
c with a quality of 15% and leaves at the same pressure as saturated vapor.

if the compressor consumes 1.6 kw of power, determine

(a) the mass flow rate of the refrigerant,
(b) the rate of heat supply,
(c) the cop,
(d) the minimum power input to the compressor for the same rate of heat supply

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.