A manufacturing plant produces an efluent as a waste product. As part of a waste heat recovery system, they want to use this for internal heating and cooling. The effluent is flown through a system where its temperature remains at 303.15 K. A 0.06-m diameter pipe carrying hot water and 0.04-m diameter pipe carrying cold air is passed through this effluent chamber. It can be assumed that the surface temperature of these air and water pipes are same as the effluent temperature. Water comes in at 328.15 K and exits at 308.15 K. The air comes in at 268.15 K and exits at 298.15 K. The mass flow rate of water and air is respectively, 1 kg/s and 0.01 kg/s. Determine the length of the water and air pipes in the system. Convert all calculations to C.

The sensible heat-transfer coefficient for a dry surface has been determined to be 50 W/(m2-C) at a certain Reynolds number. Estimate the total heat transfer to the surface per unit area at a location where the wall temperature is 10 C and the state of the moist air flowing over the surface is given by 24 C dry bulb and 18 C wet bulb. Assume that the Reynolds number does not change and the Lewis number is 0.82. Assume that the condensate present on the surface will increase the transfer coefficients by about 15 percent.

Saturated steam at 1 atm is condensed on the external surface of a copper tube withan outside diameter 16 mm and tube wall of thickness 0.5 mm. The tube is cooledinternally by water with a mass flow rate of 0.06 kg/s, which in turn is raised intemperature from 15 oC to 60 oC as it flows through the tube.Take the heat-transfer coefficient at the condensing side as 10.0 kW/m2K and theisobaric specific heat-capacity of water as 4180 J/kg K.i) Calculate the heat transfer rate to the cooling water.  ii)

.All properties should be evaluated at the temperature of the steam.Saturated, pure steam at 65 ºC condenses on the surface of a vertical tube with outersurface diameter 2 cm which is maintained at a uniform temperature of 35 ºC. Determinethe tube length for a condensate flow rate of 5 x 10-3 kg/s.