In the Rankine cycle with a feedwater heater as shown in the figure, the condensing temperature T1 is 25oC. The superheat temperature T3 is 370oC and the vaporization pressure P3 is 32 bar. Enough steam is bled from Turbine 1 at 7 bar (P2’) to heat the feedwater 2’ to a saturated liquid 2’’. Determine the thermal efficiency of this reversible cycle and compare it to a Carnot cycle operating between the same two temperature extremes. Show the cycle in a T-s diagram. Also compute the net work output per kilogram of steam.

Question 1.2 A helical coil cooler is used to cool 0.5 kg.s¹ of hot oil from 100°C down to 40°C. Cooling water with an inlet temperature of 10°C flows inside the coiled tube. The specific heat of the oil is 2 kJ.kg¹.K¹, the specific heat of the water is 4.2 kJ.kg¹.K¹, and the density of water is 1000 kg.m. a) Determine the lowest possible cooling water flow rate. (0.48 kg.s¹) b) Determine the inside diameter of the tube if a cooling water flow of 1.5 times the minimum is used, and the recommended flow velocity is 1 m.s. Select an appropriate tube from the following standard sizes: Outside diameter (mm) Wall thickness (mm) 30 1.5 35 2.0 40 2.0 45 2.5 50 3.0 c) For a heat transfer coefficient of U = 800 W.m2.K, determine the heat transfer surface area and the tube length of the heat exchanger. The oil inside the tank is mixed by a stirrer and the oil temperature at any location in the tank can be assumed to be equal to the oil outlet temperature. (Area = 4.12 m², length = 39.7 m)

A compressor is to compress 5.0 mol/s of air at 20°C and 200 kPa to 800 kPa. The ratio ofconstant pressure to constant volume heat capacity for air is 1.4. Determine the following:a) Power (in kW) required if the mechanical efficiency of the uncooled compressor is 70%.b) Outlet temperature of the uncooled compressor and whether it is safe for operation.c) The percentage of power saved if the compressor were run isothermally.

A flow of 1950 kg water/h enters at 290 K for cooling and flow outside the tube. An oil which has a heat capacity is 2.30 kJ/(kg∙K) is being cooled in a heat exchanger from 372 K to 310 K and flows inside the tube at a rate of 2600 kg/h. Calculate the water outlet temperature and heat transfer area if the overall heat transfer coefficient is 340 W/(m2·K) and the streams are countercurrent.