Propane gas enters a continuous adiabatic heat exchanger17 at 40C and 250 kPa and exits

QUESTION:

Propane gas enters a continuous adiabatic heat exchanger17 at 40C and 250 kPa and exits at 240C. Superheated steam at 300C and 5.0 bar enters the exchanger flowing countercurrently to the propane and exits as a saturated liquid at the same pressure. (a) Taking as a basis 100 mol of propane fed to the exchanger, draw and label a process flowchart. Include in your labeling the volume of propane fed (m3 ), the mass of steam fed (kg), and the volume of steam fed (m3 ). (b) Calculate values of the labeled specific enthalpies in the following inletoutlet enthalpy table for this process. References: H2O(l, 0.01C), C3H8(g, 40C) Species nin H in nout H out C3H8 100 mol H a(kJ/mol) 100 mol H c(kJ/mol) H2O mw(kg) H b(kJ/kg) mw(kg) H d(kJ/kg) (c) Use an energy balance to calculate the required mass feed rate of the steam. Then calculate the volumetric feed ratio of the two streams (m3 steam fed/m3 propane fed). Assume ideal-gas behavior for the propane but not the steam and recall that the exchanger is adiabatic. (d) Calculate the heat transferred from the water to the propane (kJ/m3 propane fed). (Hint: Do an energy balance on either the water or the propane rather than on the entire heat exchanger.) (e) Over a period of time, scale builds up on the heat-transfer surface, resulting in a lower rate of heat transfer between the propane and the steam. What changes in the outlet streams would you expect to see as a result of the decreased heat transfer?