Question

b. A stream of liquid Diesel at a mass flowrate of 20.0 kg/s must be heated from 20°C to 250°C. Utility heating is available from dry-saturated steam in a high pressure (HP) steam main at a pressure of 40 bara. Estimate the rate of consumption of steam (in kg/s), if it is assumed that the condensate from the heating unit is saturated liquid water at the same pressure as the HP main. [11 marks) c. Your HP steam main has been taken out of commission for servicing. You have a low pressure (LP) steam main available to you at a pressure of 6 bara. Assuming a minimum approach temperature of 20°C, state the maximum temperature to which you can heat the Diesel to, and further calculate the heating duty for this operation to heat the Diesel to the maximum possible temperature. [9 marks) Data: The specific heat capacity of liquid Diesel is constant at 1.75 kJ/kg.K. Dry-saturated steam at 40 bara is at a temperature of 250.0°C and has a specific enthalpy of evaporation of 1713 kJ/kg. Dry-saturated steam at 6 bara is at a temperature of 158.8°C and has a specific enthalpy of evaporation of 2010 kJ/kg.

Answer 1

Sol me = goug/s. -1-75 Cp -75 Ulugu. 171543 lg. T=30°C To=980 re o For Dogs schicted stom of From Thermodynamics of 40bcod= Ist Low m, x= me G ( TE - Ti ms=20x1075/950-80) = 14.6919/ 1113

for Ston at the Angolo King. Се 20101-Apr-1000 Teach N. 57 To-15g.se & Dimi = 30°C. T To-DTM con h diacl to head T-ISO-8-20 Timot 138.8°C Jox1-73 ( 1387-8-90) Omex = 4150 UI/ Since inox ne Qn

using given data and first law of thermodynamics we can find the required variables

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