# A stream of gas (70% air by mole and the balance CO2) enters a heat exchanger at 300 °C and a rate of 100 mol/s. The gas is heated with superheated steam which enters at 6 MPa with 25 °C of superheat....

A stream of gas (70% air by mole and the balance CO2) enters a heat exchanger at 300 °C and a rate of 100 mol/s. The gas is heated with superheated steam which enters at 6 MPa with 25 °C of superheat. The energy transferred from the steam to the gas causes the water to condense to a saturated liquid at 60 °C. The gas and the water do not contact, and no reactions take place, so the gas exits the heat exchanger with the same composition as it enters. The steam flow rate is m (kg/h) and the exit temperature of the gas is T (°C). Neglecting changes in kinetic and potential energy, and energy transferred as work:
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A stream of gas (70% air by mole and the balance CO2) enters a heat exchanger at 300 °C and a rate of 100 mol/s. The gas is heated with superheated steam which enters at 6 MPa with 25 °C of superheat. The energy transferred from the steam to the gas causes the water to condense to a saturated liquid at 60 °C. The gas and the water do not contact, and no reactions take place, so the gas exits the heat exchanger with the same composition as it enters. The steam flow rate is m (kg/h) and the exit temperature of the gas is T (°C). Neglecting changes in kinetic and potential energy, and energy transferred as work:If T = 1300 °C, what is m?If m = 3000 kg/h, what is T?

## Solution

David answered on Dec 20 2021
ID - 201106
Gas mixture -
Basis -100 moles /s
Air -70 moles /s
C02 GAS – 30 Moles /s
Temperature = t =300 oc
Steam at 6 Mpa pressure and temperature of superheat = 25 oc
P = 6000 kpa = 6000 /100 = 60 bar ( 100 kpa = 1 bar )
T = super heat temperature = 25 oc
Water condenses at 60 oc
Part -a - So what m = mass flow rate of steam at t= 1300 oc
Part b - if m = 3000 kg /h , t = ?
Super heated steam -
Temperature - 276.68 oc
Latent heat of steam – 1567 kj /k g
Specific enthalpy = 2783.44 kj /kg
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