Spring 2015

Thermodynamics – 1

An adiabatic burner is fueled with ethyl alcohol (C2H5OH). Liquid alcohol enters the burner at 25°C, 1.25 bar, 0.025 kmol/s. The burner is supplied with 10% excess air at 25°C, 1.25 bar. The products of combustion enter a heat exchanger, are cooled, and exit at 127°C, 1.11 bar. Assume that combustion products leaving the heat exchanger consist entirely of O2, N2, CO2, and H2O.

a) (30%) What is the molar flow rate of air entering the burner? What is the molar flow rate of each of the combustion products (O2, N2, CO2, and H2O) leaving the heat exchanger?

b) (50%) What is the heat transfer rate from the heat exchanger?

c) (20%) If the combustion products were further cooled at 1.11 bar pressure, at what temperature would H2O in the products begin to condense to liquid?

Air is 79% nitrogen and 21% oxygen by volume; 1 mole O2 + 3.76 moles N2 = 4.76 moles air. Tables of fuel properties, gas properties, and steam properties are attached.

Spring 2015

Spring 2015

Spring 2015