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# Consider a “cold” winter day in with an air temperature of 7.22 °C and relative humidity...

Consider a “cold” winter day in with an air temperature of 7.22 °C and relative humidity of about 20% (moisture content 0.001 g H2O/g dry air). A person waiting at a bus stop inhales at an average rate of 8 g dry air/min and exhales air saturated with water at body temperature (37°C) and 1 atm (molal humidity is 6.7%). The heat capacity of dry air is 1.05 J/g- °C. Estimate the rate of heat loss from breathing. Express your answer in units of kcal/hr. Hint: ‘molal humidity’ = moles of water vapor / moles of vapor-free (dry) gas

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