Problem 53PE

A person inhales and exhales 2.00 L of 37.0ºC air, evaporating 4.00 × 10−2 g of water from the lungs and breathing passages with each breath.

(a) How much heat transfer occurs due to evaporation in each breath?

(b) What is the rate of heat transfer in watts if the person is breathing at a moderate rate of 18.0 breaths per minute?

(c) If the inhaled air had a temperature of 20.0ºC , what is the rate of heat transfer for warming the air?

(d) Discuss the total rate of heat transfer as it relates to typical metabolic rates. Will this breathing be a major form of heat transfer for this person?

Solution 53PE

- heat transfer rate is 97.2 J
- rate of power transfer is 29.2 W
- the rate of power transfer is 9.48 W
- The heat loss in breathing is 38.7 W, while sleeping, our body consumes 83 W of power, while sitting it consumes 120 to 210 W. Therefore, the total rate of heat loss from breathing will not be a major form of heat loss for this person.