If a breath of air, with a volume of 0.5 L, is drawn into the lungs and comes to thermal equilibrium with the body at 37°C while the pressure remains constant, calculate the increase in enthalpy of the air if the initial air temperature is 20°C and the pressure is 1 bar. At a breathing rate of 12 per minute, how much heat is lost in this fashion in 1 day? Compare your answer (and that of problem, assuming a body weight of 80 kg) with a typical daily intake of 12,000 kJ of food energy. What problems might you foresee in arctic climates, where the air temperature can reach -40°C and below? Assume C pm for air is 7R/2.

Problem

If you set out to explore the surface of the Moon, you would wear a thermally insulated space suit In such activity, you might expect to generate roughly 4 kJ of heat per kilogram of mass per hour. If all this heat were retained by your body, how much would your body temperature increase per hour owing to this rate of heat production? (Assume that your heat capacity is roughly that of water) What time limit would you recommend for a moon walk under these conditions?