The aerosol can has a long history. As Wikipedia states, the first patent was is

Question

The aerosol can has a long history. As Wikipedia states, the first patent was issued to a Norwegian in 1926. The first disposable can patented in the US in 1939: production didn't take off until 1943 when "bug bombs" were supplied to US troops in the Pacific. In its simplest form, an aerosol can contains a product to be dispersed (hair care, deodorant, insecticide, paint, cooking oil ...) and a propellant. Propellants were historically hydrocarbons, with propane, n-butane and iso-butane being common. Such propellants are typically miscible with the (liquid) product so both leave the can together. Upon exiting the propellant flash vaporizes leaving small product drops heading toward a target. A typical can is 45 mm in diameter and 125 mm in height. It is filled with about 125 ml of propane, of which 50 ml is liquid. The system is originally at room temperature (assume 25 C) when the actuator at the can's top is depressed and held open until half of the propane (by mass) exits. Calculate the original mass of propane in the can. Report your answer in g. Calculate the mass of propane exiting the can. Also report your answer in g. Determine the heat transfer associated with this process. Report your answer in kJ.

Explanation / Answer

One of the practical problems associated with house construction in moist climates is that moisture from the inside of the house (due to water vapor given off from cooking, washing, people) will tend to migrate from the inside to the outside. If the moisture condenses in the glass fiber it will degrade the effective conductivity of the material as well as cause other problems. Calculate the point in the wall where the water will condense (if at all). If it does condense, will it cause a problem? Assume an indoor relative humidity of 50% and an outdoor relative humidity of 90%. (NOTE: The student will need to review psychrometrics and determine the point in the wall where the temperature drops to the dew point temperature determined by the indoor drybulb temperature and the indoor relative humidity. The student will need to use the thermal circuit and determine the surface temperatures on either side of the glass fiber insulation.

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