Science Buddies: "Ask an Expert"

The focal point of my project is centered on harnessing the steam from a shower, running the steam through a zeolite/water vapor adsorption heating system, and using the heat that is produced to heat air. I have two issues, both regarding the quantification of items for data collection: A) How can I quantify steam? B) How would I measure an increase in the temperature of the air that is heated in order to demonstrate the effectiveness of my prototype? Currently, I am using thermal efficiency as a means of quantifying the success of my device. I would calculate thermal efficiency by dividing the temperature of the heated air by the temperature of the steam that enters the device.

cessnapilot wrote:harnessing the steam from a shower

I suspect you are talking about "water vapor" and not actually "steam". At normal atmospheric pressues, steam would be water vapor at 100 degress C (212 degress F) or higher which would burn a human.

Moist air is denser than dry air at the same pressue so it has a higher latent heat content (takes more energy to heat or cool it).
So your question of "how can I quantify steam" becomes "how can I quantify moist air"?

Ignoring any scientific curiosity issues and looking at any practical commercial applications, you need to look at the entire system. Water had to be heated to be used in the shower. If the air in the building is already at a comfortable humidity, the moisture introduced by the shower has to be eliminated from the building. Water vapor is going to condense on any surface that is cooler than the air (typically bathrooom walls, mirrors, etc). Water that condenses on a surface that is not drained will have to evaporate when the conditions of the air will allow it to do so. This implies some temperature cycling.

If your device is intended to be in some exhaust fan path and be used to heat the replacement air, then the primary purpose of the device would be moisture control and will involve the temperature of the replacement air, the moisture removed, and the cost of heating and humidity control on the replacement air. Measuring thermal efficiency is probably not as important as measuring total energy efficiency. Any system to condition air in any way will consume energy so what you really need to do is to compare your system with other systems in terms of their energy efficiency. In other words, the system that uses less energy to accomplish the same level of comfort is the winner.

You may find a trip to the library very useful, look at Heating, Air Conditioning, and Ventilation. The sections on calculating the size of air conditioners usually have a good descriptions of how to control the water vapor content and the energy necessary to extract or insert it. The term latent heat refers to the energy required to condense or evaporate the water, while sensible heat refers to the energy required to raise or lower the air temperature.