Ventilation Systems: Calculating G & E Rates

[melpec]

Hi...Prbably a stupid question but here it goes:

I have some equations here, some of them have a G for rate of generation and others have E for rate of evaporation (both of them have units of volume per time).

My question is: if I know that I have 3 galons of a chemical at the beggining of the day in one tank and at the end of the day I only have 2 galon...then I lost 1 galon per day...but is this number E or G? I mean...I don't understand what is the difference, I know there is an equation relating them but I don't understand the concept.

 

[3trQN]

Is the problem that you don't understand the difference between Generation and Evaporation?

What is meant by generation in this context?

Evaporation is pretty self explanatory with regards to the description, however generation remains ambiguous with what you have described.

Generation sounds like it could possibly describe, among other things, the water condensation in a system.?

You have a variable volume, if you know the rate of evaporation and your final volume you can therefor calculate how much of the substance has entered the system ( possibly what generation is referring to here ).


Consider a sink of water. Water evaporates throughout the day, and you start with a known volume(V). At the end of the day you measure again the volume of water in the sink(V`).

From a formula for the rate evaporation (based on the conditions) you know that you loose x amount of water through evaporation during the day.

You know that the change in the volume of water is related to the amount of water lost and the amount of water gained through the day, where G is the amount gained.

(V`-V) = G - x

That is one possible interpretation of the meaning of Generation and G in this context. I am guessing though.

 

[ravenprp]

Hi there,

Your question is not a stupid one at all! It's actually a great question and shows that you are thinking critically about the equations and their meanings.

To answer your question, the difference between G and E rates is the source of the change in volume. G stands for generation, which means it is the rate at which the substance is being produced or generated. E stands for evaporation, which means it is the rate at which the substance is being lost due to evaporation.

In your example, if you started with 3 gallons of the chemical and ended with 2 gallons, then the difference is 1 gallon. This would be considered a G rate, because the change in volume was due to the generation of the substance.

However, if the change in volume was due to evaporation, then it would be considered an E rate. Let's say you started with 3 gallons and ended with 0 gallons. The difference of 3 gallons would be an E rate, because the change in volume was due to evaporation.

I hope this helps to clarify the concept for you. Keep asking questions and thinking critically about the equations, it will help you understand them better. Good luck!