Psychrometric Puns

Hi! I’m currently working on a project based on the automarizarion of evaporative air coolers. I’m trying to create a mathematical model that can help me interpret a psychrometric chart/ get the results I’d get from one using equations. Has anybody done this before? Or does anyone have any tips? Thanks!

In particular I am trying to understand how humidity works over 100C, and I think a water psychrometric chart going to 150C or 200C would get me the answers I need, but I simply cant find one. Anyone ever seen it or have a way to generate one? Thanks so much in advance.

So I have thermo question about the psychometric chart given a dry-bulb temperature and a relative humidity. Pressure is atmospheric. I need to find the mass fraction of water vapor.

My first attempt was using the partial pressure to determine the molar analysis and convert into mass fraction, but I dont even know if thats correct.

Kinda stuck here, all other questions are doable except for this one.

thanks

Edit: some development: I used the relative humidity, given, as a way to find the ratio between the mass of the air and mass of the vapor as such:

RH = 80%

RH = Mv/Ma

0.8 Ma = Mv

to find the mass fraction of the water vapor:

x = Mv/(Mv +(Mv/0.8))

x= 0.444

So I guess my question now is: Is this solution valid? or am I missing something?

Edit 2: punctuation

If you have to work with any sort of humidity and temperature levels (such as for HVAC engineering, or any engineering that entails calculating how much energy must be spent dehumidifying something), you will need to work with psychrometric (not to be confused with "psychometric", which is the measurement of mental capacities) charts at some point. These charts are famous for having axis and grid lines going every which way. There are grid lines and sets of curves for dry-bulb temperature, wet bulb temperature, humidity ratio, relative humidity, specific enthalpy, specific volume, and I think there are yet a couple more I can't remember. All this can be mind-numbingly confusing for a beginner.

This video gives the clearest introduction to how to reason with these charts. I linked directly to where the explanation begins:

How to Use a Psychrometric (Humidity) Chart

These charts never made intuitive sense to me until I saw this video.

The software he uses in this video is the Wolfram Demonstration Project of a psychrometric chart, which can be found here: Wolfram: Reading a Psychrometric Chart

This is applicable for ME TFS and HVACR. I saw the NCEES video on it and it's clear that you can't drag lines, or make parallel lines. That is complete shit. If you need the SHR then you need to be able to drag the line into the psych chart and get whatever data is needed. Also 10 lines max?! Really. And they're black? Wtf. I wish we could just get a laminated chary and dry erase markers. Has anyone who's taken either exam and used the chart found it to be reasonable or outrageous. This was more of a vent rant.

Check out these new videos about covering psychrometrics in preparation for the FE exam. You can also download a free checkoff list for mechanical engineering, instructions are shown in the last video.

FE Exam Practice - Thermodynamics - Psychrometrics - Enthalpy

FE Exam Practice - Thermodynamics - Psychrometrics - Mass Flow Rate

FE Exam Practice - Thermodynamics - Psychrometric Equations

Hey! Does anyone know of any good apps for psychrometrics? I have to write a paper on it and I guess I'll be using whatever app I download for projects on psychrometrics later on. Any help is greatly appreciated 😁

I’m looking for a calculator that will give me dry bulb as an output from an input of any 2 of RH%, Enthalpy or Dew Point. Every calculator I have found requires dry bulb as an input. Application is finding energy implications of sensibly cooling vs using steam humidification to raise humidity to meet minimum space RH% requirements.

For a psychrometric chart the affect of increasing or decreasing temperature can be seen by moving the state coordinates right or left respectively, resulting in lower or higher relative humidity respectively.

How would one visually assess the affect on temperature from varying the relative humidity? (I have a sensor that measures RH and curious if there is a graphical method as opposed to converting the reading into humidity ratio first)

I know that cooling follows along the vapor pressure until you start latent cooling.

I know the Entering air temperature, db, wb and atm_pressure. I also know the Leaving Air db and atm_pressure. How can I calculate the wb from this?

I feel like I should know this, but I am having the dumb right now.

http://i.imgur.com/9KzwfBZ.png

I'm having trouble on number a and also part b.

I know for part b you need to know the compositions and then take the difference of them and multiply by 1 lbm Dry Air and then divide by the volume (ft^3) of air fed but I'm having trouble figuring out how much was fed.

Im looking for some fun psychrometric charts, like tequila/air or whiskey/air charts. My googlefu is weak it seems.

I know itd be extremly difficult to get near alcohol saturation in air, and wetbulb should be a lesser concern then things like breathing, but like i said, its just for fun

I'm working on a homework problem, where we're told that humid air contains 2.44% w/w water and is at 50 C and 1 atm. We're then asked to estimate a bunch of properties from the psychrometric charts (easy).

But then we're told that it enters a condenser, and leaves the condenser at 10 C, with constant pressure throughout the system. Is this enough information to continue using the charts to estimate properties about the air at its new state? My only thought on what to do would be to follow the dry bulb temperature line from 50 C to 10 C, at constant absolute humidity, but I would think that because water is condensing, the absolute humidity would decrease. I just don't know how to determine how much it would decrease.

Any help greatly appreciated.

Do your worst!

For context I'm a Refuse Driver (Garbage man) & today I was on food waste. After I'd tipped I was checking the wagon for any defects when I spotted a lone pea balanced on the lifts.

I said "hey look, an escaPEA"

No one near me but it didn't half make me laugh for a good hour or so!

Edit: I can't believe how much this has blown up. Thank you everyone I've had a blast reading through the replies 😂

It really does, I swear!

They’re on standbi

Pilot on me!!