Talk:Psychrometrics

message: I've looked around the net and there seems to be a lack of formulae.  Looking at the graph the wet bulb temps appear to be a constant gradient intersecting the saturation curve but how is this derived? njh 10:16, 11 January 2006 (UTC)
thread_title: Does anyone know the relationship between <dewpoint,dry temp> and wetbulb? 

message: This calculation is trickier than it looks. The standard source is the ASHRAE Handbook: Fundamentals. Look in Chapter 6, Psychrometrics, under Numerical Calculations of Moist Air Properties, to find what you are looking for. Most libraries should have a copy in the reference section. Note that it's published in English and metric editions. Tex 16:15, 20 February 2006 (UTC)
replies: text: Not in Australia :-(.  I can probably deduce it from the Clausius-Clapeyron relation though. Thanksnjh 20:54, 20 February 2006 (UTC)

text: The relevant chapter can be downloaded from the ASHRAE website as a PDF file, for a fee which is greater than nominal but not outrageous. I think it is USD 50. Tex 23:39, 20 February 2006 (UTC)
thread_title:  Dew Point Formulas 

message: This external link  shows the relation between the Mollier diagram and the Psychrometric chart. 57.66.65.38 10:25, 11 April 2006 (UTC)
replies: text: This is a little confusing because in fact several different thermodynamic diagrams are known as "Mollier diagrams". The most common is the enthalpy-entropy, or hs diagram. Probably the next most common is the pressure-enthalpy, or ph diagram. In fact I have never heard the enthalpy-composition diagram, as discussed here, called a Mollier diagram, but apparently it can be. Old Mollier must have really been working hard in those days! Tex 15:12, 11 April 2006 (UTC)
replies: text: See Richard Mollier. Any diagram using enthalpy as one of its axes can be called a Mollier diagram, by decree of some physicists at a conference in 1923. ArthurOgawa 00:42, 23 September 2007 (UTC)
thread_title:  Mollier diagram 

message: Under the heading Psychrometric Chart, Relative Humidity, Rkinch addedThe notion that air "holds" moisture, or that moisture dissolves in dry air and saturates the solution at some proportion, is an erroneous (although widespread) concept.Frankly, I do not see Rkinch's point. In what way is the condensation of water out of, say, air not a manifestation of the saturation of a solution? I propose removing this language as a gratuitous editorialization (the claim is neither supported nor explained). Or, a reference to an explanation should be added. ArthurOgawa 00:42, 23 September 2007 (UTC)
replies: text: I agree that the notion of air "holding" moisture is flawed.  There is no affinity between water vapor and air.  Air is displaced by the presence of water vapor, in accordance with Dalton's Law of Partial Pressures.  When water vapor is liberated, either the air will go elsewhere or the local pressure will rise.  Unlike a solid dissolving (or not) in a liquid, there are are no immiscible gases.  Gases are either present in a mixture or not.  There is no "holding" of water by the air.  Warm air does not "hold" more moisture; rather, warm water vapor has a higher pressure and is able to displace a greater fraction of the air at a given local pressure. -Ac44ck (talk) 22:11, 15 June 2008 (UTC)
thread_title: Inappropriate editorialization

message: The text below the chart already discusses the concepts of dry- and wet-bulb temperatures.  Wiki articles exist for both concepts, and the text below the chart links to those articles.
I tried to fix the wet-bulb temperature section some, but it became too much of a time sink to correct it and to coordinate with the information provided beneath the chart and in the existing wet-bulb temperature article.
The discussion here about a wet-bulb thermometer is somewhat misleading.  Will a moist wick on the bulb of a thermometer always cause its reading to drop?  No.  And if does drop, it won't drop below a limiting value.
Why evaporation causes cooling isn't explained. And this article doesn't seem like the place to explain that. -Ac44ck (talk) 03:44, 25 March 2008 (UTC)
thread_title:  Sections on dry- and wet-bulb temperatures seem redundant 

message: I replaced this tag with the more general engineering tag. It really doesn't seem to apply to either chemical or bio engineering. If this doesn't reflect consensus feel free to revert, though I'd be fine with a comment here, too. Jminthorne (talk) 01:03, 24 August 2009 (UTC)
thread_title:  Wikiproject: Chemical and bio engineering tag removed 

message: There needs to be a psychrometric chart. This is what HVAC engineering and psychrometrics is based off of. The chart on there does not show up correctly. There preferably needs to be one from ASHRAE on there with a compass in the upper left corner for the sensible heat ratio and enthalpy/(humidity ratio) ratio. I have one available in either U.S. or SI units if no one else does.  —Preceding unsigned comment added by 192.31.106.34 (talk) 17:52, 10 November 2009 (UTC)
replies: text: There was a chart until it was replace with an SVG version on November 1. Maybe other browsers render the SVG version; mine doesn't. - Ac44ck (talk) 05:00, 11 November 2009 (UTC)
thread_title:  Psychrometric Chart 

message: Psychrometrics studies mixtures of condensing vapors in non-condensing gases. Neither water vapor nor air are required to be part of the mix:
:http://www.ingentaconnect.com/content/els/03645916/1996/00000020/00000003/art00030
::Psychrometric charts for hydrocarbon vapours in nitrogen
One might argue that no gas is non-condensing if the temperature is low enough. Perhaps there is a better way to describe the mixture.-Ac44ck (talk) 14:26, 31 May 2010 (UTC)
replies: text: That's how I think of it, too. But it seems to be a more general term. The structure of your first cite is not exclusive. It does not say the study of other systems cannot be known as psychrometrics. The second cite is from an industry-specific reference, where other mixtures are not relevant and would get no ink. - Ac44ck (talk) 03:58, 2 June 2010 (UTC)
thread_title:  Mixtures of other components 

message: The definitions of "absolute humidity" by the World Meteorological Organization (WMO), the American Meteorological Society (AMS) and the American Society of Heating Refrigeration and Air Conditioning Engineers (ASHRAE) are in agreement. Nevertheless some text authors and others give absolute humidity the same definition as "mixing ratio", a.k.a. "humidity ratio". This is redundant and confusing. Definitions of the Wikipedia psychrometrics page should in this contributor's opinion conform to those of the WMO, AMS, and ASHRAE. 
K289g (talk) 16:04, 18 September 2011 (UTC)
replies: text: There is EN 12792 which defines absolute humidity as moisture per mass of dry air. The standard is used for HVAC. --Ikiwaner (talk) 07:34, 8 December 2023 (UTC)
thread_title:  Absolute humidity 

message: The October 6 revision deleted the definition of specific humidity from the discussion of the psychrometric chart because the psychrometric chart does not display the property specific humidity.  The deleted definition then replaced the specific humidity definition in the "Psychrometric properties section".  Please note that the October 4 revision had two different definitions of specific humidity.  The definition in the October 6 revision agrees (with minor rewording)  with the American Meteorological Society and current ASHRAE definitions. See 20 September 2011 for references and links. K289g (talk) 22:59, 6 October 2011 (UTC)
thread_title:  Specific Humidity 

message: The thermodynamic wet-bulb temperature is a thermodynamic property of a mixture of air and water vapor. The value indicated by a wet-bulb thermometer often provides an adequate approximation of the thermodynamic wet-bulb temperature.
You haven't defined wet-bulb temperature. You haven't defined wet-bulb thermometer. You haven't said whether wet-bulb temperature and thermodynamic wet bulb temperature are the same. You have made it clear to the discerning reader that there are a number of fine distinctions here and by implication, that the wet-bulb temperature is not really the temperature recorded by a wet bulb. 84.227.241.146 (talk) 06:11, 13 September 2014 (UTC)
thread_title:  Not defined 

message: The link is no longer active. A possible replacement is:  Canadian Wood Council. http://cwc.ca/wp-content/uploads/FAQ-durability-Mould.pdf, accessed 20160711 // k289g  — Preceding unsigned comment added by K289g (talk • contribs) 13:09, 11 July 2016 (UTC)
thread_title:  Reference 3 

message: The article text states: Dry bulb temperature: These lines are drawn straight, not always parallel to each other, and slightly inclined from the vertical position. This is the t–axis, the abscissa (horizontal) axis.
However the corresponding image has vertical and parallel dry bulb temperature lines.
On the other hand I think if lines are not straight and/or parallel the corresponding curves are not an axis but rather a group of curves labelled along an axis.
Question remains: If the dry bulb curves in a true psychrometric chart are not parallel then the psychrometric chart is identical to a Mollier diagram rotated 90° CW and flipped along the horizontal axis. If they would be straigtht then it would be something different. But then the h curves would not be parallel. Which is true? --Ikiwaner (talk) 07:47, 8 December 2023 (UTC)
thread_title:  Psychrometric chart