{"id":2614,"date":"2016-03-15T10:14:00","date_gmt":"2016-03-15T10:14:00","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/?p=2614"},"modified":"2016-03-15T10:14:00","modified_gmt":"2016-03-15T10:14:00","slug":"gas-mixtures-and-psychrometricsspecific-and-relative-humidity-of-air","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/gas-mixtures-and-psychrometricsspecific-and-relative-humidity-of-air\/","title":{"rendered":"GAS MIXTURES AND PSYCHROMETRICS:SPECIFIC AND RELATIVE HUMIDITY OF AIR"},"content":{"rendered":"<div class=\"vzoii6a0dbf4cc8473\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '61e5902552e2353963d8d2f1bd1f4a8f',\n\t\t'format' : 'iframe',\n\t\t'height' : 250,\n\t\t'width' : 300,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/61e5902552e2353963d8d2f1bd1f4a8f\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.vzoii6a0dbf4cc8473 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.vzoii6a0dbf4cc8473 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.vzoii6a0dbf4cc8473 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.vzoii6a0dbf4cc8473 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.vzoii6a0dbf4cc8473 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<p align=\"justify\"><font size=\"5\"><b>SPECIFI<\/b><b>C AND RELATIVE HUMIDITY OF AIR<\/b><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">The amount of water vapor in the air can be specified in various ways. Probably the most logical way is to specify directly the mass of water vapor present in a unit mass of dry air. This is called <b>absolute <\/b>or <b>specific humidity <\/b>(also called <i>humidity ratio<\/i>) and is denoted by :<\/font><\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0027.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"GAS MIXTURES AND PSYCHROMETRICS-0027\" border=\"0\" alt=\"GAS MIXTURES AND PSYCHROMETRICS-0027\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0027_thumb.jpg\" width=\"418\" height=\"145\"><\/a><\/font><\/p>\n<h6 align=\"justify\"><font size=\"5\">where <i>P <\/i>is the total pressure.<\/font><\/h6>\n<p align=\"justify\"><font size=\"5\">Consider 1 kg of dry air. By definition, dry air contains no water vapor, and thus its specific humidity is zero. Now let us add some water vapor to this dry air. The specific humidity will increase. As more vapor or moisture is added, <\/font><font size=\"5\">the specific humidity will keep increasing until the air can hold no more moisture. At this point, the air is said to be saturated with moisture, and it is called <b>saturate<\/b><b>d air. <\/b>Any moisture introduced into saturated air will condense. The amount of water vapor in saturated air at a specified temperature and pressure <\/font><font size=\"5\">can be determined from Eq. 9\u201329 by replacing <i>P<\/i>\u03c5 by <i>P<\/i><i>g<\/i>, the saturation pres<\/font><font size=\"5\">sure of water at that temperature (Fig. 9\u201315).<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">The amount of moisture in the air has a definite effect on how comfortable we feel in an environment. However, the comfort level depends more on the amount of moisture the air holds (<i>m<\/i>\u03c5) relative to the maximum amount of moisture the air can hold at the same temperature (<i>m<\/i><i>g<\/i>). The ratio of these two quantities is called the <b>relative humidity <\/b>f (Fig. 9\u201316)<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0028.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"GAS MIXTURES AND PSYCHROMETRICS-0028\" border=\"0\" alt=\"GAS MIXTURES AND PSYCHROMETRICS-0028\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0028_thumb.jpg\" width=\"411\" height=\"142\"><\/a><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0029.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"GAS MIXTURES AND PSYCHROMETRICS-0029\" border=\"0\" alt=\"GAS MIXTURES AND PSYCHROMETRICS-0029\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0029_thumb.jpg\" width=\"146\" height=\"484\"><\/a><\/font> <\/p><div class=\"izziu6a0dbf4cc8703\" ><script type=\"text\/javascript\">\n\tatOptions = {\n\t\t'key' : '0c1eb4c533eaedb7b996f49a5a4983a9',\n\t\t'format' : 'iframe',\n\t\t'height' : 300,\n\t\t'width' : 160,\n\t\t'params' : {}\n\t};\n<\/script>\n<script type=\"text\/javascript\" src=\"\/\/www.highperformanceformat.com\/0c1eb4c533eaedb7b996f49a5a4983a9\/invoke.js\"><\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.izziu6a0dbf4cc8703 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.izziu6a0dbf4cc8703 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.izziu6a0dbf4cc8703 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.izziu6a0dbf4cc8703 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.izziu6a0dbf4cc8703 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"vqety6a0dbf4cc85c7\" ><script async src=\"https:\/\/pagead2.googlesyndication.com\/pagead\/js\/adsbygoogle.js?client=ca-pub-0778475562755157\"\n     crossorigin=\"anonymous\"><\/script>\n<!-- 300x600 hydraulics-and-pneumatics -->\n<ins class=\"adsbygoogle\"\n     style=\"display:inline-block;width:300px;height:600px\"\n     data-ad-client=\"ca-pub-0778475562755157\"\n     data-ad-slot=\"3735577695\"><\/ins>\n<script>\n     (adsbygoogle = window.adsbygoogle || []).push({});\n<\/script><\/div><style type=\"text\/css\">\r\n@media screen and (min-width: 1201px) {\r\n.vqety6a0dbf4cc85c7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.vqety6a0dbf4cc85c7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.vqety6a0dbf4cc85c7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.vqety6a0dbf4cc85c7 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.vqety6a0dbf4cc85c7 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\"><font size=\"5\">The relative humidity ranges from 0 for dry air to 1 for saturated air. Note that <\/font><font size=\"5\">the amount of moisture air can hold depends on its temperature. Therefore, the relative humidity of air changes with temperature even when its specific humidity remains constant.<\/font> <\/p>\n<h6 align=\"justify\"><font size=\"5\">Atmospheric air is a mixture of dry air and water vapor, and thus the enthalpy of air is expressed in terms of the enthalpies of the dry air and the water vapor. In most practical applications, the amount of dry air in the air\u2013water-vapor mixture remains constant, but the amount of water vapor changes. Therefore, the enthalpy of atmospheric air is expressed <i>pe<\/i><i>r unit mass of dry air <\/i>instead of per unit mass of the air\u2013water-vapor mixture.<\/font><\/h6>\n<p align=\"justify\"><font size=\"5\">The total enthalpy (an extensive property) of atmospheric air is the sum of the enthalpies of dry air and the water vapor:<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0030.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"GAS MIXTURES AND PSYCHROMETRICS-0030\" border=\"0\" alt=\"GAS MIXTURES AND PSYCHROMETRICS-0030\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0030_thumb.jpg\" width=\"414\" height=\"147\"><\/a><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">Also note that the ordinary temperature of atmospheric air is frequently re<\/font><font size=\"5\">ferred to as the <b>dry-bulb temperature <\/b>to differentiate it from other forms of temperatures that shall be discussed.<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0031.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"GAS MIXTURES AND PSYCHROMETRICS-0031\" border=\"0\" alt=\"GAS MIXTURES AND PSYCHROMETRICS-0031\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0031_thumb.jpg\" width=\"208\" height=\"395\"><\/a><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0032.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"GAS MIXTURES AND PSYCHROMETRICS-0032\" border=\"0\" alt=\"GAS MIXTURES AND PSYCHROMETRICS-0032\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0032_thumb.jpg\" width=\"412\" height=\"379\"><\/a><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0033.jpg\"><img decoding=\"async\" loading=\"lazy\" style=\"background-image: none; border-bottom: 0px; border-left: 0px; margin: 0px auto; padding-left: 0px; padding-right: 0px; display: block; float: none; border-top: 0px; border-right: 0px; padding-top: 0px\" title=\"GAS MIXTURES AND PSYCHROMETRICS-0033\" border=\"0\" alt=\"GAS MIXTURES AND PSYCHROMETRICS-0033\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/GAS-MIXTURES-AND-PSYCHROMETRICS-0033_thumb.jpg\" width=\"435\" height=\"393\"><\/a><\/font> <\/p>\n<p align=\"justify\">\n<p><font size=\"5\"><\/font><\/p>\n","protected":false},"excerpt":{"rendered":"<p>SPECIFIC AND RELATIVE HUMIDITY OF AIR The amount of water vapor in the air can be specified in various ways. Probably the most logical way is to specify directly the mass of water vapor present in a unit mass of dry air. This is called absolute or specific humidity (also called humidity ratio) and is [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/gas-mixtures-and-psychrometricsspecific-and-relative-humidity-of-air\/\" class=\"more-link\" >Continue reading&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/posts\/2614"}],"collection":[{"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/comments?post=2614"}],"version-history":[{"count":1,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/posts\/2614\/revisions"}],"predecessor-version":[{"id":2615,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/posts\/2614\/revisions\/2615"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/media?parent=2614"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/categories?post=2614"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/tags?post=2614"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}