{"id":2442,"date":"2016-03-14T14:33:21","date_gmt":"2016-03-14T14:33:21","guid":{"rendered":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/?p=2442"},"modified":"2016-03-14T14:33:21","modified_gmt":"2016-03-14T14:33:21","slug":"rankine-cycle-the-ideal-cycle-for-vapor-power-cycles","status":"publish","type":"post","link":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/rankine-cycle-the-ideal-cycle-for-vapor-power-cycles\/","title":{"rendered":"RANKINE CYCLE: THE IDEAL CYCLE FOR VAPOR POWER CYCLES"},"content":{"rendered":"<div class=\"cwrni6a0dc9c7c8eec\" ><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.cwrni6a0dc9c7c8eec {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.cwrni6a0dc9c7c8eec {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.cwrni6a0dc9c7c8eec {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.cwrni6a0dc9c7c8eec {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.cwrni6a0dc9c7c8eec {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<p align=\"justify\"><font size=\"5\">\u25a0 <b>RANKIN<\/b><b>E CYCLE: THE IDEAL CYCLE<\/b><b> <\/b><b>FO<\/b><b>R VAPOR POWER CYCLES<\/b><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">Many of the impracticalities associated with the Carnot cycle can be eliminated by superheating the steam in the boiler and condensing it completely in the condenser, as shown schematically on a <i>T<\/i><i>&#8211;<\/i><i>s <\/i>diagram in Fig. 8\u201339. The cy- cle that results is the <b>Rankin<\/b><b>e cycle, <\/b>which is the ideal cycle for vapor power plants. The ideal Rankine cycle does not involve any internal irreversibilities and consists of the following four processes:<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">1-2 Isentropic compression in a pump<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">2-3 Constant pressure heat addition in a boiler <\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">3-4 Isentropic expansion in a turbine<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">4-1 Constant pressure heat rejection in a condenser<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0335.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=\"POWER AND REFRIGERATION CYCLES-0335\" border=\"0\" alt=\"POWER AND REFRIGERATION CYCLES-0335\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0335_thumb.jpg\" width=\"545\" height=\"252\"><\/a><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">Water enters the <i>pump <\/i>at state 1 as saturated liquid and is compressed isentropically to the operating pressure of the boiler. The water temperature in- creases somewhat during this isentropic compression process due to a slight decrease in the specific volume of the water. The vertical distance between states 1 and 2 on the <i>T<\/i><i>-s <\/i>diagram is greatly exaggerated for clarity. (If water were truly incompressible, would there be a temperature change at all during this process?)<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">Water enters the <i>boile<\/i><i>r <\/i>as a compressed liquid at state 2 and leaves as a superheated vapor at state 3. The boiler is basically a large heat exchanger where the heat originating from combustion gases, nuclear reactors, or other sources is transferred to the water essentially at constant pressure. The boiler, together with the section where the steam is superheated (the superheater), is often called the <i>stea<\/i><i>m generator.<\/i><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">The superheated vapor at state 3 enters the <i>turbine, <\/i>where it expands isentropically and produces work by rotating the shaft connected to an electric generator. The pressure and the temperature of the steam drop during this process to the values at state 4, where steam enters the <i>condense<\/i><i>r<\/i><i>. <\/i>At this state, steam is usually a saturated liquid\u2013vapor mixture with a high quality. Steam is condensed at constant pressure in the condenser, which is basically a large heat exchanger, by rejecting heat to a cooling medium such as a lake, a river, or the atmosphere. Steam leaves the condenser as saturated liquid and enters the pump, completing the cycle. In areas where water is precious, the power plants are cooled by air instead of water. This method of cooling, which is also used in car engines, is called <i>dry cooling. <\/i>Several power plants in the world, including some in the United States, use dry cooling to conserve water.<\/font> <\/p><div class=\"jidil6a0dc9c7c9118\" ><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.jidil6a0dc9c7c9118 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.jidil6a0dc9c7c9118 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.jidil6a0dc9c7c9118 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.jidil6a0dc9c7c9118 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.jidil6a0dc9c7c9118 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n<div class=\"grhdj6a0dc9c7c8ff3\" ><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.grhdj6a0dc9c7c8ff3 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 993px) and (max-width: 1200px) {\r\n.grhdj6a0dc9c7c8ff3 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 769px) and (max-width: 992px) {\r\n.grhdj6a0dc9c7c8ff3 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (min-width: 768px) and (max-width: 768px) {\r\n.grhdj6a0dc9c7c8ff3 {\r\ndisplay: block;\r\n}\r\n}\r\n@media screen and (max-width: 767px) {\r\n.grhdj6a0dc9c7c8ff3 {\r\ndisplay: block;\r\n}\r\n}\r\n<\/style>\r\n\n<p align=\"justify\"><font size=\"5\">Remembering that the area under the process curve on a <i>T<\/i><i>&#8211;<\/i><i>s <\/i>diagram represents the heat transfer for internally reversible processes, we see that the area under process curve 2-3 represents the heat transferred to the water in the boiler and the area under the process curve 4-1 represents the heat rejected in the condenser. The difference between these two (the area enclosed by the cycle curve) is the net work produced during the cycle.<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><strong>Energy Analysis of the Ideal Rankine Cycle<\/strong><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">All four components associated with the Rankine cycle (the pump, boiler, tur<\/font><font size=\"5\">bine, and condenser) are steady-flow devices, and thus all four processes that make up the Rankine cycle can be analyzed as steady-flow processes. The kinetic and potential energy changes of the steam are usually small relative to the work and heat transfer terms and are therefore usually neglected. Then the <i>steady-flo<\/i><i>w energy equation <\/i>per unit mass of steam reduces to<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0336.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=\"POWER AND REFRIGERATION CYCLES-0336\" border=\"0\" alt=\"POWER AND REFRIGERATION CYCLES-0336\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0336_thumb.jpg\" width=\"382\" height=\"282\"><\/a><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">The conversion efficiency of power plants in the United States is often ex- pressed in terms of <b>hea<\/b><b>t rate<\/b>, which is the amount of heat supplied, in Btu\u2019s, to generate 1 kWh of electricity. The smaller the heat rate, the greater the efficiency. Considering that 1 kWh = 3412 Btu and disregarding the losses associated with the conversion of shaft power to electric power, the relation between the heat rate and the thermal efficiency can be expressed as<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0337.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=\"POWER AND REFRIGERATION CYCLES-0337\" border=\"0\" alt=\"POWER AND REFRIGERATION CYCLES-0337\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0337_thumb.jpg\" width=\"253\" height=\"31\"><\/a><\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">For example, a heat rate of 11,363 Btu\/kWh is equivalent to 30 percent efficiency.<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\">The thermal efficiency can also be interpreted as the ratio of the area en- closed by the cycle on a <i>T<\/i><i>&#8211;<\/i><i>s <\/i>diagram to the area under the heat-addition process. The use of these relations is illustrated in the following example.<\/font> <\/p>\n<p align=\"justify\"><font size=\"5\"><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0338.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=\"POWER AND REFRIGERATION CYCLES-0338\" border=\"0\" alt=\"POWER AND REFRIGERATION CYCLES-0338\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0338_thumb.jpg\" width=\"357\" height=\"99\"><\/a><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0339.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=\"POWER AND REFRIGERATION CYCLES-0339\" border=\"0\" alt=\"POWER AND REFRIGERATION CYCLES-0339\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0339_thumb.jpg\" width=\"416\" height=\"484\"><\/a><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0340.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=\"POWER AND REFRIGERATION CYCLES-0340\" border=\"0\" alt=\"POWER AND REFRIGERATION CYCLES-0340\" src=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-content\/uploads\/2016\/03\/POWER-AND-REFRIGERATION-CYCLES-0340_thumb.jpg\" width=\"367\" height=\"418\"><\/a><\/font> <\/p>\n<p align=\"justify\">\n<p align=\"justify\"><font size=\"5\"><\/font><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u25a0 RANKINE CYCLE: THE IDEAL CYCLE FOR VAPOR POWER CYCLES Many of the impracticalities associated with the Carnot cycle can be eliminated by superheating the steam in the boiler and condensing it completely in the condenser, as shown schematically on a T&#8211;s diagram in Fig. 8\u201339. The cy- cle that results is the Rankine cycle, [&hellip;]<br \/><a href=\"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/rankine-cycle-the-ideal-cycle-for-vapor-power-cycles\/\" 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\/2442"}],"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=2442"}],"version-history":[{"count":1,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/posts\/2442\/revisions"}],"predecessor-version":[{"id":2443,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/posts\/2442\/revisions\/2443"}],"wp:attachment":[{"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/media?parent=2442"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/categories?post=2442"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/machineryequipmentonline.com\/hydraulics-and-pneumatics\/wp-json\/wp\/v2\/tags?post=2442"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}