An evaporative, wet-bulb heat dissipation cold source for liquid cooling temperature control.<\/p>","protected":false},"menu_order":15,"template":"","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_kadence_starter_templates_imported_post":false,"cxdb_product":{"schema_version":1,"group":"liquid","model":"Open \/ Closed Type","overview":"Open or closed cooling towers use evaporative cooling to reject heat relative to the outdoor wet-bulb temperature. The source gives a 2\u20133\u00b0C approach, 27\u00b0C cooling water at 35\u00b0C dry-bulb \/ 24\u00b0C wet-bulb conditions, and 34.5\u00b0C cooling water at a 31.5\u00b0C wet-bulb condition. It cites secondary supply \u226436\u00b0C and 20 W\/kW power per unit heat exchange for that example. Annual free-cooling suitability depends on local weather and the server liquid-temperature limit.","working_principle":"","features":[],"applications":[],"notes":["Weather and water-temperature figures are source design examples, not universal performance guarantees. The secondary \u226436\u00b0C example on slide 21 differs from the 40\u201348\u00b0C efficiency guidance on slide 22 and applies to a different design discussion.","The water-use comparison on slide 23 specifically names closed cooling towers; its values are not assigned to every open tower.","W45 and W+ are retained as source designations; the presentation does not define those temperature classes further."],"source":"Liquid Cooling Manual, pp. 21\u201323","image":{"id":668,"alt":"Cooling Tower"},"diagrams":[],"tables":[{"title":"Primary-side cold-source selection","rows":[["Climate \/ cooling requirement","Water availability","Recommended cold source"],["Low ambient temperature; year-round free cooling possible","Abundant","Closed or open cooling tower"],["Low ambient temperature; year-round free cooling possible","Scarce","Dry cooler"],["High ambient temperature; mechanical-cooling backup needed","Abundant","Chiller + cooling tower + plate heat exchanger"],["High ambient temperature; mechanical-cooling backup needed","Scarce","Air-cooled chiller"]]},{"title":"Primary \/ secondary temperature design guidance","rows":[["Design parameter","Primary side","Secondary side"],["Supply temperature","Recommended \u226435\u00b0C, considering local weather and required secondary supply; W45 or W+ allowed where cooling requirements permit","Recommended 40\u201348\u00b0C for energy efficiency; temperature and flow must meet liquid-cooled component requirements"],["Supply \/ return temperature difference","6\u201310\u00b0C; ideal 8\u201310\u00b0C","5\u201310\u00b0C; recommended ideal 6\u20138\u00b0C"]]},{"title":"Closed tower and evaporative dry cooler comparison","rows":[["Comparison item","Closed cooling tower","Evaporative dry cooler"],["Energy efficiency","Relatively superior","Relatively inferior"],["Footprint","Small","Large"],["Cost","Low","High"],["Annual water consumption","Approximately 1.8\u20132.0 L\/(kW\u00b7h)","<0.5 L\/(kW\u00b7h); varies by city"],["Peak 12-hour water usage","Relatively high","Relatively low"],["Suitable regions","Abundant water resources","Water-scarce regions; strict WUE limits"],["Year-round waterless operation","Not possible","Not possible; water needed during high outdoor temperatures, waterless operation possible at other times"]]},{"title":"Cooling-tower source operating example","rows":[["Parameter","Source value"],["Type","Open or closed"],["Heat-rejection basis","Evaporative \/ wet bulb"],["Approach \u0394t","2\u20133\u00b0C"],["Reference ambient dry bulb \/ wet bulb","35\u00b0C \/ 24\u00b0C"],["Reference cooling-water temperature","27\u00b0C"],["High wet-bulb example","31.5\u00b0C"],["Cooling water at high wet bulb","34.5\u00b0C"],["Supported secondary liquid supply in example","\u226436\u00b0C"],["Power per unit heat exchange","20 W\/kW"]]}]}},"class_list":["post-638","cxdb_product","type-cxdb_product","status-publish","hentry"],"acf":[],"yoast_head":"\n