Tecnical System Catalogue Cillers for IT cooling
Cillers for IT cooling Te Rittal IT ciller in conjunction wit free cooling supplies exceptionally energy- and cost-efficient IT cooling media. Te system is specially designed for supplying critical IT applications cooled via, air/water eat excangers or CRAC systems. In tis atmosperically sealed system, redundant, speed-regulated pumps, compressors, emergency cooling or buffer stores ensure optimum operational reliability and fail-safeness. Alongside optional eat recovery from te system, connection to Rittal free cooling recooling systems ensures exceptionally energy-efficient operation. Free cooling uses cold ambient air for cooling, reduces operating costs by up to 8%, extends te service life of components, and increases operational reliability. If te free cooling performance is insufficient, te IT ciller will cut in. Redundant pumps, speed-controlled Redundant scroll compactor Intelligent control concept Interfaces: SNMP, BACnet Integral or separate free coolers (optional) Integral automatic bypass valve Flow monitor Operating costs are minimised, tanks to ig water inlet temperatures for and CRAC operation Hig COP (coefficient of performance) Integration into RiZone
Ambient conditions Te Liquid Cooling Package and CRAC systems are used to dissipate te termal load generated by IT equipment and prevent te installation site of te IT equipment from overeating. If IT systems are operated at excessive ambient temperatures, tis may under certain circumstances lead to malfunctions and restricted operation of te system. Te correct system temperature is based on manufacturer-specific information. Te Liquid Cooling Packages and CRAC systems only dissipate te termal loads from te IT equipment, but not te termal loads produced by ligting and oter eat sources; tese eat loads must be dissipated by oter air-conditioning systems. In data centres, te air-conditioning systems are responsible for air quality. Were defined requirements apply to relative umidity in te data centre for operating IT equipment, te most efficient way of acieving tis is via te air-conditioning system. If te air-conditioning system in te data centre is compliant wit VDI (ygiene requirements for air-conditioning systems and devices), ventilation and deumidification of te intake air to te air-conditioning system can be acieved more efficiently and ygienically tan wit direct IT cooling using an and CRAC system. If tere is a central air-conditioning system for basic climate control installed in te data centre, wen project-planning an cooling system to dissipate te termal loads, te following information sould be obtained: Relative umidity of te room air (intake air) in % Room air temperature (intake air temperature) Cold water system temperature (were available) Note: ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) recommends server intake air temperatures of between 8 C and 7 C. Te selected server intake air temperature sould be agreed wit te manufacturer of te IT equipment and te operator at te project planning stage. Based on te prescribed conditions, it is necessary to ceck weter cooling at te prescribed cold water temperature will cool to below te dew point. Tis can be cecked using te Mollier -x diagram. Example of determining te dew point Example : Air intake temperature C, relative umidity %, cold water temperature C % % % % % % 7 % 8 % 9 % 8 9 7 Draw a line from te C temperature point to te % curve. At tis intersection, draw a vertical line to te dew point curve. Next, draw a orizontal line from tis intersection point to te temperature scale. Te dew point temperature can be read from ere. In tis example, it is C. Dew point calculation ( C) Dew point curve ( C) spec. entalpy (kj/ + x kg) Dry-bulb temperature ( C) Humid air (g/kg)
Sensitive and latent cooling output Example of determining te dew point For energy-efficient IT cooling, it is crucially important to ceck te dew point in te prevailing conditions. If te surface temperature of te eat excanger in te or CRAC system is below te dew point, condensation will form on te eat excanger (see example ). Tis will lead to cooling output losses caused by condensation. Te surface temperature of te eat excanger is calculated as follows: θ cooler surface θ inlet + θ return Example : Server exaust air C, server intake air C, cooler temperature C, P = cooler delta Cooling output losses arise as a result of condensation on te eat excanger. Tis uses energy, but does not lower te server intake air temperature any furter. Te energy used is only needed for condensation, and is known as te latent cooling capacity. On te oter and, if working wit cold water inlet temperatures wic raise te surface temperature of te eat excanger above te dew point, energy is only used to cool te server intake air. Tis is known as te sensitive cooling capacity (see example ). Note: Te systems are designed to acieve energy-efficient IT cooling. Te specified rated cooling output always refers to an inlet temperature of C. Example : Server exaust air C, server intake air C, cooler temperature C % % % % TP P % % % % 7 % 8 % 9 % 7 8 9 TP % % % % 7 % 8 % 9 % 7 8 9 Exaust air temperature ( C) Wet-bulb temperature ( C) spec. entalpy (kj/ + x kg) Dry-bulb temperature ( C) Dry air (g/kg) Sensitive cooling output Latent cooling output (losses from condensation) Exaust air temperature ( C) Wet-bulb temperature ( C) spec. entalpy (kj/ + x kg) Dry-bulb temperature ( C) Dry air (g/kg) Sensitive cooling output
Cold water system Mixed water for IT climate control generally poses a major callenge for te functioning of te cold water system, because te IT equipment wose eat loss is dissipated by te cold water system can undergo multiple load canges per minute. Tis ysteresis is transferred directly to te cold water system, leading to a fluctuating dt in te cold water system. If te IT equipment causes a major load step, leading to a rapid increase in eat loss, cold water must be made available immediately by te cold water system. Depending on te distance of te cooling unit from te IT cold water circuit, tis can create a very significant dead time, during wic no water is available to cool te IT eat loss. Use of a ydraulic circuit can compensate for tis response, caused by te IT equipment. By assembling a ydraulic circuit suc as an injection circuit, te cold water system is able to counteract te ysteresis generated by te IT equipment. Secondary circuit Dimensioning and design of te pipework for IT climate control Bypass line Because of ysteresis induced by te IT equipment, dt fluctuations in te cold water circuit are unavoidable. Fluctuations of between K and K are not uncommon in IT climate control. For tis reason, te usual dt of K for a cold water circuit cannot be used to calculate te pipework. Wit s, te volumetric flow required for te rated cooling output is always specified. Tis specified volumetric flow is used to select te correct pipe dimensions wen calculating te pipework. Because very ig cooling outputs of up to kw are required for eac, in addition to individual sections of pipe it is also advisable to ydraulically regulate te individual connection lines. Primary circuit B A AB M Primary circuit pump Secondary circuit pump Regulating valves B A M Mixer wit motor AB
Cold water system Function of te injection circuit Te injection circuit is a tried-and-tested ydraulic circuit wic is used wenever it is necessary to make water at te correct temperature available quickly to te equipment. Te primary circuit is installed as close as possible to te secondary circuit. Te secondary circuit is assembled in te immediate vicinity of te equipment. Te cold water is able to circulate permanently in te primary circuit, and is terefore always available wen needed by te secondary circuit. Witout tis circuit, te cold water would first need to cover te entire distance from te producer to te equipment wenever te flow rate is altered by te equipment. Here too, tere may be a significantly lower temperature in te primary circuit tan in te secondary circuit (primary circuit C/secondary circuit C as a result of mixing). In tis way, te primary circuit pump permanently supplies te secondary circuit wit water. Te mixer valve in te return limits te volume of water flowing out of te secondary circuit and back into te primary circuit. Tis terefore limits te incoming water volume as well. Te secondary circuit pump allows te entire volume of water required for cooling in te secondary circuit to circulate, and is responsible for mixing te temperatures. Pump allows water from te secondary return to be injected into te secondary inlet via te bypass. In tis way, cold water from te primary circuit is raised directly to te correct temperature level. Te injection circuit is just one example of many possibilities for adapting te cold water system to te requirements of IT climate control. x 898 kg C 9 kg C 898 kg C % % %. W 898 kg/ C Circuit 9 kg C/ % % Bypass line B % % 9 kg C/ Circuit C % % A M AB % C 898 kg C 9 kg C x 898 kg C
Cold water system Operation of te and CRAC system CW units (CW ^= Cilled Water) requires a cold water system as infrastructure. To tis end, a cold water set is installed at a central point wic generates cold water to cool te system. Wen planning/project managing te cold water system, tere may often be enormous idden energy saving potential. Te more effectively te cold water system is adapted to te required server air intake temperature, te more efficiently te system will operate. Te systems operate in an inlet temperature range of C 8 C, depending on te required air inlet temperature. In systems, te air intake temperatures are regulated, and te cosen air intake temperature for te servers is maintained wit a minimal standard deviation. In consequence, te return temperature will fluctuate depending on te load situation in te enclosure. For tis reason, wen specifying te rated cooling output of te, it is also important to specify te required volume of water for project-planning te ydraulic system (dimensioning of te pipes). If te systems are to be supplied wit an existing cold water system operating at system temperatures of e.g. / C or /8 C, it is advisable to install a mixer or a water/water eat excanger. For example, if a mixer wit an injection circuit is installed upstream of te systems, tis is one way of creating te required water inlet temperature for te s. In tis way, te spread of K is largely maintained witin te system. Tere are various ydraulic circuits wic may be used depending on te ydraulic layout of te system. Fluctuations in te return temperature are likewise compensated by using a ydraulic circuit Te same results are largely acievable by using a water/water eat excanger. In tis application, te system is divided into two independent ydraulic zones: te primary circuit and te secondary circuit. If tere is eavy contamination in te system circuit, te eat excanger prevents te contaminants from being rinsed into te circuit. Tis application can also be used were glycol is used in te system circuit, making it possible to dispense wit te use of glycol in te circuit. Note: Te mixer wit ydraulic circuit is te ceaper, and often tecnically superior, alternative to te water/water eat excanger. Selecting te correct ydraulic circuit demands tecnical knowledge of te system, and must be carried out on-site. An engineering office or refrigeration specialist can assist. Tis overview is only intended as guidance for external companies. Tese services can also be provided by Rittal GmbH's service partners. Please observe te ydrological information for te respective climate control components. Before commissioning, te pipeline system must be adequately rinsed to protect te s from dirt. Connection of te s from te last sut-off valve can be made using te water connection kit D½" x ½" (.). It is.8 m long. Sut-off valve Dirt trap Tacosetter Return Inlet Manometer 7
Cold water system For an efficient cold water supply to te systems, te cold water system must be ydraulically balanced. If te ydraulics are not balanced, te systems will not be supplied omogeneously wit te required volume of cold water (see cold water diagram). Tis will adversely affect efficient operation. Hydraulic balancing can be acieved via balancing valves. However, by laying te individual connection lines for te systems according to te Ticelmann connection principle, tis will eliminate te need for ydraulic balancing. Wit tis connection variant, all individual connection lines ave te same pressure loss. Te better-adjusted te ydraulics of a cold water system are, te more accurately te volumes of water required by te cooling system can be distributed and made available. Optimum ydraulic distribution often goes and-in-and wit efficient climate control. As a general rule, all systems (except passive) include a condensate management system. Tere is a condensate tray installed in te devices. Additionally, spray eliminators are installed in te kw devices. If condensation occurs as a result of fluctuations in te room conditions, te condensate is discarged into te condensate tray. Te condensate tray as a drain wic can be set up to drain into te sewer system. Sensor monitoring of te condensate tray allows an alarm system to be configured in te event of a drainage malfunction. A condensate pump may optionally be installed in te device wit systems, but cannot be added retrospectively. Note: Te condensate drain from te systems must not be connected directly to te sewer system. An odour seal must be fitted between te two systems. Te condensate pump affords no protection from backlogs and wastewater backflow. Wen connecting te condensate tray to te sewer system, always observe te valid tecnical regulations. Cooling distribution witout ydraulic balancing Cooling distribution wit ydraulic balancing C C 7 9 7 Wen connected witout ydraulic balancing, te s receive differing supplies of cold water. Te s furtest from te circulating pump, wic ave te greatest pressure loss, do not receive a sufficient volume of water required for cooling. Wit ydraulic balancing, regulating valves trougout te entire pipework adjust any pressure losses. All s are supplied wit an adequate volume of water. Cooling distribution wit te Ticelmann system 7 8 C Circulating pump Sut-off valve Fine filter Return Inlet Pump pressure Cooling supply Pipe friction pressure loss Control valve opening Control valve Connection wit te Ticelmann system of pipework is equivalent to ydraulic balancing. All pipe sections in te system ave te same pressure loss. 8
Master/slave Master/slave operating mode In open bayed enclosure systems wic are not separate from one anoter, cooling units and air/water eat excangers wit e-comfort control sould always be used. Tese may be linked in master/slave mode via bus cable SK.: Simultaneous activation and deactivation of te devices Parallel fault and door limit switc function Even temperature distribution across all sections of te enclosure 7 Control cabinets Wall-mounted unit Roof-mounted unit e-comfort controller Door limit switc Connection terminals and of te cooling unit Master/slave combination Interface board Te interface board (SK.) is an extension for TopTerm cooling units and air/water eat excangers wit e-comfort controller. In tis way it is possible, e.g. to monitor a master/slave combination of up to cooling units. Control is acieved via standardised interfaces RS (DB9) and/or RS8, a PLC interface. Te extension card is built into a U plastic ousing. A voltage supply of V (DC) is required. Tis can be provided using a Kycon connector. Furter information may be found in our assembly and operating instructions, at www.rittal.com > Products > Product searc > SK.. Warnings and alarms from te interface board: Interior temperature too ig Icing Hig-pressure sensor Leak Condenser fan defect Evaporator fan defect Compressor defect Sensor failure, condenser temperature Sensor failure, ambient temperature Sensor failure, icing sensor Sensor failure, condensate level Sensor failure, interior temperature Pase missing or incorrect EPROM error 9
Master/slave Application example: Master/slave operation and interface board Control point/server room Recooling system Macining centre Welding robot Connection example: Master/slave operating mode wit bus cable and interface board Description: Te address of te master depends on te number of attaced slave units (9 = master wit 9 slave units). Te address of a slave unit always begins wit a. Te nd digit represents te actual address. Up to a maximum of 9 slave units may be operated wit one master unit, wereby any unit may be te master. Te maximum overall lengt of all connected units is m. Single-pase and -pase units may be connected. Serial interface card, Model No.. Serial interface cable Master/slave BUS cable, Model No.. RTT = Rittal TopTerm cooling unit / air/water eat excanger X = Supply connection/door limit switc/alarms X = Master/slave connection SUB-D, 9-pole X = Serial interface SUB-D, 9-pole St. = SUB-D connector, 9-pole Bu. = SUB-D jack, 9-pole RTT Master Adr.: 9 RTT Slave Adr.: RTT Slave Adr.: RTT Slave Adr.: 9 X X X X X X X X X X X X St. X X St. St. X St. X St. X X X Bu.St. X X Bu. St. X Bu.
Enclosures Power Distribution Climate Control IT Infrastructure Software & Services You can find te contact details of all Rittal companies trougout te world ere. XWW8EN www.rittal.com/contact