This paper describes a circulating water cooling system used at SLAC for cooling and maintaining cleanliness of the SLC type Camac Crates

Pierce, W.B.

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* ^ 0 X-/f SLAC-PUB—3465 DE85 004679 "SMR A CIRCULATING WATER COOLING SYSTEM FOR A CAMAC CRATE' W. B. PlERCB Stanford linttt Accelerator Center, Stanford Onivtnitf, Stafford, OA 9i$0S S L A C - P U B -October 1984 (1) S«65 Abstract This paper describee a, circulating water cooling system need at SLAC for cooling and Maintaining cleanliness of the SLC type Camac Cratee. A fully loaded Camae Crate can dluipate I kW of power. Recent addition! to our instrumentation and control systems have resulted in the Installation of Camac Crate* in a rather hostile environment. Tbe nek* containing the date* are sit­uated in the Klystron Gallery. This gallery ia not much more than a two-oaile-Eong unhealed, uooaoted, unclean metal shed. On a warm day temperature* of 120°F have been meamied; and over the years, dust layer* of 1/8 Inch can aecomrbte. It is be­cause of this hostile environment that a cooling system baa been designed. The system shown in Fig. 1 consists of the loaded Cannc Crate, a circulating water beat exchanger, called a Chilier Chas­sis, and a Blower Chassis to circulate the air within the closed system. To enclose tbe system, a lightweight aluminum shroud has been fabricated. The shroud is easily removed for main­tenance. It works to reduce tbe volume of air that has to be cooled and to maintain a measure of cleanliness that is deemed necessary for continued satisfactory operation of these systems over the next (ew years. The Blower Chassis consists of two globe fans that bring air in the rear of the chassis. The airflow direction is changed from horizontal to vertical by a metal deflector mounted at the front of the chassis. A diffuser Is used at tbe exhaust area of the Blower Chassis to cause a more even distribution of air Bow across the horisontal place directly above the Blower Chassis. The airflow through the diffuser alone varies from S00 to 750 CFM- This chassis requires $ units of rack apace. The Chiller Chassis it the system heat exchanger. It utilises the recirculating cooling tower water as the vehicle for removing tbe heat from tbe system. The flow rate ia between one to two gallons per minute. An automotive type radiator is mounted in the hontoata! plane. Tbe radiator is of the same dimenskne as the blower diffuter and the bottom of the module spare of the CamacCfete. The radiator acts as a second diffuser and reduces tbe flow rale and the variation in the airflow rate. With the ra­diator installed, this airflow rate varies from 450 to 500 CFM across tbe surface of the radiator (see Fig. I). The Chiller Chassis require* two units of rack apace. Tbe rear section of tbe Chiller Chassis contains a temperature switch that is per­manently set to +I32*F. When the temperature is exceeded, the power is removed from tbe CAMAC Crate, but maintained to tbe Blower Chassis. A front panel light will indicate the exis­tence of an over-temperature condition. The water Sow rate was varied between 1 and l.S gpm for our testa. At tbe rate of I gpm, tbe temperature rise across the radiator was S*F. At a l.S gpm Sow rate, the temperature rise is 4°F. The water pressure is always less then JOe) and the tem­perature Is between 68* and 7S*F. The air temperature within tbe system is most dependent on this Inlet water temperature. 'Work supported by tbe Department of Energy, Contract DE-AC03-76SF00515. Presented at a Poster Session of the Nuclear Sclent* Symposium Orlando, Florida, October 31 The circulating air out of tbe radiator ia approximately 3* to 4°F greater than the islet water temperature. The Camac Crates used at 3LAC a n special designs and are given an SLC Camac Crate nomenclature. These Crates have the regulated power supplies mounted at the rear of the Crates. The power supplies have their own cooling fan which drar sir in from tbe side of the Crate and exhausts It to tbe rear. This feature forces the enclosing inroad to have a special sliding vent to- allow cooling air to be drawn through the power supply. This vent moat be detached before installation or removal of the en­closing abroad (see Fig. «). An air flow diagram is shown in Fig. 2. Note that the inlet ah- to the power suppty "•» taken from the Camac exhaust air. The Camac Crate is the primary source of beat in tbe sys­tem. If the + and - 6-voK power supplies are deBvering max imum load, they are sourcing +300 W of power. It has been determined that the regulated power supplies dissipate 600 W. It is thus reasonable to expect I kW of power dissipated in tbe Bystem. Test results using water flow rate and temperature rise verify these figures. To enclose these three chassis, a lightweight aluminum shroud was fabricated that encloses the system. The shroud slips on from the rear and can be inserted or removed while the system is operational, with no disruption of any kind to the system. Figure 1 1B a sketch of the system. The TS numbers corre­spond to location of temperature sensor during tests with the system ia a temperature controlled oven. TSl = Radiator Exit Air Temperature TS2 = CAMAC EXIT AIR Temperature TS3 = CHASSIS TEMPERATURE TS4 = Power Supply Inlet Air Temperature TSS = Power Supply Exit Air Temperature TS6 = Blower inlet Air Temperature INLET AND OUTLET WATER TEMPERATURES WERE MONITORED SEPARATELY. The following incremental temperature difference can be determined. 1. Temperature rise across CAMAC Crate (TS2 - TSl| vari­ation WA> from 4* to 7*F-2. Temperature rise across CAMAC Power Supply [TSS -TS4] variation was 54° to 58° F. 3. Temperature drop across radiator [TS6 - TS1| typical 5" to 10'F. 4. Outlet water temperature - Inlet water temperature indi­cates the water temperature rise (Bow rate was also mon­itored) typical values were 4*F at 1.5 gpm to S°F at l.o gpm. A rack mounted sir conditioner was considered for this sys­tem. There are some distinct advantages to the air conditioner - the introduction of water into tbe rack is not highly desir­able. The complete rack could be cooled and the air conditioners arc easily moved. Tbe disadvantages ares 1) The considerable power dissipation when expanded to accommodate the complete November 2,1684 tfr accelerator; iao units would be required; the every day power COM ^Vae water cooled system is very nearly sero. 2) The cost tti the ac unit*!s close to $2000 per unit, whkh translates to ftCOO per sector. Cost estimate for the proposed enter cooled system is $4000 per sector. Over half of this coat ia far the installation of the cooling tower water circulating system. Both systems are amenable to maintaining a dean system. As pointed out earlier, these eyatema racial in a hostile eailnaunent a i 4 maintaining a clean system ia aa important to some people aa keeping the system cool. Expansion of the water cooled system is lea* expensive this the comparable ac system. An additional station can be added for approximately 1500 whereas the ac C M U again cost the $2000 plus additional power costs. Four of these water cooled systems have been installed at SI AC with a proposal in preparation Tor installation of 116 more to be installed by April of 1985. Detail drawings are available te,Lg DWG #137003. Photographs of tbe system is operation are shown in Figs. 3 SB""jgh S. A rear view of as unenclosed system is shown in fin 2 Tbe tame system is shown in Fig. 5 with the sbroud 'fl place and tbe coolJDg system in operation. Installation of thr auTud has DO effrc'- on the front panel. Figure 4 shows •iC '.£.! liiional systeru. Note that tbe presence of tbe shroud is Lr.1tiutiible. The two components that are nnicjae to this cooling system are the shroud (Fig. 6) and the beat exchange; (Fig. S). The actual beet exchanger is mounted to a chassis wKh some inter­locking electronics mounted to the nar of the beat exdnDger The eery simple electronics utilises a thermostat to aeta-ate a relay which remans power from the Camsc Crate while maintaining power to the Mower. SajnuDary Four systems ham been installed and operational for a pe­riod of nine months. To date there have been DO failures, the systems have remained cool and dean through a very hot sum­mer. The temperature of the circulating air having the beat exchanger remained within 9" to 4°F of the mtst water tem­perature, seemingly independent of ambient air. Temperature monitoring on the hottest of days indicated the system tem­perature tracked the water temperature. Tbe system temper­ature increased approximately 4*F when the ambient tempera­ture changes from 80* to 100*F. The cooling water was found to increase 4"F during this same period. Tbe temperature of the uacooled systems were very depen­dent on ambient and usually operating at a temperataure of 15° above ambient. &*££ Typical A i r T « « p ' 8 0 * l : CAMAC Croie *VP'COl A l t • Temp> 7J»F H*«l £«chong* ' ' TyP<<al A " I , Temp.e2*P f , ! - ^ - T j p i c o i a.» Tem P =82°F : Flow Role: CAMAC Cooling Chows Outlet WO»*r ' " ' I ' • * 9 < M / m " 1 : J ^ i m e . Woter Temp '?3 .e *F [|j A Temp--69"F TYPICAL COOLING SYSTEM AIR/WATER FLOW PLAN Fig. 1. Circulating Water Cooling System 5 M M 4 C Cur I4C I I f"V | ~"^ i " ^ | Biatifi A - . er. _ J T i . i c_iv v -» -«.v t>:»=~je« Fig. 2. Air and Water Circulating Systems Pig. 4. Front View of Unenclosed System Fig. 3. Reu View of Unenclosed System Fig. S. Sear View of Enclosed System DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States CweromcnL Neither the United Slates Government nor any agency thereof, nor .1) of their employees, makes any warranty, espress or implied, or assumes any legal Viability or responsi­bility for 1 he accuracy, completeness, or usefulness of any in Formation, apparatus, product, or process disclosed, or represents that its use *ould not infringe privately owm-d rights. Refer­ence herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise docs not necessarily constitute or imply its endorsement, reccm-mtfldation. or favoring by the Unhed Stales Government or any agency thereof. Toe views and opinions of authors exprcssul herein do not necessarily state or rcReci those of the United States Government or any agency thereof. 5 

Circulating water cooling system for a Camac Crate

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Circulating water cooling system for a Camac Crate

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