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Project Phase – I Review -IISolar driven Absorption Chiller (SAC) - Phase Change Material (PCM) Integrated Technology (SAPIT) for cooling telecommunication shelters in India Undertaken by: Anirudh B Mentored by: Dr.R.Velavan 11MN01 Associate Professor School of Energy PG Scholar PSG College of Technology ME Energy Engineering School of Energy PSG College of Technology
Literature survey for review IIAn experimental investigation on passive cooling system comprising phase change material and two-phase closed thermosyphon for telecom shelters in tropical and desert regionsA.Shanmuga Sundaram , R.V.Seeniraj , R.VelrajEnergy and Buildings (2010)The authors have developed a passive cooling system employing PCMand TPCT for an alternative to conventional cooling systems to providethermal management of telecommunication equipments in telecomsheltersThermodynamic and economic performance of the LiBr–H2Osingle stage absorption water chillerTomasz M.MrozApplied Thermal Engineering (2006)The authors have developed and installed a single stage LiBr-H2Oabsorption chiller in a municipal CHP plant to study the energyefficiency and economic analysis of the system
Literature survey for review IIEnergy and economic analysis of an integrated solar absorption cooling and heating system in different building types and climatesTiago Mateus , Armando C. OliveiraApplied Energy, (2009)The authors have modeled and simulated an integrated solar absorptioncooling and heating system in buildings of three different regions usingTRNSYS and evaluated the total energy cost and CO2 emissions reductionExergy calculation of lithium bromide–water solution and its application in the exergetic evaluation of absorption refrigeration systems LiBr-H2OReynaldo Palacios-Bereche, R. Gonzales, S. A. NebraInternational Journal of Energy Research(2010)The authors have calculated the physical and chemical exergies of the systemby evaluating the irreversibilities and extending it to determine the exergeticefficiency of the system, thereby providing this as a reference to calculatefor other complex systems
Cooling load calculations for telecom shelterSolar heat gain: 𝑄 𝑠 = 𝑈𝐴 𝑇 𝑠𝑜𝑙−𝑎𝑖𝑟 − 𝑇𝑖Where, U - overall heat transfer coefficient of wall and roof, 𝑊/𝑚2 𝐾 A -wall and roof area in 𝑚2 𝑇𝑖 - Indoor air temperature, 𝑜 𝐶Shelter material: interior and exterior surfaces made of galvanized steelseparated by polyurethane foamHeat transfer coefficient for galvanized steel, hgs=25 𝑊/𝑚2 𝐾Heat transfer coefficient for polyurethane foam, hi=0.0972 𝑊/𝑚2 𝐾Overall heat transfer coefficient is calculated to be, U=0.09645 𝑊/𝑚2 𝐾 𝛼𝐸 𝑡 𝜀∆𝑅Sol-air temperature: 𝑇 𝑠𝑜𝑙−𝑎𝑖𝑟 = 𝑇 𝑜 + − ℎ𝑜 ℎ𝑜 𝑇 𝑜 - outside air temperature, degC 𝛼 = 0.026 for light coloured surfacesℎ𝑜 𝜀∆𝑅 = 0K for vertical surfaces and 4K for horizontal surfacesCourtesy: ASHRAE Fundamentals 2005
Cooling load calculations for telecom shelterMonth Dry bulb temp Average daily solar Sol-air temp, Solar heat gain, deg C irradiation , 𝑾/𝒎 𝟐 𝑲 deg C W Jan 25.62 632.8 42.07 9.88 Feb 26.62 728.9 45.58 11.90 Mar 27.99 811.3 49.08 13.93 Apr 28.80 758.9 48.53 13.62 May 28.28 730.2 47.26 12.88 Jun 26.51 605.3 42.25 9.98 Jul 25.77 561.6 40.37 8.89 Aug 25.81 579.1 40.87 9.18 Sep 26.35 624.1 42.58 10.17 Oct 26.36 555.4 40.80 9.14 Nov 26.21 526.7 39.91 8.63 Dec 25.44 556.7 39.91 8.63Courtesy: NASA Surface meteorology and solar energy
Equipment heat gain in the telecom shelter:S.No Unit name Number of Heat load, W units1 Power cabinet :electronics 1 4502 2G cabinet 1:electronics 1 10503 2G cabinet 2:electronics 1 10504 2G cabinet 3:electronics 1 10505 Nokia Node B - RRU 1 1 1506 Nokia Node B - BBU 1 1007 Nokia Node B - RRU 2 1 1508 Nokia Node B - ALM 1 509 Nokia Node B - RRU 3 1 15010 2G,3G,power Cabinet door fans (150CFM) 20 10011 Rectifier fans (48CFM) 8 10 Total heat load 4310Courtesy: Bharathikrishanan Muralidharan, “Energy based Design optimization ofTelecommunication cabinets”, MS thesis, University of Texas, 2010
Tonnage of refrigeration requiredActual cooling load required for telecom shelter:Solar heat gain + Equipment heat gainBut the solar heat gain is negligible compared to the equipment heatgain therefore it is neglected.Type of Actual Signific Actual Scaled Actual Actual Scaled ScaledCooling coolin ance of cooling down TR TR down download g cooling load , cooling require require TR TR load, load W load, W d d with require require W PCM d d with PCMEquipme 4310 To be 4310 500 1.22 TR 2.5TR 0.15TR 0.5TRnt heat includegain dSolar 14 Negligib - - - - - -heat gain leDue to economic constraints, the cooling load for the telecom shelteris scaled down to 500W.
Theoretical model of SACThermal energy required by the absorption chiller, 𝑄𝑐 𝑄 𝑐ℎ = 𝐶𝑂𝑃 𝑐ℎWhere, 𝐶𝑂𝑃 𝑐ℎ is the coefficient of performance of the absorptionchiller which varies with demand is given in a fourth order polynomialfor partial load efficiency of absorption chiller, 4 3 2 𝐶𝑂𝑃 𝑐ℎ = 𝑎𝑓𝑐ℎ + 𝑏𝑓𝑐ℎ + 𝑐𝑓𝑐ℎ + 𝑑𝑓𝑐ℎ + 𝑒Where, 𝑓𝑐ℎ is the ratio of the cooling load and the chiller nominalcapacity and given by 𝑄𝑐 𝑓𝑐ℎ = 𝐶𝐻 𝑐𝑎𝑝Energy balance applied at the chiller can be given by, 𝑄 𝑐ℎ = 𝑚 𝑐ℎ 𝐶 𝑐ℎ (𝑇ℎ1 − 𝑇ℎ2 )Courtesy: N. Fumo, V. Bortone, J. C. Zambrano, “Solar Thermal Driven Cooling System for a DataCenter in Albuquerque New Mexico”, Journal of Solar Energy Engineering, ASME(2011)
Future work in phase IDaily cooling load profile of a telecom shelter in Coimbatore regionDetermination of theoretical COP for part load efficiency of absorption chiller (by polynomial curve fitting)Determination of thermal energy required by the absorption chillerDetermination of cooling load of telecom shelter under transient condition using TRNSYS softwareDetermination of the required area of the solar thermal collectorsDetermination of capacity of the other heat transfer elements in the chiller( like cooling tower, evaporator, condenser)