Chillers case study Children s Hospital of Medical University of Warsaw The project, the analysis and the solutions produced by RC Group Spa casestudy CS_14001_GB
INDEX 1... INTRODUCTION... 4 2... THE COOLING PLANT... 6 3... ENERGY EFFICIENCY... 8 4... REDUNDANCE OF COOLING PLANT... 9 5... SEASONAL ENERGY CONSUMPTION... 10 6... EFFICIENCY WITH SIMULTANEOUS CONTROL... 12 7... EFFICIENCY WITH SEQUENCE CONTROL... 13 8... CONSIDERATIONS ON EFFICIENCY AND FREE-COOLING MODE... 14 9... CENTRIFUGAL LIQUID CHILLERS... 15 9.1 LIQUID CHILLERS CONTROL AND MANAGEMENT... 16 9.2 COMPRESSORS WITH MAGNETIC LEVITATION... 17 9.3 CONDENSING SECTIONS... 18 9.4 FLOODED EVAPORATORS... 20 10... CONCLUSIONS... 21 11... REFERENCES AND APPRECIATIONS... 21 12... BIBLIOGRAPHY... 22 2
Children s Hospital of Medical University of Warsaw A case design to maximize energy efficiency, with the use of the most innovative solutions in the air conditioning of large surfaces. EXECUTIVE SUMMARY The report examines, with the use of a specific program of energy analysis RCSPECTRUM - www.rcspectrum.it - the prerogatives of a cooling plant of 4.8MW designed to cool the new Children s Hospital of Medical University of Warsaw. The main objective in the implementation of the project was to follow the cooling capacity building at any load condition, as efficiently as possible. The system consists of six groups of refrigeration condensed with air (max 35 C) 800kW each, for cooling water to 6 C. Each machine, equipped with three centrifugal compressors with magnetic levitation two-stage oil-free dual system of partial load, pre-rotation suction damper and inverters, has been selected to provide up to 1000kW of capacity. This exuberant choice, allows to get, for most of the year, very low electricity consumption: 3.6 EER at full load and efficiencies higher than 5.5 EER at reduced cooling loads. The inverter driven variable flow water circulation pumps and the cascade use of chillers, working in integration of the BMS of the building, further accentuate the optimized management of machines in each operating mode. A further energy saving is achieved with the use, in the coldest period of the year, of two units of drycooler, which implement the free-cooling mode. 3
1 INTRODUCTION The building of new Children s Hospital of Medical University helps care and hospitalization of children from Mazovia region and Poland. Special sectors are referred and used for education and medical research. The main challenge of the project concerned adapting the building to a town well consolidated, harmonized and being able to improve the area quality. The project consists in a main glazed building made up of transits, waiting areas ad ways between perpendicular wings of various hospital units for a flexible and opened structural scheme to possible future adjustments according to the most advanced medical technology requests. The hospital is so made up of 7-floor building surrounded by green areas. This solution allows the daily light to uniformly enter all buildings areas. Picture of the. A 3.000 m 2 park surrounding the hospital is available to all users, medical team, students and visitors. The total design reflects the will to create a building suitable for children, and it can provide comfortable conditions to all users. The hospital designed by Banach Street campus of Warsaw is equipped with 527 beds, 430 of which are paediatric, 57 to newborns and 40 to Gynaecology and Obstetrics. Picture of the Children s Hospital of Medical University of Warsaw. 4
The outdoor covering materials-white fibrocement panels and black wrought iron windows-are perfectly adapted to surrounding buildings colour. The building has two enclosed internal yards opened to all users at the low floor, the first is public while the second is dedicated to recreational area for users of Psychiatry area and there are two opened yards only accessible from the south side of buildings, close to the main conference hall with 300 seats and a dining room. Picture of the Children s Hospital of Medical University of Warsaw. Main building features are : Total area 97.389 m 2 7 raised floors 1 basement Covered area 40.018 m 2 Built up area 12.274 m 2 Total volume 398.048 m 3 5
2 THE COOLING PLANT The air conditioning system of this building consists in a 7.3 MW thermal station, a 4.8 MW cooling station and a series of units for primary air handling and several terminal units for each area. The maximum cooling load of the building must be satisfied, by 6 chillers 800 KW each one air cooled and a same capacity unit as stand-by supply in order to satisfy maximum redundancy during servicing operations concerning all system appliances: chillers, circulation pumps, valves etc... Picture 1 Diagram of the cooling plant del (Termo-Complex Katovice Poland). Picture 2 Diagram of the chilled water circuit (Termo-Complex Katovice Poland). 6
Each chiller is equipped with its own water circulation pump located upstream, while cooled water is sent to a common inertial tank where various direct lines come from all users and the same coming back lines to chillers. The plant s water has to be available at 6 C in order to allow air handling units to efficiently dehumidify air introduced to locals. The circulation plant of fluid, in this case pure water, needs 6K temperature differential during full-load machines working. However, this temperature differential has to be kept as long as possible during limited load working by a proportional reduction of water flow, up to the minimum accepted value of liquid chillers evaporators. This assumption influences liquid chillers choice as not all manufactures are able to offer units working with variable water flow. The possible solution is then to use chillers equipped with shell and tube flooded evaporators so it means equipped with liquid refrigerant in evaporation phase contained between the shell and the tube and water to be cooled circulating in the latter. Flooded evaporators allow to get better energy efficiency: Standard dry- expansion evaporators have in fact to supply less than 5K evaporating temperature than water to be cooled: in this case, as a +6 C coming out water temperature to be requested, refrigerant gas has to evaporate at about +1 C. On the contrary a flooded evaporator allows a lower approach between gas expansion temperature and water outlet temperature: in several cases, the approach is about 1K and it allows working at +5 C evaporating temperature. This working condition difference, linked to other project contexts, is key-factor for the machine efficiency at every working rate and outdoor air temperature. 7
3 ENERGY EFFICIENCY The following paragraph examines the EER (Energy Efficiency Ratio) of one of the six liquid chillers 800 kw capacity, comparing the version screw compressor and dry-expansion evaporator GLIDER EVO CLA, with the version of centrifugal compressors and flooded evaporator UNICO TURBO FL, at Eurovent conditions. (Picture 3). Both appliances are realized in RC Group SpA plants in Valle Salimbene, Pavia (Italy) and designed to have the lowest acoustic impact level: they are equipped with noise deading cup on compressor and a refrigerant condensing system with a low-speed air crossing. The noise reduction solutions allows to get a sound power reduction up to 8 db, with a full-load absorbed power increase of about 7%. Performance (EER) of a 800 kw water chiller at partial load Eurovent conditions Water chiller with centrifugal compressors EER (kw/kw) Cooling capacity of a single chiller (kw) Water chiller with screw compressors Picture 3 The diagram shows the performance (EER) of each centrifugal chiller (green solid line) and screw chiller (blue dotted line) at Eurovent conditions. The short green dashed line, referring to the available over boost on centrifugal chillers, takes account of a maximum constant air temperature to the condenser at 35 C. Please take note that UNICO TURBO FL liquid chiller with centrifugal compressors (green solid line) allows to have a cooling capacity up to 1000 kw. The short green dashed line in Picture 3 gives EER performance coefficients in over boosts line of a constant air temperature to the condenser at 35 C. 8
In the following diagram (Picture 4) same chillers are examined but with a 800 kw working capacity and with extreme winter air temperature. In this case too, it is possible to verify how water chiller with centrifugal compressors (green solid line) has a better energy trend than equivalent water chiller with screw compressors (blue dotted line). Performance (EER) of a water chiller 800 kw at full load Variable ambient air temperature Water chiller with centrifugal compressors EER (kw/kw) Outdoor air temperature ( C) Water chiller with screw compressors Picture 4 The diagram shows the performance (EER) of each centrifugal chiller (green solid line) and screw chiller (blue dotted line) always operating at full load (800kW) but with ambient air temperatures ranging from 35 to -15 C. 4 REDUNDANCE OF COOLING PLANT As show in previous paragraphs, the project of cooling plant needs 4,8 MW capacity by simultaneous working of 6 chillers with 800 kw each one, plus a 800 kw chiller, stand-by, to be used in case of failure of one of six working systems. Six UNICO TURBO FL centrifugal units by RC Group are able to supply an overcapacity up to 1000 kw for each one; 5 of them can supply more than the capacity required by plant complex, if one of them has to be temporary switched off for hydronic circuit maintenance. When a centrifugal group is off for maintenance (pumps, valves, etc..) the other five are able to supply the total project 4,8 kw capacity. 9
5 SEASONAL ENERGY CONSUMPTION The comparison on seasonal energy consumption of all cooling units allows to better address products choice. The active cooling groups can be whole managed by controlling devices to reduce the total load, both in parallel and in sequence. In the first case they will be all on until a total load reduction value equal to the minimum machine capacity. In the second case, as the load requested from the building reduces, each chiller will gradually stop. In order to evaluate both plants management according to seasonal energy consumption the process is focused upon average monthly thermo-hygrometric conditions of Warsaw (106 m over sea-level) as described in the Scheme 1 where weather data based on statistic web-made data are retrieved. Each month is marked by a type-day, which temperature profile (T) and humidity profile (rh), hour by hour, are written by this model 1 : e: T ext = T ext max * (1 - k n ) + T ext min * k n (1) RH = RH max * k n + RH min * (1 - k n ) (2) Where k n coefficients are described in table hour by hour and they give a minimum temperature at dry bulb at 5:00 and a maximum one at 15:00 (vice versa to relative humidity). Maximum and minimum values of 1 and 2 equations, on the contrary, match up minimum and maximum values means month by month as to statistical tables, while extreme temperature conditions are not considered. Each month is so marked by a statistical average temperature, with a daily range which is equal to maximum and minimum average gap. Furthermore, energy hour pricing are written in /kwh on informative aim. In this case: 0,15 /kwh from 6:00 to 18:00 and 0,10 /kwh in the following 12 hours. The cooling load profile for this building is calculated by the following equation: (3) where: DesignLoad cool CL 0 k u it is the project thermal load during cooling operations and it is about the maximum peak load of the building. It is referred to project weather conditions which could be the hardest ones in the installation area. it is the constant contribute, not influenced neither by hour (since it is not multiplied per k u ),nor other factors. It matches endogenous load linked to hospital appliances and it is on 24h/24h. it is the hour factor expressed in percentage. If annulled, it means load resetting (off plant, unless CL 0 is different to zero). The value considered allows to modulate according to hour, all load points included in square bracket.. 1 Ratings of cooling load from "Energy analysis for machine RCGROUP - SPECTRUM Manual 2013 RCGroup SpA Valle Salimbene (PV). 10
k w CL 1 CL 2 DCL T ext T cl T ch it is a constant for active plant (k u > 0), and (k u = 0) for off plant it is the working load, less influenced by weather conditions and reset in case of hospital operation it is the comfort load, mostly referring to building working levels (slow loads, lighting) and mostly free from weather conditions. it is the referring value to express heating indentations (heating exchangers between building covers and outdoor areas). it is the outdoor air temperature at dry bulb ( C). it is the temperature for reversing the sign of heat exchange between building cover and outdoor area. it is the maximum temperature used to calculate: it matches up maximum and minimum average of each month. Operating time MAX Temperature MIN Temperature Average Average MIN MIN Relative MAX Temperature Humidity Temperature MAX Relative Humidity Average cooling load Months h C C C C % % kw Jan 744 7,6-10,6 1,3-2,7 70,4 97,0 1371,5 Feb 672 8,2-11,0 1,8-3,2 67,6 97,0 1371,5 Mar 744 11,7-8,4 5,4-0,6 62,2 96,9 1714,3 Apr 720 19,0-5,2 12,6 2,6 48,3 95,6 2285,8 May 744 25,0 0,8 18,6 8,6 46,6 89,5 2971,5 Jun 720 28,0 3,8 21,6 11,6 50,7 95,9 3314,4 Jul 744 29,0 4,8 22,6 12,6 51,0 95,9 3428,7 Aug 744 29,0 4,8 22,6 12,6 51,0 95,9 3428,7 Sep 720 24,4 1,3 18,1 9,1 55,4 97,0 2971,5 Oct 744 18,9-3,3 12,5 4,5 60,2 97,0 2400,1 Nov 720 11,2-8,0 4,8-0,2 76,3 97,0 1714,3 Dec 744 8,6-9,6 2,3-1,7 77,5 97,0 1485,8 Table I The table shows the maximum, minimum and average temperature and humidity conditions, in the various months of the year in Warsaw. The table also calculates the hourly average cooling loads of the building required - (RCSpectrum Program ver. 2.5.31- RCGroup SpA Valle Salimbene (PV). 11
6 EFFICIENCY WITH SIMULTANEOUS CONTROL Chillers can be managed through a general device managing them simultaneously. It means that each machine is on and it reduces its cooling load according to building request. If load is 13% lower than total one, chillers will stop one after the other till the system total stop in case of no load condition or freecooling outdoor units operations. In this case season energy consumptions are well described in Table II, where only compressors and fans power input are considered, taking power absorbed by water circulation pumps into account as the same (packaged solution). Plant solution with six chillers in simultaneous control (Table II) clearly shows low consumption achieved with UNICO TURBO FL use with centrifugal compressors compared with GLIDER EVO FREE CLA hypothetical devices with incorporate free-cooling. The solution with centrifugal machines, together dry-cooler units for the free-coolig will enhance further this particular difference in efficiency. 6 CHILLERS WORKING IN PARALLEL Centrifugal chillers Screw chillers Screw chillers with free cooling Operating time Compressors power input Fans power input Average efficiency Compressors power input Fans power input Average efficiency Compressors power input Fans power input Average efficiency Free cooling Months h kwh kwh EER kwh kwh EER kwh kwh EER % Jan 744 88.006 34.520 8,33 233.130 12.990 4,15 0 74.348 13,72 100,00 Feb 672 79.143 31.179 8,35 210.162 12.222 4,14 0 70.218 13,13 100,00 Mar 744 120.202 34.520 8,24 292.019 19.485 4,09 57.766 108.542 7,67 79,80 Apr 720 184.693 34.665 7,50 387.173 25.647 3,00 277.963 80.282 4,59 26,70 May 744 296.710 42.376 6,52 515.202 31.921 4,04 501.902 53.667 3,98 0,00 Jun 720 345.503 47.660 6,07 552.387 36.549 4,05 536.185 60.836 4,00 0,00 Jul 744 378.639 51.997 5,92 591.863 40.228 4,04 573.209 67.082 3,98 0,00 Aug 744 378.639 51.997 5,92 591.863 40.228 4,04 573.209 67.082 3,98 0,00 Sep 720 287.327 40.809 6,52 498.702 30.549 4,04 486.046 51.326 3,98 0,00 Oct 744 204.832 35.923 7,42 421.260 26.495 3,99 344.127 71.836 4,29 15,70 Nov 720 115.909 33.407 8,27 281.086 18.857 4,12 49.327 106.884 7,90 83,00 Dec 744 99.489 34.520 8,25 252.094 15.155 4,14 2.249 94.131 11,47 99,20 Total 8.760 2.579.092 473.533 7,28 4.826.941 310.326 3,72 3.401.983 906.194 5,75 33,70 Total MWh 3.052,63 Total MWh 5.137,27 Total MWh 4.308,18 Table II The scheme displays monthly electrical energy consumption of 6 cooling units system, both in version with centrifugal screw and parallel-managed compressors - (RCSpectrum Program ver. 2.5.31- RCGroup SpA Valle Salimbene (PV). 12
7 EFFICIENCY WITH SEQUENCE CONTROL Another way of cooling capacity control supplied by chillers consists in gradually reducing the number of active chillers referring to reduction of load request by the building. In this case units will mainly work full-load and only one of them will modulate the capacity. The electrical power consumption is shown in Table III. Operating time Compressors power input 6 CHILLERS WORKING IN SEQUENCE Centrifugal chillers Screw chillers Screw chillers with free cooling Fans power input Average efficiency Compressors power input Fans power input Average efficiency Compressors power input Fans power input Average efficiency Free cooling Month h kwh kwh EER kwh kwh EER kwh kwh EER % Jan 744 115.301 12.085 8,01 207.263 10.119 4,69 42.413 52.041 10,80 85,20 Feb 672 104.828 11.019 7,96 188.498 9.293 4,66 39.079 47.058 10,70 84,50 Mar 744 152.903 15.289 7,58 259.012 12.640 4,70 124.778 54.940 7,10 61,20 Apr 720 216.550 22.231 6,89 338.989 17.890 4,61 271.577 49.672 5,12 23,30 May 744 332.567 34.237 6,03 476.515 29.259 4,37 459.310 48.376 4,35 0,00 Jun 720 374.779 41.754 5,73 529.940 35.336 4,22 510.945 58.485 4,19 0,00 Jul 744 410.174 46.149 5,59 575.071 39.181 4,15 553.184 64.983 4,13 0,00 Aug 744 410.174 46.149 5,59 575.071 39.181 4,15 553.184 64.983 4,13 0,00 Sep 720 320.953 32.925 6,05 459.344 28.189 4,39 442.812 46.599 4,37 0,00 Oct 744 236.288 24.513 6,85 368.100 19.730 4,60 314.278 49.544 4,91 17,40 Nov 720 147.902 14.760 7,59 255.362 12.751 4,60 116.151 55.443 7,19 62,80 Dec 744 130.085 12.556 7,75 224.299 10.836 4,70 71.845 52.020 8,92 76,30 Total 8.760 2.952.504 313.667 6,80 4.457.464 264.405 4,49 3.499.556 644.144 6,33 34,23 Total MWh 3.266,17 Total MWh 4.721,87 Total MWh 4.143,70 Table III the scheme displays monthly electrical energy consumption of 6 cooling units system, both in version with centrifugal screw and sequence-managed compressors. - (RCSpectrum Program ver. 2.5.31- RCGroup SpA Valle Salimbene (PV). 13
8 CONSIDERATIONS ON EFFICIENCY AND FREE-COOLING MODE With Tables II and III it is possible to highlight the higher efficiency achieved by UNICO TURBO FL centrifugal chillers compared to GLIDER EVO CLA screw units, both in standard version and with built-in free-cooling coils. While centrifugal chillers can be easily managed with a total both parallel and sequence control, the difference concerns the working result achieved by screw machines, preferring a sequence global control. This is possible as screw compressors have a behaviour providing efficiency in proximity of full-load operation. Since chillers with centrifugal compressors are linked to outdoor free-cooling and upstream evaporators, they are able to pre cool water when outdoor air temperature is at least 2 K lower. In this case, outdoor free-cooling coils begin to work from +7 C air temperature up to +2 C helping chillers. Under +2 C, mechanical compressors are completely off. Picture 5 shows high efficiency free-cooling coils active when outdoor air is able to pre cool plant water at a +7 C temperature. As shown in previous schemes, GLIDER EVO FREE CLA free-cooling units are not able to overshoot yearly average energy coefficient achieved by UNICO TURBO FL chillers with centrifugal compressors, as full free-cooling can be granted only for 20% of the year in Warsaw. A better global efficiency is achieved by use of dry-cooler in addition. Performance (EER) of a water chiller 800 kw at full load Variable ambient air temperature EER (kw/kw) Water Chiller with Screw compressors and free-cooling Water chiller with centrifugal compressors Outdoor air temperature ( C) Picture 5 The diagram shows the performance (EER) of each centrifugal chiller (green solid line) and screw chiller (blue dotted line) always operating at full load (800kW) but with ambient air temperatures ranging from 35 to -15 C. 14
9 CENTRIFUGAL LIQUID CHILLERS UNICO TURBO FL chillers, realized by RC Group SpA, were installed to build the cooling plant of. They are equipped with centrifugal compressors and HCF-134a refrigerant and these devices have proved to allow the most efficient load management at every outdoor temperature, as far as all examined solutions. They can work with variable water flow as well. UNICO TURBO FL air cooled chillers equipped with centrifugal compressors have specific construction and functional features in order to make them suitable for this operation. Picture 6 In close-up a liquid chiller UNICO TURBO FL, realized for (RC Group Spa Valle Salimbene (PV). Picture 7 Testing phase of a UNICO TURBO FL liquid chiller in production factory (RC Group SpA - Valle Salimbene (PV). 15
9.1 LIQUID CHILLERS CONTROL AND MANAGEMENT Chillers are controlled by the sequencer device known as Master Plant SEQ giving several working solutions, as: chillers starting and deactivation in commutation, alarms, temperature control, maximum working conditions, special events, as the restarting after a power interruption ; precision control of plant cooled water temperature; control and implementation of system energy efficiency; starting and control of cooled water circulation pumps. Other applied functions are: reduction of acoustical impact according to pre-definition threshold by reducing fans speed ; absorbed power cut-out control; time planning; automatic appliances alternation to have consumption balanced ; total control and anti-freeze system. Picture 8 The Master Plant SEQ system with some control software displays (RC Group SpA - Valle Salimbene (PV). The sequencer device allows management of cooled water flow variability too, in the primary system by managing directly primary circulation pumps within pre-defined flow limits. The optimisation of energy value ( G value) of total system is possible thanks to the design of specific functions to save energy: sequencing maps, automatic compensation, pumps control by managing, in real time, energy performances. 16
9.2 COMPRESSORS WITH MAGNETIC LEVITATION UNICO TURBO FL liquid chillers used in the new are equipped with three double-turbine centrifugal compressors, with magnetic levitation. This solution makes possible not to have lubrication oil emulsified in chiller and then to get the best heat exchange in evaporators and condensing coils. Picture 9 Each liquid chiller is equipped with 3-double-turbine centrifugal compressors, with magnetic levitation and a capacity control system by a protection coupled damper to speed variation (Danfoss Turbocor Compressors Inc. Tallahassee, FL - USA) Immagini (RC Group SpA - Valle Salimbene (PV). The extraordinary energy efficiency of adapted centrifugal compressors reduces working balance and helps minimize CO 2 equivalent production with a lower yearly energy use from 30% to 50% compared with standard compressors. These high efficiencies can help get LEED GBC points, too. The lack of surfaces exposed to mechanical wear due to oil free magnetic bearings increases compressors working life. (Picture 10). Y Back and front radial bearing Z Axial bearing Control axis X Back and front radial bearing Back radial bearing Front radial bearing Impeller Axial bearing Shaft Picture 10 Magnetic levitation bearings configuration. The rotatory shaft, in case of variable load, is exposed to axial and radial forces to balance these forces a five axes bearing system is used (Danfoss Turbocor Compressors Inc. Tallahassee, FL - USA) 17
9.3 CONDENSING SECTIONS Condensing coils of UNICO TURBO FL liquid chillers are made of aluminium micro channels. These coils are well adapted to HFC-134a refrigerant devices and they provide several technical advantages, such as: lightness: aluminium brazed-welding condensers are lighter than mechanical copper-tube condenser. Weight and gage of micro pipes batteries are up to 50% lower (in performance parity). Higher duration: by using suitable alloy for this technology and through soldering it is possible to achieve a flawless product with a better corrosion resistance. Ecological: exchangers are wholly aluminium-made, they can be recycled at the end without additional costs. Lower refrigerant load: according to its performances, micro pipes heat exchangers need 75% less refrigerant than standard heat exchangers. Lower air resistance: according to its performances, micro channels heat exchangers have lower air resistance. (30%) This allows to use fans groups with lower power and to achieve lower noise levels. Picture 11 Only aluminum micro channels coils are used. Weather resistant, they have lower refrigerant charge lower than equivalent aluminum copper ones - (Thermokey SpA - Rivarotta (UD) Italia). 18
Each UNICO TURBO FL liquid chiller is equipped with 14 axial fans with EC motors and it is able to reduce 30% of fan system medium consumption compared with AC traditional fans. Aluminium blades and special plastic nozzle provides a total corrosion protection. Nozzle multifunction fins and fans blades give excellent aero-dynamic performances. On the other hand, EC (electronic commutation) motors use permanent magnets instead of inducing a secondary magnetic field. Advantages compared with traditional axial fans technology can be summarized in: Energy consumption cut-out control. Significant sound reduction. Significant air increase High pressure stability. Rigorous electronic control. Incorporate internal protection Remote monitoring via ModBus. No corrosion danger. Picture 12 Each liquid chiller is equipped with 14 EC axial fans, with high efficiency and low acoustical impact - (Ziehl Abegg SE Künzelsau - Germania). 19
9.4 FLOODED EVAPORATORS Generally, dry expansion evaporators are designed with higher refrigerant flow speed within pipes in order to provide oil return in compressor s suction. This generates higher pressure drop influencing negatively the system energy efficiency. On the contrary, lower refrigerant pressure fall allows higher cooling efficiency. The tube bundle where water to be cooled circulates, utterly flooded in liquid refrigerant, allows to achieve a better and regular evaporation throughout exchanging surface, that means a better full-load efficiency and even better at partial load. The flooded evaporator liquid level is controlled by a specific sensor level. Shell and tube bundle is utterly and easy to clean. If marine calotte are used, maintenance can be done without removing water junctions. Picture 13 UNICO TURBO FL flooded evaporator equipped with 4 oil-free centrifugal compressors with magnetic levitation bearings in RC Group plant in Valle Salimbene (PV). In flooded evaporators carrier fluid circulating inside the 2 or 4 passes shell and tube that is totally immersed in the refrigerant. (Onda SpA - Mussolente (VI) Italia). 20
10 CONCLUSIONS Air cooled liquid chillers with centrifugal compressors UNICO TURBO FL by RC Group have proved to have higher mechanical and energy values than any other technical solution analyzed at Children s Hospital of Medical University of Warsaw. They allow a considerable yearly electric energy save: about 1.750MWh, or equivalent 202.000,00 Euro. Maintenance is reduced and limited tocondensing coils cleaning; centrifugal compressors use excludes any operation concerning system lubrication. Electronic devices of capacity control are directly managed by each compressor while general control is run by Master Plant SEQ external sequencer managing six sequence or parallel appliances according to building load required. 11 REFERENCES AND APPRECIATIONS This report has been supported by the use of RCSPECTRUM, the energy evaluation and comparison software designed by RC Group SpA in Valle Salimbene Pavia. Credits: IMTECH Poland technical department, OPEN ARCHITEKCI architecture studio of Warsaw, ARUP Poland projecting society and RC Polska products distribution and appliances society for useful documentation provided. This product got Eurovent Certification: RC Group Spa has joined EUROVENT certification program for LCP and HP (Liquid Chilling Packages and Heat Pumps). Certification validity control available on line www.eurovent-certification.com 21
12 BIBLIOGRAPHY Archello - Discover and present the world's projects and products - Children s Hospital of Medical University of Warsaw - http://www.archello.com/en/ Archello - Immagini prospettiche - http://www.archello.com/ Kandlikar, S. G., Garimella, S., Li, D., Colin, S., & King, M. R. (2006). Heat Transfer and Fluid Flow in Minichannels and Microchannels. Kidlington, Oxford: Elsevier Ltd. Danfoss Turbocor Compressors Inc. - Tallahassee, FL - USA Compressore centrifugo oil-free a doppia turbina comandato da inverter Ziehl Abegg SE Künzelsau Germania. Ventilatori assiali EC ad alta efficienza RCGroup Spa - Valle Salimbene (PV) Italia RCSpectrum versione 2.5.30 / 2.5.31 http://www.rcspectrum.it. Thermokey Spa - Rivarotta (UD) Italia - Condensatori in alluminio a minicanali. Onda Spa - Mussolente (VI) Italia Evaporatori allagati a fascio tubiero. 22
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The continuous improvement of products may imply changes in the data shown in this catalogue.. RC GROUP S.p.A. Via Roma, 5 27010 Valle Salimbene (PV), Italy www.rcgroup.it Tel. +39 (0) 382 433 811 Fax +39 (0) 382 587 148 CS_14001_GB