Thank You For Today’s Opportunity

Thank You For Today’s Opportunity

Agenda Introductions Chiller Plant Design Criteria
Chiller Plant Configurations Different Chiller Technologies Refrigerants Chiller Plant Optimization Techniques

Introductions John Calcagno-Formosa Account Manager
Sales Engineer/Account Manager-Carrier Corporation BSME Rutgers University Over 27 Years HVAC Industry Experience

Chiller Plant Design This presentation applies to typical chiller plants. The type of building or process the plant serves will affect the design. Different criteria for different applications. This presentation will focus on chillers.

Chiller Plant Design Type of application
Process Reliability, durability, life cycle cost Data Center Reliability, life cycle cost, cold condenser water. Health Care Reliability, first cost, efficiency Higher Education First cost, life cycle cost Office First cost District Cooling Reliability, life cycle cost

Design Criteria Review capacity

Design Criteria

Optimizing Chiller Plant Design

Components of Chiller Plant
Chillers Chiller Heat Rejection Distribution System Load

Piping Configurations
Variable Primary (Variprime)

Chiller Plant Configurations
“Keep things as simple as possible but no simpler”

Single Chiller Constant Flow

Single Chiller Constant Flow
Advantages Simple Low first cost Disadvantages: No redundancy Chiller cannot efficiently match the load Does not take advantage of varying load Part load-pumping water not needed

Multiple Chillers Parallel-Constant Flow

Advantages Redundancy Can better match capacity at part load Disadvantages Part load- one chiller off – mixing of chilled water supply Part load- pumping water around that is not needed

Temp Mixing

Multiple Chillers Parallel Part Load Flow Reduction
Shut down one chiller/pump at part LOAD. But what about the flow?

Multiple Chillers Parallel Part Load Flow Reduction
Advantages Redundancy Ability to match load by staging chillers Saves pump energy at part load Disadvantages Significant reduction of flow at part load Chiller production loop is hydraulically tied to chiller consumption loop

Multiple Chillers in Series-Constant Flow

Multiple Chillers In Series-Constant Flow
Advantages Eliminates temperature mixing and flow problems Full flow at all loads Series/counterflow arrangement-efficiency Disadvantages Flow rate through each chiller is entire system flow-double the flow for parallel chillers Pressure drop is additive-bigger pumps and more energy Part load-pumping water around building not needed Limited to two chillers

Multiple Chillers In Parallel Primary/Secondary System
Decoupler pipe

Multiple Chillers in Parallel-Primary/Secondary System
Advantages Decouples or separates the chilled water production piping from the chiller water consumption piping Eliminates temperature mixing and flow reduction Part load-match chiller capacity to load Part load-reduced flow Disadvantages More pumps required Moderately complicated controls required Water balancing important

Multiple Chillers In Parallel-Variable Primary System

Multiple Chillers In Parellel-Variable Primary System
Advantages Eliminates set of pumps Efficient Disadvantages Must coordinate minimum flow and rate of change with chiller manufacturer Moderately complicated controls

Variable Primary Flow Principles to follow: Confirm chiller vendors minimum acceptable flow rate (may require higher initial design cooler pressure drop) Specify flow meters or DP transmitters to measure/ maintain chiller minimum flows Design bypass for flow rates below minimum Find out what rate of change in flow is acceptable from chiller vendor(s) and put this in sequence of operation Provide ton-hr metering to measure machine capacity for sequencing logic (note, 23XRV speed is directly proportional to capacity, so speed can be used to sequence machines)

Minimum Loop Volume (gal)*
Variable Primary Flow – Rate of Change Carrier Other Model 23XRV Single Centrifugal Multiple Compressors Rate of Change (%/min) 70% 30% 10% Minimum Loop Volume (gal)* 450 900 1,800 * = 300 Tons Comfort Cooling Application Industry Best! Why is this Important?

More Flexibility = Less Nuisance Trips
Compressor response time in VPF system If the evaporator flow to the chiller is halved, the load is halved. If the chiller does not unload quickly enough (VFD, IGV staging), the chilled water temperature will drop and either result in: Recycle (LCWT too far below set point) or Worst Cases, Freeze Trip (LCWT below freeze protection value) or Surge Trip (at least for a centrifugal compressor). In VPF applications, select a machine with high acceptable rate of flow change and specify rate (in % change/Minute). More Flexibility = Less Nuisance Trips

System Decisions 0.587 0.587 0.560 0.517 0.517 0.498 0.520

Summary No right configuration for all plants
Must evaluate the design criteria Take advantage of chiller’s modern controls

Questions

Water Cooled Chiller Technologies
Centrifugal Helical Rotary (Screw) Scroll Absorption Direct Fired Absorption

Water Cooled Chiller Technologies

water-cooled Chillers
Product Portfolio Q Q 100 250 500 1,000 1,500 1,875 2,250 3,000 30MP Tons 30HX Tons 30XW Tons Single Circuit Tons Dual Circuit 23XRV Tons 23XRV Tons 19XR(V) Single Stage 200-1,600 Tons 19XR(V)E Two Stage 800-1,600 Tons 19XR6 Two Stage 1,600-2,250 Tons CENTRIFUGA L SCREW SCROLL

Scroll Compressor

Helical Rotary/Screw Compressor
Use variable frequency drive to slow down the compressor

Given the choice, aren’t fewer worries better?
Carrier 23XRV – Simple Simple: 3 moving parts No surge No purge No shaft seals No guide vanes No slide valves No EXV’s No chlorine No phase-out No refrigerant pumps No pressurization systems No bearing capacitors to change No pumps, hoses or clamps for VFD No glycol cooling required for VFD No motor heat rejection to the room Given the choice, aren’t fewer worries better?

Centrifugal Compressor
Use inlet guide vanes and variable frequency drive for unloading

Impeller IMPELLER WHEEL

Shroud Funnel-type device that ensures that the refrigerant flows through the compressor.

Diffuser PIPE DIFFUSER

Medium Pressure vs Low Pressure
Evaporator – water, contaminants are sucked into the chiller

Positive Pressure Design
Keeps Air and Contaminants Out Keeps Refrigerant In Store Refrigerant Inside Chiller Equipment Life Extended Efficiency Losses Avoided Purge Maintenance Eliminated

Refrigerants HCFC-123 Low pressure refrigerant
Subject to phase out-MAJOR reduction in production NOW (2015)! HFC-134a Medium Pressure Refrigerant No phase out!

Semi Hermetic Versus Open Drive Design

Semi Hermetic Versus Open Drive Design
Semi-hermetic: Motor and Compressor are one sealed assembly. Motor is cooled by refrigerant. Open Drive: Motor and Compressor are separate assemblies. Compressor has shaft seal to contain refrigerant in compressor.

Shaft Seals-Leakage Source
“Open drive seals lose 2% of total refrigerant charge annually.” ARI Report 11/98 Replacement of open drive shaft seals costs $3000 to $5000 every 3 to 5 Years. Life cycle cost is the combination of installed cost, operating cost and maintenance cost. We have discussed the installed cost and energy cost advantages of semi-hermetic motors, but let’s not overlook the maintenance advantages as well. It is a well known fact that open drive shaft seals are a headache. If not properly maintained, they leak refrigerant and oil and eventually fail. Typically, an open motor shaft seal must be replaced every 3 to 5 years at a cost of $ for each compressor. For a typical two chiller plant, that amounts to an additional $ $60000 in maintenance expense in a 20 year period versus a semi-hermetic installation. Not to mention the alignment and motor vibration problems inherent with open motor drive chillers, which only gets worse with age.

Motor Cooling From Ambient Air
Ventilation vents let contaminants in! (dirt, salt, production debris etc) Life cycle cost is the combination of installed cost, operating cost and maintenance cost. We have discussed the installed cost and energy cost advantages of semi-hermetic motors, but let’s not overlook the maintenance advantages as well. It is a well known fact that open drive shaft seals are a headache. If not properly maintained, they leak refrigerant and oil and eventually fail. Typically, an open motor shaft seal must be replaced every 3 to 5 years at a cost of $ for each compressor. For a typical two chiller plant, that amounts to an additional $ $60000 in maintenance expense in a 20 year period versus a semi-hermetic installation. Not to mention the alignment and motor vibration problems inherent with open motor drive chillers, which only gets worse with age.

Open Drive Design Airborne dirt and contaminants in

Open Drive design Only ONE Major Manufacturer makes an open drive chiller. If a design is used so that it is easy to repair, shouldn’t this cause some concern?

Motor Health Open Motor Hermetic Motor
Heat – most common cause of premature failure. “Each 10C rise above the rating may reduce the motor lifetime by one half” - NEMA “Class B Rise” results in 120C (248 F) operating temperature. Motors can operate cool enough that insulation is applied to prevent sweating. Dirt – abrasion can cause insulation failure, buildup increases operating temperature Motor completely exposed to dirt, dust and debris in mechanical room as it actively pulls air through the motor internal vents to cool itself. Motor completely isolated inside clean, cool refrigerant boundary, unexposed to mechanical room dirt, dust or debris. NEMA - National Electrical Manufacturers Association Heat is the enemy of a motor. The hotter you run a motor, the shorter the insulation will last. Dirt build up on motor windings creates a thermal insulation layer and increases operating temperatures. Increased operating temperatures reduce motor life. Motors may be sent out to have their windings cleaned of dirt and debris periodically. Moisture collecting on motor windings can lead to insulation failure. If humidity levels are high, mechanical dehumidification should be used. Moisture is particularly troublesome when motors are operated intermittently. Think of a chiller schedule and spare chiller application. Condensation will form on any equipment colder than the dew point. Overnight a mechanical room and the equipment may become cool. If warm, moist outdoor air enters the mechanical room the next day, it may condense on any cool surface, including a spare chiller motor. Air may enter through a door, window or be purposely brought into the mechanical room because another chiller is on. If Power is lost for several hours, the motor may need to be dried out before it is started. If power is out for a prolonged period of time, a megger test may be necessary to test the motor insulation before applying power, otherwise the motor may suffer a catastrophic failure if power is applied and the insulation resistance is compromised due to moisture. Open drive motors have fan blades built into the rotor. When the motor rotor spins, air is drawn in from the mechanical room and blown right through the motor. Any contaminants in the air (dirt, dust, debris) go into the motor. If you were renovating the mechanical room or working on an adjacent exposed space, should you shut down your chillers to prevent motor failure? Pause for a moment - is this even an option … to shut off cooling every time you do some work in the mechanical room that might release dirt, dust, debris into the air? Open motors have failed But is York going to cover the motor under warranty if it fails under such conditions? . Open drive motors require additional maintenance post installation Known to have alignment and vibration issues over time (maintenance troubleshooting costs) With shaft seal refrigerant leaks or oil leaks come troubleshooting , repair and replacement costs Semi-hermetic motors are “plug and play”. Set it an forget it. Eliminates the need to provide additional ventilation or tempering (air conditioning) of the mechanical room due to open motor designs. TEWAC (Total Enclosed Water to Air Cooled) motor. - a TEWAC motor is the closest to a hermetic motor of any open motor type. In a TEWAC motor the heat from the motor is transferred to water flowing through a heat exchanger above the motor. This limits the amount of air brought into the motor and removes the heat from the space.

Motor Health Open Motor Hermetic Motor
Moisture – reduces motor insulation resistance, can cause catastrophic failure. Open motors must be equipped with internal heaters to prevent condensation. Condensation on motor windings is not possible – it is sealed in refrigerant circuit. Vibration – can cause bearing fatigue and failure, or cracks in insulation system and failure. Compressor and motor balanced separately. Coupling can increase balance issues. Compressor and motor dynamically balanced together – no coupling. NEMA - National Electrical Manufacturers Association Heat is the enemy of a motor. The hotter you run a motor, the shorter the insulation will last. Dirt build up on motor windings creates a thermal insulation layer and increases operating temperatures. Increased operating temperatures reduce motor life. Motors may be sent out to have their windings cleaned of dirt and debris periodically. Moisture collecting on motor windings can lead to insulation failure. If humidity levels are high, mechanical dehumidification should be used. Moisture is particularly troublesome when motors are operated intermittently. Think of a chiller schedule and spare chiller application. Condensation will form on any equipment colder than the dew point. Overnight a mechanical room and the equipment may become cool. If warm, moist outdoor air enters the mechanical room the next day, it may condense on any cool surface, including a spare chiller motor. Air may enter through a door, window or be purposely brought into the mechanical room because another chiller is on. If Power is lost for several hours, the motor may need to be dried out before it is started. If power is out for a prolonged period of time, a megger test may be necessary to test the motor insulation before applying power, otherwise the motor may suffer a catastrophic failure if power is applied and the insulation resistance is compromised due to moisture. Open drive motors have fan blades built into the rotor. When the motor rotor spins, air is drawn in from the mechanical room and blown right through the motor. Any contaminants in the air (dirt, dust, debris) go into the motor. If you were renovating the mechanical room or working on an adjacent exposed space, should you shut down your chillers to prevent motor failure? Pause for a moment - is this even an option … to shut off cooling every time you do some work in the mechanical room that might release dirt, dust, debris into the air? Open motors have failed But is York going to cover the motor under warranty if it fails under such conditions? . Open drive motors require additional maintenance post installation Known to have alignment and vibration issues over time (maintenance troubleshooting costs) With shaft seal refrigerant leaks or oil leaks come troubleshooting , repair and replacement costs Semi-hermetic motors are “plug and play”. Set it an forget it. Eliminates the need to provide additional ventilation or tempering (air conditioning) of the mechanical room due to open motor designs. TEWAC (Total Enclosed Water to Air Cooled) motor. - a TEWAC motor is the closest to a hermetic motor of any open motor type. In a TEWAC motor the heat from the motor is transferred to water flowing through a heat exchanger above the motor. This limits the amount of air brought into the motor and removes the heat from the space.

Mechanical Room Renovation
When you need to install equipment, move a pipe , paint or do some sort of renovation in mechanical room … should you turn your chillers off? No … Run risk that dirt, dust or debris in air will cause motor failure or shorten motor life. Yes … Turn chillers off and cover motor intakes. Provide temporary cooling or no cooling at all. - Open drive motors have fan blades built into the rotor. When the motor rotor spins, air is drawn in from the mechanical room and blown right through the motor. Any contaminants in the air (dirt, dust, debris) go into the motor. If you were renovating the mechanical room or working on an adjacent exposed space, should you shut down your chillers to prevent motor failure? Pause for a moment - is this even an option … to shut off cooling every time you do some work in the mechanical room that might release dirt, dust, debris into the air? Open motors have failed under such circumstances, but is York going to cover the motor under warranty if it fails under such conditions? Is that considered abuse? When you evaluate open and hermetic motors in a spec or purchase, do you think the owner understands the compromise he must accept if he chooses an open motor? He’ll never have to make tough choices like this with a semi-hermetic design.

Semi-Hermetic vs. Open Motors
Condensation on motor windings is normal. Moisture degrades insulation resistance. Starting a motor with moisture on its winding can cause insulation failure and require a rewind. To prevent condensation, motor winding heaters are energized any time motors are off. If power to motor and motor winding heaters is lost, a megger test should be performed to confirm insulation strength before starting. All of this costs money. Is your customer willing to pay?

Motor Heat Rejection Open motors reject heat to the facility space, which must be tempered (air conditioned) or ventilated to a maximum of 104F indoor ambient to assure design motor and starter life Since Evergreen chillers use semi-hermetic motors, there is no need to provide additional ventilation or tempering (air conditioning) of the mechanical room due to open motor designs. Note that open motors and standard electrical switchgear are designed for not higher than 104F ambient, otherwise equipment life is reduced, so this is not a trivial matter. (This is clearly stated in York’s O&M and Installation Instructions) The point is that the extra ventilation is not free, and the air conditioning load for a 1000 ton chiller is 8.5 tons. This air conditioning load and cost must be added to the building budget. Click on the Excel speadsheet to do this calculation for your specific project. Competitor Open Motor Drive Carrier Confidential

Motor Anti-Condensation Heaters
Open motors require no moisture intrusion at start up. Moisture in windings at start up/after power loss can cause motor failure. Megger motor test required $ for insulation checks by technician after idle periods Strip Winding Heater required to prevent moisture intrusion $ in motor heater equipment costs $$ yearly heater wattage costs Specification Phrase – “For chillers with open drives, provide motor with internal electric heater, internally powered from the chiller power supply”. Megger Motor Test A megger test is normally performed on chillers, even our hermetic type, on a regular basis, usually once a year. Generally it only takes about ½ hour to perform. It should always be performed on chillers that have been idle for a period of time (think about chiller rotation applications or spare chiller configurations). Megger tests measure the level of resistance due to insulation. Low insulation MAY result in motor burnout during start up. However, if the open motor has been sitting in a very humid environment, with no winding heaters, the motor may have picked up moisture and a megger shows a low resistance. Then it may mean that the motor needs to sit with a heater and heat lamps on it until the moisture is baked out. If that does not work, a trip for the motor to a motor shop for further analysis maybe required. This would be very unlikely with a hermitic as long as the machine is tight. Wattage Usage The point is that extra heat is needed whenever the machine is not in operation, to ensure moisture does not intrude into motor. This adds additional operating costs, creating a constant electricity cost for the chiller whether in operation or not (cooling the mechanical room during operation, heating the motor when inactive). The space heaters and operating costs must be added to the building budget. Click on the Excel spreadsheet to do this calculation for your specific project. Carrier Motors The power to cool our hermetic motors is included in the IKW/TON we quote for our chiller. The lack of exposure to air eliminates the need for heaters. Competitor Open Motor Drive

Water Cooled Oil Cooler
Requires regular maintenance (scaling/cleaning with acid solution) Additional failure modes created Oil in water (EH&S safety issue) Water in oil (catastrophic failure) Successful operation of Yorks’ Oil Cooler is dependent on factors such as extra maintenance required such as scaling (Additional Costs). Without regular maintenance, more catastrophic failures of your customer’s chillers can result such as: Water in the refrigerant circuit, which causes major damage to the entire chiller circuit (Possible EH&S Issue) Oil in water source (Definitely an EH&S Issue)

Additional Costs for Purchasing Open Drive Design
Efficiency Comparison 3% for open motor 4% for harmonic filter 1-3% refrigerant loss Maintenance and Operating Costs Weekly – check the shaft seal oil bottle 3-5 Year - Shaft Seal maintenance cost Yearly – Motor Air Filter maintenance cost As Necessary – Top off refrigerant charge As Necessary – Winding cleaning maintenance cost As Necessary – Possible Megger Motor maintenance check Yearly - Mechanical Room Cooling operating cost Yearly – Strip Heater operating cost Additional Unanticipated Costs Air Conditioner for Mechanical Room TEWAC Motor Harmonic Filter Storage Tank Sound Blanket Motor Heaters Ask your customers did they think about these additional costs and factor them into York’s spec?? NO DID YOU FACTOR AN ADDITIONAL $ IN COSTS FOR YOUR CHILLER

Open Drive vs. Hermetic Home refrigerator is a hermetic design
Automobile is an open design Which design requires more refrigerant to be added?

Advantages of Semi Hermetic Design

Hermetic Motor vs. Open Drive Motor
Semi-Hermetic Motor Refrigerant cooled motor keeps motor heat out of the mechanical room Saves $ to cool mechanical room Minimizes alignment, vibration and shaft seal maintenance of open motors Saves $ in maintenance and shaft seal replacement costs Refrigerant cooled motors operate in a clean, cool environment. Saves $ in motor repair costs Open drive motors have fan blades built into the rotor. When the motor rotor spins, air is drawn in from the mechanical room and blown right through the motor. Any contaminants in the air (dirt, dust, debris) go into the motor. If you were renovating the mechanical room or working on an adjacent exposed space, should you shut down your chillers to prevent motor failure? Pause for a moment - is this even an option … to shut off cooling every time you do some work in the mechanical room that might release dirt, dust, debris into the air? Open motors have failed But is York going to cover the motor under warranty if it fails under such conditions? . Open drive motors require additional maintenance post installation Known to have alignment and vibration issues over time (maintenance troubleshooting costs) With shaft seal refrigerant leaks or oil leaks come troubleshooting , repair and replacement costs Semi-hermetic motors are “plug and play”. Set it an forget it. Eliminates the need to provide additional ventilation or tempering (air conditioning) of the mechanical room due to open motor designs. TEWAC (Total Enclosed Water to Air Cooled) motor. - a TEWAC motor is the closest to a hermetic motor of any open motor type. In a TEWAC motor the heat from the motor is transferred to water flowing through a heat exchanger above the motor. This limits the amount of air brought into the motor and removes the heat from the space.

R134a Refrigerant Warranty
Carrier Corporation announces refrigerant warranty for all new centrifugal chillers sold in USA at Engineering Green Building Conference July 20, 2004. Warranty applicable for all Evergreen centrifugal chillers shipped after October 1, 2004. Carrier will cover refrigerant leaks above 0.1% for the first five years of operation and for the life of the chiller if the owner has a service contract with Carrier Commercial Service.

The Right Technology

Questions

Chiller Part Load Performance

What is Part Load? 90%, 80%, 70%… OR
Part load performance can be… Part load capacity 90%, 80%, 70%… OR Lower condensing temperature Condenser water off the tower (80, 75, 70 degrees…) Lower outdoor air temp (90, 85, 80 degrees…) Full load is defined as 100% load on design day! All other conditions are part load.

ARI 550-590 99% ARI Part Load Weighting Factors 1 =
IPLV OR NPLV = A B C D 1 99% 1% % % % ECWT WEIGHT % LOAD % % % % To evaluate part load performance, the standard suggests that chillers be run at 4 discrete points, 100%, 75%, 50% and 25% load. The chiller’s efficiency at each point is then given a weighting factor. The higher the weighting, the more it is assumed the chiller will run at this point. For example, it is assumed that the chiller will run very little at 100% load, but much of its time at 50%. Graphically it looks like this.

Chiller Energy Compressor Input kW ~ Mass Flow X Lift
Like pumps, chiller energy consumption is a function of mass flow and differential pressure. KW = Tons x Lift Compressor Input kW ~ Mass Flow X Lift Load Chiller Cooling Tower Compressor/Cycle Efficiency Comparing Compressor Power Consumption with Pump Power Consumption formula, we find them extremely similar. In a pump it is flow x head. Chiller is “mass flow” x lift. Mass Flow is the amount of refrigerant moving through the compressor, which correlates to tons. What is lift?

Lift Requires Energy Imagine carrying a backpack of bricks up 55 flights of stairs. 97 F Saturated Condensing Temperature 55 A simple analogy for lift is to think of a person who has to carry 100 lb cylinders up many flights of stairs. Each flight of stairs represents 1 degree F of lift. Now, you can see that it is a lot less work to walk 40 floors instead of 55 for example. The saturation suction temperature is what floor you start on, the saturated condensing temperature is what floor you stop. The lower the chilled water, the lower the floor you start … 42 F Saturated Suction Temperature

Refrigerant Temperature
For refrigerant to condense, it must be warmer than leaving condenser water. 95 F + 2F approach = 97F 95F 85F To boil, refrigerant must be colder than leaving chilled water. 44F – 2F approach = 42F 44F 54F Lift is saturated condensing temperature (SCT) minus saturated suction temperature (SST). SCT is dependent upon LEAVING condenser water temperature which is dependent upon ENTERING condenser water temperature and FLOW RATE. Saturated Suction Temperature is based off of LEAVING chilled water temperature. Note: VFDs on condenser pumps don’t make sense because they raise leaving condenser water temperature, therefore raise SCT and therefore raise Lift and therefore change compressor power. Note: Lowering chilled water temperature lowers the SCT and raises lift and therefore raises chiller compressor power. Refrigerant temperatures are based on leaving water temperatures! Lift = 97F-42F = 55F

Pressure Enthalpy Chart-LIFT
42 F / 40 PSI 95F /97 F / 120 PSI SAT. LIQUID SCT Heat Rejection 97 82 Pressure Compression Reduced Lift 42 Refrigerant Effect (Capacity) SST SAT. VAPOR Remember this class in college. Using this pressure enthalpy chart we can see that as we compress the gas we move up and to the right as we add pressure and heat. At lowe lift conditions, (click mouse) we see that we can take a shortcut across the top of the pressure enthalpy chart. We don’t move as far up or to the right, demonstrating that we are doing less work. Enthalpy 80F /82F Lift = Sat Condensing Temp – Sat Suction Temp Lift 1 = 97 – 42 = 55 deg F Lift 2 = 82 – 42 = 40 deg F BETTER!! Lower Lift = Less Work = Lower kW

Pressure Enthalpy Chart-PRESSURE
42 F / 40 PSI 95F /97 F / 120 PSI SAT. LIQUID SCT Heat Rejection 97 82 Pressure Compression Reduced Lift 42 Refrigerant Effect (Capacity) SST SAT. VAPOR Remember this class in college. Using this pressure enthalpy chart we can see that as we compress the gas we move up and to the right as we add pressure and heat. At lowe lift conditions, (click mouse) we see that we can take a shortcut across the top of the pressure enthalpy chart. We don’t move as far up or to the right, demonstrating that we are doing less work. Enthalpy 80F /82F / 90 PSI 59F /61F /60 PSI 60 PSI-40 PSI = 20 PSI. Sufficient differential to provide proper refrigerant flow, oil return, and efficient consistent operation. Lower Lift = Less Work = Lower kW

How centrifugals change speed
Ideal Fan Laws Dictate the relationship between speed, flow and lift Flow ~ V, A To increase flow, increase rotor speed (with fixed flow area) Lift ~ V2 To increase lift, increase speed Power ~ Flow x Lift ~ V3 Without LIFT reduction, speed can not reduce Flow Area V Diameter A reduction in LIFT allows a speed reduction. Lift is a function of the speed squared. Power is related to the speed cubed! All centrifugal chillers are subject to Ideal Fan Law – Minimum speed approximately 65%, IGV for remainder

SAVINGS FROM COLD CONDENSER WATER
Three 1400 ton Carrier 19XRV variable speed chillers Data Center Analyze savings operating chillers with 55 deg F versus 65 deg F and 75 deg F 0.13 $/kwh simple rate Net Present Worth Savings from 55 F vs… ECWT 65F 75F 20 year life cycle $217,550 $468,880

Additional Capacity Carrier Tons 85oF 80oF 75oF 70oF <65oF
643 630 630 Carrier capacity increases as condenser water temperature decreases Carrier 600 Tons 570 550 85oF 80oF 75oF 70oF <65oF With the lower entering condenser water temperature additional cooling capacity can also be achieved, which can be significant on some applications when the interior cooling load does not vary with outdoor wet bulb temperatures. Entering Condenser Water Temperature

Questions

Chiller Heat Recovery Instead of rejecting heat to the condenser water loop, why not use this heat?

Heat Recovery Benefits
Chillers can transfer heat for as little as 25% of the cost required to create heat with a boiler.

Hot Water Systems How can we capture sufficient heat for useful purposes? Building Heat Service Hot Water Process Heat

Why Heat Recovery? ASHRAE 90.1-2004
Heat Recovery for Service Water Heating, Section § Operates 24 hours a day Total heat rejection exceeds about 400 tons of chiller capacity Service water-heating load exceeds 1,000,000 Btu/h 1,000 bed nursing home or 75 room full service hotel Provide the smaller of: 60% of the peak heat rejection load at design conditions or preheat of the peak service hot water draw to 85°F. Exceptions: Minimum 30% recovery from condenser water heat for space heating 60% or more of service water heating from site solar or cogeneration, condensate subcooling, or solar panels.

Condenser Water Heat Recovery
HEX Captures Condenser Water Heat “Wasted” Heat for Service Hot Water Make-up 85°F Make-up Water Caution: Higher LCWT Increases Chiller Lift, Reduces Efficiency Heat Out Heat Out Heat In

Over $100,000 per year in energy savings!!
Confirming Savings Real World Example i-Vu® Controls on 30XW Heat Machine at Charlotte Factory 30XW Over $100,000 per year in energy savings!!

Questions

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