Apr 05, 2018
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Chiller Efficiency Chiller efficiency is measured in Kilowatts per ton (Kw/Ton) of coolingproduced. The higher the Kw/Ton, the lower the heat transfer efficiency andthe higher the cost to produce a ton of cooling.
Chiller Log Sheet A sheet on which specific chiller readings are documented.
Chiller Manufacturer The company that built the chiller, i.e., York, Trane, Carrier, McQuay, etc.The manufacturer name is typically prominently displayed on the chillercontrol panel or technical documentation.
Chiller Stall A chiller stalls when the refrigerant is no longer moving through thecompressor and there is no cooling effect. All shaft work is being convertedinto heat in the compressor that may lead to permanent damage.
Chiller Startup The chiller manufacturers recommendation on startup including pre-heating
the compressor oil temperature prior to chiller startup.Chiller Surge When the refrigerant flows backwards through the compressor wheel every
few seconds until the pressure builds up and the refrigerant moves forwardagain. This is even more dangerous than a stall because it reverses loads ofthrust bearings in the compressor shaft.
(Inlet Guide Vanes)Chiller vanes are used to control the capacity of the compressor. As the inletguide vanes start to close, they change the gas entry angle to the impellerand reduce gas flow and compressor capacity. As the vanes near the closedposition, they throttle the refrigerant flow.
The evaporator side of the chiller system, closed to the atmosphere.
Compressor A mechanical device where the refrigerant is compressed from a lowerpressure and lower temperature to a higher pressure and higher temperature.The compressor maintains a low pressure in the evaporator by continuallyremoving refrigerant vapors. This low pressure, low temperature vapor isthen compressed into a higher pressurize, hot refrigerant vapor which leavesthe compressor and travels to the condenser. The motor in the compressor isthe main consumer of energy in the chiller system. The energy used by thecompressor is dependent on the pressure increase. The head pressure dividedby the suction pressure or the condenser pressure divided by the evaporator
pressure expresses this. If the compressor operates out of its original design,it will effect the energy consumption.
Damage to the bearings and impeller caused by poor lubrication, low oillevels or operating conditions such as liquid refrigerant carryover into thecompressor system.
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Compressor Motor Amps The energy used to power the refrigerant cycle in a chiller system. The inputenergy is dependent upon the pressure increase in the compressor. The headpressure divided by the suction pressure or the condenser pressure dividedby the evaporator pressure determines it.
TemperatureCompressor oil temperature is the temperature of the oil in the compressorbearing lubrication system. This temperature is predetermined bymanufacturers specifications.
Condensation The process a vapor goes through to change phase from vapor to a liquid.
Condenser Heat exchanger where the system heat is rejected and the refrigerantcondenses into a liquid. The condenser is where hot pressurized refrigerantvapors in the compressor are cooled and liquefied by cooling tower watercirculating through the tubes of the condenser. The condenser side is
commonly referred to as the open recirculation system or open loop.
Condenser Delta P The pressure drop between the suction side and the discharge side of achiller barrel. This pressure drop can be measured against known valuesfrom tables/charts to determine water flow through the chiller barrel. Delta Pis dependant on chiller tube ID and tube length.
Condenser Delta T The temperature difference between the entering and leaving water throughthe chiller barrel. i.e., the entering temperature is 85F and the leavingtemperature is 95F then the delta T would be 10.
Condenser Water GPM(Gallons Per Minute)
The velocity of the condenser water measured in gallons per minute. All
chiller condensers have a manufacturers design GPM flow rate.Condenser Pressure The head pressure produced in the condenser dependent on the entering
condenser water temperature and the saturated refrigerant temperature. Thecondenser pressure can affect the refrigerant cycle and heat transfer. Thepressure correlates to saturated refrigerant temperature on apressure/temperature chart for each refrigerant type.
Approach Temperature The refrigerant temperature minus the leaving water temperature. Therefrigerant temperature can be determined by locating the condenser (head)pressure on a pressure/temperature chart, or if the chiller control panelprovides this information.
Condenser Water The open recirculating system connects the chiller condenser to the coolingtower system and the atmosphere. Condenser water is subject toevaporation, debris/contamination, fouling/scaling and microbio growth.
Conditioned Fluid The fluid being acted upon by the working fluid. Example: in an airconditioning system the air is conditioned by the refrigerant (refrigerant isthe working fluid).
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Constant Speed Drive Constant speed drives are the most common type of chiller compressormotor. They have limited ability to adjust speed based on part loadconditions.
Contamination Any foreign object or substance not normally found in a specific location.
Cooling Tower Where the process of heat exchange occurs by evaporation in the openrecirculating system. The cooling tower system includes tower fans, plenum,drift eliminators, fill, levelers, hot deck and cold basin. All cooling towershave a design rated delta temperature.
Cooling TowerApproach Temperature
The difference between the leaving water temperature and the entering airwet bulb.
Cooling Tower Fan Fan system designed to remove the heat generated by the open recirculating
system through evaporation.Cooling Tower Fill Designed to brake up the circulating water into smaller particles or a thin
film. This increases the surface area of the water to enhance evaporation andheat removal.
SystemThe cooling tower system includes tower fans, plenum, drift eliminators, fill,levelers, hot deck and cold basin combined with the condenser barrel andpiping making up the open loop or open recirculating system.
Corrosion The decay and loss of a metal due to a chemical reaction between the metaland its environment. It is a transformation process in which the metal passesfrom its elemental form to a combined (or compound) form.
Cost of Blowdown The total cost of water sent to drain/sewer, typically determined on a per1,000 gallon basis. This value can be found on the water and sewer utilitybill or from the utility company.
Cost of Kw The cost of electricity charged by the electric and is typically $0.04 to $0.15per kilowatt depending on geographic location.
Cost of Makeup The total cost of water added to the condenser/cooling tower system,typically determined on a per 1,000 gallon basis. This value can be found onthe water and sewer utility bill or from the utility company.
CPLV Calculated Part
The calculated Kw/Ton derived from the effect of part load and enteringcondenser water temperature on the chiller when compared to full loaddesign.
Dead Leg A static condition that exists over a period of time in equipment or systemthat has no water flow. This condition is usually associated with lay-up andcan promote the growth of microbes and corrosion.
Debris Anything the environment can introduce that is washed out by the toweroperations, i.e., dirt, trash, chip scale flash corrosion, bugs, broken towerfill, broken tower wood, plastic, etc.
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Delta P The pressure drop between the discharge side and the suction side of achiller barrel. This pressure drop can be measured against design valuesprovided by the chiller manufacturer or previously developed charts by plantpersonnel to determine water flow through the chiller barrel.
Delta T The temperature difference between the entering and leaving water throughthe chiller barrel, i.e., entering temperature is 85F, leaving temperature is95F = delta T10F. If the actual water flow is known, delta P coulddetermine a problem if the actual delta P does not match the current waterflow.
Design Amps (Full Load) The maximum amp load on the chiller. This information can be found in thechiller technical documentation.
Design Condenser Delta T The temperature difference between the entering and leaving water through
the chiller barrel when the chiller is running at full load, i.e., the enteringtemperature is 85F and the leaving temperature is 95F then the delta Twould be 10. Modern high efficiency chillers are designed to run at 9.4Fdelta T at 3gpm/ton.
Design CondenserRefrigerant Approach
The difference between the condenser water out temperature and thecondenser leaving refrigerant temperature at design full load. Thisinformation can be found in the chiller technical documentation.
Design Condenser Water
GPMBelow is a list of design GPM ratings based on the chiller design delta T.- Entering Water Temperature: 85F- Delta T Range: 10