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Transcript of 1 Optimal Control of Chiller Condenser Sub-cooling, Compressor Speed, Tower Fan and Pump Speeds, and...
1
Optimal Control of Chiller Condenser Sub-cooling, Compressor Speed, Tower Fan and Pump Speeds, and IGV
Omer Qureshi, Hassan Javed & Peter Armstrong, June 2013
btrc.masdar.ac.ae
2
Presentation Outline
Introduction SCADA and Heat Balance Analysis Component Models Chiller System Solver Optimization Conclusion and Future Work
3
Introduction
Plant under consideration-(4x2500T).
Collection and analysis SCADA
Development of sub models for Individual chiller components
Validation of model
Development of solver- to execute these sub models and predict
chiller performance.
Optimize the model to produce set of conditions for optimum
power consumption.
4
District Cooling Plant
Selected District cool Plant
Capacity (4x2500T)
Shell and tube Evaporator and Condenser
Constant speed single stage centrifugal compressor
Capacity control by Pre-rotation vanes
Surge control Variable geometry diffuser
2-cell cooling tower each with variable speed fan (Fan diameter: 8m)
Variable speed chilled water pump
Constant speed condenser water pump
5
Chiller Unit
1. Maintenance manual of York Chiller(Source: Tabreed)
6
SCADA & Heat Balance Analysis
7
Components Models—Chiller Unit
Steady-state models based on first principleInputs
Component engineering parametersSCADA Data
Simple models, less computation timeFour Component models for district cooling plant
Evaporator Model----Shell and tubeCondenser Model----Shell and tubeCentrifugal Compressor Model (Isentropic work + loss Mechanism) • Constant speed• Variable speed
Variable speed pump model
8
Evaporator Model
ENGINEERING PARAMETERS
Tubes Copper
Length of shell 6.6 m
Tube Pass (water) 2
Total no. of tubes 1234
Tube Diameter 0.75" or 1.905x10-2 m
Tube thickness 0.028" or 7.11x10-4 m
Assumptions:
No pressure drop considered for refrigerant side
Thermal resistance from refrigerant side is neglected.
9
Evaporator Model
Evaporation Evaporation Superheating
Evaporator
Two regions for refrigerant were modeled:EvaporationSuperheating𝞮 – NTU MethodSingle Stream HX for evaporationCrossflow HX for super heating
1st Pass 2nd Pass
𝑇𝑤 ,𝑜𝑢𝑡 ,1 𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑎 𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑏
10
Evaporator Model
Equations utilized in Evaporator Model
h 𝑖𝑛 ,𝑒=0.023𝑅𝑒𝑒0.8𝑃𝑟
0.4 𝑘𝑤
𝐷𝑒 ,𝑖
𝑈𝐴𝑒=1
1𝐴𝑖𝑛 ,𝑒h𝑖𝑛 ,𝑒
+𝑅𝑃 ,𝑒
�̇�𝑚𝑖𝑛¿min [𝑐𝑝 ,𝑤�̇�𝑤 ,𝑒¿ ,𝐶𝑝 , 𝑟 �̇�𝑟 ]¿
𝐴𝑖𝑛 ,𝑒 ,1=𝜋 𝐷𝑒 ,𝑖𝐿𝑒(𝑁¿¿𝑒 /2)¿𝐴𝑖𝑛 ,𝑒 ,1𝑎=𝜋 𝐷𝑒 ,𝑖 𝑥𝑒𝐿𝑒(𝑁𝑒 /2)𝐴𝑖𝑛 ,𝑒 ,1𝑏=𝜋 𝐷𝑒 , 𝑖¿
𝑇𝑤 ,𝑜𝑢𝑡 ,𝑒=𝑇𝑤 ,𝑖𝑛 ,𝑒−𝑄𝑡 ,𝑒
𝑐𝑝 ,𝑤𝑚𝑤
Evaporation Evaporation Superheating
11
Evaporator Model
Equations utilized in Evaporator Model
𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑎=𝑇𝑤 ,𝑜𝑢𝑡 ,1−(𝑇𝑤 ,𝑜𝑢𝑡 ,1−𝑇 𝑒) (1−𝑒−𝑁𝑇𝑈𝑒 ,2 𝑎 )
𝜀2𝑏=1−𝑒𝑥𝑝 [( 1𝐶𝑟 ) (𝑁𝑇𝑈𝑒2𝑏)0.22{exp [−𝐶𝑟 (𝑁𝑇𝑈𝑒 ,2𝑏)0.78 ]−1}]𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑏=𝑇𝑤 ,𝑜𝑢𝑡 , 2𝑎−𝜀2𝑏(𝑇𝑤 ,𝑜𝑢𝑡 , 2𝑎−𝑇𝑒)
𝑇𝑤 ,𝑜𝑢𝑡 ,1=𝑇𝑤 ,𝑖𝑛 ,𝑒−(𝑇𝑤 ,𝑖𝑛 ,𝑒−𝑇𝑒) (1−𝑒− 𝑁𝑇𝑈𝑒1 )
𝐿𝑒=8.947 𝑥 10−3�̇�𝑟
2−3.6279𝑥 10−1�̇�𝑟❑+7.227
Equation for regressed length:
Equation for temperatures:
12
Evaporator Model
1. Maintenance manual of York Chiller(Source: Tabreed)
13
Evaporator Model
1.5 2 2.5 3 3.5 41.5
2
2.5
3
3.5
4
Measured Te (C)
Mod
eled
T
e (C
)
Measured Te (C) vs Modeled Te (C)
Measured Te (C)15% error line
-15% error line
RMS 0.2096 C
NRMS 0.0319
14
Condenser Model
ENGINEERING PARAMETERS
Tubes CopperLength of shell 6.6 mTube Pass (water) 2Total no. of tubes 937Sub-cooling Section:Tube Diameter 0.75" or 1.905x10-2 mNo. of tubes 180Tube thickness 0.028" or 7.11x10-4 mTube Surface Area 66.78 m2 Condensation & de-superheating Section:Tube Diameter 1" or 2.54x10-2 mNo. of tubes 757Tube thickness 0.035" or 8.89x10-4 mTube Surface Area 376.44 m2
Assumptions:
No pressure drop considered for refrigerant side
Thermal resistance from refrigerant side is neglected.
15
Condensation
Sub-cooling
Conden-sation
De-superheating
Condenser
Condenser Model
Three regions for refrigerant were modeled:
Sub-cooling
Condensation
De-Superheating𝞮 – NTU Method
1st Pass 2nd Pass
𝑇𝑤 ,𝑚𝑖𝑥 ,𝑐𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑎 𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑏
16
Equations utilized in Condenser Model
1a. Sub-Cooling Section(First Pass):
Condenser Model
h 𝑖𝑛 ,𝑐 , 1𝑎=0.023𝑅𝑒𝑐 10.8𝑃𝑟❑
0.4 𝑘𝑤
𝐷𝑐 1 ,𝑖
𝑈𝐴𝑐 , 1𝑎=1
1𝐴𝑖𝑛 , 𝑐, 1𝑎h 𝑖𝑛 ,𝑐 , 1𝑎
+𝑅𝑃 , 𝑐 ,1𝑎
𝜀𝑐 ,1𝑎=1−𝑒−𝑁𝑇𝑈𝑐 ,1𝑎 (1−𝐶𝑟 ,1 𝑎 )
1−𝐶𝑟 , 1𝑎𝑒−𝑁𝑇𝑈𝑐 ,1 𝑎(1−𝐶𝑟 ,1 𝑎)
𝑇 𝑐𝑠=𝑇 𝑐 2−𝜀𝑐, 1𝑎𝐶𝑚𝑖𝑛 ,1𝑎(𝑇 𝐶 2−𝑇𝑤 ,𝑖𝑛 , 𝑐)
�̇�𝑟 𝑐𝑝 ,𝑟
𝑇𝑤 ,𝑜𝑢𝑡 ,1𝑎=𝑇𝑤 , 𝑖𝑛 ,𝑐+�̇�𝑟 𝑐𝑝 ,𝑟 (𝑇 𝐶 2−𝑇 𝑆𝐶)�̇�𝑤 ,𝑐𝑥1 ,𝑎𝑐𝑝 ,𝑤
17
1b. Condensation Section (First Pass):
Mixing Section:
Condenser Model
h 𝑖𝑛 ,𝑐 , 1𝑏=0.023𝑅𝑒𝑐 1𝑏0.8𝑃𝑟❑
0.4 𝑘𝑤𝐷𝑐 2 , 𝑖
𝑈𝐴𝑐 , 1𝑏=1
1𝐴𝑖𝑛 , 𝑐 ,1𝑏h𝑖𝑛 ,𝑐 ,1𝑏
+𝑅𝑃 , 𝑐 ,1𝑏
𝑁𝑇𝑈 𝑐 ,1𝑏=𝑈𝐴𝑐 ,1𝑏
�̇�𝑚𝑖𝑛,𝑤
𝑇𝑤 ,𝑜𝑢𝑡 ,1𝑏=𝑇𝑤 ,𝑖𝑛 ,𝑐+𝑥𝑐𝑎�̇�𝑟 (𝐻𝐶2−𝐻𝐶 3)
�̇�𝑤 ,𝑐(1−𝑥¿¿1𝑎)𝑐𝑝 ,𝑤 ¿
𝑇𝑤 ,𝑚𝑖𝑥 ,𝑐=�̇�𝑤 ,𝑐𝑥1 ,𝑎𝑇𝑤 ,𝑜𝑢𝑡1 ,𝑎−�̇�𝑤 ,𝑐
(1−𝑥¿¿1𝑎)𝑇𝑤 ,𝑜𝑢𝑡 1𝑏
�̇�𝑤 ,𝑐
¿
18
2a. Condensation Section (Second Pass):
2b. De-superheating Section (Second Pass):
Condenser Model
h 𝑖𝑛 ,𝑐 , 2𝑎=0.023𝑅𝑒𝑐 2𝑎0.8𝑃𝑟❑
0.4 𝑘𝑤
𝐷𝑐 2 ,𝑖
𝑈𝐴𝑐 , 2𝑎=1
1𝐴𝑖𝑛 , 𝑐 ,2𝑎h𝑖𝑛 , 𝑐 ,2𝑎
+𝑅𝑃 ,𝑐 , 2𝑎𝑁𝑇𝑈 𝑐 ,2𝑎=
𝑈𝐴𝑐 , 2𝑎
�̇�𝑚𝑖𝑛,𝑤
𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑎=𝑇𝑤 ,𝑚𝑖𝑥 ,𝑐+𝑥𝑐𝑏�̇�𝑟𝑐𝑝 ,𝑟 (𝐻𝐶 2−𝐻𝐶 3)
�̇�𝑤 ,𝑐𝑐𝑝 ,𝑤
𝑇𝑤 ,𝑜𝑢𝑡 ,2𝑏=𝑇𝑤 ,𝑜𝑢𝑡 2𝑎+�̇�𝑟𝑐𝑝 , 𝑟 , 2𝑏(𝑇 𝐶1−𝑇 𝐶 2)
�̇�𝑤 ,𝑐𝑐𝑝 ,𝑤
19
Condenser Model
22 24 26 28 30 32 3422
24
26
28
30
32
34
Measured Tc (C)
Modele
d
Tc (
C)
Measured Tc (C) vs Modeled Tc (C)
Measured Tc (C)2.5% error line
-2.5% error line
RMS 0.0949 C
NRMS 0.0225
20
Condenser Model
20 25 30 3520
25
30
35
Measured Tw.out (C)
Mod
eled
T
w,o
ut (
C)
Measured Tw,out (C) vs Modeled Tw,out (C)
Measured Tw,out (C)5% error line
-5% error line
RMS 0.6481 C
NRMS 0.1471
21
Compressor Model
Integral and mathematically most complex part of chillerConstant and variable speed compressor modelNon-Dimensional loss model based on Aungier(2000)
Assumptions
• Gear efficiency is taken as 90%
• Velocity profile is assumed as constant, along the hub and tip
• The kinetic energy of refrigerant entering the diffuser is completely converted to useful energy
• Diffuser and IGV losses are not modeled
• Water flow rate for motor cooling is taken as constant
• Complex engineering parameters in impeller geometry
Centrifugal Compressor Specification
Refrigerant R134A
Rating (Btuh) 2500
Rating (kW input) 1817
Rating discharge pressure (psig) 162
Rating suction pressure psig) 34
Rating suction temperature (F) 33/34
Impeller diameter (outlet diameter) m 0.7
Impeller hub diameter (inlet diameter) 0.3
Impeller Blade Angle (degree) 45/50
22
Constant Speed Model
Variable speed Model
Compressor Model-Inputs and Outputs
Input Output
Mass flow rate of refrigerantInlet and outlet pressure of compressorInlet and outlet blade and velocity angles of impeller Impeller Inlet and outlet engineering parameters and dimensionsGear efficiency
Compressor Power Compressor RPMPressure at impeller exitTemperature at compressor outletPressure drop due to Impeller losses
Input Output
IGV PositionsConstant RPMInlet and outlet pressure of compressorInlet and outlet blade and velocity angles of impeller Impeller Inlet and outlet engineering parameters and dimensionsGear efficiency
Compressor Power Pressure at impeller exitTemperature at compressor outletPressure drop due to Impeller losses
23
Validation Constant Speed Compressor Model
0 200 400 600 800 1000 1200 14000
200
400
600
800
1000
1200
1400
1600
No. of Observations
Cop
mre
ssor
Pow
er (
KW
)
Actual Power(kW)Model Power(kW)Loss Power(kW)Model Comp Power(kW)
24
Validation Constant Speed Compressor Model
400 600 800 1000 1200 1400 1600400
600
800
1000
1200
1400
1600
Measured Power(kW)
Mod
el P
ower
(kW
)
Measured Power(kW) vs Model Power(kW)
Measured Power(kW)10% Error line
-10% Error lineRMS 108.34 KW
NRMS 0.1553
25
Variable Speed Compressor Model
𝐼𝑠𝑒𝑛𝑡𝑟𝑜𝑝𝑖𝑐 𝑊𝑜𝑟𝑘 = 𝑤𝑖𝑠𝑒𝑛 = − 1 𝑃1𝜌1 ൬𝑃3𝑃1൰
−1ൗ�− 1 𝜂𝑔𝑒𝑎𝑟൘
𝑀𝑎𝑠𝑠 𝐹𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑜𝑓 𝑟𝑒𝑓𝑟𝑖𝑔𝑒𝑟𝑎𝑛𝑡= 𝑚ሶ= 𝜙2𝐴2𝑈2𝜌2
RPM is calculated in an iterative process by satisfying the following equation
𝑟𝑒𝑠𝑢𝑙𝑡 = 𝑚ሶ𝑠𝑐𝑎𝑑𝑎 − 𝑚ሶ𝑐𝑎𝑙
Total Work
𝑊𝑎𝑐𝑡 = 𝑊𝑐𝑜𝑚𝑝 + 𝑊𝑙𝑜𝑠𝑠
𝑊𝑙𝑜𝑠𝑠 = ∆𝑃𝑡𝑟𝑉𝑟
Total Relative Pressure Drop (Due to Losses)
∆𝑃𝑡𝑟 = 𝑓𝑐(𝑃𝑡𝑟1 − 𝑃𝑠1) ഥ𝑖𝑖
Loss Model Calculations
26
Variable Speed Compressor Model-Benefits/comparison
Variable Speed Compressor (KW)Measured Compressor Power (KW)
Com
pres
sor P
ower
(KW
)
No. of Observations
Operation Conditions:1. mr (kg/s)2. Pout/Pin
Power (KW) 1504.702IGV Position 44.2
27
Impeller Loss Model
𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝐿𝑜𝑠𝑠= 1− 𝑉𝑚1𝑊1 sinሺ𝑚1ሻ൨2 + 𝑡𝑏1𝑍2𝑟𝑚1 sinሺ𝑚1ሻ൨
2
𝐷𝑖𝑓𝑓𝑢𝑠𝑖𝑜𝑛 𝑙𝑜𝑠𝑠= 0.81− 𝑊1𝑇ℎ𝑊1 ൨2 − 𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝐿𝑜𝑠𝑠
𝑆𝑘𝑖𝑛 𝐹𝑟𝑖𝑐𝑡𝑖𝑜𝑛 𝐿𝑜𝑠𝑠= 4𝑐𝑓ቆ𝑊ഥ𝑊1ቇ2 𝐿𝐵𝐷𝐻
𝐵𝑙𝑎𝑑𝑒 𝐿𝑜𝑎𝑑𝑖𝑛𝑔 𝐿𝑜𝑠𝑠= (∆𝑊 𝑊1)Τ 224
𝐸𝑥𝑝𝑎𝑛𝑠𝑖𝑜𝑛 𝐿𝑜𝑠𝑠= ቈሺ − 1ሻ𝑉𝑚2𝑊1 2
𝐶𝑙𝑒𝑎𝑟𝑎𝑛𝑐𝑒 𝐺𝑎𝑝 𝐿𝑜𝑠𝑠= 2𝑚ሶ𝐶𝐿∆𝑃𝐶𝐿𝑚 ሶ1𝑊12
𝐻𝑢𝑏− 𝑆ℎ𝑟𝑜𝑢𝑑 𝐿𝑜𝑠𝑠= (ത𝑚𝑏ത𝑊ഥ 𝑊1)Τ 26
28
Variable Speed Compressor Model-losses profile
20 25 30 35 40 45 500
20
40
60
80
100
120
Refrigerant Mass Flow (kg/s)
Pre
ssu
re D
rop
(kP
a)
Clearance gap loss (kPa)Diffusion loss (kPa)Hub-shroud Loss (kPa)Incident loss (kPa)Skin friction loss (kPa)Blade Loading Loss (kPa)Expansion Loss (kPa)
29
Effectiveness NTU Method
Cooling Tower Model
𝐻𝑒𝑎𝑡 𝑅𝑒𝑗𝑒𝑐𝑡𝑒𝑑= 𝑄𝑟𝑒𝑗𝑒𝑐𝑡𝑒𝑑 = 𝑚𝑤ሶ∗𝑐𝑝𝑤 ∗ሺ𝑇𝑐𝑤𝑠− 𝑇𝑐𝑤𝑟ሻ 𝐶𝑜𝑜𝑙𝑖𝑛𝑔 𝑇𝑜𝑤𝑒𝑟 𝑅𝑒𝑡𝑢𝑟𝑛 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒= 𝑇𝑐𝑤𝑠− 𝑄𝑟𝑒𝑗𝑒𝑐𝑡𝑒𝑑𝑚𝑤ሶ∗𝑐𝑝𝑤
𝑄𝑟𝑒𝑗𝑒𝑐𝑡𝑒𝑑 = ∗𝐶ሶ𝑚𝑖𝑛 ∗ሺ𝑇𝑐𝑤𝑠− 𝑇𝑤𝑏ሻ = 1− 𝑒−𝑁𝑇𝑈(1−)1− 𝑒−𝑁𝑇𝑈(1−)
𝑁𝑇𝑈= 𝑚_𝑤ሶ𝑚_𝑎ሶ 𝑀𝑒𝑀
𝑀𝑒𝑀= 𝐾 ∗𝑎∗𝑉𝑚_𝑤ሶ
𝑀𝑎𝑠𝑠 𝐹𝑙𝑜𝑤 𝑜𝑓 𝐴𝑖𝑟= 𝑚_𝑎ሶ = 𝑉𝑚𝑎𝑥ሶ ∗𝜌𝑎 ∗𝑓
Regression Coefficient
30
Assumptions, Specifications and Input/ Output Variables
Cooling Tower Model
Assumptions
• Air exiting the tower is saturated with water
vapor and is only characterized by its
enthalpy
• Reduction of water flow rate by evaporation is
neglected in the energy balance.
• Mass flow rate is calculated by considering
linear proportionality of mass flow rate of air
and motor speed.
Inputs Outputs
• Wet-bulb temperature• Cooling tower supply water temperature• Dry-bulb temperature • Mass flow rate of water• Cooling tower fan/motor speed
• Cooling tower return water temperature• Merkel’s Number
Cooling Tower Specifications
Rating (RT) 5000
Rating flow rate (GPM) 15300
Rating ambient wet bulb (F) 86
Rating ambient dry bulb (F) 122
Rating entering condenser water
temperature (F)
105
Fan diameter and speed (m, RPM) 8/152.6
Air flow rate (CFM) 776383
31
Cooling Tower Model
32
Pump Model
Mainly there are two mode of operation for these pumps:
Constant flow pump
Variable flow pump with a variable speed drive
To model a variable pump power following relationship is used:
Where,PMP = pump motor power at rated condition, kWC1, C2, C3 and C4 are pump performance coefficients
Also,PLRi = pump part load ratio defined as follows:
33
Pump Model
Validation Graph
+ 5%Error Line
34
Solver Description
Qt,e
Tw,in,e
Tw,in,c
Ve
Vc
dTsh,e
35
Optimization
Optimization performed with two configurations:
Chiller Water Flow Optimization
Chiller Water Flow And Condenser Water Flow Optimization
Objective Function:
Minimize total power consumption i.e. compressor power and pump(s)
power combined.
36
Optimization
Chiller Water Flow Optimization:
Vc Vc Vc VcQe 10000 KW Qe 8000 KW Qe 6000 KW Qe 4000 KW
Power Total (KW)
Ve (m3/s)
COPPower
Total (KW)Ve
(m3/s)COP
Power Total (KW)
Ve (m3/s)
COPPower
Total (KW)Ve
(m3/s)COP
2791.90 0.1419 3.58 1768.81 0.1419 4.52 1102.50 0.1419 5.44 649.15 0.1419 6.162494.66 0.1774 4.01 1617.53 0.1774 4.95 1032.45 0.1774 5.81 626.16 0.1774 6.392325.43 0.2129 4.30 1535.14 0.2129 5.21 997.69 0.2129 6.01 622.12 0.2129 6.432226.70 0.2484 4.49 1492.30 0.2484 5.36 988.83 0.2484 6.07 633.21 0.2484 6.322171.34 0.2839 4.61 1476.36 0.2839 5.42 998.06 0.2839 6.01 657.75 0.2839 6.082145.79 0.3194 4.66 1483.94 0.3194 5.39 1023.13 0.3194 5.86 695.26 0.3194 5.752149.01 0.3548 4.65 1512.07 0.3548 5.29 1065.53 0.3548 5.63 746.65 0.3548 5.362177.04 0.3903 4.59 1559.59 0.3903 5.13 1122.92 0.3903 5.34 811.97 0.3903 4.932227.85 0.4258 4.49 1623.07 0.4258 4.93 1197.94 0.4258 5.01 892.40 0.4258 4.482300.43 0.4613 4.35 1708.17 0.4613 4.68 1288.91 0.4613 4.66 988.98 0.4613 4.042389.48 0.4968 4.19 1809.82 0.4968 4.42 1397.89 0.4968 4.29 1103.05 0.4968 3.63
Tw,in,c = 25 C and Tw,in,e = 14 C0.4795 m3/s 0.4795 m3/s 0.4795 m3/s0.4795 m3/s
37
Optimization
Chiller Water Flow And Condenser Water Flow Optimization:
Qe = 10,000 kWVe,opt = 0.349 m3/sVc,opt = 0.408 m3/s
Tw,in,e = 14 C; Tw,in,c = 25 C
Vc (m3 /s)
Vc (m 3/s)
Tota
l Pow
er (K
W)
38
Optimization
Chiller Water Flow And Condenser Water Flow Optimization:
Qe = 8,000 kWVe,opt = 0.296 m3/sVc,opt = 0.355 m3/s
Tw,in,e = 14 C; Tw,in,c = 25 C
Vc (m3 /s)
Vc (m 3/s)
Tota
l Pow
er (K
W)
39
Optimization
Chiller Water Flow And Condenser Water Flow Optimization:
Qe = 6,000 kWVe,opt = 0.249 m3/sVc,opt = 0.332 m3/s
Tw,in,e = 14 C; Tw,in,c = 25 C
Vc (m3 /s)
Vc (m 3/s)
Tota
l Pow
er (K
W)
40
Optimization
Chiller Water Flow And Condenser Water Flow Optimization:
Qe = 4,000 kWVe,opt = 0.205 m3/sVc,opt = 0.251 m3/s
Tw,in,e = 14 C; Tw,in,c = 25 C
Vc (m3 /s)
Vc (m 3/s)
Tota
l Pow
er (K
W)
41
Optimization
Chiller Water Flow And Condenser Water Flow Optimization:
Tw,in,e = 14 C; Tw,in,c = 25 C
42
Optimization
Chiller Water Flow And Condenser Water Flow Optimization:
43
Conclusions
Variable Speed compressor provide savings of 30-40%
Variable speed pump for water circulation play an imperative role in
reducing overall power consumption of chiller plant.
Modeling of chiller components can be performed with limited
engineering information from manufactures.
44
Future Work
More rigorous compressor loss model
Transient model for the condenser and evaporator
Cooling tower Model
Variable Speed condenser pump
Investigate the effect of pressure drop and resistance from
refrigerant side
45
Q&A
45