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Effectiveness of RetrofittingIce Slurry Thermal Energy Storagefor an Urban Hospital Chiller Plant
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Effectiveness of Retrofitting
Ice Slurry Thermal Energy Storage
for an Urban Hospital Chiller Plant
Stan RottMarketing DirectorIDE Technologies
Executive Summary
The main purpose of this study is to investigate the effectiveness
of the retrofitting of an ice slurry storage system for the existing
central chiller plant of a large size hospital.
The study is also focused on improvement of the hospital’s
chiller plant efficiency as well as reduction of the annual electric
cost by application of an ice slurry Thermal Energy Storage (TES)
system utilizing water vapor as the primary refrigerant.
The results are a nearly FLAT monthly Peak Demand curve, which
allows for a reduction of about 2,000 kW (~30%) compared to
the hospital’s current recorded Peak Demand data.
Objectives
� Assess hospital’s current specific power consumption
� Isolate base load not related to comfort cooling
� Estimate existing chiller plant efficiency
� Evaluate chiller plant power consumption after retrofitting
with ice slurry TES, based on one Vacuum Ice Maker (VIM)
with a rated capacity of 1,000 Tons
� Compare current power consumption with the projected
power consumption after retrofit
� Quantify monthly and annual electric savings resulting
from the retrofitting of the chiller plant with TES
� Estimate the required scope of work
Existing Conditions
� Hospital Chiller Plant
• 4 x 1,000 Tons
• 3 x 1,000 Tons by Trane, plus 1 x 1,000 Tons by York
• Chiller plant age: ~26 years
• Critical application areas: Clean rooms & Surgery
• 2 x 75 Tons
• 1 x 35 Tons
• Several 5 Ton units
• Chiller plant capacity: ~4,200 Tons
• Estimated specific power consumption: ~1.1 kW/Ton
VIM & TES Reservoir
Preliminary Site Survey
1. VIM will be installed on
the rooftop
2. Rooftop structure may
need to be reinforced
3. TES Tank has no
limitation in terms of
shape, form or materials
of construction
Hospital building crawl space
would be retrofitted as a TES
Tank with total approximate
volume of 150,000 ft3 and
stored cooling capacity of
about 50,000 Ton-hours
Retrofit Scope:
• Application of a waterproof liner
• Buffer reservoir & associated piping
Design Consideration
� Storage Type
• Daily/Weekly
• Seasonal
� Tariff Structure
• Peak Demand
charges
• Peak vs. Off-peak
billing periods
� Control Strategy
• Peak Demand
reduction
• Peak Demand set
point control
Preliminary Data Analysis� Hospital’s Power Consumption Data: hourly meter reading
• October, 2009 to October, 2010
� Highest Annual Electric Peak Demand
• July 6th: 6,054 kW
Preliminary Data Analysis� Annual Load Duration Curve
• October, 2009 to October, 2010
� Hospital’s Load Analysis
• Base Electric Load: ~1,900 kW
Control Strategy� Tariff Structure
• Peak Demand Charges: 60% to 70%
• Time-of-Day Charges: minimal differences from peak to off-peakFrom Date To Date Meter # kWhr Demand,kW Charge,$/kW Charge,$/kWhr Charge,$/mo
8/25/2010 9/24/2010 5656007 518,400
5656008 528,000
5656009 432,000
5656029 523,200
7031005 518,400
Total 2,520,000 5,768
1,257,556
1,262,444
13.36 77,060.51
7.14 41,183.52
0.02 18,980.78
0.0151 19,054.56
0.0059 14,867.99
0.0039 9,941.40
1.04
37.56
9.90
16.44
4,323.59
185,477.29
64%
On Peak Energy Consumption
Off Peak Energy Consumption
CHARGES
Primary Distribution Demand
Transmission Demand
On Peak Energy Consumption
Off Peak Energy Consumption
System Benefit Charge
Tax Charges
TOTAL CHARGES
Temporary NYS Surcharge
Billing & Payment Surcharge
Total Meter Charge
Meter Reading
Meter Maitenance
Meter
Percent of Peak Demand
From Date To Date Meter # kWhr Demand,kW Charge,$/kW Charge,$/kWhr Charge,$/mo
7/27/2010 8/25/2010 5656007 566,400
5656008 499,200
5656009 628,800
5656029 614,400
7031005 614,400
Total 2,923,200 5,976
1,397,027
1,526,173
12.91 77,178.09
6.90 41,246.35
0.0061 8,535.15
0.0061 9,324.16
0.0059 17,246.87
0.0039 11,532.02
1.04
36.31
9.57
15.89
3,941.06
169,066.51
70%
On Peak Energy Consumption
Off Peak Energy Consumption
CHARGES
Primary Distribution Demand
Transmission Demand
On Peak Energy Consumption
Off Peak Energy Consumption
System Benefit Charge
Temporary NYS Surcharge
Billing & Payment Surcharge
Total Meter Charge
Meter
Meter Reading
Meter Maitenance
Tax Charges
TOTAL CHARGES
Percent of Peak Demand
Control Strategy� Terminology Description
• Process: Hospital’s Electric Load
• Disturbance to the Process: Electric Load Fluctuations
• Measurement: Real Time Electric Power Consumption Metering
• Controller: Programmable Logic Controller (PLC)
• Set Point: Monthly Peak Demand Level
• Adjustment: Chilled Water Flow Rate
Control Strategy� Implementation
11:00 pm – 4:00 am 5:00 am – 8:00 pm TES Load: 1.0 kW/Ton
∆
Disturbance
Set Point
TES Load
Process
Measurement
Design Targets� One Time Incentives offered through State Org. & Utilities
� Program Participation: Curtailable Service
Category Program
Peak Demand Reduction: 80% NYSERDA: $600.00/kW
ConEd: $500.00/kW
Demand Response: 10% NYSERDA: $200.00/kW
NISO: CSP Participation
Emergency TES Ballast: 10% N/A
ResultsMonthly Summary – March: TES Full Load Shift
Load Duration Curve LDC w/ TES
Design Day Design Day w/ TES
Ice Slurry TES Charge/Discharge
Monthly Target Peak Demand: 2,750 kW
ResultsMonthly Summary – July: Highest Peak Demand 6,054 kW
Monthly Target Peak Demand: 4,820 kW
Design Day Design Day w/ TES
Ice Slurry TES Charge/Discharge
Load Duration Curve LDC w/ TES
Results
Annual LDC: Before & After TES Monthly Peaks: Before & After TES
Load Redistribution Peak Demand Reduction
Results� Key characteristics of Ice Slurry TES
• Independent TES Charge and Discharge Loops
• Simultaneous operation of TES Charge and Discharge loops
Highest Expected Discharge Rate
ResultsIce Slurry TES Operation Period: March through October
Month Pre- kW Post- kW Reduction $/kW Savings $
Jan 3072 3072 0 - $0.00
Feb 3060 3060 0 - $0.00
Mar 3108 2750 358 $18.80 $6,730.40
Apr 4932 2812 2120 $19.00 $40,280.00
May 5580 3750 1830 $21.87 $40,022.10
Jun 5864 4500 1364 $19.81 $27,020.84
Jul 6054 4820 1234 $21.87 $26,987.58
Aug 5968 4450 1518 $19.81 $30,071.58
Sep 5748 4430 1318 $20.50 $27,019.00
Oct 4456 2650 1806 $20.50 $37,023.00
Nov 3138 3108 0 - $0.00
Dec 3066 3046 0 - $0.00
Total $235,154.50
Annuals Savings Summary*Peak Reduction
* The $/kW are indicative of ConEd service territory
Simple Payback Period: 6 years (or less in cases when adding or
upgrading chiller plant capacity)
Scope of Supply
� Retrofit Scope
• Vacuum Ice Maker – VIM850 (1,000 Tons)
• TES Reservoir Retrofit (hospital crawl space mod’s)
• Plate & Frame Heat Exchanger
• Circulation System (pumps, piping, valves, controls, etc.)
• Transportation to the Site
• VIM Installation
• VIM Maintenance Area
• Structural Reinforcements (for roof installations)
Conclusions� Accomplished Project Goals
� Peak Demand Reduction
� Demand Response
� Improved Existing Chiller Plant Efficiency
� Improved Existing Chiller Plant Reliability
� Significant Annual Operating Energy Cost Savings
� Can Earn Utility Incentives
� Key Characteristics of VIM Ice Slurry TES
• Environmentally Friendly – Uses Water Vapor as the ONLY Refrigerant
• Low Energy Consumption – less than 1.0 kW/Ton for ice making
• RAPID and VARIABLE Discharge Capabilities, with COLD supply temps
• Produces a pumpable and non-coagulating ice slurry
• Uses a compact, simple, and low cost TES Tank
Contact InformationStan Rott
Marketing Director
IDE Technologies
main: 1-516-734-0420
cell: 1-267-210-3396
www.ide-tech.com