siemens demand flow™ - airah · • case study - video (3-min duration) • case study - robina...

September 2015

SIEMENS DEMAND FLOW™

Unrestricted © Siemens AG 2015 All rights reserved.

2015-04 KM / SBT

• Central Chilled Water Plants• Typical Characteristics & Operational Shortcomings 3

• Plant Energy Consumers & Sub-systems 4

• What is Demand Flow?• Overview 5

• Differences & Effects 6

• What do we look for 7

• The Benefits

• Concept & Principles 9

• Case Study - Video (3-min duration)• Case Study - Robina Hospital 12

• Conclusion & Contacts 30

Demand Flow™Introduction / Table of Contents

Prepared by –

Lee KolomeitzSiemens Demand Flow™Principle Engineering – Asia PacificAdv Dip Mech Eng, Dip PM


2015-09 LK / SBT

Demand Flow™Central Chilled Water Plants

Typical Plant Characteristics• Most chilled water plants have some form of constant flow pumping• Most plants bypass chilled water flow – excessive pumping energy• Operate best with wide temperature splits across the chiller – at or near original design

intent (known as "delta-T")• Usually operate at design intent conditions only 5% of the time

Chilled Water Plant Operational Shortcomings• Most plants today are plagued with "Low Delta-T Syndrome"• Inefficiently operated 95% of the time due to design• The Industry has tried to solve these issues with limited success• Often plant efficiency is sacrificed for comfort• Nominal plant capacity is usually never realized – causing perceived need for additional

chillers

Ø CentralChilled WaterPlants

ØWhat isDemand Flow?

Ø Case Study-Short Video

Ø Case Study-Robina Hosp

Ø Conclusion& Contacts


2015-09 LK / SBT

Demand Flow™Central Chiller Plant Energy Use

5 fundamental subsystems of a chilled water system that consumes energy andinfluences deliverable capacity;• Chilled Water Pumping• Condenser Water Pumping• Chillers• Cooling Tower Fans• Air Side

These 5 subsystems are interdependent• Energy and deliverable capacity are interdependent• Often what is done in the name of energy conservation results is a "transfer of energy" among these 5

subsystems with no net savings realized, or increase in energy

As the Solutions Provider, Siemens understands these technical relationships, deliveringa "holistic" approach to CPO


2015-09 LK / SBT

Demand Flow™What is Demand Flow?

Overview§ Siemens have pieced it together… and created a holistic solution toform an unique energy and operational cost saving application forcentral water-cooled chiller plants.

§Demand Flow optimises central chilled water systems to reduce aplant’s total energy consumption by 20% - 50%.

§ Demand Flow is based on a proven & patented design pioneeredusing “variable system pressure curve technology”, not used in theIndustry.

Ø Central ChilledWater Plants

Ø What isDemand Flow?

Ø Case Study-Short Video


Ø Conclusion &Contacts

“Demand Flow is really an application of Thermodynamics, Pump Laws &the Refrigeration cycle via Mathematical Control Algorithms”


2015-09 LK / SBT


The Difference• Effectively establishes only One Chilled Water Loop, virtually eliminating all Bypass Water.• Dynamically balances CHW Decouplers resulting in Zero Directional Flow.• Precise control of variable water flow thru Chiller Evaporator and Condenser within

manufacturers minimum turn-down parameters.• Derive Optimised Pressure and Temperature set-points on Chilled and Condenser Water

systems based on changing system dynamics – not on “datasheet performance”.• Costly VFDs are not required on the Chillers.

Effects• Increases system deliverable tonnage by ‘unlocking’ true plant nominal capacity.• Manages compressor “lift” and maps “surge” protection point, effectively eliminates

refrigerant flow issues at low load conditions.• Significant reduction in plant wear & tear, lower pump shaft mileage and increased

equipment longevity.


2015-09 LK / SBT


What do we look for?

q Water-cooled Centrifugal and Screw type chillers with minimum plantcapacity > 400 RTons (1400 kWr) and high Ton-Hour producing Loads.

q Retrofit Applications of Existing or Problematic Plants, or NewConstruction Build Projects

q Characteristics of inefficient plant operation:§ Excessive bypass of chilled water flow§ Constant volume pumping with high pump shaft mileage§ Continuous full speed ineffective operation, or undesirable chiller plant

cycling On/Off activity.§ Comfort sacrificed for efficiencies§ Minimal operation at Design intent Conditions, plagued by Low Delta-T.

“Siemens Demand Flow simply provides – colder water, for less utility dollars”


2015-09 LK / SBT

Demand Flow™The Benefits -

ChillersReal-time mapping of optimal flowand temperature setpoints toensure chiller runs at ‘sweet-spot’under all loads conditions, 365-days/year.

PumpsTrue variable flow of chilled waterto precisely meet the actualsystem cooling needs of thefacility, instead of circulatingbypassed water resulting in anartificial load.

Cooling TowersEnsures the optimal towerapproach is achieved whenambient wet-bulb is favorable byderiving the precise condenserwater flow & fan speed.

“Demand Flow ensures we only produce & deliver the volume of water the system actually needs”


2015-09 LK / SBT

Feet of Head

GPM

Variable speed pump curves24

22

20

18

16

14

12

10

8

6

4

2

0

0 20 40 60 80 100 120 140 160 180 200

Operating points

Demand Flow™Concept & Principles

Typical Industry Practise – Control System to Constant Pressure with VFD

Constant Pressure*

*requires VFD on Pump 60Hz50Hz

40Hz

ØCentral ChilledWater Plants

ØWhat is DemandFlow?

Ø Case Study-ShortVideo


Ø Conclusion &Contacts


2015-09 LK / SBT

Feet of Head

GPM

Variable speed pump curves

24

22

20

18

16

14

12

10

8

6

4

2

0

0 20 40 60 80 100 120 140 160 180 200

Mathematically Calculated

Dynamic Variable System Pressure Curve

qDynamically calculates & resetsoptimal Setpoint before any fieldcondition goes into “stress”.

Demand Flow™Concept & Principles

Siemens VPCL logic – Creates System Efficiency Curves for Optimal Pump Speed

qContinually polling criticalzones & environmentalconditions for starved flow.

qDerive the OptimalOperating point based onSystem Demand


2015-09 LK / SBT

A

BC

DE

Saturated Evaporator Temperature / Pressure

Saturated Condenser Temperature / Pressure

Condenser Superheat

Useful Refrigerant Effect

Sub-Cooled Region Super Heat Region

Heat of Compression

Low CWET Sub-Cooling

Mixed Region

Pressure

(psia)

Enthalpy(BTU / LB)

a

c

d

R – 134 a

38.5 btu / lb 110.5 btu / lb 117.4 btu / lb

54.7 psia

113.6 psia

101.4 psia e

Demand Flow™Concept & PrinciplesPatented – Variable Pressure Curve Logic (VPCL)

q Promotes compressor suction superheat resulting in Increased Cooling Effect

30 btu / lb

q Reduces Refrigerant ‘Flash-gas’ by creating further Liquid Sub-Coolingresulting in Increased Cooling Effect.q Effortlessly manages compressor “lift & surge” protection under all Loads Conditions

11-09-2015

• Facility Overview

• Project Motivations

• Evaluation & Assessment

• Results

Robina Hospital Chiller Plant Optimisation – Case Study

Table of Contents

With permission granted by -

Queensland HealthMaree McKayService Director – Robina Hospital

Prepared by –

Lee Kolomeitz & Kieran McLeanDemand FlowBusiness DevelopmentCEM®, CMVP®

11-09-2015

Robina Hospital Chiller Plant Optimisation - Case Study

Facility Overview

Robina Hospital is the 6th largest hospital in Queensland with 364-beds anda suite of inpatient and outpatient services.

The facility has undergone constant expansion over the past 15 years:

• 2000 – Constructed as a private hospital offering some public services

• 2002 – Acquired by QLD Government

• 2007 – Stage 1 expansion adding 25 beds

• 2012 – Stage 2 & 3 expansions doubling number of beds

► FacilityOverview

► ProjectMotivations

► Evaluation &Assessment

► Results

11-09-2015


Chilled Water System – 2007




► Results

AX Building Chiller Plant1x Air-Cooled Chiller

Original Central Chiller Plant3x Reciprocating Water Cooled

Chillers (768kWr)

11-09-2015






► Results

AX Building Chiller Plant1x Air-Cooled Chiller

Original Central Chiller Plant3x Reciprocating Water Cooled Chillers

(768kWr)

Link between Chiller Plants

New Central Chiller Plant3x Centrifugal Water

Cooled Chillers(2500kWr)

11-09-2015



Facility Served by 3x Chiller Plants operating in the following modes:

• Low Load – 2x older plants serve entire facility• Normal – new plant serves entire facility• Independent – all 3 plants operate independently of each other




► Results

11-09-2015



Control Strategies

• Constant Volume Primary Pumps• Constant Volume Condenser Water Pumps• Variable Volume Secondary Pumps with Pressure Reset




► Results

11-09-2015


Project Motivations

1. Simplification of Chilled Water System Operation

2. Improve facility energy efficiency & Operational Expenditure

3. Reduce maintenance requirements of 3 separate Chiller Plants

4. Improve De-Humidification Control of Operating Theatres




► Results

11-09-2015


Evaluation and Assessment

q Two projects were initially being considered:

1. Mechanical upgrade to improve Dehumidification2. Energy Optimisation Project focusing on Chiller Plant

q Demand Flow™ provided possibility of addressing both issues

q Qld Health went to market and engaged Siemens to complete adetailed feasibility study to further understand chilled water networkand benefits of Demand Flow™




► Results

11-09-2015


Annualised Data Modeled – Baseline vs Projected Savings (Guaranteed)




► Results

11-09-2015


Annual Electrical kW Modeled – Baseline vs Projected Savings (Guaranteed)




► Results

11-09-2015


Evaluation and Assessment – Findings

§ 22-26% reduction in chilled water plant energy consumption

§ Max 3.3 year payback period guaranteed (energy savings only)

§ 22% Internal Rate of Return

§ Redundancy of 2 inefficient chiller plants

§ Improvements in dehumidification control

§ No Chiller Variable Speed Drives required

§ Simplified operation and plant for the Hospital Engineering Staff




► Results

11-09-2015

Robina Hospital Chiller Plant Optimisation

Results – More than Energy Savings!

• Plant Consolidation

• Facility Reliability Improvements

• Chilled Water System Efficiency

• Energy Savings & Greenhouse Gas Emission Reduction

• Consolidation of 3x Chilled Water Plants to 1




► Results

11-09-2015

Robina Hospital Chiller Plant OptimisationResults – First 8 Months of Savings

• 26% Saving in Chiller Plant Consumption

• 676,216 kWh saved (85% of annual target)

• Reduction of 554 Tonnes of CO2 emissions

• Anticipated payback of 2.5 ahead of a 3.3year guarantee

11-09-2015

Demand Flow™Case Study – Robina HospitalResults – First 8 Months of Savings

-

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

Nov-14 Dec-14 Jan-15 Feb-15 Mar-15 Apr-15 May-15 Jun-15 Jul-15 Aug-15 Sep-15 Oct-15

Cumulative Target vs. Actual Savings (kWh)

Cumulative Target Cumulative Actual Annual Target

11-09-2015

Robina Hospital Chiller Plant Optimisation

Results – System Efficiency Improvement

Source: "All Variable Speed Chiller Plants", ASHRAE Journal, September 2001

0.57.0

0.65.9

0.75.0

0.84.4

0.93.9

1.03.51

1.13.2

1.22.9

1.32.7

Standard Code BasedChiller Plants

New Technology,

All-Available Speed

Chiller Plants

High-Efficiency,Optimized

Chiller Plants

Older

Chiller

Plants

Chiller Plants with Repairable Design orOperational Problems

Excellent Good Fair Needs Improvement

PRE-OPTIMISATION(Annual Average 0.93 kW/Ton)

(Annual Average System COP 3.8)

POST-OPTIMISATION(Annual Average 0.66 kW/Ton)

(Annual Average System COP 5.3)

System kW/ton *

System COP *

(Annual Average)

* Includes Chiller,Pumps and CT FansCombined

11-09-2015

Robina Hospital Chiller Plant OptimisationResults – Facility Improvements

• Improved humidification control of operating theatres

• Increase in deliverable plant capacity

• Effective management of chiller lift

• Eliminates refrigerant flow issues at low load conditions

•Stripped artificial base load (& plant ton-hours) duringwinter season from over-cooling and hunting plantconditions.

11-09-2015

Lee KolomeitzDemand Flow – Principle Engineering ExpertMobile: 0428 455 244

E-mail: [email protected]

Mark DaviesAccount Manager - QldMobile: 0437 615 529


Maree McKayQld Health Service Director – Robina Hospital


Robina Hospital Chiller Plant OptimisationContact page

siemens demand flow™ - airah · • case study - video (3-min duration) • case study - robina...

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