thermal energy metering technology - airah€¦ · thermal energy metering technology presented by...

Thermal Energy Metering Technology

Presented by Aquip Systems Pty Ltd

P R E S E N TAT I O N H E A D I N G

Thermal Energy Metering

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• Instrumentation and technology company started 1991

•Offices in NSW and WA

•26 years experience in flow metering for liquids and gasses

•9 years in thermal energy metering

Brent Ladbrook

With Aquip since 2010 and With Aquip NSW since 2016

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Aquip Systems

•Learning Outcomes

• Industry Trends

•Terminology

•Standards

•Meter types

•Considerations for selection

•There is a test at the completion of the course so please pay attention and ask questions as we go

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Session Overview

•Understand the fundamentals of thermal metering

•Be able to select the best thermal metering options for an

application

•Understand the fundamentals of communication protocols

•Understand basic installation principles

•Understand that system accuracy is more important than

component accuracy

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Learning Outcomes

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Industry Trends

Trends

Increased Costs

Costs are often 50%

Increased metering

NBH has 199

meters

Cost Recovery

Increased Profit $$

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Terminology

•Flow Rate - Instantaneous amount e.g. m3/hr, l/s, kW

•Totaliser – Accumulates total for period e.g. m3, litres, kW.h

•Velocity – Speed of fluid through pipe e.g. m/s

•Zero Cut off – Value below what the meter can accurately read

and therefore reports zero

•Turndown ratio – Ratio between permanent flow and minimum

guaranteed accuracy or the measurement range

•Accuracy – How close to the real number is the reading

•Repeatability – how regularly does the meter report the same

number

•MPE – Maximum Permissible Error

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Standards

•There are NO Australian standards

•NMI is not currently possible and commonly EN1434 is

referenced

•Three main classes of Meters under EN1434

•Class 2 is the best commercially available

•Calibration certificates do not mean type approval to

EN1434

•Other standards include OIML and MID

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What is a Thermal Energy Meter

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What is a “Thermal Energy Meter”• Volume flow rates under EN1434 specified in m3/hr

qi - lower limit of the flow rate

This is usually 1/100 of qp (Expressed

as a turndown ratio of 100:1

)

qp - permanent flow rate

qs - upper limit of the flow rate (<1h/day , <200h

/year)

This is usually 2 x qp

The sensor will not read below Zero Cut off, or

above the saturation points.

This an example of a DN100 qp 100 and will vary from

model to model

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What is a “Thermal Energy Meter”

Flow Sensors should be sized to flow rate NOT pipe

size

• min, max and permanent flow rate should be

considered

• Pressure loss should be considered

• Pressure class should be considered PN16 and PN25

are common

• Meter should be no more than one standard size below

the pipe size (this is for flow dynamics reasons)

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What is a “Thermal Energy Meter”

Typical Accuracy Curve showing that

meters are less accurate at lower flow rates

MPE under EN1434-1

EMPE = 𝐸𝑐2 + 𝐸𝑡

2 + 𝐸𝑓2

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V 1 - 1 8 Types

•Types of Meters

•Heat meters

•Cooling

•Heating and cooling

•Physical sizes are standarised

•Threaded end: G¾” through to G2”

•Flanged (DN): DN15 through to DN250

•Above DN250 there are no standard sizes

•From a cost perspective threaded brass meters are

typically lower but not available above qp 10m3/h above

this a flanged meter must be used.

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Measuring Thermal Energy•Simplified heat transmission formula is:

•Energy = V x ∆Θ x k

•Where V= water volume in m3

•∆Θ = the measured temperature difference

•k = the heat coefficient of water, calculated according to

the formula of EN 1434

•Heat Meter with flow meter located in return (supply =

70°c Return = 30°c , Flow = 1 m3)

Energy = V x ∆Θ x k

≃ 1 x (70 – 30) x 1.1561

≃ 46.27 kW

If the Flowmeter is in the supply then

≃ 45.44 kW

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Flow Metering Components

•Many types of flow sensors are available however

commonly used types are either mechanical or electronic

•Mechanical types include Turbine meters and Paddle

Wheel sensors

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Mechanical Flow SensorsChallenges:

• Corrosion, erosion, scaling

• Fouling

• Incorrect installation – particularly paddle wheel

• Poor turndown ratios

• No diagnostics at all

Benefits:

•Typically low purchase price

•Paddle wheels seem easy to install but

beware of flow profile

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Electronic Flow Sensors

•Electronic types include Ultrasonic and Electromagnetic

(Mag) sensors

•They are solid state and have no moving parts

•Mag type are always “inline”

•Ultrasonic can be “inline” or “clamp-on” type

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The Principles of Electromagnetic Flow Sensors

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Electromagnetic Sensors

Challenges:

•Corrosion, erosion, scaling particularly on electrodes

• Installation issues

•Turndown ratios

•Few diagnostics

Applications

•Often used for water metering and often the best inline solution

above DN300

Benefits:


•Readily available

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Ultrasonic Sensors

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Inline Ultrasonic Sensor

Challenges:

•Minor effect corrosion, erosion, scaling

Applications:

• Pipes up to DN300 and flows up to

1000m3/h

Benefits:


•Usually good diagnostics

•Readily available

•Turndown ratios typically 100:1 or better

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“Clamp-on” Ultrasonic SensorChallenges:

•Minor effect of scale build up

•Higher purchase price

Applications:

• Large pipes or pipes where stopping the

flow is not desirable e.g. Data Centres

Benefits:

•Sized by pipe and not flow 10mm –

6500mm

•Wide dynamic range 0.01 – 25 m/s

•Easy installation – No Shutdown required

•Excellent diagnostics

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Electronic Flow Sensors

•Other types exist including

•Differential Pressure

•Vortex

•These are seldom used

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Temperature Sensors

•PT100, PT500 and PT1000

•PT stands for platinum and the number is the measured

resistance of the probe at 0˚C in ohms

•2 wire and 4 wire configurations – 4 wire is not affected by

distance

•Temperature measurement is VITAL to good energy

measurement

Accuracy

•Class A : dT = ± (0.15 + 0.002 × T) (-200 ... +650 °C)

•Class B : dT = ± (0.30 + 0.005 × T) (-200 ... +850 °C)

•Class AA : dT = ± 1/3 (0.30 + 0.005 × T) ( 0 ... +150 °C)

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Temperature Sensors - Insertion

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Thermal Calculators

•Typically will power flow part and temperature

sensors

•Will calculate and record energy, together with

other variables

• Instantaneous and totalised for some values

•Energy Flow

•Liquid Flow

•Temperature on both sensors

•Meter information

•Error codes

•Diagnostics

•Historical data

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Thermal Calculators

•Must be programmed to be on inlet or

outlet side of the measured area

dependent on where flow part is installed

as the heat coefficient is different on each

side

•Thermal calculators all have a potential

error and must be set up precisely for the

flow and temperature parts of the meter

•Some will store up to:

•1400 hours

•460 days

•36 months

•15 years

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Communications•Pulse

•Analogue (4-20mA)

•Pulse is not recommended as limited

information can be sent, pulses can get

lost, distance and scaling are issues

•Analogue is not ideal as limited information

can be sent, distance and scaling are

issues

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Communications•High Level Interface (HLI) such as:

•BACnet

•Modbus

•M-Bus (Meter Bus)

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Installation Considerations

•Site access

• Lifting considerations for larger meters

•New Pipes

•Typically inline sensors on smaller pipes

and “clamp on” could be considered on

larger pipes. This will depend of the use

of the data i.e. billing

•Allow straight lengths free from valves

and fittings

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Installation Considerations

•Existing Pipes

•What is the real cost of installation

including loss of flow?

• Is the qp known?

•What are the unknown risks?

• Is my design such that I can tolerate a

pressure loss

•Check back pressure requirements for

inline meters

•Clamp on is often an ideal solution and

can be used for temporary measurement

or establishment of qp

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Installation Considerations•Power supply

•24VAC, 240VAC, 24VDC, Battery

• Ideally have 10 straight pipe diameters

upstream and 5 downstream

•This is not always possible and

• Immediately downstream from valves is

the least favoured position

•Check the manufacturers manual

•Pressure loss

•All inline meters will have some pressure

loss

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Installation Considerations•System accuracy vs component

accuracy

•For integrated meters, NABERS requires

better than 5% accuracy across full

sensing range

•Green Building Council of Australia refer

to NABERS

•Watch out for “Frankenstein”

•Check Ingress Protection (IP) rating

•Check Zero Flow Calibration (for clamp on)

•Check maintenance recommendations

•Pressure Requirements

•Check Protocols ie. Modbus RTU / TCIP

•NABERS National Australian Built Environment Rating System

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Installation Considerations – Cost of getting it wrong

• Integration difficulties

•Missing low flows means missed revenue

•Selection and installation errors subtract

from published accuracy of meter

•Maintenance costs and recommissioning

•Small percentages can add up to a lot of

money over time

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Installation Considerations – Cost of getting it wrong

•Sum for period is 855 kWh / 10 hours

•DN100 pipe on a Boiler

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Commissioning•Meters can be “validated” using a “Master” portable

clamp on ultrasonic thermal meter

•The more diagnostics that you have the more you know

about the performance of your meters

•Many meters will have error codes that are

downloadable

•Data transmission should be validated to show that the

output from the meter received and interpreted

correctly

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Maintenance

•NABERS reference a ten year period but this relates

more to the reading system than meter accuracy

•Green Building Council of Australia reference NABERS

or “a recognised standard”

•Meters can be “validated” using a “Master” portable

clamp on ultrasonic thermal meter

•Under EN1434 10% percent of meters are checked

every 6 years and all meters replaced if meters have

drifted too far

• If you are a building owner these meters may be your

“cash registers”

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V 1 - 1 8 Case Study – Clamp on

•Major hospital - flow

interruptions are

impossible pipe was

existing

•Large pipe - high cost of

flanged meter and

installation

• Insulation easily replaced

•Allocation metering

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V 1 - 1 8 Case Study – Paddle Wheel

•Flow only in a chiller plant

•Used for monitoring flow

rates and adjusting VSD

•0-10VDC output to the BMS

•Not used for billing

•Bi directional flow on some

meters

•Meters were commissioned

and validated with a portable

clamp on ultrasonic meter

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V 1 - 1 8 Case Study – EN1434 Billing Meters

•A Sydney hotel has a third party chiller and boiler installed on site and purchase chilled and heated water from the owner of the chiller/boiler

• Inline ultrasonic sensors were selected as they are certified to EN1434 and the meters are used for billing

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Questions

Brent Ladbrook

[email protected]

u

+61 448 955 515

mailto:[email protected]

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