trane sales webinar central geothermal...

Trane Sales Webinar Central Geothermal Systems A System Overview…

Trane Sales Webinar Lee Cline P.E. Senior Principal Systems Engineer

Trane

La Crosse, WI

3

Agenda

Overview

Multiple Chiller/ Heater Bi-directional Cascade

Single Chiller/Heater Configurations

Water-to-Water Heat Pump Configurations

A Few Lessons

Additional Resources

Q&A

3

5

Distributed Geothermal System

heat pumps

water pumps vertical-loop ground heat exchanger (borefield)

WSHPs

Dedicated outdoor air units

Optional fluid cooler

Water pumps

Geo heat exchanger

5

Central Geothermal System

• Chillers provide heating and cooling

• Ground couple for an efficiency boost

• Central air handlers

• VAV terminals

• Water pumps

• Auxiliary boilers

• Fluid or dry cooler

Air handlers

chiller/heaters

Geothermal loop (borefield)

VAV boxes

6

7

Central Geothermal Customer Benefits Compared to Distributed

• Premium efficiency (LEED EA Credit #1) – Efficient central equipment

– Bi-directional cascading

– VAV

– Air economizing

– Better heat recovery management

• Easy to maintain

– Central equipment, few cooling units

– Uses equipment rooms, no access to occupied space required

– Simpler coil condensate collection

7

8

Central Geothermal Customer Benefits Compared to Distributed

• Low space noise (ASA 12.60)

– Fans and compressors away from occupied space

– Noise paths can be more easily attenuated

• Good IAQ

– Many filtration options available (LEED EQ 5 – MERV 13)

– Easier to deliver 30% more outdoor air (LEED EQ 2)

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10

Vertical Markets

• Education

– Primary and secondary

– Colleges and universities

• Government

– Federal sector

– State and county level

• Long-term owners

– Accept extended payback periods

– Interested in embracing green technologies

– Usually have space for a borefield

11

Incentives

• Utility

• Reimbursement

• Tax (if private)

www.dsireusa.org

12

Central Geothermal System Types

System Type Capacity Range Target Market

Single chiller/heater

systems

(based on typical industry units)

K / 12 Schools

Simpler / Smaller

Premium Efficiency

cascading

multi-chiller/heater

systems


High School / Secondary Ed

> 36,000 sq. ft

Super Premium Efficiency

Water-to-water

heat pump system


Small Building – Large Volume

80% of Buildings < 25,000 sq ft

Premium Efficiency

150-1500 tons

70-250 tons

5-200 tons

13

Agenda

• Single Chiller-Heater Central Geothermal Systems

– Four-pipe distribution system configuration

– Two-pipe distribution system configuration

• Multiple Unit Cascading Systems

• Water-to-Water Heat Pump Based Systems

14

Central Geothermal Systems

Single Chiller-Heater

• Allow screw compressor chiller-heater based CGS

systems down to 70-75 tons

• Simple configurations

• Simpler operation

• Two basic distribution configurations:

– 4-pipe – simultaneous heating/cooling

– 2-pipe – changeover heating/cooling

15

P-GS

4-pipe distribution / Constant flow (3-way control valves)

aux heat

cond

evap

CHR-1

Chiller/Heater

P-CH

P-HT

heating loads

cooling loads

Single Chiller-Heater CGS

to

ground

source

from

ground

source VAL-1 / VGS

16

P-GS

aux heat

cond

evap

CHR-1

Chiller/Heater

VAL-1 / VGS

P-CH

P-HT

heating loads

cooling loads Standard chilled water

system maybe constant

flow, primary/secondary or

variable primary flow

Single Chiller-Heater CGS 4-pipe distribution / Constant flow (3-way control valves)

to

ground

source

from

ground

source

17

P-GS

aux heat

cond

evap

CHR-1

Chiller/Heater

VAL-1 / VGS

P-CH

P-HT

heating loads

cooling loads Heating water system will

likely be constant flow or

primary/secondary

4-pipe distribution / Constant Flow (3-way control valves)


to

ground

source

from

ground

source

18

aux heat

heating water by-pass

chilled water by-pass

VAL-1 / VGS

P-CH

P-CD

heating loads

cooling loads

cond

evap

CHR-1

Chiller/Heater

VAL-1 / VGS

P-HT

Primary/secondary

heating water system

- for expanded

distribution delta T

and variable flow

4-pipe distribution / Decoupled pumping


to

ground

source

from

ground

source P-GS

19

aux heat

cond

evap

CHR-1

Chiller/Heater

VAL-1 / VGS

P-CH

P-HT

heating loads

cooling loads

Ground-source loop should be variable flow

for controllability and pumping efficiency

4-pipe distribution / 3-way control valves


to

ground

source

from

ground

source P-GS

20

Central Geothermal System Options

• Auxiliary heating

– NOT OPTIONAL for single unit systems

• Auxiliary heat rejection

• Auxiliary cooling

• Contingency cooling connections

21

P-GS

Contingency Cooling

Connections

aux ht reject

Central Geothermal System Options

aux heat

cooling loads

cond

evap

aux cooling

heating loads

Chiller/Heater

P-CH

P-HT

to

ground

source

from

ground

source VAL-1 / VGS

Single Chiller/Heater


23



V1

cond

evap

Chiller/

Heater

V2

auxiliary heat

V3

building loads

to

ground

source

from

ground

source

P-GS

P-DS

V4

24

Single Chiller-Heater CGS 2-pipe distribution / Constant Flow (3-way control valves)

Cooling only mode

V1

cond

evap

Chiller/

Heater

V2

auxiliary heat

V3

building loads

to

ground

source

from

ground

source

P-GS

P-DS

V4

Chilled water distribution

will likely be constant flow

or primary/secondary

25


Cooling only mode

V1

cond

evap

Chiller/

Heater

V2

auxiliary heat

V3

building loads

to

ground

source

from

ground

source

P-GS

P-DS

V4

Ground-source loop

providing cool water to the

chiller/heater condenser

26



Heating only mode

V1

cond

evap

Chiller/

Heater

V2

auxiliary heat

V3

building loads

to

ground

source

from

ground

source

P-GS

P-DS

V4

Heating water distribution

will likely be constant flow

or primary/secondary

27


Heating only mode

V1

cond

evap

Chiller/

Heater

V2

auxiliary heat

V3

building loads

to

ground

source

from

ground

source

P-GS

P-DS

V4

Ground-source loop

providing warm water to the

chiller/heater evaporator

Multi-Chiller/Heater Cascading


29

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load



VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

PB

to

ground

source

from

ground

source

30

Multi-Chiller/Heater Cascading Review

• Number of Chiller-Heaters

– 2-6 Units

Nominal 80-250 ton unit capacity

Actual 150-1500 ton plant size

• Operating conditions

– 38 leaving chilled water

– 140 leaving condenser water (lower is better)

– Not at the same time!

• Cascading has the potential to increase plant efficiency

• The energy transfer loops increase plant controllability

31

PB

VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load

Multi-Chiller/Heater Cascading Introduction

to

ground

source

from

ground

source

32

VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

Cooling system

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load


Standard Chilled Water

System may be:

• constant flow

• primary/secondary or

• variable primary flow

to

ground

source

from

ground

source PB

33

PB

VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

Heating system

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load


Heating Water System will

likely be constant flow or

primary/secondary

to

ground

source

from

ground

source

34

VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load

Ground-source loop


Ground-source loop

should be variable

flow for pumping

efficiency

to

ground

source

from

ground

source PB

35

VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load

Condenser Energy Transfer Loop


Condenser Energy Transfer

Loop brings cooling water to

condenser from ground-source

loop or heater evaporator

to

ground

source

from

ground

source PB

36

PB

VAL-3

/ VCC cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load

Evaporator Energy Transfer Loop


VAL-2

/ VEC

M

M

VAL-1 / VGSC

Evaporator Energy Transfer

Loop brings warm water to

evaporator from ground-source

loop or chiller condenser

to

ground

source

from

ground

source

37

PB

VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load

Single Chiller-Heater Operation

Multiple chiller-heater systems

can and will provide simultaneous

cooling and heating with one unit.


to

ground

source

from

ground

source

38


Water To Water Heat Pump

WWHP – Simple piping - dedicated pumps

PH

Cooling load

To wellfield

Heating load

PC

From wellfield

PW

P P P P

Water-to-Water

Heat Pumps

evap

cond

evap

cond

cond

evap

On

Cool On

Cool On

Heat Off

39

40

Key Design Issues

• Geothermal vs Heat Recovery

• Optimizing life cycle costs

– Borefield sizing

Supplemental heating

Auxiliary heat rejection

– Load shedding economizer

Application Comparison

Geothermal vs Heat Recovery

Geothermal

• Separate heating and

cooling seasons

• Relatively balanced

• Real estate for ground –

source system

• Capital availability for

ground-source system

• Energy savings driven

Heat Recovery

• Significantly cooling

dominant

• Relatively low peak or

average heating load

• “Right-sized” heat

recovery unit

• Energy and ROI driven

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42

optimizing life cycle costs

Ground-Source Sizing

• Must consider

– Peak building demand

– Annualized building energy balance

• Optimization

– Reduce peak demand – cooling and heating

– Balance annual heating and cooling loads

– Consider a hybrid system design

Fluid cooler

Pond / lake system

43

Heating Dominate Seasonal Load Profile

Building Load Profile

0

600000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

Month

Energ

y

Cooling

Heating

44

Cooling Dominate Seasonal Load Profile

Building Load Profile

0

500000

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

Month

Energ

y

Cooling

Heating

Total vs. monthly?

45

Addressing Load Profile Imbalance

• A cooling dominate building

– Reduce solar loading and/or interior loads

– Auxiliary energy rejection (e.g. fluid cooler)

– Add heat load to system (e.g. domestic hot water)

• A heating dominate building

– Auxiliary heating system (e.g. condensing boiler)

– Thermal solar heating

• Optimize the building life cycle cost

– Reducing borefield size

– Increasing borefield utilization for energy efficiency

46

cooling

load

On

Cool

PLc

PC PLe

M

M M

A

cond

evap

On

Heat

M

PH

B

cond

evap

heating

load


VAL-2

/ VEC

VAL-3

/ VCC

M

M

VAL-1 / VGSC

PB to

ground

source

from

ground

source

47

Packaged Central Geothermal Plants

48

A Few Lessons…

• Do not oversize the plant!

– Do a computerized load analysis – not rule of thumb

– Size for “block loading” - not “sum of the coil peaks”

• Apply optimization principles

– Pump pressure optimization

– Load based setpoint resets

• Have auxiliary / backup heat in single unit systems

• Watch the condenser minimum flow in heating

• Fully and carefully document control

system sequence of operation

– Do not leave the “details” to the controls field technician

49

Additional Resources

• Applications Engineering Manual - SYS-APM009-EN

includes single and multiple chiller/heater configurations.

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