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Emerging Technologies

CO2 Refrigerant Heat Pumps

Today

Janice Peterson, P.E. ACS Contractor for Bonneville Power Administration

Ken Eklund WSU Energy Program

Emerging Technologies Showcase August 16, 2017


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CO2 Refrigerant Heat Pumps

Today

Janice Peterson, P.E. ACS Contractor for Bonneville Power Administration

Ken Eklund WSU Energy Program

Emerging Technologies Showcase August 16, 2017


Need for Research

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• The 6th power plan called for a 50% penetration of heat pump water heaters (HPWH) by 2030 • Replacement of electric resistance water

heaters in over 1 million homes • 2013 market penetration around 1%

• The integrated HPWH with synthetic

refrigerants have some limitations: • Rated COP of 2.5 • Single speed • High refrigerant Global Warming Potential • Need electric resistance back up • Remove heat from conditioned space • May not fit into existing space • Noise


Game Changing Technology

Split System

CO2 Refrigerant

Variable Speed Inverter Driven

No Electric Element

From 50 to 150 F in Single Pass

1.5 kW Input/ 4.5 kW out

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Bonneville Funded Research

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2012 2013 2014 2015 2016 2017 2018

Lab and Field Tests of Domestic Hot Water (DHW) Performance

Demand Response Potential

Space + DHW in New Homes

Retrofit Combined Space + DHW

U.L.

New Applications (Pool heater, multi-family,

water source)

* Northwest Energy Efficiency Alliance (NEEA)/BPA Qualified Product List

QPL*


Hurdles to Commercial Success

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• Familiarity • First Cost • Finding a contractor

• HVAC + Plumbing + Electrical


Addressing the Barriers

Familiarity

Publish Research

News stories and other publicity

First Cost

Distributor Buy Down

Utility Incentives

More Cost Effective

Applications

Finding a Contractor

Training/ Installation Guidance

Qualified Product List

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What We Will Cover

• Research on water heating only because it is necessary to understand combined systems

• Research on combined space and water heating systems

• Lessons learned on the best practice and use of this technology

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Cutting Edge--Not for the Faint Hearted

Requires:

– Ways to import and install non UL listed equipment

– Dealing with catastrophic failure

– Designing new applications for expanded capabilities which leads to:

• Engineering new systems

• Designing monitoring for these systems

• Developing new concepts for data analysis

• Learning lessons never imagined at the design phase

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Lab Test Results

• Linear fit of Energy Factor to temperature

• Use Typical Meteorological Year 3 data to calculate an annual Energy Factor:

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0

1

2

3

4

5

0 20 40 60 80 100

Ene

rgy

Fact

or

Outside Temperature (F)

Performance vs. Outside Temperature

Climate Annual EF

Boise 2.9

Kalispell 2.6

Portland 3.0

Seattle 2.9

Spokane 2.8

Outside Air Temperature (F)

Energy Factor (EF)

COP

17 1.74 2.1

35 2.21 2.75

50 3.11 3.7

67 3.35 4.2

95 4.3 5.0


Field Monitoring

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HPWH Performance

kWh per 100 gallons water delivered

0

5

10

15

20

25

kWh

/10

0 g

allo

ns

CO2 Split Systems

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Demand Reduction Operation

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Blue lines are hot water draws

Red blocks are off-peak times when heat pump is allowed to operate


Impact on Load

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Water Heater Load Shape Total Load Shape

System Off Time in Box—Could Help Flatten the Peaks!


Impact of Demand Reduction on System Efficiency

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Reduction


IN EXISTING HOMES

TIP 338

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TIP 326 IN HIGH EFFICIENCY HOMES

BPA Funded Research on Combined Systems


Split System Combi Success!

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• 10 systems in climates ranging from Northern California to the Coastal Pacific Northwest provided space and water heat through one to three winters

• Much was learned regarding – Equipment design – System design, setup and optimization – Monitoring


Successful Background

• Extremely efficient as a dedicated water heater. Average 7 kWh per 100 gallons=less than 1/3 the energy used by an electric resistance water heater

• System serves large loads while operating 25% of time in very cold weather

• Decided to try adding another load

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Project Design

• Targeted homes with design heating loads of 10 to 15 thousand Btu per hour—current WA code house design load is 20 to 30 thousand Btu per hour.

• NEEA provided recruitment, technical assistance to builders, engineering and monitoring through its Next Step Home program

• BPA provided program management, building code support, installation support, lab testing and data analysis and reporting

• 10 original field sites with 7 located in Heating Climate Zone 1 (≤6,000 Heating Degree Days (HDD)—Coastal), 1 in Zone 2 (6,001 to 7499 HDD—Inland) and 2 in Zone 3 (≥7,500 HDD—Mountain)

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Combi System

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Monitoring and Analysis

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• Monitoring and analyzing the performance of two loads from the same source is challenging

• In the field study there are more than double the number of sensors in the dedicated water heating research

• A follow-on lab study was designed to capture the interaction of the two loads


Field Energy Factor

Field Energy Factor is a concept created by WSU Energy to represent the total system performance

It accounts for heat pump energy plus all system inefficiencies including:

– Tank loss – Pipe loss – Pump energy – Controls – Defrost – Freeze Protection (including heat tape)

The formula is FEF = (QDHW + QSpaceHeat) / QEnergy In

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Performance

Bellingham, WA McCall, ID Olympia, WA Milwaukee, OR Seattle (Ballard), WA Tacoma, WA

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• Lowest performance correlates with highest return water temperature (5) • Performance of Site 5 doubled in Non Heating due to colder supply water • Where DHW use drops, performance during Non Heating drops (1 & 7) • Largest daily water use correlates with highest FEF due to cold water (10)

0 20 40 60 80 100 120

1

5

7

10

Heat Return Temperature

Performance Factors

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0

0.5

1

1.5

2

2.5

3

3.5

4

1 5 7 10

F

E

F

Site

Heat

Non Heat

0

20

40

60

80

100

120

140

160

180

1 5 7 10

G

P

D

Heat

Non Heat


Design Issues—Opportunities for Improvement

• Defrost issues in cold weather when operating as a space heater were addressed in new UL listed model

• Systems worked best where design load was within heat pump limits—even if load was met by total capacity

• A system froze during a 10 hour power outage at 20 °F

• Tank destratification occurred—especially in cold climates and with high temperature heating systems—which reduced efficiency

• Cross flow may have contributed to reduced operating efficiency at some sites

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Defrost Failure

• Results from supplying water hotter than 90⁰F to the outdoor unit which tricks the defrost into turning off

• Designed as a water heater—not as a space or pool heater

• Manufacturer immediately began working to solve the problem. Now has a UL listed version that defrosts up to 140⁰F supply temp

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Matching Capacity to Load

• Sites 4 and 6 were both unoccupied but heated during the same period in winter 2015

• At Site 4, design load is 21,061 Btu per hour—at Site 6 it is 6,226

• Heat pump capacity for both sites was 13 to 15 thousand Btu per hour depending on outdoor air temperature

• Site 4 in McCall had sufficient capacity—heat pump plus backup—to meet design load (-16 °F)

• During this test period the temperature at McCall plunged from 26 to -8 °F impacting load

• Note the large difference in FEF The very low FEF at Site 4 indicates the system did not function properly The solution is a larger heat pump

Site OAT FEF

4 25 0.13

6 48 2.05

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Tank Destratification

• Occurs when the heat demand on the tank results in heat supply flow rates that cycle the storage tank making it all one temperature (at 4 GPM an 80 gallon tank cycles in 20 minutes)

• Without temperature difference transcritical operation efficiency plummets

• To maintain tank stratification:

– Match load to heat pump output

– For split systems use a larger tank in combined systems—120 gallon is recommended

– Return water to tank location closest to its temperature

– Stop circulation when tank reaches bottom of hot water layer and allow heat pump too recover

– Like Site 10 use lots of hot water which pulls cold water into the bottom of the tank—maintaining stratification

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Reduce Temperature of Return Water

• Low temperature systems such as radiant slab floors work best with hydronic heat pumps

• Run high temperature return water through a useful temperature sink such as a preheater for a heat recovery ventilator before returning it to the tank

• Once again use lots of hot water which pulls cold water into the system

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Water Supply

Sanden Hot Water Storage Tank

Sanden Heat

Pump

Cross Flow

Tempering Valve

Cross Flow

Tempering Valve Highway to Reduced Performance

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Optimized Efficiencies

Using these lessons will help attain the combined system efficiencies predicted in the Ecotope Lab Study of Combined Systems

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Climate Annual Efficiency

Water Heating

Space Heating

Combined

Boise 2.9 2.3 2.5

Kalispell 2.6 2.1 2.2

Portland 3.0 2.6 2.7

Seattle 2.9 2.6 2.7

Spokane 2.8 2.2 2.4


SPLIT SYSTEM COMBI DR TEST AT PNNL LAB HOMES G3 FIELD TEST CALIFORNIA SITE FIELD TEST DHP + HOT WATER FIELD TEST ECO RUNO LAB & FIELD TEST

TIP 338

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Technology Innovation Projects


Eco Runo

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System Setup

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• Cold weather test in McCall, Idaho starting February 24, 2017

• Focused on space heating because the water heater aquastats were not installed until July, 2017

• The results demonstrate that more research is needed and why field research is so critical

Two Sites

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Outdoor Air Temperature During Field Test

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Temperatures Inside and Out

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Eco Runo Average Daily Field Energy Factor

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Site One Not Shown


• Site 2 is a dream system—the kind of cold weather heat pump we’ve always wanted

• Site 1 is a learning opportunity! The results: o Are an analysis puzzle

o May be due to a glitch in our monitoring—but that has recently been recommissioned

o May be due to the heat exchange/control unit—the programming will have to be compared to Site 2’s

o May have something to do with the set up, control or function of the heat pump

Welcome to a Brand New Emerging Technology!

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Next Steps

• Analyze split system combi sites and monitoring for 2016 and 2017—Courtesy of NEEA

• Field Test a Ductless Heat Pump plus DHW—Courtesy of BPA and NEEA

• Field test the Eco Runo for electric forced air furnace conversion—Courtesy of NEEA

• Final BPA TIP 338 report due September 30, 2017

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Conclusion

• We learn by doing—the lab test never gives us the whole story. Field testing takes us into a much broader field of variables that must be considered

• We have a real improvement in water heating technology

• This same water heater can provide space and water heating for energy efficient homes in moderate climates—there is much experience that should be followed to optimize performance

• There is evidence that the Eco Runo may possibly be the next great emerging technology for cold climates and less efficient homes—if you are a Pacific Northwest utility that wants to join our research please call me

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Contact Information

Ken Eklund, Building Science & Standards Lead Washington State University Energy Program [email protected] Project Principle Investigator and Manager

Janice Peterson, Energy Efficiency Engineer ACS Contractor for Bonneville Power Administration [email protected] Project Manager

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Next ET Showcase Webinars

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• RETAC 2.0 & the Regional Technical Forum Aug 30

• High Efficiency Heat Pump Clothes Dryers Sept 7

• Window Attachments Sept 20

• Alternative Refrigerants Sept 28

Join our email list at [email protected]

Webinar information and registration at www.e3tnw.org/webinars

More information about emerging technologies: • ET Program: www.bpa.gov/EE/Technology/EE-emerging-technologies/

Thank you for attending!

mailto:[email protected]



http://www.e3tnw.org/webinars

http://www.bpa.gov/EE/Technology/EE-emerging-technologies/






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CO2 Refrigerant Heat Pumps Todaye3tnw.org › Portals › 0 › E3TFiles › ET FINAL...

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