This paper presents a study which was conducted to evaluate the performance of a commercially available heat pump water heater (HPWH) with modified controls. The HPWH is first characterized experimentally under a series of different thermal conditions and draw parameters. The test tank contains a 1500 W electric auxiliary heater that provides on demand heat to the top 0.30 m (1 ft) of the tank, and a wrap-around heating coil. An air source heat pump (ASHP), using R-134A as the refrigerant, draws air from, and returns air to the surrounding space and provides heating to the whole tank through the coil. The tank has been tested using Canadian Standards Association draw profiles to characterize performance under different hot water demands. Electricity consumption and thermal flux is measured for each vertical tank section, and various performance metrics are calculated using energy balances. A trnsys model is then calibrated to the experimental data to allow for the flexibility of varying multiple parameters over various climates. Using this calibrated trnsys model, an optimal control strategy and tank setpoints can be determined for use in cold climates. As expected from previous work, there is a decrease in performance of the HP when heating the tank to higher temperatures to facilitate thermal storage, but the benefits from taking advantage of shifting electrical demand (of water heating) to space heating demand can outweigh the loss of performance.

References

References
1.
Maguire
,
J.
,
Fang
,
X.
, and
Wilson
,
E.
,
2013
, “
Comparison of Advanced Residential Water Heating Technologies in the United States
,”
National Renewable Energy Laboratory
,
Golden, CO
.
2.
Hudon
,
K.
,
Sparn
,
B.
, and
Christensen
,
D.
,
2012
, “
Heat Pump Water Heater Technology Assessment Based on Laboratory Research and Energy Simulation Models
,”
National Renewable Energy Laboratory
,
Golden, CO
.
3.
DOE
,
2014
, “
Residential Water Heater Standards
,”
U.S. Department of Energy
,
Washington, DC
.
4.
Natural Resources Canada
,
2012
,
Energy Use Handbook—1990 to 2010
,
Office of Energy Efficiency
,
Ottawa, Canada
.
5.
Dickinson
,
R. M.
,
2012
,
Analysis and Development of Draw Strategies for a Multi-Tank Thermal Storage System for Solar Heating Applications
,
Carleton University
,
Ottawa, ON, Canada
.
6.
Morrison
,
G.
,
Anderson
,
T.
, and
Behnia
,
M.
,
2004
, “
Seasonal Performance Rating of Heat Pump Water Heaters
,”
Sol. Energy
,
76
(
1–3
), pp.
147
152
.
7.
Morrison
,
G.
,
1994
, “
Packaged Solar Heat-Pump Water Heaters
,”
Sol. Energy
,
53
(
3
), pp.
249
257
.
8.
Morrison
,
G. L.
,
1994
, “
Simulation of Packaged Solar Heat-Pump Water Heaters
,”
Sol. Energy
,
53
(
3
), pp.
249
257
.
9.
Baldwin
,
C.
,
2013
,
Design and Construction of an Experimental Apparatus to Assess the Performance of a Solar Absorption Chiller With Integrated Thermal Storage
,
Carleton University
,
Ottawa, ON, Canada
.
10.
Maguire
,
J.
,
Burch
,
J.
,
Merrigan
,
T.
, and
Ong
,
S.
,
2013
, “
Energy Savings and Breakeven Cost for Residential Heat Pump Water Heaters in the United States
,”
National Renewable Energy Laboratory
,
Golden, CO
.
11.
Maguire
,
J.
,
Burch
,
J.
,
Merrigan
,
T.
, and
Ong
,
S.
,
2014
, “
Regional Variation in Residential Heat Pump Water Heater Performance in the U.S.
,”
National Renewable Energy Laboratory
,
Golden, CO
.
12.
Canadian Standards Association
,
2004
,
CAN/CSA-F379.1-88: Solar Domestic Hot Water Systems (Liquid to Liquid Heat Transfer)
,
Canadian Standards Association
,
Mississauga, ON
.
13.
Brultech Research Inc
,
2012
, “
Greeneye Monitor Manual
,”
Brultech Research
,
St. Catherines, ON, Canada
.
14.
National Instruments
,
2005
,
Labview Version 8.0
,
National Instruments
,
Austin, TX
.
15.
Figliola
,
R.
, and
Beasley
,
D.
,
2011
,
Theory and Design for Mechanical Measurements
,
5th ed.
,
Wiley
,
Hoboken, NJ
.
16.
Thermal Energy Systems Specialists
,
2012
,
Storage Tank Library Mathematical Reference
,
Thermal Energy Systems Specialists
,
Madison, WI
.
17.
Guo
,
J.
,
Wu
,
J.
,
Wang
,
R.
, and
Li
,
S.
,
2011
, “
Experimental Research and Operation Optimization of an Air-Source Heat Pump Water Heater
,”
Appl. Energy
,
88
(
11
), pp.
4128
4138
.
18.
Genkinger
,
A.
,
Dott
,
R.
, and
Afjei
,
T.
,
2012
, “
Combining Heat Pumps With Solar Energy for Domestic Hot Water Production
,”
Energy Procedia
,
30
, pp.
101
105
.
19.
Bourke
,
G.
, and
Bansal
,
P.
,
2010
, “
Energy Consumption Modeling of Air Source Electric Heat Pump Water Heaters
,”
Appl. Therm. Eng.
,
30
(
13
), pp.
1769
1774
.
20.
Li
,
H.
, and
Yang
,
H.
,
2010
, “
Study on Performance of Solar Assisted Air Source Heat Pump Systems for Hot Water Production in Hong Kong
,”
Appl. Energy
,
87
(
9
), pp.
2818
2825
.
21.
Cruickshank
,
C. A.
,
2009
, “
Evaluation of a Stratified Multi-Tank Thermal Storage for Solar Heating Applications
,” Ph.D. Thesis, Queen's University, Kingston, ON, Canada.
22.
Moran
,
M.
, and
Shapiro
,
H.
,
2008
,
Fundamentals of Engineering Thermodynamics
,
6th ed.
,
Wiley
,
Hoboken, NJ
.
23.
Morrison
,
G. L.
,
2014
,
TRNAUS–14.1 TRNSYS Extensions for Solar Water Heating
,
University of New South Wales
,
Sydney, Australia
.
24.
Makin
,
T.
,
2014
,
Legionella Bacteria and Conditions for Its Growth and Thermal Disinfection in Stored, Pre-Heated Water for Domestic Purposes
,
Water Regulations Advisory Scheme
,
Stockport, UK
.
25.
Dickinson
,
R. M.
,
Cruickshank
,
C. A.
, and
Harrison
,
S. J.
,
2012
, “
The Effect of Discharge Configurations on the Thermal Behaviour of a Multi-Tank Storage System
,”
Energy Procedia
,
30
, pp.
215
224
.
26.
Klein
,
S.
,
2009
,
TRNSYS 17—A TRaNsient SYstem Simulation Program
,
University of Wisconsin-Madison Solar Energy
,
Madison, WI
.
27.
Stiebel Eltron
,
2013
,
Operation and Installation Manual
,
Stiebel Eltron
,
West Hatfield, MA
.
28.
Spur
,
R.
,
Fiala
,
D.
,
Nevrala
,
D.
, and
Probert
,
D.
,
2006
, “
Performances of Modern Domestic Hot-Water Stores
,”
Appl. Energy
,
83
(
8
), pp.
893
910
.
29.
Hepbasli
,
A.
, and
Kalinci
,
Y.
,
2009
, “
A Review of Heat Pump Water Heating Systems
,”
Renewable Sustainable Energy Rev.
,
13
(
6–7
),, pp.
1211
1229
.
30.
Klein
,
S.
, et al. ,
2009
,
TRNSYS 17—A TRaNsient SYstem Simulation Program
,
University of Wisconsin-Madison Solar Energy
,
Madison, WI
.
You do not currently have access to this content.