Techno-economic assessment of cascade air-to-water heat pump retrofitted into residential buildings using experimentally validated simulations

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Abstract

Cascade air-to-water heat pumps have better overall efficiency than single-stage air-to-water heat pumps when operating at low ambient temperatures for high temperature water supply. While many studies in the literature investigated the specific features of equipment performance of cascade heat pumps, there is little information about retrofit applications of these heat pumps in residential buildings using experimentally validated dynamic building simulations. In this study, the techno-economic assessment of a variable capacity cascade air-to-water heat pump retrofitted into residential buildings is conducted by means of experimentally validated TRNSYS simulations. The cascade heat pump coupled with thermal energy storage operating in different scenarios is further studied. Laboratory and field trial results were obtained to develop and validate a cascade heat pump model integrated with a dynamic building simulation model. Regarding the heat pump system without storage, the predicted annual COPs were almost below 2.5 at ambient temperatures of from −11.2 °C to 29.5 °C, even the heat pump adopted weather compensation control. Simulation results also indicated that the cascade heat pump could not defeat gas boilers and high-efficiency oil boilers (90%) in terms of operating costs, but there were CO 2 reductions (from 14% to 57%). As for the heat pump coupled with storage, simulation results showed that at ambient temperatures of between −5.6 °C and 23.8 °C, the continuous coupling between the heat pump and the storage revealed the lowest annual performance (actual COP of 1.41), while the direct heating obtained the highest efficiency (actual COP of 2.12) followed by the load-shifting (actual COP of 1.88).

LanguageEnglish
Pages633-652
Number of pages20
JournalApplied Energy
Volume250
Early online date10 May 2019
DOIs
Publication statusPublished - 15 Sep 2019

Fingerprint

Cascades (fluid mechanics)
Pumps
Economics
air
Air
economics
simulation
Water
water
Boilers
Hot Temperature
residential building
heat pump
Temperature
Heat pump systems
temperature
Thermal energy
Water supply
Operating costs
Energy storage

Keywords

  • Cascade air-to-water heat pump
  • thermal energy storage
  • retrofit performance
  • TRNSYS simulation
  • energy performance
  • running costs
  • carbon emissions
  • Running costs
  • Thermal energy storage
  • Energy performance
  • Retrofit performance
  • Carbon emissions

Cite this

@article{19742efd66e1403abe512bee5c2bc09a,
title = "Techno-economic assessment of cascade air-to-water heat pump retrofitted into residential buildings using experimentally validated simulations",
abstract = "Cascade air-to-water heat pumps have better overall efficiency than single-stage air-to-water heat pumps when operating at low ambient temperatures for high temperature water supply. While many studies in the literature investigated the specific features of equipment performance of cascade heat pumps, there is little information about retrofit applications of these heat pumps in residential buildings using experimentally validated dynamic building simulations. In this study, the techno-economic assessment of a variable capacity cascade air-to-water heat pump retrofitted into residential buildings is conducted by means of experimentally validated TRNSYS simulations. The cascade heat pump coupled with thermal energy storage operating in different scenarios is further studied. Laboratory and field trial results were obtained to develop and validate a cascade heat pump model integrated with a dynamic building simulation model. Regarding the heat pump system without storage, the predicted annual COPs were almost below 2.5 at ambient temperatures of from −11.2 °C to 29.5 °C, even the heat pump adopted weather compensation control. Simulation results also indicated that the cascade heat pump could not defeat gas boilers and high-efficiency oil boilers (90{\%}) in terms of operating costs, but there were CO 2 reductions (from 14{\%} to 57{\%}). As for the heat pump coupled with storage, simulation results showed that at ambient temperatures of between −5.6 °C and 23.8 °C, the continuous coupling between the heat pump and the storage revealed the lowest annual performance (actual COP of 1.41), while the direct heating obtained the highest efficiency (actual COP of 2.12) followed by the load-shifting (actual COP of 1.88).",
keywords = "Cascade air-to-water heat pump, thermal energy storage, retrofit performance, TRNSYS simulation, energy performance, running costs, carbon emissions, Running costs, Thermal energy storage, Energy performance, Retrofit performance, Carbon emissions",
author = "Khoa Le and M Huang and Nikhilkumar Shah and Christopher Wilson and Paul MacArtain and Raymond Byrne and Neil Hewitt",
year = "2019",
month = "9",
day = "15",
doi = "10.1016/j.apenergy.2019.05.041",
language = "English",
volume = "250",
pages = "633--652",
journal = "Applied Energy",
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AU - Le, Khoa

AU - Huang, M

AU - Shah, Nikhilkumar

AU - Wilson, Christopher

AU - MacArtain, Paul

AU - Byrne, Raymond

AU - Hewitt, Neil

PY - 2019/9/15

Y1 - 2019/9/15

N2 - Cascade air-to-water heat pumps have better overall efficiency than single-stage air-to-water heat pumps when operating at low ambient temperatures for high temperature water supply. While many studies in the literature investigated the specific features of equipment performance of cascade heat pumps, there is little information about retrofit applications of these heat pumps in residential buildings using experimentally validated dynamic building simulations. In this study, the techno-economic assessment of a variable capacity cascade air-to-water heat pump retrofitted into residential buildings is conducted by means of experimentally validated TRNSYS simulations. The cascade heat pump coupled with thermal energy storage operating in different scenarios is further studied. Laboratory and field trial results were obtained to develop and validate a cascade heat pump model integrated with a dynamic building simulation model. Regarding the heat pump system without storage, the predicted annual COPs were almost below 2.5 at ambient temperatures of from −11.2 °C to 29.5 °C, even the heat pump adopted weather compensation control. Simulation results also indicated that the cascade heat pump could not defeat gas boilers and high-efficiency oil boilers (90%) in terms of operating costs, but there were CO 2 reductions (from 14% to 57%). As for the heat pump coupled with storage, simulation results showed that at ambient temperatures of between −5.6 °C and 23.8 °C, the continuous coupling between the heat pump and the storage revealed the lowest annual performance (actual COP of 1.41), while the direct heating obtained the highest efficiency (actual COP of 2.12) followed by the load-shifting (actual COP of 1.88).

AB - Cascade air-to-water heat pumps have better overall efficiency than single-stage air-to-water heat pumps when operating at low ambient temperatures for high temperature water supply. While many studies in the literature investigated the specific features of equipment performance of cascade heat pumps, there is little information about retrofit applications of these heat pumps in residential buildings using experimentally validated dynamic building simulations. In this study, the techno-economic assessment of a variable capacity cascade air-to-water heat pump retrofitted into residential buildings is conducted by means of experimentally validated TRNSYS simulations. The cascade heat pump coupled with thermal energy storage operating in different scenarios is further studied. Laboratory and field trial results were obtained to develop and validate a cascade heat pump model integrated with a dynamic building simulation model. Regarding the heat pump system without storage, the predicted annual COPs were almost below 2.5 at ambient temperatures of from −11.2 °C to 29.5 °C, even the heat pump adopted weather compensation control. Simulation results also indicated that the cascade heat pump could not defeat gas boilers and high-efficiency oil boilers (90%) in terms of operating costs, but there were CO 2 reductions (from 14% to 57%). As for the heat pump coupled with storage, simulation results showed that at ambient temperatures of between −5.6 °C and 23.8 °C, the continuous coupling between the heat pump and the storage revealed the lowest annual performance (actual COP of 1.41), while the direct heating obtained the highest efficiency (actual COP of 2.12) followed by the load-shifting (actual COP of 1.88).

KW - Cascade air-to-water heat pump

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KW - running costs

KW - carbon emissions

KW - Running costs

KW - Thermal energy storage

KW - Energy performance

KW - Retrofit performance

KW - Carbon emissions

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JF - Applied Energy

SN - 0306-2619

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