Experimental performance of ejector heat pump operating in the sub-critical mode

Jeremy Spitzenberger; Ramy H. Mohammed; Laith Ismael; Pengtao Wang; Hongbin Ma; Ahmad Abu-Heiba; Stephen Kowalski; Kashif Nawaz

doi:10.1016/j.enconman.2023.116724

Experimental performance of ejector heat pump operating in the sub-critical mode

Jeremy Spitzenberger, Ramy H. Mohammed, Laith Ismael, Pengtao Wang, Hongbin Ma, Ahmad Abu-Heiba, Stephen Kowalski, Kashif Nawaz

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

Abstract

Ejector heat pump (EHP) is an efficient-energy technology with a promising potential to replace the vapor compression cycle in heating and cooling applications. It can be powered by low-grade waste heat and uses environmentally friendly working fluids. EHP has also become a viable solution in research seeking cooling applications. However, little attention has been paid to using EHP for heating purposes. In order to investigate this, a steam EHP for domestic water heating was designed and built. The coefficient of performance (COP) is evaluated at various operating and design conditions in sub-critical operational modes to achieve higher condensation temperatures. Two primary nozzles with a throat diameter of 1.5 mm and 2.0 mm were investigated. The primary nozzle is movable along the ejector's axis, allowing investigation of its positional effects on the EHP's COP. Experimental measurements revealed that using a smaller throat diameter results in a high COP and low back pressure. The EHP COP and back pressure increase when the LTE temperature increases. Using a throat diameter of 1.5 mm, the EHP COP increases as the nozzle exit position (NXP) becomes closer to the constant area section. A COP of 2.42 and a back pressure of 4.28 kPa are achieved at a high-temperature evaporator (HTE) temperature of 130 °C and a low-temperature evaporator (LTE) temperature of 30 °C using a primary nozzle with 1.5 mm.

Original language	English
Article number	116724
Journal	Energy Conversion and Management
Volume	278
DOIs	https://doi.org/10.1016/j.enconman.2023.116724
State	Published - Feb 15 2023

Funding

This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The U.S. government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( https://energy.gov/downloads/doe-public-access-plan ). This material is based upon work supported by the US Department of Energy, Office of Science, Office of Energy Efficiency and Renewable Energy, Building Technologies Office. This research used resources of the Building Technologies Research and Integration Center of the Oak Ridge National Laboratory, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the US Department of Energy.

Funders	Funder number
U.S. Department of Energy
Office of Science
Oak Ridge National Laboratory
Building Technologies Office	DE-AC05-00OR22725

Keywords

COP
Heat pump
Steam ejector
Sub-critical conditions
Water heating

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10.1016/j.enconman.2023.116724

Cite this

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title = "Experimental performance of ejector heat pump operating in the sub-critical mode",

abstract = "Ejector heat pump (EHP) is an efficient-energy technology with a promising potential to replace the vapor compression cycle in heating and cooling applications. It can be powered by low-grade waste heat and uses environmentally friendly working fluids. EHP has also become a viable solution in research seeking cooling applications. However, little attention has been paid to using EHP for heating purposes. In order to investigate this, a steam EHP for domestic water heating was designed and built. The coefficient of performance (COP) is evaluated at various operating and design conditions in sub-critical operational modes to achieve higher condensation temperatures. Two primary nozzles with a throat diameter of 1.5 mm and 2.0 mm were investigated. The primary nozzle is movable along the ejector's axis, allowing investigation of its positional effects on the EHP's COP. Experimental measurements revealed that using a smaller throat diameter results in a high COP and low back pressure. The EHP COP and back pressure increase when the LTE temperature increases. Using a throat diameter of 1.5 mm, the EHP COP increases as the nozzle exit position (NXP) becomes closer to the constant area section. A COP of 2.42 and a back pressure of 4.28 kPa are achieved at a high-temperature evaporator (HTE) temperature of 130 °C and a low-temperature evaporator (LTE) temperature of 30 °C using a primary nozzle with 1.5 mm.",

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AB - Ejector heat pump (EHP) is an efficient-energy technology with a promising potential to replace the vapor compression cycle in heating and cooling applications. It can be powered by low-grade waste heat and uses environmentally friendly working fluids. EHP has also become a viable solution in research seeking cooling applications. However, little attention has been paid to using EHP for heating purposes. In order to investigate this, a steam EHP for domestic water heating was designed and built. The coefficient of performance (COP) is evaluated at various operating and design conditions in sub-critical operational modes to achieve higher condensation temperatures. Two primary nozzles with a throat diameter of 1.5 mm and 2.0 mm were investigated. The primary nozzle is movable along the ejector's axis, allowing investigation of its positional effects on the EHP's COP. Experimental measurements revealed that using a smaller throat diameter results in a high COP and low back pressure. The EHP COP and back pressure increase when the LTE temperature increases. Using a throat diameter of 1.5 mm, the EHP COP increases as the nozzle exit position (NXP) becomes closer to the constant area section. A COP of 2.42 and a back pressure of 4.28 kPa are achieved at a high-temperature evaporator (HTE) temperature of 130 °C and a low-temperature evaporator (LTE) temperature of 30 °C using a primary nozzle with 1.5 mm.

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Experimental performance of ejector heat pump operating in the sub-critical mode

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