Experimental performance of ejector heat pump operating in the sub-critical mode. (15th February 2023)

• Record Type: Journal Article
• Authors: Spitzenberger, Jeremy; Mohammed, Ramy H.; Ismael, Laith; Wang, Pengtao; Ma, Hongbin; Abu-Heiba, Ahmad; Kowalski, Stephen; Nawaz, Kashif
• Is Part Of: Energy conversion and management. Volume 278(2023)
• Publication Date: 2023-02-15
• Subjects: Steam ejector -- Heat pump -- COP -- Sub-critical conditions -- Water heating; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2023.116724
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: An ejector heat pump was built for domestic water heating. Two different primary nozzles were investigated. A smaller throat diameter results in a high COP and low back pressure. The optimal position of the primary nozzle was about the middle of the suction chamber. The ejector map is provided to help selecting the proper operating conditions. 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.