scholarly journals Numerical Investigation on the Performance of Two-Throat Nozzle Ejectors with Different Mixing Chamber Structural Parameters

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6900
Author(s):  
Fatong Jia ◽  
Dazhang Yang ◽  
Jing Xie
Keyword(s):  
Structural Parameters ◽  
Operational Performance ◽  
Water Heater ◽  
Chamber Length ◽  
Heat Pump Water Heater ◽  
Mixing Chamber ◽  
Optimal Value ◽  
Nozzle Geometries ◽  
Converging Angle ◽  
Chamber Diameter

In this study, the effects of the mixing chamber diameter (Dm), mixing chamber length (Lm) and pre-mixing chamber converging angle (θpm) were numerically investigated for a two-throat nozzle ejector to be utilized in a CO2 refrigeration cycle. The developed simulated method was validated by actual experimental data of a CO2 ejector in heat pump water heater system from the published literature. The main results revealed that the two-throat nozzle ejectors can obtain better performance with Dm in the range of 8–9 mm, Lm in the range of 64–82 mm and θpm at approximately 60°, respectively. Deviation from its optimal value could lead to a poor operational performance. Therefore, the mixing chamber structural parameters should be designed at the scope around its optimal value to guarantee the two-throat nozzle ejector performance. The following research can be developed around the two-throat nozzle geometries to strengthen the ejector performance.

Simulation and experiment study of the self-excited oscillating mixer with abrasive jet used for the descaling of rusty steel

2019 ◽  
Vol 233 (5) ◽  
pp. 1109-1127 ◽  
Author(s):  
Hui Ji ◽  
Xiurong Cao ◽  
Songlin Nie ◽  
Fanglong Yin
Keyword(s):  
Simulation Experiment ◽  
Inlet Pressure ◽  
Abrasive Water Jet ◽  
Strip Steel ◽  
Chamber Length ◽  
Mixing Chamber ◽  
Excited Oscillation ◽  
Simulation And Experiment ◽  
Jet Characteristics ◽  
Chamber Diameter

A novel self-excited oscillating mixer is developed for the descaling of strip steel, which synthesizes the post-mixed abrasive water jet and self-excited oscillation. The realizable k-ɛ model is selected to investigate the effects of different abrasive entrance, inlet pressure, mixing chamber diameter, and length on the jet characteristics. Meanwhile, the effects of different inlet pressure and target distance on the outlet velocities for two kinds of mixers (including the developed mixer and conventional post-mixing mixer) with or without abrasive jet are investigated through simulation. Experiment as well as simulation results exhibited: (1) The oblique abrasive entrance can accelerate the mixture of water and abrasive due to its larger turbulent kinetic energy, and its outlet velocity is larger than that of radial and axial abrasive entrances. (2) For the developed mixer, the outlet velocity is preferable when the mixing chamber diameter is about 40–50 mm and the mixing chamber length is 20 mm. (3) The descaling efficiency of the developed mixer is superior to that of conventional post-mixing mixer. The research will lay foundation to optimize the structure of self-excited oscillating mixer for the descaling of rusty steel.

scholarly journals Optimisation Analysis of Structural Parameters of an Annular Slot Ejector Based on the Coanda Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Fengliang Wu ◽  
Zhisheng Li
Keyword(s):  
Structural Parameters ◽  
Turbulent Transport ◽  
Internal Field ◽  
Entrainment Ratio ◽  
Chamber Length ◽  
Annular Slot ◽  
Quantitative Correlation ◽  
Mixing Chamber ◽  
Single Factor Analysis ◽  
Grey Relational

To investigate the effect of structural parameters on the performance of an annular slot ejector, a series of numerical simulations were conducted with single-factor analysis. Moreover, a multifactor grey relational analysis was applied to examine the correlations between the structural parameters and entrainment ratio. Subsequently, the optimised model was verified by comparing the simulated results with experimental data. Results show that the performance of the optimised ejector model was improved. The RNG k-ε turbulent transport mode can simulate the internal field characteristics of an annular slot ejector, and the corresponding simulated results, as verified by experiment, satisfy engineering requirements. In addition, a quantitative correlation between structural parameters and entrainment ratio was obtained as follows: e (nozzle clearance) > θ (diffusing chamber angle) > HL (mixing chamber length) > d (throat diameter) > KL (diffusing chamber length). This work may provide a certain guiding significance for the design and application of annular slot ejectors.

scholarly journals The Influence of Internal Heat Exchanger on the Performance of Transcritical CO2 Water Source Heat Pump Water Heater

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1787
Author(s):  
Fan Feng ◽  
Ze Zhang ◽  
Xiufang Liu ◽  
Changhai Liu ◽  
Yu Hou
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Internal Heat ◽  
Water Source ◽  
Hot Water ◽  
Operational Performance ◽  
Water Heater ◽  
Source Temperature ◽  
Internal Heat Exchanger ◽  
Heat Pump Water Heater

The characteristics of the transcritical CO2 heat pump water heater (HPWH) system are; a lower inlet hot water temperature (Ti-hw) (sometimes this is lower than the water source temperature), and an outlet gas cooler temperature (To-gc) which is affected by the Ti-hw and often lower than the critical temperature. In order to study the effects of the internal heat exchanger (IHX) on the operational performance of the transcritical CO2 HPWH when To-gc is low, a transcritical CO2 water source HPWH experiment platform is established to conduct experimental research and comparative analysis on the operational performance of the transcritical CO2 water source HPWH, with or without IHX. It is found that, if only the coefficient of performance (COP) and heating at the optimal exhaust pressure of the transcritical CO2 water source HPWH were considered, COP and the heating of the non-IHX system would be slightly higher than those of the IHX system at the lower hot water flow and water source temperature, and this increase was not obvious. At the higher hot water flow rate and water source temperature, COP and the heating of the non-IHX system were also higher than those of the IHX system, and the increase was obvious. The experiment results showed that, near the optimal exhaust pressure, the variation range of COP and heating of the IHX system is relatively small, and the system has a relatively high stability.

Research and development of an air-cycle heat-pump water heater. Final report

1979 ◽  
Author(s):  
J.T. Dieckmann ◽  
A.J. Erickson ◽  
A.C. Harvey ◽  
W.M. Toscano
Keyword(s):  
Research And Development ◽  
Heat Pump ◽  
Final Report ◽  
Water Heater ◽  
Heat Pump Water Heater

Numerical analysis of the heat pump water heater with immersed helically coiled tubes

2021 ◽  
Vol 39 ◽  
pp. 102547
Author(s):  
Sami Missaoui ◽  
Zied Driss ◽  
Romdhane Ben Slama ◽  
Bechir Chaouachi
Keyword(s):  
Numerical Analysis ◽  
Heat Pump ◽  
Water Heater ◽  
Heat Pump Water Heater

Energy Consumption Modeling of a Heat Pump System for Combined Space Conditioning and Residential Water Heating in a Typical Household in Quito, Ecuador

2016 ◽  
Author(s):  
Gabriel Agila ◽  
Guillermo Soriano
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Thermal Storage ◽  
Hot Water ◽  
Water Heating ◽  
Water Heater ◽  
Pump System ◽  
Detailed Model ◽  
Heat Pump Water Heater ◽  
Residential Water

This research develops a detailed model for a Water to Water Heat Pump Water Heater (HPWH), operating for heating and cooling simultaneously, using two water storage tanks as thermal deposits. The primary function of the system is to produce useful heat for domestic hot water services according to the thermal requirements for an average household (two adults and one child) in the city of Quito, Ecuador. The purpose of the project is to analyze the technical and economic feasibility of implementing thermal storage and heat pump technology to provide efficient thermal services and reduce energy consumption; as well as environmental impacts associated with conventional systems for residential water heating. An energy simulation using TRNSYS 17 is carried to evaluate model operation for one year. The purpose of the simulation is to assess and quantifies the performance, energy consumption and potential savings of integrating heat pump systems with thermal energy storage technology, as well as determines the main parameter affecting the efficiency of the system. Finally, a comparative analysis based on annual energy consumption for different ways to produce hot water is conducted. Five alternatives were examined: (1) electric storage water heater; (2) gas fired water heater; (3) solar water heater; (4) air source heat pump water heater; and (5) a heat pump water heater integrated with thermal storage.

Assessment of a heat pump water heater

1985 ◽  
Vol 9 (1) ◽  
pp. 77-89 ◽  
Author(s):  
J. A. Anderson ◽  
R. A. Bradford ◽  
C. G. Carrington
Keyword(s):  
Heat Pump ◽  
Water Heater ◽  
Heat Pump Water Heater
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