A combined thermal power and ejector refrigeration cooling cycle is proposed in this paper to harness low-grade solar energy. It explores the possibility of utilizing abundant and low-cost hydrocarbon as the working fluid. Hydrocarbon fluid has been identified as a promising alternative to existing high global-warming-potential (GWP) refrigerants (i.e., HFCs) in next-generation cooling and organic thermal power systems. Several typical alternative refrigerants are evaluated by considering their fundamental thermophysical properties: absolute pressure level, volumetric cooling capacity, surface tension, saturated liquid/vapor density ratio, and kinematic viscosity. Comparing with R1234yf, R1234ze, and R744 (CO2), hydrocarbon refrigerants, such as R290 (propane) and R601 (pentane), do have inherent advantages for either cooling or power generation purposes in hot climates. Fundamental phase stability and transition issues have been considered in designing hydrocarbon ejectors for combined power and cooling cycles operating at high ambient temperature. Thermodynamic energy and exergy analysis has indicated that the proposed stand-alone solar thermal system offers an effective way to sustainable energy production in hot and dry climates.
Functional parts require high a level of strength and the current Fused Deposition Modelling (FDM) cannot be fully utilized as the end used parts. The poor mechanical strength is caused by the incomplete layer bonding during the printing process. In the printing process, the interlayer bonding is made too quick thus the layers are not fully fused together causing the reduced tensile strength. This paper presents a possible solution to this problem by incorporating vacuum technology in FDM system to improve tensile strength of 3D printed specimens. In this study, a desktop FDM machine was placed and operated inside a low pressure vacuum chamber. The results obtained show an improvement of 12.83 % of tensile strength compared to the standard specimen. This paper concludes that the low pressure environment is useful in reducing the heat loss due to convection of air, hence directly improves the specimen's tensile strength.
The field of computational fluid dynamics has been rekindled by recent researchers to unleash this powerful tool to predict the ejector design, as well as to analyse and improve its performance. In this paper, CFD simulation was conducted to model a 2-D axisymmetric supersonic ejector using NIST real gas model integrated in ANSYS Fluent to probe the physical insight and consistent with accurate solutions. HFOs (1234ze(E) and 1234yf) were used as working fluids for their promising alternatives, low global warming potential (GWP), and adhering to EU Council regulations. The impact of different operating conditions, performance maps, and the Pareto frontier performance approach were investigated. The expansion ratio of both refrigerants has been accomplished in linear relationship using their critical compression ratio within ±0.30% accuracy. The results show that R1234yf achieved reasonably better overall performance than R1234ze(E). Generally, by increasing the primary flow inlet saturation temperature and pressure, the entrainment ratio will be lower, and this allows for a higher critical operating back pressure. Moreover, it was found out that increasing the degree of superheat for inlet primary flow by 25 K improved the entrainment ratio by almost 20.70% for R1234yf. Conversely, increasing the degree of superheat to the inlet secondary flow has a relativity negative impact on the performance. The maximum overall ejector efficiency reached was 0.372 and 0.364 for R1234yf and R1234ze(E) respectively. Comparing the results using ideal gas model, the ejector entrainment ratio was overestimated up to 50.26% for R1234yf and 25.66% for R1234ze(E) higher than using real gas model. systems relying on fossil fuels and the use of harmful substances such as chlorofluorocarbons (CFCs) as refrigerants. In fact, the emissions from these systems also contribute to ozone depletion which is most likely to increase the demand for air-conditioning, especially for thermal comfort [2].Compared with conventional systems, ejector refrigeration systems (ERS) are more attractive, especially as we become more energy conscious. ERS come with advantages such as simple mode of function, lack of moving parts in construction, low cost, long lifespan, in addition to simplicity of installation and maintenance. This refrigeration system utilizes an ejector, generator and a liquid pump in place of the compressor which is electricity driven [3]. For a low-grade heat source, the liquid pump may consume up to 1% of the supplied heat to the ejector system. Compared to other conventional systems of the same refrigerating capacity, the ejector system may consume only one fifth of electricity consumed by the other systems [4,5].Coefficient of performance (COP) is one of the main parameters for measuring ejector efficiency. The cooling systems of the refrigeration system may be analyzed from the COP. There exists a healthy relationship between the COP and the entrainment ratio in ejector cooling systems such that systems with high COP have high entrainme...
Theoretically, each Sharp Edged Seat has fully open stem travel based on the port and ball diameters. Gas lift valve 1.5" has 6 different port diameters (3/16", ¼", 5/16", 3/8", 7/16" and ½"). For each port the ball diameter is usually larger than the port diameter by 1/16". Laboratory testing for sharp edged seats showed that the actual flow area is less than theoretically calculated area resulting from the bellows stacking before the stem reaches the fully open. Consequently, the valve stem restricts the flow and the flow rate through the valve declines. The purpose of this work is to examine the possibility of improving the efficiency of the gas lift valve by using larger ball size than conventionally used. For each port, different ball sizes were tested at different stem positions for the same condition (Injection pressure & Temperature). Results obtained from benchmark test displayed increasing in the flow rate as the ball size increases at the same stem travel.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.