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1
Content available remote A computational analysis of different geometric ratios at the input of a secondary fluid that affects the efficiency of a subsonic air-air ejector
Hincapie-Montoya Jhon Fredy, Sierra-Del-Rio Jorge Andres, Torres-Lopez Edwar, Hincapie-Zuluaga Diego Andres
Engineering Transactions
|
2021
|
Vol. 69, iss. 3
257--269
EN
For this study, the computational fluid dynamics (CFD) technique was used to investigate the combined effects of different geometric parameter relationships; inclination angle variation of the secondary fluid inlet, different lengths of the mixing chamber, and different separation values between the nozzle outlet and the input of the mixing chamber, in an air-air ejector used in a subsonic regime. As a working fluid, the air was used as an ideal gas and its viscosity was expressed as a constant both in the primary and secondary fluids. The renormalization group (RNG) κ−ε turbulence model was used to predict more accurately the way the pressure recovers along the ejector and suitability/applicability to for recirculation flows. It was found in the numerical results that there is an optimal value of the inclination angle for the secondary fluid inlet, the length of the mixing chamber and the separation between the nozzle outlet and the mixing chamber inlet, where the ejector obtains its maximum mass flow ratio. In addition, it was found that the efficiency of the air-air ejector is related to the inclination angle of the secondary fluid inlet.
2
Content available Experimental study of a two-phase ejector for CO2 transcritical refrigeration system
Haberschill Philippe, Nehdi Ezzeddine, Kairouani Lakdar, Elakhdar Mouna Abouda
Archives of Thermodynamics
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2021
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Vol. 42, no 4
217--246
EN
The geometry and operating parameters have an important influence on the performance of ejectors. The improvement of the refrigeration cycle performance and the design of the ejectors for the compression energy recovery requires a detailed analysis of the internal ejector working characteristics and geometry. To this aim, an experimental investigation of an ejector refrigeration system is conducted to determine the effect of the most important ejector dimensions on ejector working characteristics and system performance. Different dimensions of ejector components are tested. The influence of the ejector’s geometrical parameters on the system performance was analysed. The experiments with respect to the variation of ejector geometry such as the motive nozzle throat diameter, the mixing chamber diameter and the distance between the motive nozzle and diffuser were carried out. There exist optimum design parameters in each test. The experimental results show that the performance (entrainment ratio and a compression ratio of the ejector) increases significantly with the position between the primary nozzle and the mixing chamber. A maximum entrainment ratio of 57.3% and a compression ratio of 1.26 were recorded for the different parameters studied. The results obtained are consistent with experimental results found in the literature.
3
Content available remote Zagadnienia zastosowania strumienic w sprężarkowych i absorpcyjnych układach chłodniczych
Dudar A.
Instal
|
2018
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nr 10
21--25
PL
W pracy zawarto analizę zastosowań strumienic w układach chłodniczych. Opisano budowę i zasadę działania strumienic dwufazowych jako najczęściej stosowanych w układach chłodniczych, oraz ich wpływu na podwyższenie wydajności energetycznej urządzeń chłodniczych.
EN
The paper contains an analysis of the applications of ejectors in refrigeration systems. Describes the design and operation of two-phase ejectors as the most commonly used in refrigeration systems, and their effect on increasing the efficiency of cooling devices.
4
Content available remote Analiza egzergetyczna pracy strumienicy dwufazowej w układach chłodniczych sprężarkowych
Dudar A.
Instal
|
2018
|
nr 12
26--31
PL
W wielu gałęziach gospodarki poszukuje się rozwiązań umożliwiających zmniejszenie, w różnej formie, zużycia energii bądź też jej efektywniejszego wykorzystania. Podobne prace trwają również w dziedzinie chłodnictwa i pomp ciepła. W pracy zaprezentowano metodę podniesienia efektywności energetycznej obiegów lewobieżnych poprzez zastosowanie strumienicy dwufazowej pracującej jako podprężarka. Przedstawiono efekty analizy teoretycznej pracy układu sprężarkowego jak również jego współpracy z ze strumienicą dwufazową dla wybranych czynników.
EN
In many branches of the economy, solutions are sought for reducing, in various forms, energy consumption or its more efficient use. Similar work also continues in the field of refrigeration and heat pumps. The paper presents a method of increasing the energy efficiency of the left-side cycles by using a two-phase injector working as a compressor. The results of the theoretical analysis of the operation of the compressor system as well as its cooperation with a two-phase streamer for selected factors are presented.
5
Content available Thermodynamic analysis of a new dual evaporator CO2 transcritical refrigeration cycle
Abdellaoui E. Y., Kairouani L. K.
Archives of Thermodynamics
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2017
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Vol. 38, no. 1
39--62
EN
In this work, a new dual-evaporator CO2 transcritical refrigeration cycle with two ejectors is proposed. In this new system, we proposed to recover the lost energy of condensation coming off the gas cooler and operate the refrigeration cycle ejector free and enhance the system performance and obtain dual-temperature refrigeration simultaneously. The effects of some key parameters on the thermodynamic performance of the modified cycle are theoretically investigated based on energetic and exergetic analysis. The simulation results for the modified cycle indicate more effective system performance improvement than the single ejector in the CO2 vapor compression cycle using ejector as an expander ranging up to 46%. The exergetic analysis for this system is made. The performance characteristics of the proposed cycle show its promise in dual-evaporator refrigeration system.
6
Content available Design and optimisation of exhaust system of light turboprop airplane
Stalewski W.
Journal of KONES
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2016
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Vol. 23, No. 2
341--348
EN
Innovative exhaust system for light turboprop airplane has been developed and optimised. Apart from the basic function of removing exhaust from turboprop engine, the system supports cooling of the engine bay. To do this, the system removes hot air from the engine bay, utilising the ejector-pump effect, where the exhaust stream generates under-pressure, sucking the hot air through the ejector slot and removes the air together with the exhaust gases. The design and optimisation of the exhaust system has been conducted based on computational methods of Computer-Aided Design and Optimisation and Computational Fluid Dynamic. Three-dimensional analysis of flow around the airplane (including effect of propeller) and inside the exhaust system was conducted by application of URANS solver ANSYS FLUENT. Using these software the trajectories of exhaust particles, both inside the exhaust ducts and outside the airplane, have been determined. Parametric model of the designed exhaust system has been developed using the in-house software PARADES. As design parameters the diameter, length and direction of exhaust ducts as well as few parameters describing a shape of the ejector, have been established. The optimisation process aimed at designing of the exhaust system, which removes the exhaust gases possibly far away from the airframe, especially during a descent flight of the airplane. Additional objectives were maximisation of the mass flow rate of hot air sucked through the ejector and minimisation of the drag force generated by external part of the exhaust system. The optimised exhaust system should have also fulfilled requirements of permissible total-pressure losses inside the exhaust ducts. The optimised exhaust system has been implemented on the light turboprop airplane and validated during flight tests.
7
Content available remote Zagadnienia produkcji chłodu z niskotemperaturowych źródeł ciepła z zastosowaniem strumienicowych układów chłodniczych
Pawluczuk A., Butrymowicz D.
Instal
|
2016
|
nr 11
26--32
PL
Przedstawiono podstawowe zagadnienia zastosowania układów chłodniczych strumienicowych w aspekcie wykorzystania niskotemperaturowego ciepła odpadowego jako źródła napędowego. Oceniono efektywność energetyczną tych układów oraz scharakteryzowano stosowane w nich czynniki robocze. Omówiono aspekty aplikacji inżektora dwufazowego w tych układach.
EN
Review on applications of ejection refrigeration systems with usage of low grade heat sources as motive heat was presented. The energy efficiency of these systems was assessed along with short analysis of the potential working fluids. The issues of application of two-phase vapour-liquid injectors in these systems were presented.
8
System klimatyzacji strumienicowej z napędem solarnym – wpływ temperatury powierzchni absorbera na sprawność układu
Gil B.
Logistyka
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2013
|
nr 4
PL
W artykule przedstawiono analizę pracy solarnego systemu klimatyzacji strumienicowej. Badania teoretyczne przeprowadzone zostały dla dwóch czynników z grupy węglowodorów: izobutanu (R600a) oraz pentanu (R601). Do wyznaczenia optymalnych warunków pracy układu posłużono się dwoma modelami: jednowymiarowym modelem strumienicy oraz modelem próżniowego, płaskiego kolektora słonecznego stanowiącego źródło napędu. Warunki pracy systemu zmieniano w zakresie: te 0–10°C, tc 30– 40°C, tg 70–120°C dla izobutanu oraz 100–180°C dla pentanu. Zmiana temperatury absorbera i generowanej pary napędowej wpływają na sprawność pracy obiegu napędowego. Efektywność chłodnicza obiegu zależy od temperatury odparowania i skraplania czynnika roboczego. Badania pokazały, iż wzrost temperatury skraplania wpływa niekorzystnie na uzyskiwaną moc chłodniczą. Wartości COPo w optymalnym punkcie pracy wyniosły 0,425 i 0,358, odpowiednio dla izobutanu i pentanu.
EN
In this paper the overall performance of the solar-powered ejector air-conditioning system using isobutane (R600a) and pentane (R601) as refrigerants is presented. One dimensional model of the ejector and model of the flat, evacuated solar collector were used to determine optimum operating point. The efficiency of the solar collector cycle is determined by absorber and primary vapor temperatures. A study has shown that COP highly depends on evaporating and condensing temperatures of the working fluids. Condensing temperature also had the important influence on the achieved cooling capacity. Maximum overall systems’ value of COP obtained for refrigerants R600a and R601, were 0.425 and 0.358, respectively, with operating conditions as follow: te 0–10°C, tc 30–40°C, tg 70–120°C for iso-butane and 100–180°C for pentane.
9
Content available Energy efficiency for the transcritical compression CO2 cycle with the use of the ejector as the first stage of the compression
Kozioł J., Gazda W., Wilżyński Ł.
Archives of Thermodynamics
|
2010
|
Vol. 31, no. 4
61-69
EN
An analysis of energy efficiency for transcritical compression unit with CO2 (R744) as the refrigerant has been carried out using empirical operating characteristics for the two-phase ejector. The first stage of the refrigerant compression is carried out in the ejector. The criterion adopted for the estimation of energy efficiency for the cycle is the coefficient of performance COP. The analysis is performed for the heat pump and refrigeration systems. The results of COP for the systems with the ejector has been compared with the COP[L], values for the single stage Linde cycle.
10
Content available remote Badania obiegu strumienicowego dla układu klimatyzacji solarnej
Trela M., Butrymowicz D., Karwacki J., Ochrymiuk T., Śmierciew K.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
|
2007
|
nr 132
287-296
PL
W referacie zaprezentowano ideę klimatyzacji solarnej opartej na zastosowaniu strumienicowego urządzenia chłodniczego napędzanego ciepłem promieniowania słonecznego. Przedstawiono stanowisko badawcze, wstępne wyniki badań uzyskane dla czynnika R-123 oraz wyniki modelowania numerycznego strumienicy parowej.
EN
The basic principles of solar air-conditioning based on the ejection refrigeration system motivated by solar radiation heat has been presented. The testing rig, preliminary test results obtained with R-123 refrigerant as well as numerical modeling results of vapour ejector have been presented in the paper.
11
Geothermal heat pumps with two-phase condensing ejector
Bergander M.
Archiwum Gospodarki Odpadami i Ochrony Środowiska
|
2006
|
Vol. 4
1-12
EN
The paper describes the development of a novel vapor compression cycle for refrigeration with regenerative use of the potential energy of two-phase flow expansion, which in traditional systems is lost in expansion valves. The new cycle includes a second step compression by an ejector device, which combines the compression with simultaneous throttling of the liquid. The compressor compresses the vapor to approximately 2/3 of the final pressure and additional compression is provided in an ejector, thus the amount of mechanical energy required by a compressor is reduced and the efficiency is increased. Investigations described here were performed under the funding from the US Department of Energy. The thermodynamic model was developed for R22 refrigerant, showing a possible efficiency improvement of 38% as compared to the traditional vapor compression cycle. The theoretical work was followed by building a 10 kW prototype and practical demonstration of 16% energy savings in the first attempt.
PL
W artykule opisano rozwój systemów chłodniczych wykorzystujących energię potencjalną dwufazowego rozprężanie, która jest tracona w tradycyjnych systemach. Nowy cykl zawiera dodatkowy etap sprężania przy użyciu ejektora, który łączy sprężanie z jednoczesnym dławieniem płynu. Kompresor spręża pary do około 2/3 końcowego ciśnienia, a dodatkowe sprężanie ma miejsce dzięki ejektorowi. Z tego względu całkowita energia dostarczana do kompresora jest zmniejszona i tym samym sprawność jest podniesiona. Prace opisane w artykule były prowadzone dzięki wsparciu Ministerstwa Energii USA. Model termodynamiczny został rozwinięty dla czynnika R22, pokazując możliwe podniesienie sprawności o 38% w porównaniu do tradycyjnego cyklu sprężania. Prace teoretyczne zostały wzbogacone przez wybudowany 10kW prototyp i pokaz rzeczywistej oszczędności 16% energii przy pierwszej próbie.
12
Content available remote Modelling of energetic optimal working point of an ejector air conditioner combined with a flat solar collector
Kasperski J., Pietrowicz S.
Archives of Thermodynamics
|
2006
|
Vol. 27, no. 4
111-122
EN
An article describes prototype of multi-layer solar air-conditioner of small refrigerating capacity. In a compact device installed in a hipped roof end or in a wall of building, a ejector refrigerating cycle is supplied with a steam generated in a flat solar collector. Compiling the equations describing the phenomena occur in a steam ejector and the heat exchangers a physical model of the device was proposed. Numerical version of that model was used to create the characteristics of cooperating devices. The obtained characteristics allowed to determine an optimum point of device work. Finally the general guidelines for design engineers were formulated.
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