scholarly journals Caracterización del IHX en un sistema de refrigeración automotriz y el COP con refrigerante R134A

2017 ◽  
Vol 2 (1) ◽  
pp. 45
Author(s):  
Bolívar Cuaical ◽  
Paúl Montúfar
Keyword(s):  
High Pressure ◽  
Standard Deviation ◽  
Heat Exchangers ◽  
Cooling System ◽  
Experimental Tests ◽  
Low Pressure ◽  
Coefficient Of Performance ◽  
Pressure Line ◽  
Pressure Zone ◽  
R 134A

The present work has the objective of characterizing several coaxial heat exchanger geometries in an automotive cooling system and its effect on the performance coefficient, using R-134a as refrigerant by means of experimental tests. In the first instance, the experimental tests were carried out with different geometries of coaxial interchanges involved in the high-pressure line between the condenser and the expansion valve, as well as the low pressure line between the evaporator and the compressor, Between the volume of the exchanger and the coefficient of performance by means of a multifactorial analysis. The development of the research entails complying with parameters for the acquisition of experimental data and the development of an adequate experimental design.  Statistical regressions  were  developed  with  R2  of  86.86%  and  a standard deviation of 2.2 for the low-pressure zone, while for the high pressure zone The regression determined a R2 of 95.17% and a standard deviation of 0.57. As for the COP and the T variables is statistically significant with a value of R2 of 99.97%, thus helping to design the heat exchangers to decrease fuel consumption in vehicles. Index Terms— : IHX,COP, R-134a, Cooling cycle Automotive, heat exchangers

scholarly journals Investigation of Pressure Oscillation and Cavitation Characteristics for Submerged Self-Resonating Waterjet

2021 ◽  
Vol 11 (15) ◽  
pp. 6972
Author(s):  
Lihua Cui ◽  
Fei Ma ◽  
Tengfei Cai
Keyword(s):  
Sudden Change ◽  
Three Dimensional ◽  
Pressure Oscillation ◽  
Experimental Tests ◽  
Low Pressure ◽  
The Self ◽  
Two Phase ◽  
Cavitation Phenomenon ◽  
Pressure Zone ◽  
Unsteady Characteristics

The cavitation phenomenon of the self-resonating waterjet for the modulation of erosion characteristics is investigated in this paper. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the unsteady characteristics of the self-resonating jet. The numerical model employs the mixture two-phase model, coupling the realizable turbulence model and Schnerr–Sauer cavitation model. Collected data from experimental tests were used to validate the model. Results of numerical simulations and experimental data frequency bands obtained by the Fast Fourier transform (FFT) method were in very good agreement. For better understanding the physical phenomena, the velocity, the pressure distributions, and the cavitation characteristics were investigated. The obtained results show that the sudden change of the flow velocity at the outlet of the nozzle leads to the forms of the low-pressure zone. When the pressure at the low-pressure zone is lower than the vapor pressure, the cavitation occurs. The flow field structure of the waterjet can be directly perceived through simulation, which can provide theoretical support for realizing the modulation of the erosion characteristics, optimizing nozzle structure.

Improved µ-Scale Turbine Expander for Energy Recovery

2010 ◽  
Author(s):  
Marcus Keding ◽  
Piotr Dudzinski ◽  
Alexander Reissner ◽  
Stefan Hummel ◽  
Martin Tajmar
Keyword(s):  
High Pressure ◽  
Power Output ◽  
Energy Recovery ◽  
Turbine Blades ◽  
Low Pressure ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Work Recovery ◽  
Micro Power ◽  
Pressure Part

Micro power converters for energy recovery are increasingly important for a number of future applications. The Austrian Institute of Technology (AIT) is presently developing an innovative μ-scale turbine expander for work recovery in transcritical CO2 heat pumps. The main drawback of a lower COP (coefficient of performance) of transcritical CO2 heat pumps compared to conventional heat pump systems can be compensated by utilizing the pressure difference between the high pressure and low pressure part of the pump for work recovery. Work recovery can be realized by substituting the expansion valve between the high and low pressure side by a Pelton turbine with specific two phase flow turbine blades. In order to increase the power output, the generator was integrated into the turbine to reduce the friction losses and hence increase the overall efficiency. An important aspect is that the generator is directly connected with the high pressure part of the turbine. One part of the project is the optimization of the turbine geometry via simulation tools. The paper will give an overview about our microturbine development as well as a comparison of the power output of each turbine generation. Furthermore the present paper discusses a concept that utilizes our microturbine together with a micro combustion module that enables a micro power generator with very high power-to-weight ratios based on green fuels.

scholarly journals PENGUJIAN PENGARUH VARIASI PUTARAN MESIN TERHADAP PERFORMANSI SISTEM PENGKONDISIAN UDARA PADA KENDARAAN PENUMPANG 1.500 cc

2017 ◽  
Vol 5 (3) ◽  
pp. 25
Author(s):  
Suadi Suadi
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Drive Belt ◽  
R 134A

Kompresor yang merupakan komponen utama memiliki peranan penting dalam mensirkulasikan dan mengkompresikan aliran refrigeran di dalam sistem pengkondisian udara. Dalam pengoperasiannya, kompresor diputar dengan crankshaft pulley mesin melalui sabuk (drive belt). Semakin tinggi putaran mesin, maka semakin tinggi pula putaran kompresor, begitu juga sebaliknya. Dapat dikatakan bahwa perubahan putaran mesin akan mempengaruhi kerja kompresor, yang pada akhirnya akan mempengaruhi performansi sistem pengkondisian udara pada kendaraan. Pengujian dilakukan dengan variasi putaran mesin mulai dari 788 rpm sampai dengan 3.288 rpm. Data-data awal yang didapat berupa tekanan rendah (low pressure) pada selang masuk kompresor dan tekanan tinggi (high pressure) pada pipa keluar kondensor. Berdasarkan kedua tekanan tersebut dapat diketahui properti refrigeran R-134a dengan menggunakan program miniREFPROP. Dari hasil pengujian pengaruh variasi putaran mesin terhadap performansi sistem pengkondisian udara yang pada kendaraan, dapat disimpulkan bahwa seiring meningkatnya putaran mesin, menyebabkan daya yang diperlukan kompresor semakin meningkat. Energi panas yang dilepaskan refrigeran di kondensor dan energi panas yang diserap refrigeran di evaporator (kapasitas pendinginan) juga mengalami peningkatan, sedangkan koefisien prestasi mengalami penurunan. Pada putaran mesin 788 rpm, koefisien prestasi yang dihasilkan sebesar 2,91. Pada kenaikan putaran mesin berikutnya koefisien prestasi mengalami penurunan sampai pada putaran mesin 3.288 rpm, koefisien prestasi yang dihasilkan sebesar 1,16.

scholarly journals Research and application of supramolecular gel plugging agent in abnormal pressure reservoir

2021 ◽  
Vol 2045 (1) ◽  
pp. 012006
Author(s):  
B Baletabieke ◽  
Y X Gu ◽  
T Zhou ◽  
D X Duan ◽  
J T Liu ◽  
...  
Keyword(s):  
High Pressure ◽  
Oil And Gas ◽  
Adhesion Force ◽  
Fiber Composite ◽  
Low Pressure ◽  
Effective Rate ◽  
Pressure Zone ◽  
Composite Gel ◽  
Pressure Area ◽  
Strong Adhesion

Abstract The Aktobe project is the largest oil and gas producing area of PetroChina in Central Asia. However, after years of exploitation, the pressure of the reservoir has dropped, making it difficult to increase the production of a single well. Both the Kenkyak block and North Troyes block of the project have induced fractured leakage, and frequent leakage affects safe and efficient drilling and completion operations and production. Therefore, the research on leakage prevention and control technology is very necessary. This article focuses on the characteristics of the cracks in the high-pressure area of the Kenkyak block and the cracks in the low-pressure area of the North Troyes block. Aiming at the fracture characteristics of the high-pressure zone in the Kenkyak block and the low-pressure zone in North Troyes block, and taking advantage of the synergistic effect of supramolecules, a supramolecular plugging-while-drilling agent was developed based on the deformable fiber composite gel. It forms a strong adhesion plugging layer on the inner wall of the leakage channel through the strong adhesion force, and it achieves a good plugging effect. The 300-500mD sand disc bearing pressure could reach 700psi when adding 3% agent, and the bearing pressure of 3-5D permeability sand disc could reach above 450psi. A supramolecular static plugging agent was also developed based on the dilatant gel. It is rich in strong shear reversible gel with supramolecular structure, which guarantees its pumpability and plugging performance. The effective rate of one-time plugging is over 80%, and the viscosity is greatly reduced after the gel is broken for 72hr, which benefits the reservoir protection.

Experimental Investigation on Effect of High Pressure Coolant with Various Cutting Speed and Feed on Surface Roughness in Cylindrical Turning of AISI 1060 Steel Using Carbide Insert

2014 ◽  
Vol 984-985 ◽  
pp. 3-8 ◽  
Author(s):  
M. Subha Shree ◽  
M. Vijaya Ganesa Velan ◽  
M. Padmakumar
Keyword(s):  
Surface Roughness ◽  
Experimental Investigation ◽  
High Pressure ◽  
Tool Life ◽  
Surface Finish ◽  
Cooling System ◽  
Cutting Speed ◽  
Low Pressure ◽  
High Pressure Coolant ◽  
Very High

Providing sufficient provisions to transfer heat from the work-tool interface is a key to improve tool life and surface integrity. With the conventional flood cooling system where the coolant is directed towards the work-tool interface at very low pressure, there are possibilities for the coolant to get heated up and produce vapors which in turn insulates the cutting zone from the coolant. This reduces the purpose of coolant. Supplying coolant at very high pressure and very high velocity may provide the best control to reduce cutting temperature and tool wear and correspondingly increases tool life. This paper deals with an experimental investigation on the effect of high pressure coolant on surface finish in cylindrical turning of AISI 1060 Steel using tungsten carbide turning insert. Surface Roughness values are captured with different cutting speed and feed rates with high pressure and low pressure coolant supply. It is observed that there was a considerable improvement in surface finish with the use of high-pressure coolant (HPC) under various cutting speed and feed rate.

Optimal Allocation of Heat Exchanger Inventory for Maximum COP and Exergetic Performance of a Two-Stage Vapor Compression Cycle

2013 ◽  
Author(s):  
Yousef M. Abdel-Rahim ◽  
S. A. Sherif
Keyword(s):  
High Pressure ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Thermal Load ◽  
Low Pressure ◽  
Coefficient Of Performance ◽  
Vapor Compression ◽  
Exergetic Efficiency

In the present study the optimum heat exchanger inventory allocation to maximize the thermal performance of a two-stage vapor compression system with two evaporators has been investigated. Both the cooling (A/C) and heating (H/P) Carnot and non-Carnot non-isentropic cycles have been considered. The optimum operating ranges of cycle parameters that maximize both the coefficient of performance (COP) and exergetic efficiency (η2) of the cycles for both cooling and heating purposes are discussed. The research upon which this paper partly reports covered all possible ranges of cycle parameters using the Monte-Carlo method. For the Carnot cycle, maximum values of the cooling coefficient of performance (COPC), cooling exergetic efficiency (ηIIC), heating coefficient of performance (COPH), and heating exergetic efficiency (ηIIH) were found to be 9.6, 0.47, 10.7 and 0.87, respectively. The low-pressure (LP) thermal load and temperature difference in the condenser were found to critically affect both the A/C and H/P performance, while the heat conductance ratio and the mass flow rate ratio were found to have a pronounced effect on only the H/P performance. The best A/C and H/P cycle performance may be achieved by having the two evaporators with both the thermal load and mass flow rate in the high-pressure loop to be 20% less than that in the low-pressure loop. The analysis performed on the non-Carnot two-compressor, two-evaporator A/C and H/P non-isentropic cycles determined both the feasible and optimal ranges of variations of the controlling parameters. The combined maximum values of the low- and high-pressure evaporator thermal loads was found to be 10–15% lower than the maximum value of the condenser heat rejection rate, thus reflecting the relative sizes of these units as heat exchangers. Other factors that may help provide guidance for utilizing the system for cooling and heating purposes include the values of the COPC and COPH, the relative amounts of the mass flow rates in the low-pressure and high-pressure loops of the cycle, and the values of the low-pressure and high-pressure compressor powers.

scholarly journals Hard time to be parents? Sea urchin fishery shifts potential reproductive contribution of population onto the shoulders of the young adults

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3067 ◽  
Author(s):  
Barbara Loi ◽  
Ivan Guala ◽  
Rodrigo Pires da Silva ◽  
Gianni Brundu ◽  
Maura Baroli ◽  
...  
Keyword(s):  
High Pressure ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Reproductive Potential ◽  
Low Pressure ◽  
Size Class ◽  
High Density ◽  
Pressure Zone ◽  
High Pressure Zone ◽  
Commercial Size

BackgroundIn Sardinia, as in other regions of the Mediterranean Sea, sustainable fisheries of the sea urchinParacentrotus lividushave become a necessity. At harvesting sites, the systematic removal of large individuals (diameter ≥ 50 mm) seriously compromises the biological and ecological functions of sea urchin populations. Specifically, in this study, we compared the reproductive potential of the populations from Mediterranean coastal areas which have different levels of sea urchin fishing pressure. The areas were located at Su Pallosu Bay, where pressure is high and Tavolara-Punta Coda Cavallo, a marine protected area where sea urchin harvesting is low.MethodsReproductive potential was estimated by calculating the gonadosomatic index (GSI) from June 2013 to May 2014 both for individuals of commercial size (diameter without spines, TD ≥ 50 mm) and the undersized ones with gonads (30 ≤ TD < 40 mm and 40 ≤ TD < 50 mm). Gamete output was calculated for the commercial-size class and the undersized individuals with fertile gonads (40 ≤ TD < 50 mm) in relation to their natural density (gamete output per m2).ResultsThe reproductive potential of populations was slightly different at the beginning of the sampling period but it progressed at different rates with an early spring spawning event in the high-pressure zone and two gamete depositions in early and late spring in the low-pressure zone. For each fertile size class, GSI values changed significantly during the year of our study and between the two zones. Although the multiple spawning events determined a two-fold higher total gamete output of population (popTGO) in the low-pressure zone, the population mean gamete output (popMGO) was similar in the two zones. In the high-pressure zone, the commercial-sized individuals represented approximatively 5% of the population, with almost all the individuals smaller than 60 mm producing an amount of gametes nearly three times lower than the undersized ones. Conversely, the high density of the undersized individuals released a similar amount of gametes to the commercial-size class in the low-pressure zone.DiscussionOverall, the lack of the commercial-size class in the high-pressure zone does not seem to be very alarming for the self-supporting capacity of the population, and the reproductive potential contribution seems to depend more on the total density of fertile sea urchins than on their size. However, since population survival in the high-pressure zone is supported by the high density of undersized sea urchins between 30 and 50 mm, management measures should be addressed to maintain these sizes and to shed light on the source of the larval supply.

Study on EGR Technology Routes of Vehicle Engine - A Review

2013 ◽  
Vol 805-806 ◽  
pp. 1416-1420
Author(s):  
Li Zhou
Keyword(s):  
High Pressure ◽  
Cooling System ◽  
Basic Structure ◽  
Low Pressure ◽  
Vehicle Engine ◽  
Technical Requirements ◽  
Emission Regulations

An introduction was given to the basic structure principles and testing programs of EGR system. The technical key elements which can improve the comprehensive performances of EGR system were put forward, and these elements were composed of the choice of high pressure loop (HPL) and low pressure loop (LPL) EGR system, the design of EGR valve, the design of EGR cooling system, the uniformity of EGR in every cylinder and the matching with VGT system. Finally, a sum that EGR technical requirements meet different emission regulations was established

Laboratory Infrared Thermal Assessment of Laser-Sintered High-Pressure Nozzle Guide Vanes to Derisk Engine Design Programs

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Benjamin Kirollos ◽  
Thomas Povey
Keyword(s):  
High Pressure ◽  
Thermal Performance ◽  
Cooling System ◽  
Guide Vane ◽  
Experimental Tests ◽  
Laser Sintering ◽  
University Of Oxford ◽  
Engine Design ◽  
Nozzle Guide ◽  
Pressure Nozzle

The continuing maturation of metal laser-sintering technology (direct metal laser sintering (DMLS)) presents the opportunity to derisk the engine design process by experimentally down-selecting high-pressure nozzle guide vane (HPNGV) cooling designs using laboratory tests of laser-sintered—instead of cast—parts to assess thermal performance. Such tests could be seen as supplementary to thermal-paint test engines, which are used during certification to validate cooling system designs. In this paper, we compare conventionally cast and laser-sintered titanium alloy parts in back-to-back experimental tests at engine-representative conditions over a range of coolant mass flow rates. Tests were performed in the University of Oxford Annular Sector Heat Transfer Facility. The thermal performance of the cast and laser-sintered parts—measured using new infrared processing techniques—is shown to be very similar, demonstrating the utility of laser-sintered parts for preliminary engine thermal assessments. We conclude that the methods reported in this paper are sufficiently mature to make assessments which could influence engine development programs.

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