scholarly journals Numerical and experimental studies on circulation of working fluid in liquid droplet radiator

2006 ◽  
Vol 59 (1-5) ◽  
pp. 192-199 ◽  
Author(s):  
Tsuyoshi Totani ◽  
Takuya Kodama ◽  
Kensuke Watanabe ◽  
Kota Nanbu ◽  
Harunori Nagata ◽  
...  
Keyword(s):  
Liquid Droplet ◽  
Experimental Studies ◽  
Working Fluid

scholarly journals Investigation of a Turbogenerator Based on the Vortex Expansion Machine with a Peripheral Side Channel

2021 ◽  
Vol 8 (1) ◽  
pp. F11-F18
Author(s):  
S.M. Vaneev ◽  
V.S. Martsynkovskyy ◽  
A. Kulikov ◽  
D.V. Miroshnichenko ◽  
Ya.І. Bilyk ◽  
...  
Keyword(s):  
Electricity Generation ◽  
Experimental Studies ◽  
Geometric Parameters ◽  
Working Fluid ◽  
Advantages And Disadvantages ◽  
Lateral Channel ◽  
Different Types ◽  
Flow Part ◽  
Special Stand ◽  
Constant Improvement

The creation of energy-saving turbogenerators is an essential component of the development of small energy systems. The gradual growth of interest in distributed electricity generation necessitates the constant improvement of these units. Moreover, they implement a more environmentally friendly generation method than when using microturbine units that use fuel to carry out the work process. Nowadays, turbogenerators are created based on different types of expansion machines, which have their advantages and disadvantages, given in this article. Compared to competitors, vortex expansion machines have good prospects and the necessary potential to expand their research and produce turbogenerators. An experimental vortex expansion machine with a peripheral-lateral channel and ability to change the geometric parameters of its flowing part was created to meet these needs. Experimental studies of the machine were performed on a special stand with air as a working fluid. As a result of the tests, the data were successfully obtained and processed. They are presented in the form of tables and graphical dependencies. The nature of the influence of thermodynamic parameters and geometric parameters of the flow part on the efficiency of the vortex expansion machine and turbogenerator based on it to further improve and create new turbogenerators is clarified.

scholarly journals Theoretical and Experimental Studies of the Temperature Difference at the Inlet and Outlet of a Pump as a Function of Time and Pressure

2021 ◽  
Vol 285 ◽  
pp. 07013
Author(s):  
M. N. Kostomakhin ◽  
I. M. Makarkin ◽  
N. A. Petrischev
Keyword(s):  
Temperature Difference ◽  
Experimental Studies ◽  
Variable Pressure ◽  
Working Fluid ◽  
Pressure Curve ◽  
Difference Curve ◽  
Gear Pumps

In the article, the characteristics of the function of temperature difference of a working fluid at the inlet and outlet of gear pumps with different efficiency and at different pressures are theoretically and experimentally investigated. A method is proposed for determining the efficiency of pumps during its operation at variable pressure, based on the hypothesis that the performed useful work of the pump is characterized by the area under the pressure curve, and the lost energy is the area under the temperature difference curve.

Heat Pump-Organic Rankine Cycle Hybrid Systems for Co/Tri-Generation Applications: A State-of-the-Art Overview

2020 ◽  
Author(s):  
Wahiba Yaïci ◽  
Evgueniy Entchev ◽  
Pouyan Talebizadeh Sardari ◽  
Michela Longo
Keyword(s):  
Hybrid Systems ◽  
Control Strategies ◽  
Current System ◽  
Experimental Studies ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Economic Feasibility ◽  
Working Fluid ◽  
Future Research ◽  
Component Level

Abstract The following paper aims to explore a heat pump’s (HP) as well as an organic Rankine cycle’s (ORC) novel combination for the development of both an efficient and low-emissions heating and cooling systems. This latest review examines both benefits and possibilities of a combined HP-ORC system. Previously, studies have explored several different combinations, such as directly-coupled and reversible combination units as well as parallel configurations units in addition to indirectly-coupled ones. Following defining aforementioned configurations, a discussion on their performance is carried out in detail. Considerations for the optimisation of the architecture, overall of such hybrid systems via utilising the same sources while also discussing heat source, sink selection and operating temperatures as well as thermal energy storage, expander/compressor units, control strategies in addition to working fluids’ selection and managing seasonal temperatures that are increasingly variable, have been identified. Additionally, the experimental studies that have been performed reveal increasingly practical obstacles as well as other areas that require more research while serving to shed light on experimental techniques, which can be applicable to this research’s area. Based upon research, it has been revealed that regional conditions including temperatures and annual weather as well as the cost of energy produce a colossal effect on such systems’ economic feasibility framework as well as partially dictating the overall system configuration’s selection. Additionally, the review disclosed how important the following elements are: 1) a greater temperature differential amid the source of heat and heat sink; 2) proper source of heat and sink selection; 3) working fluid selection; and 4) thermal storage for the maintenance of the difference. Comparatively, from the research works from the past, additional optimisation based on individual component level as well as through control strategies of either an advanced or predictive method, these produce a smaller effect and are worth performing an evaluation on economically due to them not being feasible for the current system. Lastly, based on investigated research, there are certain areas for which recommendation have been provided with regard to future research and this includes a technology configurations’ comparison for understanding different regions’ optimal system, a sensitivity analysis for understanding key system elements for both optimisation as well as design, both an investigation as well as testing carried out for available units and applicable systems that are presently available, and identifying novel use cases.

scholarly journals First-Principles Study of AlPO4-H3, a Hydrated Aluminophosphate Zeotype Containing Two Different Types of Adsorbed Water Molecules

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 922 ◽  
Author(s):  
Michael Fischer
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Pore Space ◽  
Experimental Studies ◽  
Adsorbed Water ◽  
Working Fluid ◽  
Water Molecules ◽  
Small Pore ◽  
Experimental Crystal ◽  
Heat Transformation

Porous aluminophosphate zeotypes (AlPOs) are promising materials for heat transformation applications using water as a working fluid. Two “types” of adsorbed water molecules can be distinguished in hydrated AlPOs: Water molecules adsorbed in the direct proximity of framework aluminium atoms form bonds to these Al atoms, with the coordination number of Al increasing from four to five or six. The remaining water molecules that are adsorbed in other parts of the accessible pore space are not strongly bonded to any framework atom, they interact with their environment exclusively through hydrogen bonds. The APC-type small-pore aluminophosphate AlPO4-H3 contains both types of H2O molecules. In the present work, this prototypical hydrated AlPO is studied using dispersion-corrected density functional theory (DFT) calculations. After validating the computations against experimental crystal structure and Raman spectroscopy data, three interrelated aspects are addressed: First, calculations for various partially hydrated models are used to establish that such partially hydrated phases are not thermodynamically stable, as the interaction with the adsorbed water molecules is distinctly weaker than in fully hydrated AlPO4-H3. Second, IR and Raman spectra are computed and compared to those of the dehydrated analogue AlPO4-C, leading to the identification of a few “fingerprint” modes that could be used as indicators for the presence of Al-coordinated water molecules. Finally, DFT-based molecular dynamics calculations are employed to study the dynamics of the adsorbed water molecules. All in all, this in-depth computational study of AlPO4-H3 contributes to the fundamental understanding of hydrated AlPOs, and should therefore provide valuable information for future computational and experimental studies of these systems.

scholarly journals Automatic Circulation Control of Working Fluid in Liquid Droplet Radiator

2012 ◽  
Vol 10 (ists28) ◽  
pp. Pf_1-Pf_8
Author(s):  
Tsuyoshi TOTANI ◽  
Takuhiro TAKEKOSHI ◽  
Masashi WAKITA ◽  
Harunori NAGATA
Keyword(s):  
Liquid Droplet ◽  
Working Fluid ◽  
Circulation Control

Constructal Placement of Discrete Heat Sources With Different Lengths in Vertical Ducts Under Natural and Mixed Convection

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Bugra Sarper ◽  
Mehmet Saglam ◽  
Orhan Aydin
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Hot Spot ◽  
Experimental Studies ◽  
Vertical Channel ◽  
Working Fluid ◽  
Heat Sources ◽  
Ansys Fluent ◽  
Cooling Performance ◽  
Spot Temperature

In this study, convective heat transfer in a discretely heated parallel-plate vertical channel which simulates an IC package is investigated experimentally and numerically. Both natural and mixed convection cases are considered. The primary focus of the study is on determining optimum relative lengths of the heat sources in order to reduce the hot spot temperature and to maximize heat transfer from the sources to air. Various values of the length ratio and the modified Grashof number (for the natural convection case)/the Richardson number (for the mixed convection case) are examined. Conductive and radiative heat transfer is included in the analysis while air is used as the working fluid. Surface temperatures of the heat sources and the channel walls are measured in the experimental study. The numerical studies are performed using a commercial CFD code, ANSYS fluent. The variations of surface temperature, hot spot temperature, Nusselt number, and global conductance of the system are obtained for varying values of the working parameters. From the experimental studies, it is showed that the use of identical heat sources reduces the overall cooling performance both in natural and mixed convection. However, relatively decreasing heat sources lengths provides better cooling performance.

Effect of Thin Film Condensation on Thermal Performance of Oscillating Heat Pipes

2006 ◽  
Author(s):  
S. B. Liang ◽  
G. P. Xu
Keyword(s):  
Thin Film ◽  
Liquid Film ◽  
Heat Pipe ◽  
Heat Transport ◽  
Slug Flow ◽  
Thin Liquid Film ◽  
Experimental Studies ◽  
Heat Pipes ◽  
Film Condensation ◽  
Working Fluid

Self-sustainable motions of the slug flow in oscillating heat pipes have been investigated in the paper. Thin film condensation in the capillary channels of the condenser of the oscillating heat pipes was studied. Instability of the thin liquid film on the characteristics of heat pipes was analysed. The extra thermal resistance caused by the thickness of the thin liquid film was taken into account for the numerical simulation of the oscillatory motions of the slug flow in the heat pipes. Saturated temperatures and pressures of the working fluid in the condenser were obtained. Thermoacoustic theory was applied to calculate heat transport through the adiabatic section of the heat pipes. Experimental studies were carried out to understand the heat transfer behaviours of heat pipes. One heat pipe with the working fluid of HFC-134a was evaluated. The heat pipe is made of aluminium plate and has the width of 50 mm and thickness of 1.9 mm. Numerical and experimental results relevant to the heat transport capability of the heat pipe were analysed and compared.

A Review on Desiccant Coated Heat Exchangers

2016 ◽  
Author(s):  
Asadullah Saeed ◽  
Ali Al-Alili
Keyword(s):  
Heat Exchangers ◽  
Energy Savings ◽  
Fixed Bed ◽  
Experimental Studies ◽  
Cooling Water ◽  
System Level ◽  
Working Fluid ◽  
Component Level ◽  
Potential Applications ◽  
Desiccant Material

Fixed bed and rotatory desiccant systems have been widely studied and used for dehumidification; they suffer from decreasing sorption capacity as the desiccant’s temperature increases due to the released heat of adsorption. The desiccant coated heat exchangers (DCHX) overcome this limitation. Such heat exchangers are able to deliver combined heat and mass transfer between the process air and the working fluid. The process air can be cooled and dehumidified simultaneously by pumping cooling water/refrigerant in the DCHX. The DCHX has to be heated cyclically to regenerate the desiccant material. This paper presents a review on the studies conducted on air-to-liquid DCHX. It summarizes various modeling approaches used to simulate the performance of DCHX as well as the experimental studies conducted to validate these models. It also reviews the current and potential applications of these heat exchangers. Current work in this field consists of experiments conducted on the DCHX as standalone equipment (i.e. component level) as well as an integrated component into cooling and dehumidification systems (system level). The integration of the DCHX in such systems was found to improve the COP, leading to energy savings.

Experimental Studies on the Gas-Stack Heat Transfer in a Thermoacoustic Refrigeration System

2003 ◽  
Author(s):  
Phani R. Gurijala ◽  
Emmanuel C. Nsofor
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Experimental Studies ◽  
Heat Losses ◽  
Inert Gases ◽  
Working Fluid ◽  
Sound Waves ◽  
Thermoplastic Material ◽  
Pressure Transducers ◽  
Thermoacoustic Refrigeration

Thermoacoustic refrigeration employs inert gases as the working fluid and uses high intensity sound waves to pump heat energy. The major components of the system are the resonator, the acoustic driver, the heat exchangers and the stack. The useful thermoacoustic process for cooling in the system takes place between the gas particles and the stack. The system was designed and constructed. Experimental studies on the gas-stack heat transport and the Streaming Reynolds Number, which play crucial roles in the heat transport behavior, were studied. Input signals for the experiments, for the data acquisition system was from thermocouples and pressure transducers. Results from the study were used to make recommendations for the system. It was observed that for a given frequency, the heat transfer increases with drive ratio. Results from the comparison of the heat losses for a stainless steel stack and a stack built of thermoplastic material show that the plate heat losses can be significantly reduced if the stack with thermoplastic material is used for the system.

scholarly journals РЕКОМЕНДАЦИИ ПО ПРОЕКТИРОВАНИЮ ГИДРОСТАТОДИНАМИЧЕСКИХ ПОДШИПНИКОВ СКОЛЬЖЕНИЯ СДВОЕННОГО ТИПА

2020 ◽  
pp. 100-105
Author(s):  
Владимир Иосифович Назин
Keyword(s):  
Dynamic Characteristics ◽  
Fluid Layer ◽  
High Reliability ◽  
Experimental Studies ◽  
Working Fluid ◽  
Stable Operation ◽  
Static And Dynamic Characteristics ◽  
Start Up ◽  
Bearing Materials

The task is to develop recommendations for the design of dual-type hydrostatodynamic plain bearings based on the existing experience in designing this type of plain bearings, as well as based on many theoretical and experimental studies performed by the author of this work. The number of the most necessary parameters for the design of dual-type hydrostatodynamic bearings is determined. Particular attention was paid to the development of recommendations for additional parameters specific to the design of double type plain bearings. Attention is paid to the selection of double-type bearing materials and it is shown that the problem of selecting materials for hydrostatic dynamic bearings is not so relevant, however, sometimes in start-up and shutdown modes, as well as in emergencies, to ensure high reliability of the designed machine, it is necessary to pay attention to the choice of bearing materials. The influence of various forms of chambers on the static and dynamic characteristics of hydrostatodynamic bearings is analyzed and it is shown that the greatest distribution in practice, they got rectangular cameras. It is shown that the flow regime of the working fluid also significantly affects both the static and dynamic characteristics of the bearing. It is noted that even with a non-rotating rotor in a hydrostatodynamic bearing, the most turbulent mode of flow of the working fluid is most often observed. The influence of the thickness of the working fluid layer on increasing the rigidity of the supports and expanding the range of stable operation is considered. It is shown that with a decrease in the clearance in the bearing, its bearing capacity increases and the range of stable operation expands, however, this increases the friction power loss, increases the likelihood of clogging of the slit bearing path, and also increases the requirements for the quality of manufacture of the bearing working surfaces. It is recommended that in the double hydrostatodynamic bearing in the outer and inner parts to assign the same clearances. It is shown that in a dual hydrostatodinamic bearing, the existing recommendation on the number of chambers can lead in some cases to large working fluid flow.

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