scholarly journals Development of geothermal binary-cycle working-fluid properties: information and analysis of cycles. Final report

1981 ◽  
Author(s):  
K.E. Starling ◽  
Z.I. Malik ◽  
C.T. Chu



1978 ◽  
Author(s):  
K.E. Starling ◽  
H.H. West ◽  
C.T. Chu ◽  
J. Milani ◽  
T. Merrill


1979 ◽  
Author(s):  
Kenneth E. Starling ◽  
K.Z. Iqbal ◽  
Z.I. Malik ◽  
C.T. Chu ◽  
S. Ramaswamy ◽  
...  


1981 ◽  
Author(s):  
K.E. Starling ◽  
K.H. Kumar ◽  
Z.I. Malik ◽  
B. Batson ◽  
P. Plumb


2017 ◽  
Vol 39 (1) ◽  
pp. 263-273
Author(s):  
Ankit Khare ◽  
Uma Shankar Pande ◽  
Mrinmoy Majumder


Author(s):  
Xia Li ◽  
Qun Chen ◽  
Xi Chen

Due to the peculiar physical properties, supercritical carbon dioxide (sCO2) is considered as a promising working fluid in power generation cycles with high reliability, simple structure and great efficiency. Compared with the general thermal systems, the variable properties of sCO2 make the system models obtained by the traditional modelling method more complex. Besides, the pressure distribution in the system will affect the distribution of the fluid properties, the fluid properties influencing the heat transfer process will produce an impact on the temperature distribution which will in turn affect the pressure distribution through the mass flow characteristics of all components. This contribution introduces the entransy-based power flow method to analyze and optimize a recompression sCO2 power generation system under specific boundary conditions. About the heat exchanger, by subdividing the heat transfer area into several segment, the fluid properties in each segment are considered constant. Combining the entransy dissipation thermal resistance of each segment and the energy conservation of each fluid in each segment offers the governing equations for the whole heat transfer process without any intermediate segment temperatures, based on which the power flow diagram of the overall heat transfer process is constructed. Meanwhile, the pressure drops are constrained by the mass flow characteristics of each component, and the inlet and outlet temperatures of compressors and turbines are constrained by the isentropic process constraints and the isentropic efficiencies. Combining the governing equations for the heat exchangers and the constraints for turbine and the compressors, the whole system is modeled by sequential modular method. Based on this newly developed model, applying the genetic algorithm offers the maximum thermal efficiency of the system and the corresponding optimal operating variables, such as the mass flow rate of the working fluid in the cycle, the heat capacity rate of the cold source and the recompression mass fraction under the given heat source. Furthermore, the optimization of the system under different boundary conditions is conducted to study its influence on the optimal mass flow rate of the working fluid, the heat capacity of the cold source and the maximum system thermal efficiency. The results proposes some useful design suggestions to get better performance of the recompression supercritical carbon dioxide power generation system.



2021 ◽  
Vol 2119 (1) ◽  
pp. 012088
Author(s):  
A. A. Litvintceva ◽  
N. I. Volkov ◽  
N. I. Vorogushina ◽  
V. A. Moskovskikh ◽  
V. V. Cheverda

Abstract Heat pipes are a good solution for temperature stabilization, for example, of microelectronics, because these kinds of systems are without any moving parts. Experimental research of the effect of operating parameters on the heat transfer in a cylindrical heat pipe has been conducted. The effect of the working fluid properties and the porous layer thickness on the heat flux and temperature difference in the heat pipe has been investigated. The temperature field of the heat pipe has been investigated using the IR-camera and K-type thermocouples. The data obtained by IR-camera and K-type thermocouples have been compared. It is demonstrated the power transferred from the evaporator to the condenser is a linear function of the temperature difference between them.



Author(s):  
Vishal Sethi ◽  
Fulvio Diara ◽  
Sina Atabak ◽  
Anthony Jackson ◽  
Arjun Bala ◽  
...  

This paper describes the structure of an advanced fluid thermodynamic model which has been developed for a novel advanced gas turbine simulation environment called PROOSIS. PROOSIS (PRopulsion Object Oriented SImulation Software) is part of the VIVACE-ECP (Value Improvement through a Virtual Aeronautical Collaborative Enterprise - European Cycle Programme) project. The main objective of the paper is to determine a way to achieve an accurate, robust and reliable fluid model. The results obtained demonstrate that accurate modeling of the working fluid is essential to avoid convergence problems of the thermodynamic functions thereby increasing the accuracy of calculated fluid properties. Additionally, the impact of accurately modeling fuel thermodynamic properties, at the point of the injection, is discussed.



Author(s):  
Scott S. Wujek ◽  
Predrag S. Hrnjak ◽  
Christopher J. Seeton

Refrigeration and air-conditioning (AC) systems employ refrigerant as the working fluid; however, a portion of oil is discharged from the compressor as part of the compression process and also circulates through the system. This small amount of parasitic fluid causes heat transfer and pressure drop correlations that were developed for pure refrigerant flow to fail and needs to be determined for proper design of heat exchange equipment and connection piping. It is desired to be able to measure the small concentrations of oil circulating as a component of the working fluid online in real time. The oil in circulation as a fraction of the total fluid flow rate is termed the oil circulation rate or oil circulation ratio (OCR). The goal of this study was to determine which combination of fluid property measurements could be used to accurately and precisely quantify OCR. Oil, which is needed to lubricate the compressor, is carried with the refrigerant throughout the system. Oil affects fluid properties such as enthalpy, thermal conductivity, and viscosity and can impact the ability to accurately measure heat exchanger and system performance. Fluid property and flow maps have been developed for various refrigerant-oil mixtures; in combination with these maps the ability to accurately measure OCR online may prove to be a powerful tool in quickly measuring, analyzing, and improving system performance. Without this ability to accurately measure the oil circulation rate over the range of operating conditions, it is impossible to create accurate thermodynamic balances based entirely on the properties of the refrigerant portion of the working fluid. The refrigerant-lubricant mixture selected for this study is a commonly used mixture for automotive AC systems: R134a with ND-8 oil. In a typical air conditioner, utilizing R134a with ND-8, a single phase exists only in subcooled portions of the condenser and the liquid line. Therefore, the experiments were conducted at typical automotive AC conditions between 20 °C and 45 °C, pressures ranging from the saturation pressure up to 1900 kPa, and an OCR between 0% and 12%, and a fixed mass flux of nominally 300 kg/m2s. For a single phase fluid comprised of two components, it is necessary to measure three independent fluid properties to completely describe its state. Since the temperature and pressure are easily obtainable, additional readily available properties to determine the liquid composition were selected: density, ultra-violet light absorptivity, and refractive index. The accuracy and precision of calculating the OCR with these measurements are compared analytically and experimentally. The experimental apparatus was located within an environmental chamber which was capable of controlling the temperature over the range of test conditions. The working fluid was circulated using an oil free gear pump and the pressure of the mixture was controlled via a hydraulic cylinder which was attached to a variable pressure source. Precise quantities of oil were incorporated into the working fluid with a high pressure liquid chromatography pump. A length of clear nylon tubing permitted flow visualization.



1998 ◽  
Author(s):  
Jerzy Motylewski ◽  
Bogdan Wislicki ◽  
Kazimierz Krawczyk


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